Drylands (41 and 35% of global land and population, respectively) have the lowest biological productivity of any ecosystem, contain populations with the highest growth rates on earth, and share a significant fraction of global poverty for which desertification is implicated. A global assessment of the available information indicates that the inherent low productivity of drylands, when combined with other adverse factors, can generate poverty. It additionally indicates that while the drylands may exist in a locally stable and sustainable state, this is readily destabilized by non-linear, threshold-crossing transitions to an alternative steady-state leading to desertification, poverty and conflicts. The ''desertification paradigm'' (human and climatological pressures driving overexploitation of land resources, leading to desertification, poverty and reduced security) is challenged by its ''counter-paradigm'' (adversity elicits innovation, leading to ingenuous solutions for avoiding desertification). But the latter does not account for the inevitability of continued and increasing pressure on the finite dryland resources, expected to be further exacerbated by a globally increasing need for agricultural land. A companion paper points out that this situation can be avoided by reducing dependence on land productivity, through adoption of ''alternative livelihoods.'' These livelihoods, while economically advantageous, reduce pressure on land resources.

There is limited information available on the status of and threats to mangroves in developing countries in the Asia-Pacific region. In the recent years, there has been a significant increase in scientific and volunteer surveys. However, this information is usually not well integrated with information on human activities that have the potential to contribute to the degradation of these ecosystems. A project "Coastal Habitats at Risk" is being developed jointly by the United Nations University (UNU) and the World Resources Institute, and in partnership with UNESCO and the International Society for Mangrove Ecosystems (ISME), in an effort to ameliorate this situation through standardized assessment of anthropogenic threats to mangroves in East and Southeast Asia. The geographic focus of the project includes Brunei, China, Cambodia, Indonesia, Malaysia, Myanmar, the Philippines, Singapore, Taiwan, Thailand and Vietnam. Threats from pollution, over-harvesting, aquaculture development, boating/shipping, flooding/freshwater input, siltation and other coastal development are examined with this map-based analysis. The study particularly emphasizes information regarding the human element of these ecosystems, with an eye towards community-based management and action. A geographic information system (GIS)-based tool will be developed to examine different coastal development and management scenarios and their implications for mangrove health, diversity and value. The results will serve as an indication of the threats to these ecosystems, not as an actual measure of degradation. This information generation can be seen as a first step toward assessing global needs for the world's mangrove ecosystems that to date remain largely unassessed. The analysis is intended to recommend policies, participatory approaches and management strategies to promote integrated coastal ecosystem approaches. It will help fill an information void through much-needed policy guidance on management and priority setting.

The millennium ecosystem assessment report on global assessment of desertification has highlighted its worldwide impacts on the environment-increasing dust storms, floods and global warming-as well as on societies and economies. It links sustainable management of resources, and inter alia well-being of dryland populations, to reducing societal pressures on dryland ecosystems through adoption of alternative livelihoods. This paper, in combination with a companion paper by Safriel and Adeel, presents the conceptual underpinnings of this approach as well as examples of how innovative approaches for creating livelihoods can help reduce the pressure on marginal drylands.

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