Application of multi-criteria analysis in land use decisions

[摘要] Global land use trends have resulted in extensive transformation and loss of biodiversity in natural landscapes. In South Africa these trends are apparent in the Grassland Biome. Although it has a very high level of biodiversity and provides essential ecosystem services for economic development, only 2% is formally protected and it is one of the most threatened biomes in the country. With over 60% transformed and less than 1% formally protected, the Mistbelt Grassland of KwaZulu-Natal is a priority for urgent conservation attention. The continued transformation of natural landscapes due to economic pressures and the limited opportunity for an increase in protected areas where production and development needs must be met, presents a challenge to biodiversity conservation. This study was motivated by the need for a strategic focus in the evaluation of the impacts of land use on the biodiversity integrity of landscapes in order to facilitate integrated environmental management and guide land use decisions that would promote conservation of biodiversity and sustainable development. A methodology for this evaluation is proposed that exploits the hierarchical approach to characterizing biodiversity and employs multi-criteria analysis in the form of the Analytic Hierarchy Process and decision-making by experts. Separate evaluations of the impacts of land use on biodiversity integrity in the Mistbelt Grassland of KwaZulu-Natal and the moist sub-biome of the Grassland Biome were conducted to examine the application of the methodology at the vegetation-type and biome levels. Accordingly, five land uses and fourteen biodiversity indicators were selected for the Mistbelt Grassland study, and ten land uses and fifty-two indicators for the Grassland Biome study. Indicators for the integrity of landscape composition, structure and function were selected. The overall relative weights for land uses were obtained from rankings of the impacts of each land use on indicator criteria. Relative impacts of land uses on landscape composition, function and structure were consistent and provided an unambiguous statement of the overall impact on biodiversity integrity. The greatest impact of land use was associated with that on landscape structure and was the result of the extent of transformation and fragmentation. The integrity of grassland habitat is important for landscape composition, while nutrient leakage and fire regime are considered important for landscape function. Urban settlements were considered to have the greatest negative impact on biodiversity, while timber plantations, croplands and rural settlements also had a high impact. Pastures and livestock ranching were associated with low impacts. Against the benchmark of conservation, activities like game ranching, livestock ranching and tourism accounted for slight impacts on biodiversity integrity and are recommended for the maintenance of landscape biodiversity. While timber plantations, dairy farming, rural settlements and croplands were considered to make little contribution to the maintenance of biodiversity, their spatial orientation was considered to be critical for the maintenance of regional connectivity and the biodiversity integrity of the greater landscape. In accordance with the methodology employed and insights obtained in the evaluation of land use impacts on biodiversity integrity, the Land Use Evaluation Model is proposed as an integrated environmental management tool. Within a single integrated, cost-effective evaluation procedure that allows for input by key stakeholders, the hierarchy of decisions in the Analytic Hierarchy Process can be expanded to accommodate a limitless number of indicator criteria to rank the impacts of alternative development plans or projects on the social, economic and biodiversity components of the environment. An examination was made of the Land Use Evaluation Model in strategic environmental assessments and its role in facilitating environmental impact assessment and the integrated development planning processes.

[发布机构] University of the Free State