or watershed level) and water uses between major centers of production. This approach would hinder disease transmission, moderate negative impacts on wild fish populations, and reduce the contribution of aquaculture to water eutrophication. The second approach is creating synergies with other economic activities in the watershed. The farming of aquatic plants (such as seaweed) and the filter feeding of detritivorous organisms (such as mussels, clams, and sea cucumbers, which together represent about 40 percent of total global aquaculture) reduce nutrient loading from livestock, agriculture, and other sources. Fish production in cages or culture-based fisheries can be conducted in reservoirs and irrigation systems to amortize costs, improve water quality, reduce weeds, and replace wild catch where dams have destroyed indigenous fish stocks. Mixed fish and rice production systems are widespread in low-lying areas and flood plains, taking advantage of synergies between the water and land management approaches. Although dispersing fish farms is good for the environment, it does raise costs, in part because of the losses from agglomeration. Thus, green growth strategies will require practical fi nancial and market incentives to support spatial dispersing, technical guidelines on green technology, and government policies that encourage investors to avoid the traditional practice of copying successful production/ market models and instead explore new partnerships at the watershed level.
Plantation forests Afforestation—the planting of forests in areas that were not forested in recent times—is expected to meet an increasing share of the demand for wood and fiber, possibly reducing pressure on primary and natural forests. In 2010, the global area under plantation forests (forested areas artificially created by planting or seeding) accounted for 7 percent of total forest area and 40 percent of industrial timber production (FAO 2011). Plantation forests provide a growing share of industrial timber, both because the area
under plantation forests has increased and because productivity has risen. Areas under bamboo and rubber plantation are also increasingly being used to provide timber products, providing an important source of income for rural households. Reforestation and restoration of degraded woodlands also play a role in plantation forestry. Whether plantation forests help or hurt the environment depends on the land use systems they replace. In China, for example, bamboo plantations have helped control soil erosion by replacing agriculture on steep slopes. But in some provinces, where plantations have replaced natural forests in areas not well suited to bamboo, soil erosion has increased. The Chinese government has tried to address these negative environmental effects by establishing environmental regulations, but these regulations have been resisted in some cases (Ruiz-Perez and others 2001). More recently, China has supported programs with species better adapted to local ecosystems (World Bank 2010c). Agroforestry systems, in which trees are incorporated into the broader production landscape, are widespread in some areas. They can yield the “triple wins” of climatesmart agriculture by enhancing productivity, resilience, and carbon sequestration, as they have in Kenya and the Sahel (Liniger and others 2011).
Nonprovisioning services: Creating knowledge and markets for economic valuation In addition to ecosystems that provide food and water (“provisioning services”) are ecosystems that regulate, support, and offer cultural services (“nonprovisioning” services). This group includes nature-based tourism supported by biodiversity, watershed services, and climate-regulating services. The main challenge in this area is to create markets for these services so that they become part of the visible economy and are efficiently provided. Another challenge is coping with the timing of benefits. Although efforts to reduce the
Published on May 23, 2012
Published on May 23, 2012
As the global population heads toward 9 billion by 2050, decisions made today will lock countries into growth patterns that may or may not b...