Climate change impacts on temperate fruit and nut production: a systematic review

Temperate fruit and nut crops require distinctive cold and warm seasons to meet their physiological requirements and progress through their phenological stages. Consequently, they have been traditionally cultivated in warm temperate climate regions characterized by dry-summer and wet-winter seasons. However, fruit and nut production in these areas faces new challenging conditions due to increasingly severe and erratic weather patterns caused by climate change. This review represents an effort towards identifying the current state of knowledge, key challenges, and gaps that emerge from studies of climate change effects on fruit and nut crops produced in warm temperate climates. Following the PRISMA methodology for systematic reviews, we analyzed 403 articles published between 2000 and 2023 that met the defined eligibility criteria. A 44-fold increase in the number of publications during the last two decades reflects a growing interest in research related to both a better understanding of the effects of climate anomalies on temperate fruit and nut production and the need to find strategies that allow this industry to adapt to current and future weather conditions while reducing its environmental impacts. In an extended analysis beyond the scope of the systematic review methodology, we classified the literature into six main areas of research, including responses to environmental conditions, water management, sustainable agriculture, breeding and genetics, prediction models, and production systems. Given the rapid expansion of climate change-related literature, our analysis provides valuable information for researchers, as it can help them identify aspects that are well understood, topics that remain unexplored, and urgent questions that need to be addressed in the future.

Complementary ecosystem services from multiple land uses highlight the importance of tropical mosaic landscapes

Tropical agricultural landscapes often consist of a mosaic of different land uses, yet little is known about the spectrum of ecosystem service bundles and materials they provide to rural households. We interviewed 320 households on the different benefits received from prevalent land-use types in north-eastern Madagascar (old-growth forests, forest fragments, vanilla agroforests, woody fallows, herbaceous fallows, and rice paddies) in terms of ecosystem services and plant uses. Old-growth forests and forest fragments were reported as important for regulating services (e.g. water regulation), whilst fallow lands and vanilla agroforests as important for provisioning services (food, medicine, fodder). Households reported the usage of 285 plant species (56% non-endemics) and collected plants from woody fallows for varying purposes, whilst plants from forest fragments, predominantly endemics, were used for construction and weaving. Multiple land-use types are thus complementary for providing ecosystem services, with fallow lands being particularly important. Hence, balancing societal needs and conservation goals should be based on diversified and comprehensive land management.

Plant species diversity, plant use, and classification of agroforestry homegardens in southern and southwestern Ethiopia

The attainment of ever more sustainable agricultural production and reconciling agriculture with conservation are the main challenges that human beings are confronted with head-on in the future. Through expanding and enhancing agroforestry homegardens at the agricultural landscape level, biodiversity can be increased and maintained while addressing several utility values, ensuring both ecological and socioeconomic sustainability. This study was conducted in agroforestry homegardens of southern and southwestern Ethiopia, to examine plant species richness and other diversity indices, plant use, and classify and identify different types of homegardens based on their species composition and abundance. In total, 93 homegarden owners participated in the study. Two hundred and six (mean 15.44 per homegarden) different plant species (excluding weeds) that belonged to 161 genera and 66 plant families were identified across the studied sites. Fifteen species (about 7.28% of all species recorded) are endemic and threatened to Ethiopia. The overall mean plant species richness per agroforestry homegardens, mean individual density and other diversity parameters varied strongly among sites (P < 0.05). In all of the agroforestry homegardens, roots, and tubers food producing plant species tended to be more dominant (based on summed dominance ratio, SDR) than other species, except the cereal crops barley and maize. Based on cluster analysis, four groups of agroforestry homegardens were identified including, 'small-sized, low plant diversity, barley-potato-enset-apple homegardens (Cluster-1)'; 'intermediate-sized, taro-enset-coffee homegardens (Cluster-2)'; 'large-sized, maize-taro-sweet potato-teff-enset homegardens (Cluster-3)'; and 'small-sized, high plant diversity with mixed-use category homegardens (Cluster-4)'. The results also indicate that agroforestry homegardens as ecological niches are valuable for the conservation and maintenance of biological diversity both for crop genetic as well as forest tree resources, including harboring of endemic and threatened species in those human-dominated landscapes.

