Climate-smart agroforestry systems and practices: A systematic review of what works, what doesn't work, and why

The prevailing global environmental distress, particularly in rural areas, calls for the adoption of integrated sustainable rural development strategies like climate-smart agroforestry (CSA) practices. CSAF is a new name for an old farming practice among the world's traditional farmers, a holistic approach to land use in which trees, crops, and sometimes animals are combined within a managed farmland, a sustainable farming system and practice, and a pathway toward the mitigation and adaptation of the biggest challenge of our times: climate change. CSAF systems and practices provide a range of goods and services vital for human well-being, particularly for people who live below the poverty line. Yet a number of important knowledge, research, and adoption gaps remain regarding human-environment interactions, and the urgency behind these gaps reflects the need to inform evidence-based policymaking and practice to realize the potential for CSAF to support farmers' livelihoods. We conducted a review of CSAF system practices that contribute to achieving the SDGs, in particular those related to increased human well-being, and prosperity, soil and water conservation, bioenergy, climate change response, biodiversity conservation, and landscape management, from the SDGs outlook. The study specifically identifies, (i) what has been innovatively achieved in CSAF practices to cope with climate risks for environmental stability, improved farm productivity, farm income, and food security (what works), (ii) challenges facing smallholder farmers to adopt CSAF practices (what doesn't work), and (iii) room for a significant contribution of CSAF practices in smallholder farmers' productivity beyond what has been observed. Generally, the results show that CSAF practices have the potential to optimize different socio-economic returns and sustain environmental services. Farming with CSAF technologies has many advantages in both ecological and economic aspects that support the achievement of several of the SDGs, specifically SDG1 (no poverty), SDG2 (zero hunger), SDG3 (good health and well-being), SDG5 (gender equality), SDG6 (clean water and proper sanitation), SDG7 (affordable and clean energy), SDG13 (climate action), and SDG15 (life on land). Results showed that despite its contribution to the SDGs and its global widespread, the challenge remains linking knowledge and action in CSAF research, education, and capacity development. Farmers will not be able to solve the challenge of sustainable agriculture by themselves. Thus, efforts are required from both the public and the industry and effective public-private partnerships along the agricultural and food value chain. There are multidimensional aspects to CSAF which require in-depth scientific analysis for the extensive application of CSAF practices in sustainable land management endeavors. Moreover, in this perspective, CSAF should keep its identity while seeking a role in the nexus of SDGs. We hope this review will provide a clearer picture of what the state-of-the-art in practicing smarter technologies in a changing climate is and provide a more holistic understanding of CSAF systems and practices, and the gaps regarding human-environment interactions, and the way forward to overcoming them.