Community-driven tree planting greens the neighbouring landscape

Holl K.D., Brancalion P.H.

Tree planting must be carefully planned and implemented to achieve desired outcomes

Willemen L., Barger N.N., Brink B.T., Cantele M., Erasmus B.F., Fisher J.L., Gardner T., Holland T.G., Kohler F., Kotiaho J.S., von Maltitz G.P., Nangendo G., Pandit R., Parrotta J.A., Potts M.D., et. al.

The assessment of land degradation and restoration by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services shows that land degradation across the globe is a wide and severe issue and is showing no signs of slowing down. This trend must be halted and reversed.

Lenton T.M.

Tipping points exist in social, ecological and climate systems and those systems are increasingly causally intertwined in the Anthropocene. Climate change and biosphere degradation have advanced to the point where we are already triggering damaging environmental tipping points, and to avoid worse ones ahead will require finding and triggering positive tipping points towards sustainability in coupled social, ecological and technological systems. To help with that I outline how tipping points can occur in continuous dynamical systems and in networks, the causal interactions that can occur between tipping events across different types and scales of system—including the conditions required to trigger tipping cascades, the potential for early warning signals of tipping points, and how they could inform deliberate tipping of positive change. In particular, the same methods that can provide early warning of damaging environmental tipping points can be used to detect when a socio-technical or socio-ecological system is most sensitive to being deliberately tipped in a desirable direction. I provide some example targets for such deliberate tipping of positive change. This article is part of the theme issue ‘Climate change and ecosystems: threats, opportunities and solutions'.

De Giusti G., Kristjanson P., Rufino M.C.

The promotion of agroforestry as a mitigation practice requires an understanding of the economic benefits and its acceptability to farmers. This work examines the agroecological and socio-economic factors that condition profitability and acceptance of agroforestry by smallholder farmers in Western Kenya. We differentiate the use of trees according to the permanence of carbon sequestration, introducing a distinction between practices with “high mitigation benefits” (timber) and practices with “low mitigation benefits” (fuelwood). This study goes beyond the analysis of incentives to plant trees to identify incentives to plant trees that lead to high mitigation outcomes. We show that environmental factors shaping the production system largely drive the choice for planting trees with high mitigation benefits. Most trees in the area are used for fuelwood, and the charcoal economy outweighs economic factors influencing planting of trees with high mitigation benefits. Larger households tend to produce more fuelwood, while high mitigation uses are positively related to the education level of the household head, and to the belief that trees play a positive role for the environment. Where trees contribute significantly to incomes, the norm is that they are owned by men. We conclude that although agroforestry is not perceived to be more profitable than traditional agricultural practices, it plays an important economic and environmental role by supporting subsistence through provision of fuelwood and could relieve pressure upon common forest resources. In areas with high tree cover, it also represents a way of storing capital to deal with risks and cope with uncertainty.

Gichenje H., Godinho S.

Gorelick N., Hancher M., Dixon M., Ilyushchenko S., Thau D., Moore R.

Google Earth Engine is a cloud-based platform for planetary-scale geospatial analysis that brings Google's massive computational capabilities to bear on a variety of high-impact societal issues including deforestation, drought, disaster, disease, food security, water management, climate monitoring and environmental protection. It is unique in the field as an integrated platform designed to empower not only traditional remote sensing scientists, but also a much wider audience that lacks the technical capacity needed to utilize traditional supercomputers or large-scale commodity cloud computing resources.

Webb N.P., Marshall N.A., Stringer L.C., Reed M.S., Chappell A., Herrick J.E.

Land degradation and climate change pose enormous risks to global food security. Land degradation increases the vulnerability of agroecological systems to climate change and reduces the effectiveness of adaptation options. Yet these interactions have largely been omitted from climate impact assessments and adaptation planning. We examine how land degradation can influence climate‐change impacts and the adaptive capacity of crop and livestock producers across agroecological systems. We then present novel strategies for climate‐resilient agriculture that support opportunities to integrate responses to these challenges. Forward‐looking, climate‐resilient agriculture requires: (1) incorporation of land degradation processes, and their linkages with adaptive capacity, into adaptation planning; (2) identification of key vulnerabilities to prioritize adaptation responses; (3) improved knowledge exchange across local to global scales to support strategies for developing the adaptive capacity of producers; and (4) innovative management and policy options that provide multiple “wins” for land, climate, and biodiversity, thus enabling global development and food security goals to be achieved.

