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granite outcrops as models for vertically heterogeneous ecosystems thomas brown + brooks bryant


pages 02 03 - 05 06 - 07 08 - 09 10 - 11 12 - 13 14 - 17 18 19

history+intro outcrop communities concept study area analysis + planning vision design ongoing resources


history + intro

The Southeastern piedmont region of the United States is one of the country’s fastest growing areas, as well as home to unique granite outcrop ecologies. Over the past half-century environmental ignorance, widespread quarrying, and rapid suburbanization have substantially degraded these delicate ecosystems, which serve as one of the world’s oldest, most unique landscapes, fostering a number of endemic plants and remaining a time capsule of evolution. As construction and human intervention damaged these ecosystems, ROOF(ROX) seeks to use those same technologies and practices to rehabilitate them, using urban rooftops as habitats for granite outcrop communities. By using a native ecosystem as a model for roof ecology we not only accomplish the typical sustainable goals of green roofs, but also shift the focus of green roof design away from the anthropocentric benefits and reprioritize the programmatic elements of a green roof so that they mesh with current regional ecological needs.


OUTCROP COMMUNITIES

Extensive outcrop studies by Madeline Burbanck and Robert Platt (Emory University) in the 1960s defined the exposed granite rock ecosystem into four primary communities based on soil depth and subsequent vegetation. UNDERSTANDING THESE COMMUNITIES IS ESSENTIAL AS THEY WILL EVENTUALLY SERVE AS THE MODELS FOR OUR PROPOSED GREEN ROOF SYSTEMS. TO THE left IS AN EXAMPLE OF A TYPICAL SOUTHERN OUTCROP AT ARABIA MOUNTAIN, GEORGIA, FEATURING THE 4 PLANT ZONES: 1) DIAMORPHA, 2) LICHEN-ANNUAL HERB, 3) ANNUAL-PERENNIAL HERB, 4) HERB-SHRUB.


01

THIS KEYSTONE PLANT COMMUNITY SERVES AS THE BUILDING BLOCK FOR THE REST OF THE GRANITE ROCK OUTCROP COMMUNITIES BY PROVIDING THE ORGANIC MATERIAL FOR THE CREATION OF SOIL. DUE TO THE NATURE OF ITS GROWING CONDITIONS, THE DIAMORPHA COMMUNITY IS ALSO THE LEAST DIVERSE COMMUNITY, AND ONLY OCCURS DURING THE SHORT GROWING PERIOD ASSOCIATED WITH ANNUALS. THIS SYSTEM, WHILE SMALL AND SIMPLE, IS CRUCIAL TO THE OVERALL SYSTEM THAT IS FOUND ON THE OUTCROPS.

02

THIS COMMUNITY IS COMPOSED OF LICHEN, MOSSES, AND ANNUAL HERBS AND have A DEEPER SOIL BASE THAN THAT OF THE DIAMORPHA COMMUNITY. THE COMMUNITY IS PRESENT YEAR ROUND, AS THE DIFFERENT FLORA ARE PRESENT DURING THE DIFFERENT GROWING SEASONS. THE COMMUNITY IS UNIQUE IN THAT IT FAVORS THE SLOUGHING OF THE GRANITE SHELVES, AND THRIVES IN THE MICRO-CLIMATES THAT ARE GENERATED IN THESE DEBRIS PILES. DIAMORPHA COMMUNITIES ARE COMMONLY PRESENT AT THE PERIMETER OF THESE ZONE.

03

AS THE MOST DIVERSE SYSTEM IN THE SOUTHEAST GRANITE OUTCROP, ANNUAL+PERENNIAL HERB COMMUNITIES SERVE AS THE BEST REPRESENTATION OF PLANT LIFE IN THE OUTCROP. WITH ITS DEEPER SOILS, THE ANNUAL+PERENNIAL HERB COMMUNITY IS ABLE TO HOUSE MORE THAN 50 FLORA SPECIES, RANGING FROM MOSSES AND LICHENS TO THE OCCASIONAL WOODY PLANT. THESE SYSTEMS ARE ALSO IMPORTANT FOR VARIOUS BIRD AND ANIMAL SPECIES, ACTING AS SOURCES FOR FOOD AND HABITAT.

