A Journey Through the Midwest in Photographs and Words
Daniel P. Shepardson
A Journey Through the Midwest in Photographs and Words
Daniel P. Shepardson
Dedication For my family who over the years have endured many hikes as I photographed nature. To my parents, Mary and Phil, who instilled in me an appreciation for all places wild. To my sister, Laura, who waited patiently on many hikes as I took my time to create a number of the images in this book. And to Susan Britsch, a good friend, colleague, and companion, who provided suggestions and edits for formatting and writing this book, and who critiqued some of the images shown here. Finally, for all of nature's beautiful places that I have explored and photographed in the process of producing this book.
Nature First Publishing ÂŠ2012 Daniel P. Shepardson ISBN 978-0-9884158-0-5
Contents Introduction 5 Weathered and Eroded Lands 9 Glacial Landforms 41 River Run 65 Wetlands 101 Prairie Beautiful 145 Into the Woods 191 Locations 239 Bibliography 241
Introduction Visualizing Nature
Visualizing Nature blends image and text as a way of reading nature. It takes the reader on an exploration of natural landscapes found in many local places in the Midwest.
In Chapter 3, “River Run,” readers are invited to experience the fluvial processes associated with rivers and the landforms and landscapes they create through the erosion, transportation, and deposition of sediments. This takes readers on a voyage along the river, from source to mouth, past waterfalls and sand bars.
As the reader’s eye moves from page to page, images of nature are complemented by explanatory text. These are meant to merge in a way that gives meaning to nature, the ability to see and read not only the image but also nature itself. Each chapter aims to help readers visualize the importance of local, natural places, perhaps inspiring a reading of natural places that are more local to the readers’ own context.
In Chapter 4 “Wetlands,” readers explore the hydrologic and ecological importance of wetlands that were formed along rivers or by glaciers past. Readers learn how such places mitigate flooding, filter pollutants from runoff, store water, and provide critical habitats for waterfowl and wildlife.
I have organized this book around today’s rivers, wetlands, prairies and woods and the shaping of these landscapes by natural forces of the past.
In Chapter 5 “Prairie Beautiful,” readers traverse the open and rolling terrain of the prairie landscape. Covered with a sea of grasses, flowers or forbs, and the occasional tree and shrub, prairies give the sense of a boundless and limitless landscape awash with both brilliant and subtle colors.
Chapter 1, “Weathered and Eroded Land,” addresses the geological processes of uplift, weathering and erosion, and mass wasting as these contour natural landscapes. Chapter 2, “Glacial Landforms,” explores the marks left by glaciers past eroding rock and depositing rock as fascinating landforms that influence today’s rivers, wetlands, prairies and woodlands.
Chapter 6, “Into the Woods,” takes readers on a hike through the seasonal landscapes of the deciduous forest. The journey starts with the great bloom of the spring wildflowers, followed by the summer ferns and fungi, then the brilliant
colors of fall that give way to a wonderland of snow and ice.
behavior of pelicans as they court. When I frame the subject and set the exposure, I create a representation that gives nature additional meaning through the image itself. The story is always there for me to relive by rereading the image.
The photographs in this book reflect my many experiences with nature, my efforts to capture its beauty, its power, and its mystique. I have had the privilege of reading many natural landscapes, explored during different seasons, different weather events, and different times of day. I have walked river channels, climbed sand dunes, hiked both woods and prairies, and waded into wetlands. I have trekked to the bottom of canyons and to the tops of mountains and glaciers. I attempt to convey a similar experience to readers through the images and text in the chapters that follow.
I hope this work inspires readers to explore their own local natural places, to capture nature with a camera, and to share their representations of nature with others.
I present this book not only as a legacy to the natural places I have visited, the events I have experienced, and the scenes I have seen, but also to inspire readers to appreciate the precious few natural places that remain. For me, the joy of photographing nature is divided into two parts. First, the hike in nature--experiencing its beauty, its wildness, and its freedom of place--is rewarding in its own right. The next reward is capturing nature through the lens, the immersion in natural light as I wait for a cloud to pass, or the
The author (Photo courtesy of Susan Britsch)
Chapter 1 Weathered and Eroded Lands
To the human eye, the land often appears to change very little over time. Yet the Earth constantly undergoes dramatic change over geologic time. The land shifts, rises, tilts, and subsides, more in some regions than in others. Some regions are built as others are worn down. The geologic evidence of the forces that shape the Earth surrounds us. The landscapes we see today have taken millions of years to form; they are products of the Earth's forces of tectonic uplift and weathering and erosion. These opposing forces continue to create distinctive landscapes throughout the land.
see how the landscape was shaped in the past and we can imagine how weathering and erosion may sculpt and contour it in the future. Weathering and erosion are opposite sides of the same coin. Weathering breaks down rock while erosion transports and deposits earth materials. Weathering drives erosion, for without rock fragments or sediments to be transported there would be no erosion or deposition. Wind, water, ice (including past glaciers), and gravity are agents of erosion. These transport the sediments produced from the weathering of rock. As the sediments are transported, they are further reduced in size and are eventually deposited in layers. This deposition takes place when the agents of transport lose kinetic energy and no longer have sufficient force to overcome the weight and friction of the sediment being transported. Deposition, then, is the geological process of adding earth material, sediments, to a landscape.
The Great Lakes, the flowing rivers, the gentle rolling hills of the grasslands, the wetlands and lakes of the woods and prairies, and even the woodlands themselves were shaped by the forces of the Earth. If we take a closer look, at the land, we can read its clues and begin to see how the Earth's forces have shaped the landscapes we see today. Exposed limestone might suggest that the area was once under water, covered by a sea or ocean. A coal bed may provide evidence of an ancient swamp; a layer of gypsum could indicate that a body of salt water once covered the land. A deep sandstone canyon hints at the work of glacial meltwater and water erosion. Thus, we can
The rate at which the land is weathered and eroded depends upon the climate, geology, topography, and biology of the region. Climate determines the frequency and severity of the wind and water forces exerted on the land.
Geology includes the type of rock exposed to the forces of weathering and erosion, their hardness or resistance to weathering and erosion. Topography determines the gradient or slope of the land and its drainage pattern, the flow of water over the land. Biology, primarily vegetation or the lack of, determines how well soils are bound together by plant roots.
tectonically active regions. Similarly, precipitation can affect weathering as well; in drier regions, rates of weathering are slower than in wetter regions and landforms are more angular.
Many factors affect the rate and extent of erosion. Regions with more frequent precipitation and storm events tend to experience more weathering and erosion because more water runs off the land. Soils high in sand or silt content are more easily eroded than soils high in clay. Landscapes with steep slopes erode more easily than more level plains. The porosity and permeability of the soil affects the rate at which rain or snowmelt percolates into the ground and how much water it can hold, affecting surface runoff. More surface runoff tends to result in more erosion. Softer rock is more easily weathered and eroded than harder rock; this differential rate of weathering and erosion leads to cliff, bluff, and canyon formation. In addition, landscapes in more stable regions weather and erode more slowly than landscapes in more
Sedimentary rocks are formed from the weathering and erosion of rock. As rock disintegrates into small fragments or sediments of clay, silt, sand, and gravel, these sediments are transported by wind, water, and glaciers. At last, they are deposited in loose, unconsolidated layers. Over time, these buried sediments are cemented and compacted (lithified) into sedimentary rock. The "stacking" of different sediment layers forms a bedding sequence. Bedding is the formation of a sedimentary layer based on the composition and depositional pattern of the deposited sediment. The photograph shows two sedimentary rock layers (beds) that have been exposed as a result of glacial meltwater and stream erosion. The lower, or oldest, bed is made of siltstone and the upper bed is sandstone. The bedding sequence tells a story about the geological processes and environmental conditions, at the time of deposition. The siltstone most likely formed from silt deposited in an ancient river delta. Over millions of years the sea retreated and the land was eroded. The sandstone suggests that an ancient river then flowed over the land, depositing sand on top of the silt.
Cross bedding is the deposition of sediments at an angle or incline that results in a tilted layer or strata known as a cross-bed. Cross bedding occurs in fluid flowing (water or wind) depositional environments, such as rivers or beaches (sand dunes). Here, an ancient river deposited sand in a delta slope (the bottom tilted layer) and, over time, deposited sand on top of the tilted layer (the top horizontal layer). Uplift and erosion bring the rock layers to the surface, exposing the rock to chemical and physical weathering.
Rocks are weathered through physical and chemical processes. Physical weathering breaks down rock through direct contact with water, wind, ice and pressure, disintegrating the rock into fragments, grains, and particles with no chemical change. Chemical weathering, on the other hand, involves the disintegration of rock through changes in the chemical composition of the rock, dissolving and oxidizing rock material. Water is the principle erosive agent here, starting as rain or snow. Flowing water then transports sediments, downhill, following the path of least resistance. This erodes the land with an abrasive force, cutting the rock. Over geologic time, this flowing water erodes softer, less resistant rock to form bluffs, cliffs, and canyons.
Glacial meltwater initially carved this canyon in sandstone. Over time, rain and snowmelt will continue to erode the canyon until it reaches base level, the elevation at which the water no longer flows downhill. Many scenic sandstone and limestone landforms were carved in this way, by glacial meltwater, and are further eroded today by rain and snowmelt.
Water percolating through sandstone drips from an overhang, forming stalactite-like columns of white mineral precipitate. Because of naturally occurring carbon dioxide in the atmosphere, rain is slightly acidic. This carbonic acid further weathers rocks and minerals that are carried by water until they precipitate out. Because of the moist environment, moss grows on the white precipitate.
Water percolating through this sandstone leaches out minerals, which are exposed to air and oxidized, creating colorful tapestries. The tan and yellow hues are contributed by a blend of quartz and feldspar, while the reds and browns result from the presence of iron. Greens and blues derive from lichens and mosses that have taken up residence on the rock. All rocks have zones of weakness along which they crack, or fracture. The joints or cracks in this sandstone show that the zones of weakness lie along the bedding plain formed by the layering of sediments. Uplift and erosion bring the rocks to the surface, which opens the fractures to expose the rock to chemical and physical weathering.
A sinkhole is a natural depression in the land's surface. Sinkholes form in karst environments where the bedrock consists of carbonate rock, such as limestone. Slightly acidic rain water or snowmelt percolates through the soil to the underlying limestone bedrock, where it chemically dissolves the limestone. As more and more of the limestone is dissolved a void forms and the ground sinks filling the void. This forms a soil-lined bowl on the surface. Sinkholes vary in their depth and diameter. Over time, trees and other plants grow in and along the sides of the bowl.
Occasionally a sinkhole may collapse, revealing a cavern or subterranean river. In karst landscapes flowing groundwater dissolves the limestone or carbonate bedrock along fractures in the rock or along the bedding plane. As time passes the groundwater dissolves more and more of the limestone, enlarging the fracture, creating a cavern and an underground drainage system, eventually forming a subterranean river. As water percolates through the cavern karts features are formed: stalagmites and stalactites. The overburden may also be deposited as sediment on the floor of the cavern. Karst environments provide important habitat for unique organisms such as the blind cave fish, an endangered species, and bats, which are susceptible to white nose syndrome.
