A sustainable agricultural landscape model for tropical drylands

Finding a balance between ecosystem conservation and the production of goods and services that societies need to prosper is fundamental to the long-term sustainable development of any region, but this balance varies within the region’s landscapes. We tested the hypothesis that landscapes with intermediate structure complexity (i.e., those that combine natural vegetation and human-transformed ecosystems) are the most efficient to produce food, water and energy for local populations in Caatinga, South America’s largest dryland. We used empirical data and computer simulations to simultaneously assess the trade-offs between the production of these three ecosystem services and the landscape structure. The results supported the hypothesis. Moreover, we found that increasing the percentage of natural lands in the landscape increased the production of biomass energy, water and food. However, water production stabilized when natural lands occupied more than 80 % of the landscape, and food production decreased when natural lands occupied more than 50 % of the landscape. Increasing the percentage of agricultural land in the landscape increased the production of all three ecosystem services, but biomass energy production and water production declined when agricultural lands reached 20 % and 35 % of the landscape, respectively. Finally, the production of all three ecosystem services declined when the percentage of degraded lands (i.e., lands that lost most of their natural productivity due to human-caused processes) in the landscape increased, but food production declined faster than the production of energy and water. To achieve groundwater, food, and long-term energy security, agricultural landscapes in tropical drylands require more conservation (including the restoration of degraded areas), more diversification of agriculture practices, and a better integration of individual initiatives at a larger spatial scale.