04

SERVING AS THE ECOTONE BETWEEN THE PIEDMONT FOREST AND GRANITE OUTCROPS, THE HERB+SHRUB COMMUNITY FEATURES SOILS OF SIGNIFICANTLY GREATER SOIL DEPTH (UP TO 20 INCHES) AND PLANT SPECIES WITH HIGHER LEVELS OF BIOMASS. THESE COMMUNITIES VARY IN COMPOSITION FROM PREDOMINATELY SHRUB TO MOSTLY TREE (DEPENDING ON WATER AVAILABILITY AND WEATHER), BUT GENERALLY RESEMBLE THE TYPICAL PIEDMONT FOREST IN PLANT AND ANIMAL MAKEUP.


concept

While green roofs are a step towards more sustainable cities, we have only scratched the surface in terms of possibilities. As of now green roof construction is a fairly standardized system with a similar, homogenized plant palate being used across the entire country. ROOF(ROX) aims to use native environments as models for, what we call, vertically heterogeneous ecosystems. While we may understand some of the environmental benefits of green roofs, few have tested the waters of actual animal and insect habitats or the rehabilitation of regional environments. By creating a new system of complex, ecologically relevant green roofs we expand the possibilities of urban ecology and improve our connection to the natural world.


urban metaregions eco-regions migratory routes protected land river systems

study area

extended ecology

While green roofs are a step towards more sustainable cities, we have only scratched the surface in terms of possibilities. As of now green roof construction is a fairly standardized system with a similar, homogenized plant palate being used across the entire country. ROOF(ROX) aims to use native environments as models for, what we call, vertically heterogeneous ecosystems. While we may understand some of the environmental benefits of green roofs, few have tested the waters of actual animal and insect habitats or the rehabilitation of regional environments. By creating a new system of complex, ecologically relevant green roofs we expand the possibilities of urban ecology and improve our connection to the natural world.


local ecology

regional ecology

athens limits outcrop locations rail corridors green space

outcrop locations city limits conservation land piedmont region


analysis + planning

after significant research, eight topical areas of analysis were chosen based on their influence on green roof suitability as well as connectivity to existing natural corridors and green space. our project uses the outcrop communities and their environmental requirements as a basis for analysis, creating a matrix that will designate outcrop communities to specific rooftops. Using available G.I.S. reports, data manipulation, first-hand observation, and professional guidance rooftops were analyzed in the eight topical areas, pertaining specifically to green roof suitability. As seen in our analytic diagrams, different outcrop communities relate to particular areas of analysis with various weights placed on their connections. This process creates a more accurate analysis and better framework for planning and design.


vision

the vision of roof(rox) was to create a city-wide system of vertical landscapes that would not only benefit humans but also address the issue of degradation to native habitats and ecosystems. a patchwork of relevant rooftop green spaces would serve as the foundation of a true integration between urban and natural networks.


design 01 diamorpha extensive green roof

As the life-force of the granite outcrop, the Diamorpha community serves to create the organic material for the rest of the outcrop ecosystem. While small and simple (only three endemic plant species), this community is crucial as a pioneer for plant and insect life. As a result, the conceptual program and design for the Diamorpha system incorporates ideas of plant colonization, soil generation, solar energy, natural outcrop forms, and transplantation of native outcrop insect and plant species to act symbiotically.


02 lichen+annual extensive green roof

Acceptable air quality is an ongoing concern in urban environments, and lichen species have historically been used as indicators of excessive pollution. Thus the design features several methods for air quality testing, as well as swelling beds which create shaded microclimates for lichen growth (northside), and exposed areas for annuals (southside). EPS blocks form the undulating pattern while maintaining extensive green roof soil depths and creating the necessary elevation fluctuations for insect habitation.


03 annual+perennial intensive green roof

For the granite outcrop’s most biologically diverse community, programming centers around ideas of plant propagation, distribution, and colonization. The community has significance to avian species, providing both food and nesting habitats, therefore it was important to include space for bird wayfinding, roosting, and forging. This is also the first design to incorporate public access, which would be used for educational purposes as well as research of bird behavior and passive plant colonization possibilities. Planting plots take on agricultural forms and can be used to grow and distribute truly native species.


04 herb+shrub intensive green roof

In nature Herb+Shrub communities serve as ecotones between the exposed rock bluffs and typical piedmont forest. As a result these areas tend to accommodate more animal life than other outcrop communities, thus the program for these designs focuses on the training and habitation of small mammals. Infrastructure would also be implemented to research the behavior and success of animal species on green roofs, a topic with limited literature and study thus far.


ongoing

WHILE OUR PROJECT FOCUSES ON AN ECOSYSTEM SPECIFIC TO THE SOUTHEASTERN UNITED STATES, THE HOPE IS THAT DESIGNERS WILL BEGIN SERIOUSLY LOOKING AT OTHER NATIVE ENVIRONMENTS AS MODELS FOR GREEN ROOF TECHNOLOGY AND DESIGN IN GENERAL. WHILE THESE SYSTEMS ARE GAINING POPULARITY FOR THEIR ECOLOGICAL AND ECONOMICAL ASPECTS, THERE IS STILL ROOM FOR GROWTH, AND BY INCORPORATING INDIGENOUS PLANTS/LANDSCAPES WE CAN DRIVE THE MARKET FOR NATIVE PLANT MATERIAL AND BETTER EDUCATE THE PUBLIC TO ISSUES OF LOCAL ECOLOGY. AS OUR URBAN ENVIRONMENTS GROW AND CONTINUE TO ENDANGER SURROUNDING ENVIRONMENTS, IT IS IMPERATIVE TO INFUSE LANDSCAPE INTO THE CITY. AS ROOFTOPS ARE OFTEN UNUSED AND UNRECOGNIZED SPACES, THEY POSE INTRIGUING POSSIBILITIES FOR NATIVE HABITATS.