We do not often think of ice as a change agent, yet in seasonal climates where moisture is available and temperatures fluctuate above and below freezing, the freeze-thaw process breaks down rock. This frost wedging is an extremely efficient process for weathering rock. Moisture that seeps into rock cracks and fractures expands when it freezes. This force pushes outward, creating a wedge and eventually cracking and fracturing the rock. This repeated freeze-thaw cycle splits rock along joints so that blocks of rock detach and fall due to the pull of gravityâ€”mass wasting.
As snowmelt percolates through sandstone and limestone bluffs or cliffs, freezing and thawing, icicles form that fracture the rock. In spring, the ice will melt and the water will flow, dissolving the rock, and carrying it to the canyon floor in a gush and a splatter.
Rocks are also physically weathered through the process of exfoliation. Because of temperature changes, rock expands and contracts unevenly. This causes flat sheets of rock to fracture and detach from a cliff or bluff, forming an uneven rock surface. The purplish color is due to manganese found in the rock.
Frost wedging has weathered this sandstone to grains of sand that have been deposited at the base of the bluff. Humans have also had a role in physically weathering the sandstone by carving the rock, further exposing it to the chemical actions of air and water. Finally, gravity has pulled down sandstone boulders that were weakened by the freeze-thaw cycle to the base of the bluff, forming a talus.
Biological weathering involves both physical and chemical processes. Lichens and mosses that grow on rocks create moist, humid environments that chemically weather the rock. At the same time, their attachment to the rock physically disintegrates the rock. Trees, shrubs, and ferns take root along ledges and fractures in the rock. As their roots enlarge, they exert an outward force, expanding the fracture and further cracking the rock. The roots also furnish a pathway through which moisture infiltrates the rock and chemically weathers it from the inside out. Plants play an important role in forming soil by weathering rock.
Wind transports soil and sand, sculpting the land. Sand dunes form where large deposits of sand accumulate in deserts and along the shores of Lake Michigan and Lake Superior. Here, the force of the wind relentlessly picks up and transports the sand inland to build sand dunes. The dunes themselves are ever moving and changing, burying trees and other plants in their path. The shifting sand eventually lead to the demise of these trees. Buried alive and later uncovered, they serve as an eternal testament to the force of the wind.
Chapter 2 Glacial Landforms
Today, glaciers are found only in high latitude and high elevations, yet during the Pleistocene (about two million years ago) they covered northern North America, extending as far south as St. Louis. During this time period, four different continental glaciers advanced, retreated, and stagnated on the land. These Nebraskan, Kansan, Illinoisan, and Wisconsinan glaciers actually created much of today's landscapes.
down the rock. This created the fine-grained sediment known as rock flour. As the glaciers continued to flow forward, they gouged out the land. They stripped Canada of its bedrock and deposited it in the United States. This left shallow depressions that filled with glacial meltwater, forming Canada's many lakes. At the same time, much of Canada was left barren and rocky. This denuded land barley supports vegetation today.
During the Pleistocene the climate was much colder then today, which allowed snow and ice to accumulate over long periods of time, giving rise to mile-thick ice sheets or continental glaciers. As snow accumulated, it compacted to form granular ice. As more snow fell on top of the granular ice it was further compacted and cemented to form dense glacial ice. The pressure of the accumulated snow and ice caused the basil ice to melt. This meltwater served as a lubricant, causing the glacier to flow downhill. As the glaciers flowed over the land, they eroded it through abrasion. The weight of the flowing glacier fractured the bedrock and lifted blocks of rock up into the ice, where they became part of the glacier. Both the ice and the plucked rocks then exerted an abrasive force on the bedrock, like sandpaper grinding
As the climate warmed, the glaciers stagnated and retreated, leaving behind striking landforms such as kettles, moraines, drumlins, kames, and eskers, as well as lakes and wetlands. In mountainous terrain, they created stunning Ushaped valleys and cirques. Earth materials ranging in size from pebbles to boulders were also deposited as the glaciers melted. These glacial erratics consisted of igneous (e.g., granite, basalt) and metamorphic (e.g., gneiss) rocks transported from Canada. These are considered glacial erratics because they differ from the sedimentary rocks that make up the local Midwest landscape. As the meltwater flowed downhill away from the glacier, it also transported the eroded clay, silt, sand, and gravel, later depositing them as
till to form outwash plains. As the till dried, the fine sediments were further transported by winds and deposited as loess, a rich loamy soil that gave us the Corn Belt in the Midwest.
eventually reaches the oceans and ocean levels rise accordingly. On the other hand, during cold periods glaciers expand as water evaporates from the oceans and is deposited and stored on the glaciers as snow and ice. As a result, less water returns to the oceans and ocean levels fall. In this way, glaciers and oceans are linked by the hydrologic cycle. A changing climate affects both glaciers and oceans.
The glaciers also altered the hydrology of the land. They changed the course of rivers; they formed new rivers from glacial meltwater; they created lakes, wetlands, and the prairie potholes. Prior to the Pleistocene, Midwestern rivers drained northward; neither the Missouri and Mississippi Rivers drain as they do today. The glaciers redirected these rivers to drain south while huge amounts of glacial meltwater flowed south to create new rivers or to deepen others. The Illinois and Wabash River valleys, for example, were altered by the glacial meltwater, as was the gorge of the upper Mississippi River. Niagara Falls and the course of the Ohio River are products of the last glaciation. As the last glacier retreated, the meltwater filled the basin it carved, forming the Great Lakes. Glaciers are also indicators of climate change. During prolonged periods of global cooling, glaciers expand as snow and ice accumulate. As global temperatures rise, glacial snow and ice melt faster than they accumulate so that glaciers contract or retreat. The meltwater
The initial advance of glaciers was followed by a period of stagnation during which the stationary glaciers began to melt and retreat. This released tremendous amounts of meltwater. As a result, great outwash rivers flowed from the glaciers. The huge amounts of glacial meltwater cut deep into the bedrock, eroding the land into the narrow, steep-walled canyons and vertical bluffs we see today. This exposed the layers of sandstone formed from ancient sediments deposited in a shallow sea millions of years ago. These picturesque sandstone and limestone canyons and bluffs offer exceptional scenic and botanical qualities that have been preserved in many state parks and local nature areas. The red is from iron that was leached from the rock.
The images taken in summer and winter are of a bowl, an ancient pothole carved into the sandstone by rock fragments swirling in glacial meltwater. Today, rain and snowmelt running off the land continue to erode the canyon deeper, taking the path of least resistance. The flowing water will continue to erode the canyon until it reaches base level, the elevation at which the water no longer flows downhill.
Drumlins--glacial landforms formed from till deposited by earlier glaciers--create a rolling, linear hill topography. A landscape covered in prairie grasses and forbes, and hills topped with trees. Drumlins formed under glaciers, oriented in the direction that paralleled the glaciers movement. Most drumlins were formed during the Wisconsin glaciation.
Glacial kames protrude upward from the prairie-covered outwash plain. Kames are small shaped hills formed when streams running on top of the glacier deposited their sediment in depressions on the glacier's surface or at the edge of the glacier. When the glacier melted, the mass of sediment was deposited on the land as a small hill. Kames often consist of assorted gravels. The kame in the lower image was once mined for sand and gravel.
Eskers are winding, snake-like mounds-- glacial landforms formed by the deposition of sand and gravel--in rivers that once flowed under glaciers. The top image presents a panoramic view that shows the esker rising upward from the level plain. The bottom left image presents a view from the top of the esker while the image at bottom right view is from the north slope of the esker. Eskers create microhabitats. The north slope is a Sugar Maple woods and the south slop is an OakHickory woods.
Lake Defiance is an aging kettle lake. Kettle lakes were formed when advancing glaciers buried blocks of ice in sediment. As the glacier melted and retreated, the ice blocks that were left behind melted, and this caused the sediment to subside. This resulted in depressions that then filled with water to create the kettle lake. As kettle lakes age they transform into wetlands. Most natural lakes, ponds, and wetlands found throughout the Midwest were formed by glaciers in this way. Note the tree-covered ridge that surrounds and slopes downwards toward the lake. This sloping ridge is a key indicator of a kettle. Also notice the rolling hills or glacial moraines-kames--deposited next to the lake.
The last of the great glaciers, the Wisconsin Glacier, melted and retreated some 15,000 years ago leaving its mark on the land and giving rise to Lake Michigan. As the glacier melted, it formed a large lake that shrank in stages over time. This left a series of sand dunes that ring the southeastern edge of Lake Michigan. These still mark the shoreline of the shrinking ancient lake. Today these ancient sand dunes are covered with vegetation and are exposed through erosion. The glaciers also deposited seeds such as Arctic Bearberry and Jack Pine that survive today. This series of sand dunes creates a natural botanical garden, as plant succession occurs. Marram grass grows on new dunes along with cottonwoods. As the dunes stabilize and organic matter or humus increases, Jack pines take root. Older sand dunes are covered by an oak-hickory woods. Note the smog over the lake likely from Gary Indiana and Chicago Illinois.
These boulders of granite, basalt, and gneiss were transported in and on glaciers and deposited by glacial meltwater. They are considered erratics because they are different from the local sedimentary rocks. Eroded rock and sediment may be transported hundreds of miles before it is deposited as till.
In mountainous terrain, snow and ice accumulated on the mountain tops to form tongues of ice. These slowly flowed outward and downhill, creating impressive glacial landforms such as cirques, horns, U-shaped valleys, and hanging valleys. All of these are seen in the image. The accumulation of snow and ice on the head of the glacier eroded the mountain to form a cirque. This amphitheaterlike basin curves downward toward the valley floor. When alpine glaciers form on different sides of a mountain peak, they erode the peak into a pyramid-shaped horn. As alpine glaciers flow down mountain valleys, they erode the valley wider and deeper, creating U-shaped valleys with steep upper walls that grade to a flat valley floor. Hanging valleys form when tributary glaciers of different size merge as they advanced downhill. The larger glacier erodes a deeper valley than the smaller glacier. As the glaciers melt and retreat the smaller or hanging valley is left sitting high above the deeper valley. This differential rate of erosion creates spectacular waterfalls.
This image of the curved cirque of Grinnell Glacier comes from Glacier National Park. Cirques are eroded landforms carved in mountain peaks by alpine glaciers. The ice and snow is all that remains of a once mighty glacier that flowed down the mountain valley. Today, because of a changing climate, snow and ice no longer accumulate and the glacier slowly melts and retreats. The melted snow and ice fills the cirque to create a mountain lake (Frozen in this photo). It is estimated that Grinnell Glacier will be completely melted by 2020. Most glaciers in Glacier National Park are predicted to melt away by 2030.