The potential impact of future climate change on the production of a major food and cash crop in tropical (sub)montane homegardens

Tropical agroforestry systems support the wellbeing of many smallholder farmers. These systems provide smallholders with crops for consumption and income through their ecological interactions between their tree, soil, and crop components. These interactions, however, could be vulnerable to changes in climate conditions; yet a reliable understanding of how this could happen is not well documented. The aim of this study is to understand how tree-soil-crop interactions and crop yield are affected by changes in climate conditions, which has implications for recognising how these systems could be affected by climate change. We used a space-for-time climate analogue approach, in conjunction with structural equation modelling, to empirically examine how warmer and drier climate conditions affects tree-soil-crop interactions and banana yield in Mt. Kilimanjaro's homegarden agroforest. Overall, the change in climate conditions negatively affected ecological interactions in the homegardens by destabilizing soil nutrient cycles. Banana yield, however, was mainly directly influenced by the climate. Banana yields could initially benefit from the warmer climate before later declining under water stress. Our findings imply that under increasingly warmer and drier climate conditions, homegarden agroforestry may not be a robust long-term farming practice which can protect smallholder's wellbeing unless effective irrigation measures are implemented.

Role of tea plantations in the maintenance of bird diversity in Anji County, China

Background

Tea plantations support regional sustainable development and have the potential to support more biodiversity than urban open spaces. Numerous studies have shown the value of low-intensity agroecosystems for preserving biodiversity, however tea plantations have received less attention. The relationship between tea plantations and the diversity of macro-organisms, such as birds, is still not fully understood.

Methods

We investigated the bird diversity and vegetation conditions and calculated landscape metrics in 30 tea plantations in Anji County, Zhejiang Province, China. At these 30 sampling sites, we recorded 262 individuals belonging to 37 species, which were classified into two guilds: nature- and urban-dependent birds. We used cluster analysis to group the sampling sites based on the abundance of the birds. Then we evaluated the effects of associated plant diversity in tea plantations and the surrounding landscape composition on these bird guilds using species association computation and a generalized linear model.

Results

The results show that the maintenance of bird diversity by tea plantations benefits both nature- and urban-dependent birds. We found that landscape-scale factors surrounding the tea plantations mainly affected the bird richness due to their habitat selection. Landscape agglomeration and habitat quality were the dominant landscape-scale metrics. Patch-scale factors of tea plantations, especially the vegetation structure, had a strong influence on the abundance of the birds. Nature-dependent birds preferred to occur in tea plantations with perennial herbs, while urban-dependent birds were attracted by the general distributed plants, as annual herbs. Therefore, we concluded that tea plantations play an important role as a transitional zone between natural habitats and urban areas, thus reducing the impact of urbanization and maintaining bird diversity in low-quality habitats.

Ecological quality as a coffee quality enhancer. A review

As both coffee quality and sustainability become increasingly important, there is growing interest in understanding how ecological quality affects coffee quality. Here we analyze, for the first time, the state of evidence that ecological quality, in terms of biodiversity and ecosystem functions, impacts the quality of Coffea arabica and C. canephora, based on 78 studies. The following ecosystem functions were included: pollination; weed, disease, and pest control; water and soil fertility regulation. Biodiversity was described by the presence, percentage, and diversity of shade trees. Coffee quality was described by the green bean physical characteristics, biochemical compounds, and organoleptic characteristics. The presence and diversity of shade trees positively impacted bean size and weight and reduced the percentage of rejected beans, but these observations were not consistent over different altitudes. In fact, little is known about the diversity of shade trees and their influence on biochemical compounds. All biochemical compounds varied with the presence of shade, percentage of shade, and elevation. Coffee beans from more diverse tree shade plantations obtained higher scores for final total organoleptic quality than simplified tree shade and unshaded plantations. Decreasing ecological quality diminished ecosystem functions such as pollination, which in turn negatively affected bean quality. Shade affected pests and diseases in different ways, but weeds were reduced. High soil quality positively affected coffee quality. Shade improved the water use efficiency, such that coffee plants were not water stressed and coffee quality was improved. While knowledge on the influence of shade trees on overall coffee quality remains scarce, there is evidence that agroecosystem simplification is negatively correlated with coffee quality. Given global concerns about biodiversity and habitat loss, we recommend that the overall definition of coffee quality include measures of ecological quality, although these aspects are not always detectable in certain coffee quality characteristics or the final cup.