Eckert S., Kiteme B., Njuguna E., Zaehringer J.

Borish D., King N., Dewey C.

This case study examines the impact of the Bwaliro Primary School feeding and agroforestry program on the human, financial, natural, and social capitals of the surrounding Bwaliro community in western Kenya. Additional to the targeted improvements in attendance and educational performance, program spillover effects likely included enhanced child health, community agroforestry knowledge, increased tree planting and diversity of crops and trees, saved household income, and improved relations within the family unit and among community members. Participants suggested that increasing the community's capacity to contribute to and collaborate with the school is necessary for program sustenance and for further community development.

Mafongoya P., Rusinamhodzi L., Siziba S., Thierfelder C., Mvumi B.M., Nhau B., Hove L., Chivenge P.

Conservation agriculture (CA) is increasingly promoted in southern Africa as a strategy to improve food security and reverse soil degradation in the face of climate change. However, the performance of CA under different environments and its ability to improve ecosystem services is still unclear. The effects of the CA options; direct seeding, rip-line seeding, and seeding into planting basins on maize grain yield, soil health and profitability across agro-ecological regions in Zimbabwe were evaluated through a review of literature in combination with meta-analysis. Overall, CA improved maize yield over conventional agriculture. Compared to conventional agriculture, direct seeding, rip-line seeding, and seeding into planting basins increased yield by 445, 258 and 241 kg ha−1, respectively. However, there was an initial yield decline in the first two years. CA practices reduced soil erosion and bulk density, and increased soil water content in most studies. Under high levels of residue retention (6 Mg ha−1), CA systems exhibited greater macro fauna abundance and diversity than conventional agriculture, particularly termites. Weed pressure tended to increase labour requirement for hand-hoe weeding under CA compared to conventional agriculture. However, the use of herbicides reduced weeding labour demand during the early season. The benefits of CA are tied to the farmers’ management intensity including: time of planting, weeding, fertiliser and herbicide application, and adequate training on equipment use. Economic analysis results showed that on average, a farmer incurs losses for switching from conventional agriculture to CA in the main maize growing regions of Zimbabwe. Based on the six seasons’ data, the losses were least with the ripper in drier areas and worst with the direct seeder in wetter areas. Incorporation of chemical herbicides worsens the economic returns of CA tillage options in all the agro-ecological zones. Overall, the study showed that the rip-line seeding is more attractive in the drier areas than direct seeding. Although not costed in this study, critical is the cumulative reversal of soil degradation associated with consistent CA practice which can sustain agriculture. Results from this review suggest that the benefits of CA depend largely on the type and context of CA being practised. It is thus imperative to profile the technology, the farmer socio-economic circumstances and the bio-physical environment in which the farmer operates for proper geographical and beneficiary targeting to achieve greater impact. More longer-term studies are required to fully elucidate the benefits and context of CA options and practice.

Ilstedt U., Bargués Tobella A., Bazié H.R., Bayala J., Verbeeten E., Nyberg G., Sanou J., Benegas L., Murdiyarso D., Laudon H., Sheil D., Malmer A.

Water scarcity contributes to the poverty of around one-third of the world’s people. Despite many benefits, tree planting in dry regions is often discouraged by concerns that trees reduce water availability. Yet relevant studies from the tropics are scarce and the impacts of intermediate tree cover remain unexplored. We developed and tested an optimum tree cover theory in which groundwater recharge is maximized at an intermediate tree density. Below this optimal tree density the benefits from any additional trees on water percolation exceed their extra water use, leading to increased groundwater recharge, while above the optimum the opposite occurs. Our results, based on groundwater budgets calibrated with measurements of drainage and transpiration in a cultivated woodland in West Africa, demonstrate that groundwater recharge was maximised at intermediate tree densities. In contrast to the prevailing view, we therefore find that moderate tree cover can increase groundwater recharge and that tree planting and various tree management options can improve groundwater resources. We evaluate the necessary conditions for these results to hold and suggest that they are likely to be common in the seasonally dry tropics, offering potential for widespread tree establishment and increased benefits for hundreds of millions of people.

