Do trees on agricultural landscapes buffer the impacts of climate change?
Does the presence of trees buffer annual food crops from climate variability? Are trees in agricultural landscapes a relevant part of climate change adaptation strategies? van Noordwijk et al review these hypotheses in a chapter entitled Agroforestry solutions for buffering climate variability and adapting to change in a recent publication — Climate Change Impact and Adaptation in Agricultural Systems — by the Centre for Biosciences and Agriculture International (CABI).
Agricultural systems are society’s main source of agricultural goods and services. They can be crop- or livestock-based, or combine the two, and their main characteristics differ depending on region and level of management intensity. They, in turn, differ in their sensitivity to projected climate change, and efforts to increase their resilience to climate change must be tailored to the specific needs of each system.
Climate Change Impact and Adaptation in Agricultural Systems focuses on future global climate change and its implications for agricultural systems. In 17 chapters the book delves into the impacts of climate change on ecosystems, food security, water resources and economic stability. Starting off with climate projections for 2050, the publication then reviews climate sensitivity and climate change challenges for key agricultural systems around the world. Strategies to develop sustainable systems that minimize impact on climate are also presented, along with options for adaptive and mitigative management.
Agroforestry as a concept resists and tries to counteract the way agriculture has been segregated from forests and forestry. Agroforestry solutions for buffering climate variability and adapting to change, the chapter by van Noordwijk et al focuses on increasing the adaptive capacity of agricultural systems in tropical and subtropical regions through agroforestry. Understanding, using and improving agroforestry implies a focus on the interactions between trees, annual crops and domestic stock—in the backdrop of local abiotic and biotic contexts, and the use of land, external inputs, labour and knowledge. The authors pose and review the hypothesis that the presence of trees increases the degree of buffering of climate variability from the perspective of annual food crops, and that retention and the increase of trees in agricultural landscapes can be a relevant part of climate change adaptation strategies.
Some key points from the chapter:
- Trees have mostly been discussed in climate change in terms of their carbon storage and the contributions they make to the global carbon balance but their more direct effect on micro- and mesoclimate is largely absent from the climate change debate, including that involving agriculture. The authors argue that important adaptive opportunities are missed if we continue to ignore trees in that context.
- Mitigation efforts cannot contain global climate change to the level that adaptation is not needed. This necessitates synergy of mitigation and adaptation actions across all sectors, and recent support for agroforestry as a part of agricultural adaptation strategies is also moving in this direction.
- Climate science recognises the impacts of trees on wind speed, humidity, temperature and even rainfall, but climate maps and models are generally based on tree-less landscapes. There have been no attempts to show climate maps of the same area with different degrees of tree cover. The chapter reviews data to suggest that local tree cover has a substantial impact on major weather variables at local scales, and that variations in tree cover in an agricultural landscape may, for the next 30 years or so, exceed the predicted patterns of climate change on key climatic variables for many locations.
Supply and demand of buffering functions in the landscape, and the impact of trees on wind speed, water balance and progressive climate are all looked at in detail in the chapter.
Research on how landscapes provide buffering and other ecosystem services may benefit from assessments of supply and demand, current sufficiency and trends of buffering, the authors say. They also assert that the challenges to realizing the full contributions agroforestry can make to food production systems, multifunctional landscapes and rural livelihood systems are probably:
(i) The mindset of agricultural scientists trained to think that open-field agriculture is the norm and standard;
(ii) Climate scientists who have not even started serious downscaling of climate change predictions to include the effects of local land cover change on local temperature, humidity, wind speed and other parameters of direct human relevance;
(iii) The makers and shapers of agricultural, forestry and land-use policies who treat forestry and agriculture as opposite sides of a coin that can only fall on either side of the institutional divide.
Conversely, the main supporters of the emergence of agroforestry as part of the solution are the farmers of the world who have defied the advice to oversimplify and overspecialize their farms and landscapes. Farmers perceive that trees substantially reduce their exposure to climate risk, and part of the research community is recognising this, but for now most of the analysis of climate change adaptation in agriculture is still not thinking outside of the specialization box.
Other chapters in the book focus on climate sensitivity, challenges, mitigative and adaptive strategies for varied agricultural systems around the world including intensive rice-wheat systems in tropical Asia; low-input cropping and grazing systems in Australia; fruit and vegetable production in the UK; and organic and agroecological farming systems in Latin America—to name some. Concluding chapters shed light on the use of seasonal climate forecasts in climate adaptation; new approaches to knowledge and learning in agricultural adaptation to climate change; and factors influencing choice of coping strategies for extreme climate events with farmers in Ethiopia’s Nile Basin as a case study.
van Noordwijk M, Bayala J, Hairiah K, Lusiana B, Muthuri C, Khasanah N, and Mulia R, 2014. Agroforestry solutions for buffering climate variability and adapting to change. Chapter 14 in: J. Fuhrer and P.J. Gregory (Eds.) Climate change Impact and Adaptation in Agricultural Systems. CAB-International, Wallingford (UK), pp 216-232.
Landscape management for environmental services, biodiversity conservation and livelihoods is a key focus of the CGIAR’s Collaborative Research Project 6 on Trees, Forests and Agroforestry—of which the World Agroforestry Centre is a key partner.