Chapter 3 River Run
Although glaciers shaped the land in the past, rivers now work as the chief geologic agent that contours the land. Rivers slowly but surely carve the land, wear it away, and create spectacular river valleys, bluffs, canyons, and floodplains as well as sand bars and waterfalls.
to meander. Finally, all rivers transport earth materials. The geologic processes associated with rivers and the deposits and landforms created by them are called fluvial—pertaining to a river. Fluvial processes involve the erosion of earth materials, the transport of sediments, and the deposition of sediments. Sediments are loose earth materials that range in size from clay to silt to sand to gravel to pebbles to cobbles to boulders. They are formed from the weathering of rock.
Rivers come in all sorts of ever changing shapes and sizes. Although no two rivers are alike, they all have common characteristics. In order to transport the water, the channel must slope downwards so that gravity causes the water in the channel to flow. Rivers always follow the easiest, least resistant path downhill, and as they flow, they erode their channels.
Geologically, younger rivers tend to have steeper gradients, greater flow, and fewer tributaries. They also tend to erode the channel more deeply rather than widening it. The Yellowstone River in Yellowstone National Park is an example of a younger river. More mature rivers tend to have lower gradients, slower flow, and many tributaries that give them greater discharge and sediment loads. In contrast to younger rivers, mature rivers tend to widen the channel instead of deepening it. The Mississippi River is an example of a mature river.
Rivers erode downward until they reach base level, the lowest point (elevation) to which they can flow. This may be the level at which the river merges with another river, empties into a lake or reaches an ocean—the ultimate base level. A river with a high headwater relative to its base level will have a high gradient and will down cut due to the energy of the rapidly flowing water. Over a long geologic time frame, a river erodes the high points, reducing the difference between its source and base level and lowering the gradient. As the gradient lowers, the river’s velocity slows and it deposits more sediments and begins to cut laterally and
A river’s journey ends at its mouth, where it empties into another river, a lake, or the ocean.
At its mouth the river reaches its base level. Here, the river slows and its sediments are deposited. The deposition of sediments in a lake or ocean often forms a delta, where large sediments settle out first and smaller sediments are deposited last.
creates a "riparian zone," an important transition between the land and the river that provides a number of essential ecological and environmental services.
We do not often think of rivers as part of the hydrologic cycle, yet rivers serve as a link between the atmosphere, the land, and the oceans. A riverâ€™s existence is dependent upon the hydrologic cycle to circulate its water. This involves processes such as evaporation, precipitation, and infiltration, as well as the storage of water in rivers, lakes, oceans, and the ground. The cycle is driven by the sunâ€™s energy, which causes land and water to warm and lose water to the atmosphere through evaporation. The sun also draws water from plants through evapotranspiration. Once in the atmosphere, the water is circulated around the Earth by moving air. As the air cools, the water condenses to form clouds that eventually deposit the water on the land and oceans as rain, snow, or sleet. Water that falls on the land either percolates into the ground or runs off into a river. Rivers are naturally bordered by trees, shrubs, and grasses. This adjacent plant community
A river's journey starts at its headwaters or source, where water either springs forth from the ground or runs off the land. This forms a small, channeled watercourse that erodes the land and transports earth materials. The linking of watercourses forms a river system, a network that crisscrosses the land collecting water, earth materials, and other substances that run off the land and are transported downriver.
A river constantly picks up and deposits earth materials and rock fragments from its channel bed. When flow is fast, more earth materials and rock fragments are picked up but less is deposited. When flow is slow, more is deposited than picked up. The flow velocity along with the size and type of earth material determine when and where erosion and deposition start and stop along the river. Larger earth materials, such as boulders, are transported downriver based on seasonal highflow rates. Heavy spring rains and snowmelt cause faster high-flows as more water drains from the land. This leads to bank erosion and perhaps even to flooding. As the riverbank erodes it exposes tree roots. As this process continues, less soil is available to support the surrounding trees and they eventually fall into the river as a result of mass wasting. Dry summer weather causes slow low-flows because little water drains from the land, resulting in less erosion. Notice the glacial erraticsâ€”igneous and metamorphic cobbles and boulders.
A riverâ€™s flow is influenced by precipitation events and by the seasons, changes linked to climate as well as the hydrologic cycle, the form and amount of precipitation. Heavy spring rains and snowmelt cause faster high-flows as more water drains from the land. Turbulence results from channel roughness and high-flow after a storm event. The brownish color of the water in this image comes from the increased sediment load caused by storm runoff.
Rivers constantly change themselves and the shape of the land through hydraulic action and abrasion. Hydraulic action--the erosive force exerted by flowing water itself--cuts at the channel, particularly during periods of high flow. Abrasion occurs where earth materials, such as sand, or rock fragments carried by the river strike the channel bed. In so doing, they chisel or chip off earth materials or rock fragments that are then transported downriver as sediment load, adding to the abrasive force of the flowing water. This cuts the channel deeper and wider. Rock fragments swirling in eddies or small whirlpools may further scrape and grind away the channel bedrock, forming potholes. Simultaneously, the rock fragments are ground down, becoming smaller, smoother, and more rounded in a process known as attrition.
Some exposed rock layers are more easily eroded than others. As water flows, it cuts a channel into the least resistant rock. In landscapes where rivers flow rapidly downward this creates erosional landforms such as Vshaped canyons. The V-shaped profile forms because the river erodes the channel downward at a faster rate than the lateral erosion of the canyon walls from runoff and frost wedging. In this image the differential rate of erosion forms a series of rock steps called a cascade falls.
When rivers encounter bedrock that is weaker and more susceptible to erosion, they wear away the rock at a more rapid rate than they would erode more resistant bedrock. This differential rate of erosion results in an outcropping of harder bedrock, called the "knickpoint:" a steep and vertical drop that the water flows over, forming a waterfall. Over time, the waterfall erodes the knickpoint upriver, eventually smoothing the riverâ€™s grade. As the waterfall recedes back upriver, it forms a canyon downriver. As the water flows over the outcropping, the resistant cap rock is eroded and collapses to add blocks of rock at the base of the waterfall. These blocks of rock are then broken down into smaller boulders that are weathered and eroded downriver.
Waterfalls take many forms. Cascades form when the river descends in a series of rock steps. In contrast, a cataract is a single vertical drop in the channel. Cataracts can be either small waterfalls or large and powerful ones where the water descends vertically for hundreds of feet and loses contact with the bedrock. A plunge pool often forms at the base of large cataracts. If the falling water maintains contact with the bedrock and spreads horizontally as it descends, it is known as a fan waterfall. If the water is constricted as it falls and then spreads out at the base to form a pool, it is known as a punchbowl falls. For some, there is nothing more emotionally stirring than falling water. The sight and sound of cascading water can be visually and auditorally pleasing or calming.
Rivers contain rapids and riffles. Rapids and riffles form where the upriver channel bed is more resistant to the erosive force of the river in comparison with the channel bed downriver. This creates a gradient. The channel bed is also covered with gravel, pebbles, cobbles, and boulders that creates turbulence. The rocky channel bed churns air, oxygen, into the water, producing a white color (“whitewater”). The difference between a rapids and a riffle lies in the gradient of the channel. A rapids has a steeper channel, creating greater velocity. A riffle’s channel bed consists of smaller rocks— gravel and stones—resulting in less turbulence. Riffles, however, provide an important habitat for macroinvertebreates (aquatic arthropods, including insect larva and nymphs) that serve as a food source for fish and other aquatic organisms.
Sand, mud, and gravel bars may develop where river velocity slows and sediment deposition occurs. This results in localized shallowing of the river. When flow is low, mid-channel bars of sand, mud, and gravel may form. This forces the river to take the path of least resistance and flow around the bar. Over time, the river may erode the channel downward around the bar. Alternatively, additional sediment may be deposited on the bar elevating the bar above the river. If high flow events occur, the bar may be completely eroded away and washed downriver. If the bar remains in place for a period of time, grasses, shrubs and thickets may grow there.
As a riverâ€™s gradient lowers and its velocity slows, the river tends to meander, bending and looping to form a sinuous course. A meander is formed when the river cuts the bank along the outside of a bend, widening it outward. At the same time, sediments are deposited on the inside of the meander because the water flowing near the channel bed pushes the sediments across the channel bed where they are deposited. They fill the inside curve of the river, and this builds a point bar of sorted sedimentsâ€”sand, mud, and gravel. The ongoing outside bank erosion and inside sediment deposition gives the river its snaking pattern. Meanders tend to grow outward during high-flow seasons because of extreme storm events.
As rivers meander, they change course and erode a new channel into the land. The old channel bed is then left behind as a basin, its sloping banks as the only evidence of its existence.
An oxbow lake is formed when a meandering river cuts a new channel and leaves the old channel to form a narrow U-shaped lake. Because the lake is curved, it resembles an oxen yoke, thus its name. Oxbow lakes form as the hydraulic action and abrasion of a meandering river erodes the bank creating a curved channel. As bank erosion continues, the river curves back onto itself forming a new straighter channel. The original channel or meander loop is abandoned to form a cutoff: the old river channel. Eventually, the deposition of sediments seals the cutoff and the oxbow lake is formed in the old meandering river channel. This process may require a few years or several decades, depending on the flow regime of the river.
A unique property of water is that as it freezes it expands and becomes a solid, ice. Because liquid water is more dense than ice, ice floats. Absent this property, rivers might freeze from the bottom up, which would kill bottom dwelling plants and animals. The ice also allows sunlight to pass through for algal growth while protecting aquatic organisms from extreme weather conditions. As spring approaches, and temperatures warm, the ice breaks up and may form "packs," or ice drifts. Winds and river currents move the ice drifts and may cause them to pile up. Ice may be transparent or opaque or bluish-white in color. The bluish color is a result of light being refracted and reflected by the ice. The color also depends upon the presence of impurities and air bubbles. Sediments may color the ice, giving it a brownish rust color, or even a green or gray hue.
As the land flattens, floodplains form adjacent to the river. During times of high water, or at flood stage, a river overflows its bank and inundates the land surrounding the river, depositing layers of sedimentâ€”clay, silt, sandâ€” on the floodplain. These unconsolidated sediments accumulate, gradually building up the floodplain. The flooding river also deposits sediments on its bank, forming a ridge or natural levee. Over time, the high water flow may erode the floodplain back, forming a terrace. Geologically, old floodplains may sit above the present floodplain, revealing the former course of the river, and forming multiple terraces.
The vegetation adjacent to a river creates a plant community or a "riparian zone," an important transition between the land and the river. The vegetation stabilizes the land and the bank as the plant roots bind soil. This reduces soil erosion, filters fertilizers, pollutants and sediments from surface runoff, protecting water quality. It also provides wildlife habitat and corridors that increase biodiversity and enable organisms to move along the river system. Overhanging trees shade and cool the river. Because cooler water holds more oxygen, the river can support a more diverse aquatic community. In addition, the plant litter and insects that fall into the water can serve as a food source for aquatic organisms.