Zhang Y., Peng C., Li W., Tian L., Zhu Q., Chen H., Fang X., Zhang G., Liu G., Mu X., Li Z., Li S., Yang Y., Wang J., Xiao X.

China has launched multiple afforestation programs since 1978, including the ‘Three North’ Shelterbelt Development Program (TNSDP), the Beijing–Tianjin Sand Source Control Program (BSSCP), the Nature Forest Conservation Program (NFCP), and the Grain to Green Program (GTGP). These programs focus on local environment restoration by planting trees in semi-arid and arid regions and by protecting natural forests. However, the effectiveness of these programs has been questioned by several previous studies. Here, we report an increasing trend of greenness in this region using the satellite-retrieved normalized difference vegetation index (NDVI) from GIMMS, GIMMS-3g and MODIS datasets in the past 32 years. The NDVI increase for the ‘Three North’ region was 0.28%–0.38% yr −1 in 1982–2000 and 0.86%–1.12% yr −1 in 2000–2013, which is much higher than the country's means of 0.060%–0.063% yr −1 and 0.27%–0.30% yr −1 , respectively. Most of the increase occurred in low and sparsely vegetated areas; and enlarged the moderate vegetated area (growing season mean NDVI above 0.5) from 16.5% to 25.7% for the two time periods, respectively. We also analyzed changes in the length of the growing season and the climate conditions including temperature, precipitation and two drought indices. However, these environmental factors cannot completely explain the changes in vegetation activity. Our study suggests these multiple afforestation programs contributed to the accelerated greening trend in the ‘Three North’ region and highlight the importance of human intervention in regional vegetation growth under climate change condition.

Le Q.B., Nkonya E., Mirzabaev A.

Land degradation affects negatively the livelihoods and food security of global population. There have been recurring efforts by the international community to identify the global extent and severity of land degradation. Using the long-term trend of biomass productivity as a proxy of land degradation at global scale, we identify the degradation hotspots in the world across major land cover types. We correct factors confounding the relationship between the remotely sensed vegetation index and land-based biomass productivity, including the effects of inter-annual rainfall variation, atmospheric fertilization and intensive use of chemical fertilizers. Our findings show that land degradation hotpots cover about 29 % of global land area and are happening in all agro-ecologies and land cover types. This figure does not include all areas of degraded lands, it refers to areas where land degradation is most acute and requires priority actions in both in-depth research and management measures to combat land degradation. About 3.2 billion people reside in these degrading areas. However, the number of people affected by land degradation is likely to be higher as more people depend on the continuous flow of ecosystem goods and services from these affected areas. Land improvement has occurred in about 2.7 % of global land area during the last three decades, suggesting that with appropriate actions land degradation trend could be reversed. We also identify concrete aspects in which these results should be interpreted with cautions, the limitations of this work and the key areas for future research.

Schmocker J., Liniger H.P., Ngeru J.N., Brugnara Y., Auchmann R., Brönnimann S.

Land and water management in semi-arid regions requires detailed information on precipitation distribution, including extremes, and changes therein. Such information is often lacking. This paper describes statistics of mean and extreme precipitation in a unique data set from the Mount Kenya region, encompassing around 50 stations with at least 30 years of data. We describe the data set, including quality control procedures and statistical break detection. Trends in mean precipitation and extreme indices calculated from these data for individual rainy seasons are compared with corresponding trends in reanalysis products. From 1979 to 2011, mean precipitation decreased at 75% of the stations during the ‘long rains’ (March to May) and increased at 70% of the stations during the ‘short rains’ (October to December). Corresponding trends are found in the number of heavy precipitation days, and maximum of consecutive 5-day precipitation. Conversely, an increase in consecutive dry days within both main rainy seasons is found. However, trends are only statistically significant in very few cases. Reanalysis data sets agree with observations with respect to interannual variability, while correlations are considerably lower for monthly deviations (ratios) from the mean annual cycle. While some products well reproduce the rainfall climatology and some the spatial trend pattern, no product reproduces both.