literature

resources

biodiversity of the southeast: upland terrestrial communities _ Ed William H. Martin, Stephen G. Boyce, and Arthur C. Echtemacht GUIDE TO THE PLANTS OF THE GEORGIA OUTCROP _ William H. Murdy and M. Eloise Brown Carter THE NATURAL ENVIRONMENTS OF GEORGIA _ Charles H. Wharton GRANITE OUTCROP COMMUNITIES OF THE PIEDMONT PLATEAU _ Madeline P. Burbanck and Robert B. Platt EVIDENCE OF PLANT SUCCESSSION ON GRANITE OUTCROPS OF THE GEORGIA PIEDMONT _ Madeline P. Burbanck and Robert B. Platt LICHENS OF NORTH AMERICA _ Irwin M. Brodo, Sylvia Duran Sharnoff, and Stephen Sharnoff THE ARENARIAS OF THE SOUTHEASTERN GRANITE ROCK FLATS _ Richard E. Weaver, Jr. ECOLOGY OF DIAMORPHA CYMOSA _ Deems N. Wiggs and Robert B. Platt SURVIVAL OF BOTHYNUS GIBBOSUS ON HELIANTHUS SPECIES _ C.E. Rogers, T.E. Thompson, and M.J. Wellik ENDEMISM IN ROCK OUTCROP PLANT COMMUNITIES OF UNGLACIATED EASTERN U.S.: AN EVALUATION OF THE ROLES OF THE EDAPHIC, GENETIC AND LIGHT FACTORS _ Jerry and Carol Baskin US/IBP AEROBIOLOGY PROGRAM WORKSHOP AND CONFERENCE _ IBP Aerobiology Newsletter: August 1972 EVALUATION OF THE POLLUTION AND DROUGHT HYPOTHESIS IN RELATION TO LICHEN AND BRYOPHTES IN URBAN ENVIRONMENTS _ Fabius Leblanc and Dhruva N. Rao EFFECTS OF STRATIFICATION ON THE GERMINATION OF OUTCROP SPECIES AND DEVELOPMENT OF A MODEL PIEDMONT ROCK OUTCROP HABITAT GARDEN _ American Bryological and Lichenological Society PLANTING GREEN ROOFS AND LIVING WALLS _ Nigel Dunnett and Noel Kingsbury GREEN ROOF SYSTEMS: A GUIDE TO PLANNING, DESIGN, AND CONSTRUCTION OF BUILDING OVER STRUCTURE _ Susan Weiler and Katrin Scholz Barth GROUND-NESTING BIRDS ON GREEN ROOFS IN SWITZERLAND: PRELIMINARY OBSERVATIONS _ Natalie Baumann EXTENSIVE GREEN ROOFS IN LONDON _ Gray Grant RARE INVERTEBRATES COLONIZING GREEN ROOFS IN LONDON _ Gyongyver Kadas GREEN ROOFS AND FACADES: A HABITAT TEMPLATE APPROACH _ Jeremy T. Lundholm LONG-TERM VEGETATION RESEARCH ON TWO EXTENSIVE ROOFS IN BERLIN _ Manfred Kohler SPACE FOR URBAN WILDLIFE: DESIGNING GREEN ROOFS AS HABITAT IN SWITZERLAND _ Stephan Brennelsen

PERSONAL

MELISSA CASPURY _ GRANITE RESEARCH ASSISTANT: STATE BOTANICAL GARDENS OF GEORGIA DAVID MATHENY _ PRINCIPAL ENGINEER: ARMENTROUT + ROEBUCK + MATHENY CONSULTING GROUP HENNING VON SCHMELLING _ DIRECTOR OF OPERATIONS: CHATTAHOOCHEE NATURE CENTER BRAIN LAHAIE _ ASSOCIATE PROFESSOR: UNIVERSITY OF GEORGIA DOUG PARDUE _ ASSISTANT PROFESSOR: UNIVERSITY OF GEORGIA ALFIE VICK _ ASSISTANT PROFESSOR: UNIVERSITY OF GEORGIA


ROOF(ROX) © 2010 THOMAS BROWN + BROOKS BRYANT


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