Ecologically, rivers serve as pathways for seasonally migrating waterfowl and shorebirds. The river provides water, food, and cover that birds require during their migration to and from their wintering and spring breeding grounds. These migrating American White Pelicans are resting along the Illinois River.
Chapter 4 Wetlands
When many people think about wetlands images of "scary places," "mosquitoes," or "dumping grounds" mistakenly fill their minds. Wetlands are critical environments that serve both ecological and hydrological purposes. They make vital links between the land and water, necessary for plant and animal life. Water that flows from the land is often stored in wetlands; for this reason, wetlands provide critical habitat for wildlife.
lilies and pondweeds. Areas with water-logged soils but less standing water are dominated by sedges and grasses to form wet meadows. Different to marshes, bogs form in poorly drained areas with highly acidic water. These conditions slow plant decomposition and result in a buildup of peat (plant material) that often floats as a mat on the surface of the water. Plants, such as sphagnum moss, orchids, and even Larch and Tamarack trees, root and grow on this floating mat. Unlike bogs, fens form in soil saturated with surface water and/or groundwater that is alkaline in nature. Finally, swamps form in wooded areas where standing water remains most of the year. This wetland type is dominated by woody plants like Silver and Red Maple, Buttonbush, willows, cottonwoods, and Bald Cypress.
"Wetlands" is an all encompassing term for marshes, bogs, swamps, fens, and other areas that are saturated with standing water. Technically wetlands consist of hydric soils, soils that are different from those found in dry, upland areas. Wetlands are also dominated by hydrophytes--plants adapted to grow in fluctuating water levels, such as cattails and sedges. Water, then, is the primary factor that defines a wetland and that influences the plant and animal life associated with it.
The variety or richness of the plants and animals, and their numbers or abundance is what makes wetlands so productive. Many different animal species rely on wetlands for all or part of their lifecycle. Without wetlands, wood ducks, muskrat, cattails, and countless other species would not survive or even exist today. Wetlands provide many wading and waterfowl bird species with food, water and shelter during migration.
Because marshes form in areas where water stands, soft-stemmed herbaceous plants, known as emergents, grow here. The stems of emergent plants, such as cattails and arrowheads, grow partially in and partially out of the water. In deeper marshes, floating and submerged aquatic plants grow, such as water
Wetlands also serve a variety of hydrologic purposes. They intercept surface runoff, collecting and filtering the water. This reduces flooding because the stored water is slowly released or seeps into the groundwater, recharging it. Additionally, the stored water is filtered of nutrients, pollutants, and sediments as it percolates into the ground or is absorbed by plant roots, and this provides clean drinking water.
Wetlands also formed along rivers, in the floodplain (as described in Chapter 3), on the margins of ponds and lakes, and in bottomlands where water seeped from hillsides. This created unique ecological systems, each dominated by different species of plants and animals. Although wetlands are hydrologically and ecologically important, they also contribute to the aesthetics of our environment as a natural part of our heritage. Evening sunsets and early morning sunrises create majestic landscapes. Great Egrets hunting for fish and Mallards diving for food provide spectacular sights of survival. Great Blue Herons roosting and nesting on dead trees stir emotions. The hovering and matting of dragonflies and damselflies draw our attention. There is beauty in wetlands if we take the time to see it.
Wetlands have been greatly impacted by humans over the years, often because their ecological and hydrological functions were misunderstood. Today, fewer than half of our original wetlands remain. Drained for agricultural purposes or due to urban sprawl and development. Countless other wetlands have been ecologically and hydrologically degraded as a result of nutrient and sediment runoff, or air and water pollutants. In the Midwest, most of our natural wetlands originated as the Pleistocene glaciers advanced, stagnated, and retreated some two million years ago. This glacial process gouged the land, forming depressions that filled with glacial meltwater (as described in Chapter 2). This gave rise to prairie potholes, marshes in the woodlands and grasslands, and the Great Lakes.
Wetlands play an important role in the hydrologic cycle. They temporarily store water, reducing floods and recharging groundwater. The stored water is evaporated and resupplies the atmosphere with water. As rain and snowmelt run off the land, wetlands trap and filter the runoff, "purifying" the water. The cattails, duckweed, algae, and other aquatic plants in the wetlands in this photograph absorb the nutrients that run off the land, improving water quality. The nutrient runoff increases the growth of aquatic plants that, in turn, provides food to herbivores, cattails for muskrats, and duckweed for Mallards and other ducks.
The plants and animals of wetlands interact in complex and dynamic ways to form food chains and food webs. Wetlands are unique in that they often have two basic food chains: a grazing food chain where energy is directly transferred from plants to herbivores and a detrital food chain where energy is transferred from the dead leaves and stems of plants to living organisms. The dead leaves, stems, twigs, and branches that fall into the water are decomposed by bacteria, aquatic worms, and insects. Decomposition releases nutrients that are absorbed by wetland plants and used for growth. Dead plant material in the water also breaks down to detritus that provides food for aquatic insects, snails, clams, and small fish. These serve as a food source to larger predators--large fish, reptiles, amphibians, birds, and mammals. In this way, matter is cycled and energy is transferred through the ecosystem.
Wetland plants have adapted to grow in saturated soil that provides little oxygen to their roots. Herbaceous plants, like cattails and reeds, have developed an extensive cellular network between their leaves and roots that transports oxygen through the plant. In contrast, woody plants (like trees and shrubs) either grow roots filled with air or form small openings (lenticels) on their bark that allows more air to enter. Cattails are common perennial plants of shallow water wetlands. They spread from creeping rootstocks to form dense stands that die-back every fall. Cattails provide critical habitat for red-winged blackbirds and muskrats. Red-winged Blackbirds are commonly found perched on the cattails singing to claim their territory and attract mates. Muskrats feed extensively on cattails. Native American and early European settlers used cattails as a food source, grinding the rootstocks into meal and boiling the immature flower spikes into cobs.
Cattails, sedges, reeds, and lily pads are sure signs of a marsh. Marshes vary in their water level, ranging from six inches to three feet, and some even dry up during periods of drought. Deep water marshes exhibit three zones or types of plants: emergents, floaters, and submergents. Emergents are plants that grow both in and above the water, such as cattails, Water Plantain, Arrow Arum, sedges and rushes. These are found in the shallower waters of the marsh. As the water deepens, floating plants appear, such as water lilies rooted in the muck with their leaves floating on the surface. Other plants such as Duckweed routinely float on the surface. Submergent plants grow in the deepest water. These plants, like milfoils, pondweeds, and Elodea, grow in the water column.
The Green Heron, a stocky bird, is small in size and stature when compared to its distant cousins, the stately Great Blue Heron and the majestic Great Egret. Yet this small wading bird is unique in its hunt for prey. While the Great Blue Heron and the Great Egret often wade knee-deep while pursuing their prey, the Green Heron stalks its prey from tree branches, logs, and stumps next to or in the water, almost as if it preferred to hunt without getting its feet wet. The hunt is a necessity of life and has a purposeâ€”in this case the survival of the Green Heron. The Green Heron hunts the frog. The frog hunts the dragonfly. The dragonfly hunts the fly, and so on. Predator and prey, a tangled web of life and death. Although many wetland bird populations have increased because of protective measures, the Green Heron is one of the few wetland bird populations that continues to decline.
Like the Great Blue Heron, the Great Egret is a wader. As a group, waders stand in the water or perch on logs searching for prey. This Great Egret waits without movement in knee-deep water looking for fish and frogs. The spear-like bill functions like tweezers, more for grasping instead of spearing. Great Egrets often perch in trees in colonies. The Great Egret population was decimated in the early 1900s for its plumage. Today, its population has recovered due to conservation efforts as well as wetlands protection and restoration.
Perhaps the most ecologically important aspect of marshes is their function as a refuge for the breeding, nesting, and wintering habitat of waterfowl and wading birds. Like the Great Egret, this Great Blue Heron, nests and perches on dead trees in colonies. Herons build bulky stick nests where the female lays three to six eggs, raising one brood each year. Both parents feed the young by regurgitating food. Great Blue Herons are the largest of the wading birds in North America and they feed on crustaceans, vertebrates and small mammals. Their call, or croak, is loud and harsh. They are most vocal during breeding and defense of their territory. Like most waders, they migrate southward during the fall as the water freezes over.
A gregarious species, Mallards form pairs to breed. As it swims about a wetland, the drake, or male, makes a high-pitched whistle; the hen, or female, returns a deep quacking sound. In terms of feeding, Mallards are "dabblers." They feed by tipping their tails upward and submerging their heads to consume the aquatic plants and animals that lie near or at the bottom of the marsh. Unlike Mallards, other ducks, such as the Canvasback, are "divers." They feed in deeper water, diving in search of aquatic plants and animals. Diving ducks have shorter legs than dabblers, located further back on their bodies. This allows them to better dive and swim underwater.
Perhaps the most common and familiar waterbird in the American Midwest is the American Coot. The coot is a rail, a waterbird that has a laterally compressed body with a short tail and wings. The coot also has strong legs with long slender toes that allow them to easily move through dense vegetation or to walk on floating vegetation. Unlike most rails, which are secretive and elusive, coots congregate in large flocks and may be seen swimming, diving for submerged vegetation, standing on one leg, or wading along the shoreline. They are often seen swimming and feeding with other ducks. To take flight, they must run a great distance along the surface of the water into the wind; this allows them to achieve sufficient lift to fly.
Marshes are also home to the muskrat, a mammal. The muskrat is a semi-aquatic rodent native to North America. Its name is derived from the "musky" odor it emits from scent glands near its tail. This odor marks its territory. Muskrats prefer wetlands, but may also be found along rivers, ponds, and lakes. They feed primarily on cattails and aquatic vegetation, and this consumption creates open areas in the marsh for aquatic birds. Muskrats live in family groups, building lodges of cattails and other vegetation and mud. The lodge protrudes upward from the water and protects the family from the elements and predators. Like most rodents, muskrats give birth to several litters each year, raising six to eight young in each litter. They often follow trails that they forge in the marsh. During the winter, when the water freezes, muskrats swim under the ice, following these trails.
The marsh is also home to many reptiles-snakes and turtles. Painted turtles, like the one in this image, are the most abundant turtle species in the Midwest. They can often be seen sunning themselves on logs. They rely on the warmth of the sun to raise the body temperature, and are active only during the day. At night they sleep lying on the bottom of the marsh. During winter they hibernate by digging into the muddy bottom of the marsh. The painted turtle eats aquatic vegetation, aquatic insects, crustaceans, and small fish. They struggle to survive, as their eggs are often eaten by skunks, squirrels, raccoons, coyotes, birds, and snakes. Hatchlings are frequently preyed upon by fish, herons, bullfrogs, and snakes. Adult painted turtles, however, are protected from most predators by their hard shells, and may live up to 50 years. Painted turtles may mate twice a year--spring and autumn. The female digs a nest on land close to the water, laying approximately eight eggs. After laying her eggs, she returns to the water, leaving the nest unprotected from predators.