Meijer S.S., Catacutan D., Ajayi O.C., Sileshi G.W., Nieuwenhuis M.

Despite the great potential of agricultural innovations, the uptake by smallholder farmers in sub-Saharan Africa seems to be slow. We reviewed existing theories and frameworks for the uptake of agricultural innovations and found that these tend to emphasize the role of extrinsic factors such as the characteristics of the adopter and the external environment in the decision-making process. In this paper, we argue that intrinsic factors such as the knowledge, perceptions and attitudes of the potential adopter towards the innovation play a key role, but this has been less studied. We present an analytical framework that combines both extrinsic and intrinsic factors in farmers' decisions to adopt new agricultural technologies and apply the framework to agroforestry adoption as a case study. We review the literature on agroforestry adoption in sub-Saharan Africa and identify the extrinsic and intrinsic variables affecting the uptake of agroforestry technologies. We conclude that the uptake of agricultural tech...

Reddy M.K., Debnath S., Singh P., S S.R., Ram A., Kumar S., Kumar N., Prasad R., Dwivedi R.P., Arunachalam A.

Agroforestry, a sustainable land-based management system integrates trees with crops and livestock, has deep historical roots in Asian and African countries. Apart from providing numerous social, economic, and environmental benefits agroforestry plays crucial role in bolstering climate resilience within agricultural systems. This chapter presents different case studies from Asia and Africa showing the potent of tree-based farming practices in enhancing soil health, water management, biodiversity conservation, besides helping to ensure food and nutritional security of rural households. Countries like India, Bangladesh, Nepal, and Uzbekistan have demonstrated agroforestry's potential in boosting agricultural productivity, improving soil health, and diversification of income sources. Similarly, in Africa, agroforestry plays a vital role in combating food insecurity, poverty, and land degradation. This chapter summarizes the pre-requisites for unlocking agroforestry's potential to create a sustainable and climate resilient agricultural landscape.

Pienkowski T., Jagadish A., Battista W., Blaise G.C., Christie A.P., Clark M., Emenyu A.P., Joglekar A., Nielsen K.S., Powell T., White T., Mills M.

Many attempts to scale conservation actions have failed to deliver their intended benefits, caused unintended harm or later been abandoned, hampering efforts to bend the curve on biodiversity loss. Here we encourage those calling for scaling to pause and reflect on past scaling efforts, which offer valuable lessons: the total impact of an action depends on both its effectiveness and scalability; effectiveness can change depending on scale for multiple reasons; feedback processes can change socio-ecological conditions influencing future adoption; and the drive to scale can incentivize bad practices that undermine long-term outcomes. Cutting across these themes is the recognition that monitoring scaling can enhance evidence-informed adaptive management, reporting and research. We draw on evidence and concepts from disparate fields, explore new linkages between often isolated concepts and suggest strategies for practitioners, policymakers and researchers. Reflecting on these five lessons may help in the scaling of effective conservation actions in responsible ways to meet the triple goals of reversing biodiversity loss, combating climate change and supporting human wellbeing. This Perspective encourages conservation practitioners to learn from past efforts to scale conservation actions in the hope that enhanced understanding of linkages between scaling, effectiveness and social justice will benefit future attempts to scale up, out and deep.

Nurlia A., Widarti A., Mindawati N.

Abstract Small-scale forests (SSF) are essential to the community’s ecological, social, and economic aspects. The tree species that many people choose to develop in small-scale forests is sengon. Sengon has various advantages and can be developed in agroforestry with various plants. The research question in this study is how flexible the sengon agroforestry pattern is in Small-Scale Forest Development in Indonesia? The study aimed to determine the flexibility of sengon agroforestry in small-scale forests and the added value of small-scale forests from the economic and ecological aspects. The study was conducted using a systematic review. The results show that small-scale forest development with an agroforestry pattern can diversify income sources from the same land management, thus providing a sustainable income. The sengon agroforestry pattern in small-scale forests can be made with various types of plants (a) woody trees, (b) food crops, (c) plantation crops, (d) horticultural crops, (e) medicinal plants and (f) animal feed crops. Small-scale forest agroforestry patterns can provide economic, ecological, and social benefits. By knowing various alternative agroforestry cropping patterns, communities will be more motivated to improve their small-scale forest management to increase their economy.

