Climate change adaptation in and through agroforestry: four decades of research initiated by Peter Huxley

Abstract

Agroforestry (AF)-based adaptation to global climate change can consist of (1) reversal of negative trends in diverse tree cover as generic portfolio risk management strategy; (2) targeted, strategic, shift in resource capture (e.g. light, water) to adjust to changing conditions (e.g. lower or more variable rainfall, higher temperatures); (3) vegetation-based influences on rainfall patterns; or (4) adaptive, tactical, management of tree-crop interactions based on weather forecasts for the (next) growing season. Forty years ago, a tree physiological research tradition in aboveground and belowground resource capture was established with questions and methods on climate-tree-soil-crop interactions in space and time that are still relevant for today’s challenges. After summarising early research contributions, we review recent literature to assess current levels of uncertainty in climate adaptation assessments in and through AF. Quantification of microclimate within and around tree canopies showed a gap between standard climate station data (designed to avoid tree influences) and the actual climate in which crop and tree meristems or livestock operates in real-world AF. Where global scenario modelling of ‘macroclimate’ change in mean annual rainfall and temperature extrapolates from climate station conditions in past decades, it ignores microclimate effects of trees. There still is a shortage of long-term phenology records to analyse tree biological responses across a wide range of species to climate variability, especially where flowering and pollination matter. Physiological understanding can complement farmer knowledge and help guide policy decisions that allow AF solutions to emerge and tree germplasm to be adjusted for the growing conditions expected over the lifetime of a tree.

Competition, stress and benefits: Trees and crops in the transition zone of a temperate short rotation alley cropping agroforestry system

“…No temporal differentiation, for example concerning the effect of solar radiation reduction on different developmental stages of crops is possible. Nevertheless, supported by literature, for example on recent studies of light interception by trees (Van Noordwijk et al., 2021), our results can provide some indications to explain our observations of crop yield and development in the transition zone. In the present study, a slight delay in the phenological development of winter wheat and barley in the transition zone was observed, and plants remained small and developed grains with lower thousand grain and hectoliter weights compared with the control (data not shown, Lamerre, 2017).…”

Agroforestry-Based Ecosystem Services: Reconciling Values of Humans and Nature in Sustainable Development

“…Trees play many symbolic roles, ranging from the "tree of life" to the peace-making rituals of tree planting as joint relational effort to (symbolically) transcend conflicts [61]. The popularity of tree planting as activity that responds to global climate change and is expected to protect people from harm has had various instrumental rationalizations but has relational roots [62,63]. Seeing both trees and forests at the same time is a recognized challenge.…”

Introduction: Ten Years of Forests, Trees and Agroforestry Research in Partnership for Sustainable Development

“…Tree roots, depending on their architecture, can reduce landslide risks (Hairiah et al 2020b). Since dealing with water-related risks (droughts and floods) is a major part of climate-change adaptation (van Noordwijk et al 2021), as well as forest landscape restoration (Guariguata and Evans 2020), local issues spill over to the global teleconnections category. Local knowledge and ways of interpreting tree-cover transitions need to be reconciled with those of downstream stakeholders, if effective feedback mechanisms and landscape governance are to be established (Leimona et al 2015a;van Noordwijk et al 2020b;Seijger et al 2021).…”