Amphibians, frogs, toads, and salamanders, are cold-blooded animals common to wetlands. The life cycle of many amphibians involves laying their eggs in the water, hatching waterbreathing juveniles. As they mature, these juveniles often metamorphose into airbreathing adults. Bullfrogs and Green Frogs are common to wetlands; however, many amphibian populations have declined in the past decade and are now threatened or endangered. The decline in amphibian populations is viewed as one of the major threats to biological diversity on our planet. Although water quality, habitat destruction, pollution, climate change, and disease have contributed to this decline, the exact cause is not well understood. Because amphibians are sensitive to changes in the environment, they are considered to be ecological indicators of environmental quality.
A multitude of insects from dragonflies and damselflies to mosquitoes and midges live in marshes and are dependent upon these wetlands for survival. These insects serve as a food source for frogs, salamanders, fish, and birds. As shown in the photograph, insects such as dragonflies lay their eggs on the water's surface where they develop into carnivorous nymphs. They emerge as flying adults that prey on other insects. Although adult dragonflies may be confused with damselflies, the two are distinct. Dragonflies hold their wings open, perpendicular to their bodies while damselflies close their wings above their bodies. Dragonflies also have bigger, thicker bodies than damselflies.
Vernal pools form in shallow depressions where winter snowmelt and spring rains collect or pool. They are temporary pools found in woods and grasslands that dry by summer. Yet, they provide critical habitat for amphibians and aquatic arthropods, including insects. Because they are temporary, shallow pools of water they are void of fish. This makes vernal pools safe breading waters for amphibians. Various frogs, toads, and salamanders visit vernal pools to reproduce, laying their eggs in the standing water, completing their life cycle by summer. Vernal pools also provide habitat for daphnia and fairy shrimp, which serve as a food source for the amphibians. Many vernal pools have been lost over the years to development and agriculture, and tend to be found only on protected lands such as state and national parks and local nature preserves.
Although swamps are often viewed as a Southern phenomenon of slow moving water and cypress trees, the Midwest has its share of hardwood, bottomland swamps. Hardwood bottomland swamps often form near rivers in floodplains and in poorly drained lowlands or depressions where water periodically saturates the soil. The soil is highly organic, forming a thick, black, nutrient-rich environment. Red Maple, Silver Maple, Pin Oak, and American Elm are common trees found in Northern hardwood swamps. Hardwood swamps provide critical habitat for Wood Ducks and other wetland species.
Shrub swamps form where the water is shallower. These consist of shrub-like vegetation such as Buttonbush, Willow, and Dogwood instead of trees. In Buttonbush swamps, the multi-stem growth of the Buttonbush forms a tangled mass of stems and branches. This in conjunction with the canopy gives the swamp a haunting feeling. Buttonbush swamps provide important habitat for turtles, salamanders, and frogs. They also provide exceptional nesting places for wetland bird species.
Skunk cabbages, like those in this photograph, prefer moist soils, woodland bottomlands and river floodplains. These wetlands provide the soft soil the plant needs for root growth. The roots of skunk cabbage contract downwards into the soil, pulling the plant deeper into the mud. This makes older plants nearly impossible to dig up. The foul smell produced from tearing a leaf gives the plant its name. The odor attracts pollinators, flies, stoneflies, and bees. It also discourages animals from eating or digging up the plant. In addition to its foul smell, the skunk cabbage is known for its ability to generate heat, which thaws the frozen soil. This enables the plant to emerge from the ground in early spring.
Fens, like bogs, are peat-forming wetlands but unlike bogs, fens receive nutrients and water from upslope drainage. The movement of water downslope transports and deposits minerals from the upland soils, creating alkaline conditions. This allows for a more diverse flora and fauna community than that found in bogs. Grasses, sedges, rushes and wildflowers cover the land. Blue Flag, the type of iris in this image, is common to both fens and marshes. Because most fens were drained or minded for their peat they are one of the rarest types of wetlands.
Wet meadows resemble grasslands and are often found in poorly drained soils, shallow basins, depressions, and low-lying fields. Most wet meadows lack standing water except during seasonal periods of high water: spring snowmelt and spring rains. Grasses, sedges, rushes, cattails, and a variety of wetland wildflowers grow in the fertile soil. They provide vital habitat for insects, amphibians, reptiles, birds, and mammals. Wet meadows also collect and store runoff and filter nutrients from the water. Prevalent in farming areas, they have historically been drained and filled for agricultural uses.
The marshy areas surrounding lakes and ponds provide important breeding and nesting grounds and resting and feeding grounds for migrating birds. Wetland management and restoration over the years has contributed to improved and thriving populations of wetland birds, such as the American White Pelican, like the two that are courting in this photograph. In breeding pairs, the bills brighten to a deep orange-red, as do the legs and feet.
Chapter 5 Prairie Beautiful
Not all grasslands are prairies, but all prairies are grasslands. Prairie means "meadow" and "grassland" in French, thus the name bestowed by early French explorers. Prairie landscapes consist of rolling terrain covered in a sea of grasses and dotted with forbs (wildflowers), other herbaceous plants (non-woody), and the occasional tree and shrub. This contributes to the sense of boundless space that characterizes prairie landscapes. Landscapes with both brilliant and subtle colors, these are nonetheless harsh environments with hot and dry summers and cold winters with bitter winds.
the trees for water and soil nutrients and blanketing the land with grasses. Next, the Pleistocene glaciers deposited sediments, till, shaping the land and leaving behind the fertile soil required by the prairie grasses and forbs. As the glaciers retreated, the forests returned along the rivers that flowed from the melting glaciers. The rivers eroded the prairie landscape, cutting downward, and creating floodplains (as discussed in Chapter 3). This created shaded slopes and wet soils that allowed the trees to outcompete the grasses. As a result, elms, cottonwoods, ashes, maples and other trees took root. Prairie wildfires kept the forests from encroaching further into the grass lands.
The prairies of the Midwest originated in the uplift of the Rocky Mountains and the advance of the Pleistocene glaciers (as described in Chapter 2). As the Rocky Mountains began pushing upwards some 65 million years ago, the land eastward was covered in trees. A vast forest stretched across the flat, stable interior platform of the continent. As the peaks of the Rockies grew ever taller, they created a rain shadow effect; in other words, a drier climate that caused the forests to die out and the grasses to flourish. Over time the grasses evolved and spread eastward, out-competing
Just as the grasses transformed the land, animals, too, evolved. Mammals developed teeth for grinding grasses; their long legs and hoofed feet made for easier movement across the prairie; their chambered stomachs better digested the grasses. The prairie also became home to burrowing animals--Prairie dogs, ground squirrels, gophers, and Burrowing Owls--as well as burrowing predators--weasels, ferrets, foxes, and badgers.
Traveling west toward the Rockies, the climate becomes drier and the grasses grow shorter. The prairie shifts from a tallgrass prairie to a mixed grass prairie to a shortgrass prairie, due in part to a decreasing moisture gradient. Grasslands can take hold in regions that receive between 10 and 39 inches of precipitation annually. The deep and massive root structure of most prairie grasses and forbs allow them to reach and extract water deep within the soil. This enables prairie plants to survive in dry climates and weather drought conditions better than trees and other plants.
Cool season grasses grow during the spring and fall when temperatures are cooler and more precipitation occurs. Tall Fescue, Kentucky Blue Grass, and Timothy are types of coolseason grasses. Warm-season grasses grow best during hot summer temperatures. Big and Little Bluestem, Indian Grass, and Switch Grass are warm-season grasses. Although the work of the plow cannot be undone, people today have become interested in the prairie and its conservation and restoration. Efforts across the Midwest have resulted in the protection of remnant prairies and the restoration of former grass lands. Prairie parks have emerged and backyard gardens now bloom with prairie forbs. A balance between agriculture, development, and the prairie will ensure future generations the opportunity to experience the natural community and beauty of the prairie landscape.
Moisture greatly influences the type of prairie community found in a location. Wet prairies are located in depressions or downslope, areas of poor drainage. As a result, the soil is saturated throughout the growing season. Mesic prairies form in areas of good drainage, the soil is fertile and moist during the growing season. In contrast, dry prairies are often found on upland slopes, where water drains quickly, leaving behind dry soil. The temperate grasslands found in the Midwest have seasonal temperatures with warm summers and cold winters. Because of these temperature fluctuations, two types of grasses have evolved: cool and warm season grasses.
The Pleistocene glaciers deposited till to create the gentle rolling hills and downward sloping outwash plains of the prairie. Thus, the retreating glaciers left behind the fertile soil that the prairie grasses and forbs needed to grow. Here, an early spring thunderstorm passes over the tallgrass prairie, resupplying the soil with valuable water that the tall grasses and forbs need to survive. The plant community that makes up a prairie depends upon the interaction between biotic factors (for example plant genetics or grazing) and abiotic factors (water, sunlight, temperature, soil, or fire). Slight variations in these abiotic factors create local gradients in the plant community.
An approaching thunderstorm darkens the sky, casting a shadow on the tallgrass prairie. Over half of the precipitation in the tallgrass prairie falls as rain during the growing season, May to July. A second peak in rain often occurs in September. Hot, humid summers are followed by severe cold and snowy winters. As with all grasslands, the tallgrass prairie experiences extreme variability in precipitation, with hot, scorching summer droughts common. Today, the once expansive tallgrass prairie is one of the rarest biomes found in North America.
The stems of prairie grasses are round and hollow, except where the leaf attaches to the stalk forming a solid joint. Leaves are narrow with parallel veins that are vertically arranged. These leaf characteristics provide for maximum exposure to the sun for photosynthesis, yet reduce the surface area exposed to the evaporative force of the sun and wind. Many prairie grasses send out tillers, or shoots, that form a dense mat or sod. Other grasses grow in bunches forming clumps with space between each plant. Prairie grasses form dense fibrous root systems that bind the soil. This system makes up most of the biomass and may reach a depth twice that of its height. This means that more than half of the biomass is found underground in the root system. The roots store food, extract water from the soil, and help build the soil. Because the growing tissue of the grass is located at the base of the plant, grazing and fire have little impact on the survival of the plant, and may actually stimulate growth.
Grasses are considered to be flowering plants because they produce tiny, inconspicuous flowers that cluster as vertical spikes or branching panicles. The blossoms have capsules instead of petals. These hang downward to enclose the feathery pistil, or female parts (the stigma, style, and ovary) and stamens, or male parts (the anther and filament). The flowers open only once, usually in the morning for less than an hour. Grasses rely on the wind for pollination, so no bees, butterflies, or other insects are needed. The seeds are also dispersed by the wind.
