The Role of Trees in Agroecology and Sustainable Agriculture in the Tropics

The Role of Trees in Agroecology and Sustainable Agriculture in the Tropics


Numerous and interacting socioeconomic and biophysical factors are driving land degradation and declining agricultural productivity in the tropics and the subtropics. Population growth and the lack of new forest to clear for the practice of shifting cultivation has led farmers to become sedentary smallholders without the financial resources to access fertilizers and other technologies to replenish soil fertility. Current estimates are that land degradation affects two billion hectares (38% of world cropping area), with soil erosion affecting 83% of the global degraded area. Agriculture needs to be more sustainable and more productive, and business as usual is not an option.

Conclusions & Takeaways

This review offers suggestions on how to examine agroecological processes in more detail for the most effective rehabilitation of degraded land. The author suggests a three-step agroforestry approach to simultaneously resolve the issues driving food and nutritional insecurity, poverty, and environmental degradation. The first step consists of the restoration of agroecological functions and diversification of the farming system using a number of leguminous nitrogen-fixing trees and shrubs, which will increase soil fertility and crop yields freeing up space to diversify the cropping system with other income-generating crops. The second step consists of the generation of income from the domestication of indigenous tree species that produce useful and marketable products for local and regional trade. Finally, product commercialization (step 3) creates business and employment opportunities in cottage industries engaged in processing, value adding, and marketing of the products of these agroforestry trees. This way, agroforestry becomes a powerful new tool to address the cycle of land degradation and social deprivation.



Leakey RRB. The Role of Trees in Agroecology and Sustainable Agriculture in the Tropics. Annual Review of Phytopathology. 2014;52:113–133. doi:10.1146/annurev-phyto-102313-045838.


  • Department of Marine and Tropical Biology, James Cook University, Cairns, Australia