Management of agrolandscapes for sustainability both influence and is influenced by biodiversity (Paoletti, 1995). Landscape planning is a process through which the conservation and management of biodiversity can be pursued (Rook-wood, 1995).
Turner et al. (1995) stressed that there exists a three-way interaction of biodiversity, ecosystem processes, and landscape dynamics at greater scales. Sustainable agricultural practices leading to increased crop and genetic diversity have resulted in increased agroecosystem stability (Cleveland, 1993). For example, increasing crop diversity benefits agriculture by reducing insect pests (Altieri et al., 1983). Other sustainable agricultural practices, such as conservation tillage, are known to increase habitat diversity, wildlife diversity, and numbers of beneficial insect species (Barrett, 1992; McLaughlin and Mineau, 1995).
Although the importance of a landscape approach for management of biodiversity is well recognized (Franklin, 1993), little is known regarding how biodiversity affects landscape pattern and dynamics (Turner et al., 1995). Turner et al. (1995) have suggested that there exists a three-way interaction among biodiversity, ecosystem processes, and landscape dynamics. In addition, it is well documented that there exists a reciprocal relationship between sustainability and biodiversity (Paoletti, 1995). Thus, as biodiversity and sustainability are increased by management practices at the landscape level (e.g., agrolandscape management), the resulting increase in biodiversity will likely have important benefits concerning the conservation and efficiency of these processes and dynamics (Culotta, 1996; Tilman et al., 1996).
It is important to recognize that, by definition, the agrolandscape approach requires the consideration of biological diversity in the management of agroecosys-tems (Paoletti et al., 1992). Paoletti et al. (1992) and Paoletti (1995) note that sustainable strategies in food production in agriculture improve the existing biodiversity. These strategies include proper management of natural vegetation, better use and recycling of organic residues, introduction of integrated farming systems, reduced tillage, intercropping, crop rotation, biological pest control, and increased number of biota involved in human food webs. McLaughlin and Mineau (1995) point out, however, that agricultural activities such as tillage, drainage, rotation, grazing, and extensive usage of pesticides and fertilizers have significant implications for wild species of flora and fauna. Therefore, reduced or (no-till) farming, in contrast to conventional tillage, benefits biological diversity in terms of maintaining wild or native species populations.
Increased biodiversity at the landscape level (in the form of increased habitat or agroecosystem diversity) will play a key role in protecting diversity and in providing a linkage between urban and rural areas in our sustainable landscape approach. For example, that an optimum balance between solar-powered and subsidized systems in suburban areas is critical to this linkage. The success of obtaining this optimum balance will almost certainly be enhanced by increasing the diversity of habitat types across the total landscape. Greenways or natural corridors will also enhance the linkage and conserve biological diversity between urban and rural areas (Little, 1990). Management of agroecosystems and agrolandscapes for sustainability will lead to increased habitat and genetic diversity, which, in turn, will lead to increased agroecosystem stability (Altieri et al., 1983; Cleveland, 1993). Likewise, increased biodiversity within individual systems should also increase the diversity and stability of these systems within the total landscape or watershed.
Agrolandscapes should also be managed to increase species diversity within landscape patches and to increase and/or to conserve genetic material among landscape patches (Barrett and Bohlen, 1991). In recent years, there has been increased emphasis on the connectivity and integration of the agricultural landscape with the urban landscape (see Lockeretz, 1988, including a special issue of Landscape and Urban Planning, Volume 16, for details). However, most studies at the watershed or agrolandscape levels have failed to encompass or integrate the urban environment into the agrolandscape concept. Since the approach to sustainable agriculture is based on natural ecosystems serving as the model system for efficient agricultural management (Jackson and Piper, 1989; Barrett, 1990), urban systems should also be designed and based on natural ecological systems serving as model systems to ensure maximum ecological and economic efficiency. Thus, sustainability and biodiversity share an important interrelationship that is more fully understood when questions are addressed at the agro-urban landscape scale, and when research designs and management strategies are based on ecological theory.
Importantly, there is growing recognition that cities need to be managed based on the concept of sustainability (Stren et al., 1992). This approach is based on an ecological understanding of how natural ecological systems are organized, and most important, how they function. As with sustainable agriculture, an urban perspective based on sustainability means working with, rather than against, nature. Recently, there has been increased effort in urban areas to maximize the efficiency of energy use, to increase the rate of recycling of goods and materials, and to reduce pollutants entering the system. In addition, "green city" movements have placed emphasis on preservation of natural areas, and on the establishment of vegetable gardens (i.e., solar-powered patches, Figure 2) in urban areas (Stren et al., 1992). Continued efforts to increase solar-driven productivity, while simultaneously decreasing maintenance costs, in urban areas will greatly enhance the sustainability of the total agro-urban landscape. Equally important is the need to plan for (or to zone) future suburban areas, encompassing a productivity/maintenance ratio equal to 1, if we are to achieve regional landscape sustainability (Figure 4). This strategy must also make every effort to increase biodiversity at the genetic, species, and landscape levels.
Lockeretz (1988) stressed the importance of protecting and creating natural linkages between urban and rural areas. Urban greenways (Little, 1990) provide noteworthy examples of these natural linkages. Although greenways take many different forms, they are primarily natural areas set aside for their ecological, recreational, or aesthetic value within urban areas. Greenways also provide natural corridors for movement of wildlife species and transfer of genetic materials between urban and rural areas.
Suburban areas also represent a vital linkage (transition or ecotone) between urban and rural systems. Therefore, it is important to manage these areas as a "transitional zone" between urban population centers and rural farmland (Figure 4) with an optimum balance existing between land area devoted to natural (solar-powered) systems and those managed as subsidized systems. Management plans aimed at establishing a new approach to suburban development should strive to attain an integration of autotrophic and heterotrophic systems. The success of these man agement plans will greatly depend on an increased ecological literacy of people living within and in consort with future land-use policies (Orr, 1992; Barrett et al., 1997).
In recent years, numerous forms of land-use policies have been instituted to protect agricultural land at urban-fringe areas (Luzar, 1988) and to promote sustainable agriculture research and education (Hess, 1991). Although these programs have been moderately successful (Harsch, 1991; National Research Council, 1996), there still is much to learn regarding the most effective combination of strategies for a particular region. There is urgent need for a new integrative "greenway" strategy. For example, the words ecology and economics are both derived from the Greek root oikos, meaning "household" (logos meaning "study of' and nomics meaning "management of"). Thus, ecology is the study of the household or the study of natural systems, whereas economics is the management of the household or the management of natural/socioeconomic systems. We must now integrate greenways, green meaning primary production or green meaning "greenbacks" or dollars, with ways, meaning progress in a specific direction, as a new integrative ecologic/eco-nomic strategy.
Determining optimum land use is a difficult task (Werner, 1993). For example, the most effective land-use strategy for urban-rural fringe areas depends on agricultural, cultural, demographic, and socioeconomic characteristics of an area (Lockeretz, 1988). The development of appropriate management strategies at the agrolandscape level will require the cooperation of diverse fields of study (Barrett, 1992). This cooperation will enhance biotic diversity at the landscape level, will provide numerous societal benefits, and will protect both natural capital (goods and services provided by nature) and economic capital (goods and services provided by socioeconomic systems) as a long-term strategy (Costanza et al., 1997). The longer the wait, the greater are the long-term costs regarding the loss of biodiversity, the continued loss of soil and nutrient resources, the degradation of water quality, and an increased cost to restore habitat quality.
Was this article helpful?