Forbs, or wildflowers, are herbaceous plants that have adapted to survive in the prairie in much the same way as grasses. Although they lack the extensive and massive fibrous root system of grasses, they do produce deep, branching taproots. In addition, their leaves are often leathery and covered with hairs to reduce evaporation and grazing. Many of the forbs are of the composite, or daisylike, flowers and legumes (pealike flowers and seed pods). The yellow flowering Compass Plant is common to mesic prairies that are neither wet nor dry. It grows to a height of eight feet. The irregularly lobed basal leaves tend to point in a northsouth direction, hence its name. It is also a late bloomer, contributing to the late season parade of color exhibited in prairie environments. Black-eyed Susan, Yellow Coneflower, and pale blue Bee Balm (Horsemint) bloom in the shadow of the Compass Plant in the photograph.
The variety of flower colors seen on the prairie derives almost completely from composites (Compositae). Composites are actually a cluster of tiny flowers that form florets or discs surrounded by petals. Many composite flower heads form unique spiral patterns. The center cone of the Purple Coneflower contains the cluster of tiny brownish-orange disc flowers. This rough and prickly dome-shaped cone is surrounded by drooping petal-like rays (ray flowers) ranging from magenta to pale purple. The forb makes a popular herbal tea that is thought to strengthen the immune system and prevent colds.
The Purple Prairie Clover is an example of a legume. It grows in patches throughout the Midwest in native and relict prairies. It prefers soils that are well-drained and dry. The slender and erect stems of the Purple Prairie Clover rise from deep, spreading roots. The flower is not typical of legumes because of its tiny, individual flowers that cluster around a cylindrical cone to form a spike. These flowers first bloom in a ring around the base of the spike and move upwards with the season. Because it is a legume, the Purple Prairie Clover enriches the prairie soil by adding nitrogen. Specialized bacteria live in nodules on its roots. These bacteria convert gaseous nitrogen in the soil to nitrate, a form of nitrogen that may be used by other prairie plants.
The prairie landscape is ever-changing from season to season. As spring approaches and the sun warms the soil, grasses quietly emerge from the ground, dominating the scene and coloring the landscape in hues of green (top image). When May arrives, the first forbs show their colors, beginning a progression in color that continues until frost (bottom image). Wave after wave of color paints the prairie in hues of indigo, lavender, white, purple, magenta, and yellow. Different forbs bloom at different times throughout the spring, summer, and fall. Spring forbs and cool-season grasses complete their life cycles before the tall grasses reach their maximum height. This progression creates a landscape of varying colors and heights. Low growing plants include Purple Prairie Clover and pasque flowers and tall growing forbs include Prairie Dock, Compass Plant, coneflowers, Black-eyed Susan, and Blazing Star. Late flower composites include: sunflowers, goldenrods, coneflowers, and asters.
As fall approaches the summer forbs begin to fade, the grasses brown, and the late summer forbs take their turn, painting the prairie in hues of yellow. The prairie becomes a speckled landscape of greens, browns, and yellows. The heads of sunflowers begin to shrivel and shed their seeds and goldenrods dominate the scene with their bright yellow flowers. Insects flutter from forb to forb collecting the last of the pollen and nectar. Grasshoppers appear and blanket the stems and leaves of the forbs and grasses, feeding in a frenzy before the first frost.
Swaying gracefully in the late summer wind, Prairie Dock stands tall above a field of sunflowers and goldenrods. Prairie Dock sends a naked stalk upward to 10 feet, dividing into panicles of green spherical buds and yellow composite flowers. Its height keeps its yellow flowerheads above the lower growing forbs and grasses, attracting honeybees and bumble bees. Its taproot grows downwards to 12 feet, seeking water and securely anchoring the plant in the ground. Offsets may spread from the taproot but a short distance from the mother plant.
As winter approaches, the prairie grasses and forbs go dormant and the stems and leaves die. The dead stems and leaves are known as â€œstanding dead.â€? This dry plant material now serves as a food source for grazing animals. It also provides organic matter to the soil. Bacteria and other decomposers break down the stems, leaves, and roots of dead prairie plants recycling the nutrients to the soil for use by new plant growth. During winter, the snow and wind often flatten the grasses and forbs. Not until mid-summer do the tall grasses once again reach their maximum height.
The prairie can be a cold and harsh winter environment where bitter winds and snowpack make life a struggle. The prairie appears lifeless and bleak, colored in monochromatic tones of white and gray. Where forest and prairie communities meet they compete for water, light, and soil nutrients. Local variation in light, water, wind, temperature, and soil influence which plant community prospers, as well as which plant species survive. The slope of the land as well as the permeability and waterholding capacity of the soil determine how much water is available to a particular grass or tree. Wind also affects the competition between forest and prairie; the broad leaves of trees give up more moisture through evapotranspiration than do the narrow leaves of grasses. As leaves wilt and die, less food is produced and the tree may die, opening the ground to sunlight and allowing the grasses to take over.
The most common upland prairie tree is the Bur Oak, but in this image, Sycamores thrive in bottomland wet soil next to a stream. This island of trees surrounded by a sea of grasses is growing where the soil is wetter. This wetter soil gives the trees the competitive advantage over grasses. The "extra" water stimulates growth and enables the trees to win the competition for sunlight, eventually shading out the grasses.
On the prairie's edge, where prairie and forest meet, savannas may form. They are a transition zone between the prairie and the broadleaf and mixed forests of the East. The landscape of savannas is dotted with oaks and an understory of grasses, typically Little Bluestem, as well as forbs. These oaks are spaced such that the canopy remains open so that light can reach the understory and support the grasses and forbs. The soil is often dry and fire controls the growth and spread of the trees. Oaks have a higher tolerance for fire than do most tree species, which is why they are the dominate species of the savanna. Black Oak is predominant in sandy soils while Bur Oak prevails in rich soils. In general, prairies have less than 10% tree cover while savannas may have up to 50% tree cover.
Although grasses can grow almost anywhere, they cannot flourish where trees shade the ground. In addition to precipitation, wildfires are essential to maintaining the prairies of the Midwest. Most natural fires occur in the spring before the grasses green or, alternatively, in the fall when the vegetation has died. For this reason, flames do little harm to the grasses, as prairie plants re-grow from the root structure found below the soil surface. Prairie wildfires, however, kill the vascular tissue of trees, killing the tree. Fire not only removes the invading trees and shrubs, but converts dead plant matter (litter) to ash that releases nutrients to the soil. Fire also adds space to the environment, resulting in additional light and water for grass growth. Without wildfires, the trees and shrubs of the woodlands would encroach on the prairie. Their canopy would eventually shade the ground and suppress the growth of the prairie grasses and forbs, outcompeting the grasses for sunlight.
Grasslands provide habitat to many large ungulates (or herbivores) such as bison, elk and white-tailed deer. Wolves, coyotes, and fox also roam, or once roamed, the prairie. Prairie dogs, mice, snakes, birds (quail, hawks, owls, meadowlarks, blackbirds), and a potpourri of insects (including grasshoppers, milkweed beetle and butterflies) live in grasslands.
Unlike grasses, the prairie forbs are dependent upon insects for pollination. The transfer of pollen from the anther to the stigma results in fertilization and the development of seeds, essential to the survival of the forbs. Bees, butterflies, moths, and wasps are the main pollinators, but beetles, flies and other insects also pollinate the prairie forbs. The forbs use odor, bright colored petals, and shape to attract and provide "landing" space for these insects. As the pollinators visit each flower, pollen sticks to their mouths, legs, heads, and abdomens. In this way, it is carried from one flower to another where it sticks to the stigma and cross-pollinates the flowers.
Milkweed is a common forb of the prairie. Its name comes from the white milky alkaloid sap that it produces, which is toxic to many insects, birds, and mammals. Some insects, however, have adapted to live and feed on the plant. The alkaloid makes them toxic to potential predators. Many are brightly colored to warn predators of their toxic taste. Although milkweed beetles (top right) and milkweed bugs (bottom right) inhabit milkweed plants, they occupy different niches. Milkweed beetle larvae overwinter on the roots, and the adults emerge in summer to feed on the leaves and flowers. After mating they lay their eggs on the ground next to the stem of the plant. Adult milkweed bugs overwinter in leaf litter or migrate southward, returning in summer. Clusters of adults and nymphs may be seen sucking sap and nectar from the milkweed; they prefer the seeds. Monarch butterflies often lay a single egg on a milkweed plant. In the image at the top left, a caterpillar feeds on the leaves. In the image at bottom left, aphids use their piercingsucking mouthparts to extract juices from the plant.
Because prairies are rich in forbs that produce large quantities of seeds, many species of birds are attracted to such an environment. Prairie birds are also voracious eaters of insects. Here, a Red-Winged Blackbird perches on a Compass Plant to scan the prairie for flying insects as it sings to claim its territory. Many prairie birds also make use of the grasses to build nests on the ground, but prairie bird populations have declined over the years as the remaining prairies slowly disappear. This loss of habitat due to urban sprawl, the development of wind energy, and the continued expansion of agriculture, has taken its toll.
The introduction of the steel plow by John Deere allowed early Europeans to farm the fertile soils of the prairie. The plowâ€™s steel blade could cut through the massive root structure of the prairie plants, opening the land to agriculture. This fertile land gave rise to the Midwest Corn Belt, a landscape covered in corn and soybeans. Today, the tallgrass prairie landscape has been transformed into an agriculture landscape. Of the original tallgrass prairie, less than 1% still exists in remnant lands along railroads, in cemeteries and other areas not suited for farming.
Prairie restoration restores prairie lands lost to farming and other human development. Because prairie grasses and forbs are more resistant to drought, hot summer temperatures, disease, and native insect pest than other non-native plants, the restoration process works to prevent the erosion of exposed soil. It also benefits butterflies and other native pollinators through the reemergence of flowers. This, in turn, maintains biodiversity and helps to store carbon, reducing atmospheric greenhouse gases. Prairie restoration may take place in an area as large as a state park or it may be confined to a backyard.
Chapter 6 Into the Woods
Although a single oak or maple tree may have individual beauty, oaks and maples are quite impressive when massed to form a forest. Because trees are long-lived, humans often think of forests as serene, timeless, and enduring places. Yet, the deciduous forest undergoes a constant and cyclical change from season to season and year to year. There is a perennial struggle to survive, and a competition for the elements of life.
forest floor. Next, the sub-canopy is composed of suppressed juvenile or immature trees awaiting an opening in the canopy for light, enabling them to grow. The woody shrub layer lies below the sub-canopy and consists of shrubs and seedlings that tolerate shade. These species must also be capable of photosynthesis with limited light. Finally, the lowest and most diverse area is the herbaceous or ground layer (forest floor) consisting of herbs, ferns, fungi, and mosses. The degree to which these layers are developed can depend upon either human or natural disturbance.
