Taking Tree-Based Ecosystem Approaches to Scale: Impacts, Drivers and Mechanismswca2014-1560 Louise Willemen 1 2Abigail K. Hart 1 2,*Christine Negra 2Sara J. Scherr 2Bastiaan Louman 3Celia A. Harvey 4Frank Place 5Lars Laestadius 6Robert Winterbottom 6 1Department of Natural Resources, Cornell University, Ithaca, 2EcoAgriculture Partners, Washington, DC, United States, 3Climate change and watershed management, Centro Agronómico Tropical de Investigación y Enseñanza, Turrialba, Costa Rica, 4Conservation International, Arlington, United States, 5World Agroforestry Centre, Nairobi, Kenya, 6World Resources Institute, Washington, DC, United States
Tree-Based Ecosystem Approaches (TBEAs), which include a variety of land and forestry management systems and practices that combine trees with agricultural production, to seek to sustain or increase productivity, enhance ecosystem services supply, are widely documented. Their potential for economic development, poverty reduction and climate resilience has inspired growing interest and investment, however processes that underpin the scaling up of TBEAs are poorly identified and described, and evidence of the impacts of TBEAs on livelihood improvement is lacking. We conducted a review of peer-reviewed and gray literature on TBEAs to gain insight on: (1) the impacts of TBEAs specifically on food security, resilience to climate change, carbon sequestration, and income generation, and (2) drivers that explain the adoption of TBEAs. Of the 292 documents identified, the 93 containing relevant data for our analysis reported on 40 different tree-based practices across 111 sites in 53 countries where TBEAs are in some stage of scaling up. The most commonly reported drivers leading to the adoption of TBEAs were soil quality improvement, income and subsistence production of food and fodder. External NGOs and local or collaborative mechanisms were frequently reported mechanisms for supporting TBEA implementation or maintenance. We found a wide variety of quantitative and qualitative descriptions for TBEA impacts and poor description of the actual levels of adoption and extent of TBEAs suggesting the need to: 1) develop a shared conceptual framework and assessment strategy to inform cross-site comparative impact analysis; 2) conduct spatial analyses to determine geographic distribution and extent of TBEAs; and 3) conduct comprehensive case studies of TBEAs to better understand scaling processes and dynamics at landscape scale.