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Three concepts of agroforestry interact with three aspects of climate change, linking local to global scales. Scientific knowledge can contribute to public policy development in four distinct phases: grasp, commit, operationalize and innovate. This contribution highlights three ways agroforestry can be part of a climate change response: adapt to increased risks and uncertainties, facilitate an energy transition (while capturing and storing carbon), and restoring landscape multifunctionality to allow current human resource appropriation to become sustainable, fitting sustainable development goals within planetary boundaries.

Jatropha curcas L. is a biofuel crop that has not lived up to expectations due to a combination of hype and disappointment and biophysical factors. This PhD thesis is based on the plant production component of the JARAK programme which aimed to bridge the gap between truth and fiction. This study reviewed the jatropha hype and disappointment and further investigated the hypothesis that jatropha growth and yield are limited by biophysical factors of plant characteristics, cropping systems, and management. My review of the hype and disappointment shows that despite the high expectations fuelled by market pull and technology push, and numerous actors, the commercial potential for jatropha is limited by policy and governance, economics, social, technology, logistical, and environmental. A study of the biophysical components confirms that no current varieties suited to different cropping systems and locations are available. Jatropha aboveground biomass is partitioned predominantly into a structure of stem, branches, and twigs. The below to aboveground biomass ratio was 0.5 and fruit which was found only on productive twigs accounted for the smallest portion of biomass measured. Seed yields were disappointingly small (109 kg ha-1) and were largest in monoculture, followed by intercropping and hedgerows in that order, although yields were influenced by age and management of pruning and fertiliser. Seed yield across the three cropping systems can be predicted using plant height and the number of productive twig/branch, although the number of inflorescence clusters per productive twig may be important. Intercropping between jatropha and maize (Zea mays L.) resulted in competition for resources both belowground and aboveground that reduced maize yields. Shoot pruning was effective in managing aboveground competition, while root pruning and root barriers effectively managed competition belowground. Leaf prunings provided a limited, but positive fertility effect on maize yield

Nudging the development trajectory of tropical landscapes towards sustainability requires a global commitment and policies that take diverse contexts and forest transitions into account. Out-scaling and upscaling landscape-level actions to achieve sustainable development goals globally need to be based on understanding of extrapolation domains and interconnectivity of products and services. We evaluated three portfolios of tropical landscape observatories and quantified extrapolation domains across ecological zones, stages of forest transition, human development index (HDI), population density and potential prominence of four dominant tropical tree crops (arabica coffee, cacao, rubber and oil palm). The ASB Partnership for Tropical Forest Margins portfolio was focussed on active humid forest margins and the Poverty and Environment Network on early stages of forest transition. The portfolio of sentinel landscapes of the Forests, Trees and Agroforestry (FTA) research programme provides a 5% sample of pantropical area, 8% of people, 9% of tree cover and 10–12% of potential tree crop presence, with quantified biases across zones, transition stages and HDI. In the ‘water tower’ configuration, relatively high population density coincides with biodiversity, coffee expansion and contested ecosystem services. The extrapolation domain of the FTA portfolio includes trade-off (tree loss) and synergy (restoration) phases of tropical forest transition.

Flood damage depends on location and adaptation of human presence and activity to inherent variability of river flow. Reduced predictability of river flow is a common sign of degrading watersheds associated with increased flooding risk and reduced dry-season flows. The dimensionless FlowPer parameter (Fp), representing predictability, is key to a parsimonious recursive model of river flow, Qt = FpQt-1 + (1-Fp)(Pt-Etx), with Q, P and E expressed in mm d-1. Fp varies between 0 and 1, and can be derived from a time-series of measured (or modeled) river flow data. The spatially averaged precipitation term Pt and preceding cumulative evapotranspiration since previous rain Etx are treated as constrained but unknown, stochastic variables. A decrease in Fp from 0.9 to 0.8 means peak flow doubling from 10 to 20% of peak rainfall (minus its accompanying Etx) and, in a numerical example, an increase in expected flood duration by 3 days. We compared Fp estimates from four meso-scale watersheds in Indonesia and Thailand, with varying climate, geology and land cover history, at a decadal time scale. Wet-season (3-monthly) Fp values are lower than dry-season values in climates with pronounced seasonality. A wet-season Fp value above 0.7 was achievable in forest-agroforestry mosaic case studies. Interannual variability in Fp is large relative to effects of land cover change; multiple years of paired-plot data are needed to reject no-change null-hypotheses. While empirical evidence at scale is understandably scarce, Fp trends over time serve as a holistic scale-dependent performance indicator of degrading/recovering watershed health.