The temperate forest is dominated by deciduous or broad-leaved trees that lose their leaves in winter, an understory covered in shrubs and a forest floor painted in annual and perennial herbs (wildflowers) that give the deciduous forest a high species richness. Although the deciduous forest is dominated by oaks, hickories, maples, and beeches, it also contains coniferous trees like pines, cedars, and hemlocks. Many are relics from past glaciers, and survive in unique areas of the forest.
The productivity of the forest is closely linked to decomposition. The forest floor is covered by detritus or decomposing leaves, branches, bark and dead animals that support large numbers of invertebrates, fungi, and bacteria. The litter eventually decomposes and adds humus, or organic matter, to the soil. This furnishes nutrients that the forest plants require for growth. The forest litter also protects the soil from thawing and freezing in the winter, and acts like a mulch during the summer to prevent the soil from drying out.
Looking closely at the forest one can differentiate zones, or layers, determined in part by light. The canopy (or upper zone) consists of the branches and leaves of mature trees. During the summer, most of the sun's light is absorbed by this canopy and only a small fraction of light reaches the understory and
The emergence of spring woodland wildflowers is perhaps one of the most spectacular displays of color in the deciduous forest, equaling the
spring bloom of alpine flowers, the desert bloom following spring rains, and the summer bloom of prairie flowers (described in Chapter 5). As the sun reaches the forest floor, it warms the soil, stimulating the growth of the beauties of the deciduous forest. This window of growth is short-lived; as the leaves of the forest trees gradually unfold, they block more and more of the sunâ€™s rays. This, in turn, blocks the light needed for photosynthesis by the spring wildflowers
The tilt of the Earth as it continues its orbit around the sun results in a decrease in the amount and intensity of the sun's energy. Days become shorter and colder, and rain turns to snow and ice. The forest again changes from a landscape of vibrant color to one of grays and whites. At first glance, all seems lifeless, motionless, and barren. Dormant trees, void of leaves, stand tall and naked. Life slows with the cold winds, but a closer look reveals movement. Squirrels scurry about; birds flutter from tree to tree; and deer roam as they search for food, water and shelter.
By summer, the thickening canopy diminishes the amount of light that reaches the forest floor. Once covered in colorful displays of spring wildflowers, the floor now supports the growth of green shrubs and summer herbs that need less light and display less conspicuous flowers. Mosses and other non-flowering plants: Ferns, fungi, and lichens also make their presence known.
Winter fades slowly, but surely and on cue as the Earth completes its orbit. Then the days lengthen and warm and the forest again transitions in step with the sun's warmth to the blossoms of spring. Cycles of life and earth link as one.
As fall approaches, the deciduous forest once again undergoes a drastic change in color, transitioning from tints and tones of greens to a range of reds and yellows. Because the production of green chlorophyll declines in autumn, the colors of these other leaf pigments are revealed.
Trees in a forest, and even leaves on a tree, compete for sunlight to survive. Through photosynthesis, plants use the sun's energy to convert carbon dioxide and water into organic compounds or carbohydrates (sugars), releasing oxygen as a byproduct. Photosynthesis takes place in chloroplasts, organelles that contain chlorophyll, a green pigment that absorbs the sun's energy. Although any green parts of a plant contain chloroplasts, most of the sun's energy is captured in the plantâ€™s leaves. In temperate regions, broad leaves work as an advantage because the larger surface area absorbs more sunlight.
The composition of the different layers of the forest are determined in part by the relative amount of available light. The canopy, or upper layer, consists of the branches and leaves of mature trees. The shade-tolerant understory consists of tree seedlings and saplings, shrubs, and herbs. Openings in the canopy allow sunlight to reach this understory, creating favorable conditions for photosynthesis and the growth of saplings and immature trees. In this way, the forest regenerates cyclically. The forest floor is covered with detritus, or leaves, branches, and bark. This litter eventually decomposes and adds humus to the soil, providing nutrients that the forest plants need for growth. Fallen logs also decompose, releasing nutrients to the soil for use by other plants, recycling matter through the forest.
Snags are partly or completely dead standing trees, often without branches. Snags provide critical habitat and a source of food for many forest organisms; for example, woodpeckers must have snags for nesting and feeding. This Red-bellied Woodpecker is digging a nesting cavity in a snag at the edge of the forest. Redbellied Woodpeckers depend upon large trees and snags for nesting and will not be found in any abundance in deforested areas. The female lays four or five eggs in a clutch, frequently using the same nesting cavity year after year. Although Red-Bellied Woodpeckers mainly pluck insects and other arthropods from tree trunks and snags, they also consume fruits, nuts, and seeds. Its name is misleading in that its belly is not red, and the prominent red plumage is found on its head.
Nothing is wasted in the forest. Throughout its lifespan a tree uses the sun's energy to produce wood. As the fallen log decomposes, nutrients are released to the soil for use by other plants, recycling matter through the forest. Bark that once protected the tree becomes loosened and spongy, creating an environment for decomposers. In the images at the bottom left and right, fungi sprout. Wood-boring beetles and termites are among the first insects to arrive. They create tunnels that serve as channels through which water and bacteria enter, further rotting the wood. As the wood becomes softer and spongier, more insects and fungi invade--even snails appear and crickets eat at the rotting wood. Carpenter ants tunnel in, creating nesting chambers. Centipedes arrive to prey on insects. Birds, like nuthatches, feed on the insects. As the wood decays, the insect tunnels collapse and the log slowly merges with the soil. This, in turn, provides humus, encouraging the growth of the ferns and wildflowers that appear in the top image.
The forest terrain is far from level. The land was and is shaped by wind, water and ice (as discussed in Chapters 1 and 2). This produces rolling hills, sloping ravines, and deep canyons. This topography results in microclimates, environments with different sun exposures, amounts of soil moisture, and air temperatures. These different environmental, or abiotic, factors support different plant communities. In the deciduous forest, differing microclimates support the growth of hemlocks and other coniferous (evergreen) trees. Hemlock trees, as seen here, are well adapted to grow in shady, moist soil where the summer temperature is cool, such as north-facing ravines and slopes.
The emergence of the spring woodland wildflowers is perhaps one of the most spectacular displays of color in the deciduous forest. Spring wildflowers have adapted to complete their life cycles before the oaks, hickories, maples, and beeches leaf out and block the sun. It is the sun's springtime warming of the soil that stimulates the growth of wildflowers in the deciduous forest. Each species of wildflower has but a brief moment of grandeur. The timing and the species, of course, depends upon local conditions, but the patterns are similar--a delicate dance ensuring that one species fades as another emerges, so that all survive.
A sure sign of spring is the emergence of Spring Beauty and the trilliums that appear in the top left photograph. Bloodroot, seen at the top right, and Dutchman's Breeches, shown in the bottom photograph. Spring Beauties are located in moist woodland areas. Often, they emerge in clearings in large colonies that carpet the forest floor, presenting a spectacular display of color. Three is the key number for trilliums: three leaves, three green sepals, three colored petals, a three-chambered pistil, and three stigmas. In fact, “trillium” is Latin for “three.” Bloodroot is a short-lived flower that displays a single eloquent, but fragile, white flower. It opens in full sunlight and closes at night. Its name is derived from its red root sap. Dutchman’s Breeches are easily identified by their delicate white, pantaloon-shaped flowers on a leafless, pinkish colored stalk protruding above a mass of greenish and deeply divided leaflets. A short lived flower of rich woods, it is pollinated by bumblebees and bees.
The Virginia Bluebells in the top photograph prefer moist woods, bottomlands, and river floodplainsâ€”in other words, wet soils. Rarely found in meadows, they are easily identified by the cluster of nodding trumpet-like bluish flowers that are pinkish in color before blooming. Virginia Bluebells often grow in masses, carpeting the forest floor. As spring progresses, the Wild Geranium shown in the bottom left image and Wild Blue Phlox, in the bottom right image emerge, adding waves of color to the forest floor. Wild Geranium is a leafy herb with showy flowers. The pink-towhite flowers cluster atop deeply toothed and lobed leaves, and bloom from April through June. They provide an impressive display of color when found in patches on the forest floor. Wild Blue Phlox also blooms in rich woods from April to June, and is common in Midwestern woods. Wild Blue Phlox is marked by its beautiful, dense cluster of light blue flowers atop leafy stems. The Phlox Family is found mainly in North America, where the species is grown as an ornamental flower.
Wild Ginger, with its distinctive large, hairy, and heart-shaped leaves, often overshadows its ground level flower. Blooming from April to May, its flower has an odor of rotting meat that attracts flies as pollinators. Ants often carry away the seeds of Wild Ginger, thus distributing the plant to new locations. Although Wild Ginger is found in rich woods, it is unrelated to the tropical spice after which it is named. In fact, it has an acrid taste that discourages plant eaters.
. The Mayapples in the top and left photographs are large herbaceous plants found in rich woods and damp shady clearings. Mayapples produce a solitary, white nodding flower between a pair of large and deeply lobed leaves. Single leafed plants do not produce a flower or a fruit. The name â€œMayappleâ€? comes from the typical May blooming time of the plant. The Shooting Star shown in the bottom right image, has a cluster of nodding flowers with sweptback petals atop a single stalk. The plants flourish in open woods and prairies, preferring well drained soils. Bees are the chief pollinators; however, the Shooting Star is capable of self-pollination. Even so, the herb's abundance has declined since European settlement. The image at bottom left frames a Wild Leek with its wide, elliptical leaves emerging from an underground bulb, usually in April. The leaves yellow and wither by midsummer, leaving a naked stem topped by a starburst-like cluster of white flowers. By late summer, there is no trace of the plantâ€™s existence. Wild Leek, an onion, is a member of the Lily Family, a diverse group ranging from day lilies to asparagus to trilliums.
The presence of these Jack-in-the Pulpits indicate a damp woods or moist environment. The Jack-in-the Pulpit is a member of the Arum Family, a group of erect herbs with fleshy, clubshaped spikes (the spadix) surrounded by a showy, curved bract or â€œpulpitâ€? (or spathe) beneath one or two large, long-stalked leaves. The spathe (flower) is green or purplish in color, fading to yellow; a cluster of shiny red berries develops by summer.
Green Dragon is related to Jack-in-the-Pulpit, producing a single leaf with 7 to 13 leaflets that grow horizontally over the plant. Green Dragon has one long orange-colored spadix-the dragon's tongue--that protrudes about 10 inches beyond the narrow green spathe. In late summer, the green berries turn red and produce only one to three seeds. Like its relative, Green Dragon resides in wet woodlands, but is rare in comparison to Jack-inthe-Pulpit. In Canada, Green Dragon is listed as a vulnerable species.