Ettinger A.K., Bratman G.N., Carey M., Hebert R., Hill O., Kett H., Levin P., Murphy-Williams M., Wyse L.

AbstractClimate change is exacerbating the need for urban greening and the associated environmental and human well-being benefits. Trees can help mitigate urban heat, but more detailed understanding of cooling effects of green infrastructure are needed to guide management decisions and deploy trees as effective and equitable climate adaptation infrastructure. We investigated how urban trees affect summer air temperature along sidewalks within a neighborhood of Tacoma, Washington, USA, and to what extent urban trees reduce risks of high summer temperatures (i.e., the levels regulated by state outdoor heat exposure rules intended to reduce heat-related illnesses). Air temperature varied by 2.57 °C, on average, across our study area, and the probability of daytime temperatures exceeding regulated high temperature thresholds was up to five times greater in locations with no canopy cover within 10 m compared to those with 100% cover. Air temperatures decreased linearly with increasing cover within 10 m, suggesting that every unit of added tree cover can help cool the air. Our findings highlight the value of trees in mitigating urban heat, especially given expected warming with climate change. Protecting existing urban trees and increasing tree cover (e.g., by planting street trees), are important actions to enhance climate change resilience of urban areas.

Muthuri C.W., Kuyah S., Njenga M., Kuria A., Öborn I., van Noordwijk M.

Agroforestry is a powerful practice for sustainable and regenerative intensification because it promotes multifunctional landscapes that deliver ecological functions that contribute to livelihoods, land productivity, biodiversity conservation, and other ecosystem services. Despite a large body of literature on agroforestry in East Africa, a systematic understanding of its livelihood benefits and contribution to carbon sequestration is still lacking. A systematic review was used to provide a quantitative and qualitative synthesis of available evidence and knowledge gap from 185 publications that met the selection criteria regarding the contribution of agroforestry to livelihoods (n=152) and carbon sequestration (n=43) in East Africa. The main livelihood benefits include fodder, food, firewood and income, reported in over 70, 63, 56 and 40 publications, respectively. These and other benefits diversify livelihoods of rural communities and act as safety nets in times of climate shocks. Agroforestry systems in East Africa stock an average of 24.2±2.8 Mg C ha−1 in biomass and 98.8±12.2 Mg C ha−1 in the soil. Much of the aboveground carbon is held in homegardens (34.3±7.9 Mg C ha−1), perennial tree-crop systems (29.9±12.7 Mg C ha−1) and trees on boundaries (26.7±14.1 Mg C ha−1). Empirical studies are needed for better understanding of belowground carbon in agroforestry and emission of greenhouse gases in different agroforestry practices. A smaller number of studies reported income from sale of carbon credits, suggesting a gap in the development of science regarding carbon rights, land tenure, tree tenure rights, and the potential impact of climate change on the growing niches of tree species in the region. The results show that agroforestry is a powerful climate adaptation and mitigation solution as it can increase household resilience and sequesters significant amounts of carbon dioxide from the atmosphere.

Pascual U., McElwee P.D., Diamond S.E., Ngo H.T., Bai X., Cheung W.W., Lim M., Steiner N., Agard J., Donatti C.I., Duarte C.M., Leemans R., Managi S., Pires A.P., Reyes-García V., et. al.

Abstract Transformative governance is key to addressing the global environmental crisis. We explore how transformative governance of complex biodiversity–climate–society interactions can be achieved, drawing on the first joint report between the Intergovernmental Panel on Climate Change and the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services to reflect on the current opportunities, barriers, and challenges for transformative governance. We identify principles for transformative governance under a biodiversity–climate–society nexus frame using four case studies: forest ecosystems, marine ecosystems, urban environments, and the Arctic. The principles are focused on creating conditions to build multifunctional interventions, integration, and innovation across scales; coalitions of support; equitable approaches; and positive social tipping dynamics. We posit that building on such transformative governance principles is not only possible but essential to effectively keep climate change within the desired 1.5 degrees Celsius global mean temperature increase, halt the ongoing accelerated decline of global biodiversity, and promote human well-being.