Once covered in colorful displays of spring wildflowers, the forest floor transforms to a green growth of shrubs and summer herbs in summer. Solomon's Seal, shown in the top image, and False Solomon's Seal, shown in the lower image, spread their leaves to capture the diffuse and sparse sunlight, taking over where the spring beauties left off. Solomon's Seal produces green to white bell-shaped flowers that hang from its arching stem. The berries turn bluish-black in fall. This distinguishes the plant from False Solomon's Seal, which produces a mass of creamy white flowers at the tip of the stem. The berries, initially green, become speckled with red and eventually turn bright red. Both plants may grow to over three feet and are members of the Lily Family.
As the canopy closes, blocking the sun's light, the forest floor is covered with ferns, other herbs, and fungi. A diverse group of plants adapted to grow in a variety of places, ferns prefer moist and shady locations. They can grow as well on rock ledges as they do on tree stumps. Like other vascular plants, ferns have stems, leaves, and roots, but no flowers or seeds. Instead, ferns reproduce via spores; some produce spores on the underside of their leaves while others actually produce separate, spore-bearing leaves. Native ferns lose their leaves in autumn, changing from shades of green to yellows to papery browns.
Fungi such as mushrooms and toadstools are diverse decomposers of the forest floor. They seem to appear from nowhere, often popping up after a warm summer rain. The main part of the fungus, the mycelium, lies underground. The mycelium grows in a tangled mass or web that functions as do the roots, stem, and leaves of plants. Because fungi have no chlorophyll, they cannot produce their own food. Instead, the mycelium absorbs water and nutrients from organic matter in the soil. Thus, fungi obtain their food by extracting nutrients from dead organic matter, in the process decomposing this matter and recycling its nutrients. As the mycelium grows it produces a bud that pushes upward through the soil. A stem forms and the bud unfolds like an umbrella. Gills on the underside of the umbrella release millions of microscopic spores. If the spore lands in a favorable spot, a new fungus will sprout as shown here.
The forest is home to many different insects, including Cicadas. Cicadas are of the order Hemiptera and are often incorrectly called locusts. They fill the warm late summer air with song in an attempt to attract a mate. Cicadas have two prominent eyes with three smaller eyes located in between. They have short antennae that protrude from the head and clear membranous front wings. Adults suck sap from trees and females lay their eggs under the bark. After the eggs hatch, the nymphs emerge and fall to the ground, where they burrow and remain, feeding on root juice, until they emerge years later. The emerging nymphs then climb nearby trees and plants where they molt, shedding their skin, and transforming into adults. The adults mate, lay their eggs, and die. Most cicadas have a two to five-year life cycle, but the red-eyed North American cicada, Magicicada, shown in the image, has a 17-year life cycle.
Box turtles are long-lived, land-dwelling reptiles that prefer moist woods. They are omnivores, and as such, eat a variety of foods, including earthworms, snails, slugs, insects, fruits, berries, mushrooms, flowers and carrion. Box turtles overwinter by digging a den in the ground where they hibernate. Because box turtles mature slowly and produce few offspring, they are highly susceptible to environmental changes and human impact. Although box turtles are not an endangered species, there is concern for their well-being throughout the Midwest, especially in Indiana, Michigan, and Ohio.
As autumn approaches, daylight decreases and temperatures cool. Once again this causes a drastic color change in the deciduous forest. The forest transforms from tints and tones of green to a range of reds and yellows. A green leaf indicates an abundance of chlorophyll that masks the colors of other pigments. By autumn, the production of chlorophyll stops. As a consequence, other leaf pigments can emerge. Carotenoids give the leaf a orangeyellow color. Anthocyanins give the leaf a red to purple color. The anthocyanins are produced during the fall and often combine with the carotenoids to produce deeper yellows and fiery reds.
The tilt of the Earth relative to its orbital plane plays a major role in the seasons. Different latitudes on Earth directly face the sun as the Earth moves through its orbit. When it is winter in the Midwest, the Northern Hemisphere is tilted away from the sun. The lower altitude of the sun causes the sunlight to strike the Earth at an oblique angle. This spreads the sunlight out over a larger surface area, reducing the intensity of the sun's energy. In addition to the shorter days, this results in colder temperatures. Climate is the statistical average of temperature, precipitation, humidity, and wind for a region over long periods of time. Weather, in contrast, is the present condition of these meteorological elements. In temperate climate regions, four seasons are recognized: spring, summer, fall, and winter. Winter is the season with the lowest temperatures. During this time period, precipitation often takes the form of snow in the Midwest. Blizzards occur when heavy snows are blown about by strong winds, reducing visibility to near whiteout conditions, as seen in the image.
In temperate regions, ecologists often recognize six seasons instead of four, adding pre-spring and late-summer seasons. These ecological seasons are based on changes in plant and animal activity, changes in events, or behavioral changes in plants and animals that may be linked to changes in sunlight. For some, like White-Tailed Deer, autumn light signals the start of the rutting season. It is also a time to eat, to increase body fat for survival in the coming winter months. White-Tailed Deer are generalists and eat a large variety of foods including nuts, seeds, and leaves. Their coats turn from a reddish-brown in the spring and summer to a grayish-brown for fall and winter. Today, they are the most abundant hoofed mammal in North America and have become overpopulated in many areas of the Midwest. The loss of natural predators--wolves and cougars--and the cutting of the forests has contributed to their overpopulation.
Gray squirrels remain active during the winter, relying on stored food and seeds buried in the ground or cached in hollow trees. Their tracks are often visible in the snow as the squirrels move back and forth from their nests to their food caches, where they feed. Because snow cover insulates the forest floor, mice, voles, and other small mammals also remain active, feeding on plants and moving about under the blanket of snow. Other animals reduce their energy use during the winter by becoming less active. This, in turn, reduces their need for food and water, which is scarce during winter. Raccoons spend more time sleeping in their dens and are rarely seen during winter. In winter, reptiles, amphibians, and insects take shelter in decaying logs and hollow trees, where they remain dormant until spring warms the air. Many insects reproduce and lay their eggs as fall approaches and then die in winter. Yet other animals migrate to escape the bitter cold. Insect-eating birds like warblers and swallows move south as the temperature drops. Seed-eating birds like waxwings and jays remain, seeking out seeds while woodpeckers and nuthatches work trees, snags, and logs, feeding on insects.
Human, or anthropogenic, factors affect forests. Humans have cleared forest land for farming, urban sprawl, and for timber (logging). Humans have caused fires, acid rain, and introduced invasive species. Natural factors, too, affect forests, including lightning-caused fires, insects, diseases, weather, and competition between trees. Few old-growth forests exist today. Much of the forest today is secondary growth, or the regrowth of forests after the land was cleared by early European settlers. In fact, European settlers cleared 95% of the original deciduous forest. Secondary forests, as shown in the image, tend to have more dense stands where trees are spaced closer together as well as more undergrowth than old-growth forests. Old-growth forests tend to contain larger and older trees, large dead trees or snags, as well as large logs. These environments often provide habitat to rare, threatened, and endangered species of plants and animals.
The images in this book were taken over the years during different seasons and under different weather conditions at the following locations:
Backyard, IN Bliss Woods Forest Preserve, IL Burnett Creek, IN Celery Bog Nature Area, IN Coral Woods Conservation Area, IL Fall Creek Gorge, Nature Conservancy Preserve, IN Freeman Kame-Meagher Forest Preserve, IL Glacial Park Conservation Area, IL Glacier National Park, MT Horticulture Park, IN Indiana Dunes State Park, IN McCormick's Creek State Park, IN Merritt Prairie Forest Preserve, IL Moraine Hills State Park, IL Nachusa Grasslands, Nature Conservancy Preserve, IL Pecatonica Forest Preserve, IL Pine Hills Nature Preserve, IN Portland Arch Nature Preserve, IN Prophetstown State Park, IN Prairie Kame/Sauer Family Forest Preserve, IL
Ross Hills Park and Ross Camp, IN Russell Woods Forest Preserve, IL Rutland Forest Preserve, IL Shabbona Lake State Park, IL Shades State Park, IN Shakamak State Park, IN Spring Mill State Park, IN Starved Rock State Park, IL Tippecanoe River State Park, IN Turkey Run State Park, IN Wildcat Park, IN Yellowstone National Park, WY
Bailey, J. (2004). The Facts On File Dictionary of Ecology and the Environment. Market House Books Ltd.: New York. Bennett, M. R.; Glasser, N.F. (1996). Glacial Geology: Ice Sheets and Landforms. John Wiley & Sons Inc.: New York. Brown, L. (1997). Grasslands. Alfred A. Knopf, Inc.: New York. Easterbrook, D.J. (1999). Surface Processes and Landforms. Prentice-Hall, Inc.: New Jersey. Goudie, A. (2001). The Nature of the Environment. Blackwell Publishers: Oxford, UK. Herbert, P.D.N. & Kundell, J. (2011). River. Encyclopedia of Earth, http://www.eoearth.org. C. J. Cleveland, Ed. Environmental Information Coalition, National Council for Science and the Environment: Washington, D.C. Kaufmann, R.K. & Cleveland, C.J. (2008). Environmental Science. McGraw-Hill: New York. Kerski, J. & Ross, S. (2005). The Environment. Hodder Arnold: London. Miller, G.T. Jr. (2006). Environmental Science. Thomson Learning, Inc.: Belmont, CA. Mitsch, W.J. & Gosselink, J.G. (1993). Wetlands. Van Nostrand Reinhold: New York.
Mitsch, W.J., J.G. Gosselink, C.J. Anderson, and L. Zhang. (2009). Wetland Ecosystems. John Wiley & Sons, Inc.: New York. Montgomery, D. (2008). Dirt: The Erosion of Civilizations. University of California Press: Berkeley, CA. National Geographic (1999). The National Geographic Desk Reference. National Geographic Society: Washington, DC. National Geographic (2006). Complete Birds of North America. National Geographic Society: Washington, D.C. Niering, W.A. (1997). Wetlands. Alfred A. Knopf, Inc.: New York. Ornes, H., Hogan, C.M., & Cleveland, C. (2010). Wetland. Encyclopedia of Earth, http://www.eoearth.org. C. J. Cleveland, Ed. Environmental Information Coalition, National Council for Science and the Environment: Washington, D.C. Pidwirny, M. & Ventura, G. (2006). Weathering. Encyclopedia of Earth, http://www.eoearth.org. C. J. Cleveland, Ed. Environmental Information Coalition, National Council for Science and the Environment: Washington, D.C. Press, F., Siever, R., Grotzinger, J., & Jordan, T.H. (2004). Understanding Earth. W.H. Freeman and Company: New York.
Spencer, E.W. (2003). Earth Science: Understanding Environmental Systems. McGraw-Hill: New York. U.S. Environmental Protection Agency (2011). What are Wetlands? http://water.epa.gov/type/wetlands/what.cfm. U.S. Geological Survey (2011). Earth's Water: Rivers and Streams. http://ga.water.usgs.gov/edu/earthrivers.html.
Visualizing Nature is a nature photography and natural history book about Midwest landscapes
Published on Oct 3, 2012
Visualizing Nature is a nature photography and natural history book about Midwest landscapes