Bee and non-bee pollinator importance for local food security

Pollinators are critical for food security; however, their contribution to the pollination of locally important crops is still unclear, especially for non-bee pollinators. We reviewed the diversity, conservation status, and role of bee and non-bee pollinators in 83 different crops described either as important for the global food market or of local importance. Bees are the most commonly recorded crop floral visitors. However, non-bee pollinators are frequently recorded visitors to crops of local importance. Non-bee pollinators in tropical ecosystems include nocturnal insects, bats, and birds. Importantly, nocturnal pollinators are neglected in current diurnal-oriented research and are experiencing declines. The integration of non-bee pollinators into scientific studies and conservation agenda is urgently required for more sustainable agriculture and safeguarding food security for both globally and locally important crops.

A systems approach framework for evaluating tree restoration interventions for social and ecological outcomes in rural tropical landscapes

The science guiding design and evaluation of restoration interventions in tropical landscapes is dominated by ecological processes and outcomes and lacks indicators and methods that integrate human wellbeing into the restoration process. We apply a new systems approach framework for tree restoration in forest-agricultural landscapes to show how this shortcoming can be addressed. Demonstrating 'proof of concept', we tested statistical models underlying the framework pathways with data collected from a case study in Tanzania. Local community perceptions of nature's values were not affected by levels of self-reported wildlife-induced crop damage. But mapped predictions from the systems approach under a tree restoration scenario suggested differential outcomes for biodiversity indicators and altered spatial patterns of crop damage risk, expected to jeopardize human wellbeing. The predictions map anticipated trade-offs in costs and benefits of restoration scenarios, which we have started to explore with stakeholders to identify restoration opportunities that consider local knowledge, value systems and human wellbeing. We suggest that the framework be applied to other landscapes to identify commonalities and differences in forest landscape restoration outcomes under varying governance and land use systems. This should form a foundation for evidence-based implementation of the global drive for forest landscape restoration, at local scales. This article is part of the theme issue 'Understanding forest landscape restoration: reinforcing scientific foundations for the UN Decade on Ecosystem Restoration'.

2,3-Butanediol from the leachates of pine needles induces the resistance of Panax notoginseng to the leaf pathogen Alternaria panax

Compared with the use of monocultures in the field, cultivation of medicinal herbs in forests is an effective strategy to alleviate disease. Chemical interactions between herbs and trees play an important role in disease suppression in forests. We evaluated the ability of leachates from needles of Pinus armandii to induce resistance in Panax notoginseng leaves, identified the components via gas chromatography-mass spectrometry (GC-MS), and then deciphered the mechanism of 2,3-Butanediol as the main component in the leachates responsible for resistance induction via RNA sequencing (RNA-seq). Prespraying leachates and 2,3-Butanediol onto leaves could induce the resistance of P. notoginseng to Alternaria panax. The RNA-seq results showed that prespraying 2,3-Butanediol onto leaves with or without A. panax infection upregulated the expression of large number of genes, many of which are involved in transcription factor activity and the mitogen-activated protein kinase (MAPK) signaling pathway. Specifically, 2,3-Butanediol spraying resulted in jasmonic acid (JA) -mediated induced systemic resistance (ISR) by activating MYC2 and ERF1. Moreover, 2,3-Butanediol induced systemic acquired resistance (SAR) by upregulating pattern-triggered immunity (PTI)- and effector-triggered immunity (ETI)-related genes and activated camalexin biosynthesis through activation of WRKY33. Overall, 2,3-Butanediol from the leachates of pine needles could activate the resistance of P. notoginseng to leaf disease infection through ISR, SAR and camalexin biosynthesis. Thus, 2,3-Butanediol is worth developing as a chemical inducer for agricultural production.

Leaf functional traits and pathogens: Linking coffee leaf rust with intraspecific trait variation in diversified agroecosystems

Research has demonstrated that intraspecific functional trait variation underpins plant responses to environmental variability. However, few studies have evaluated how trait variation shifts in response to plant pathogens, even though pathogens are a major driver of plant demography and diversity, and despite evidence of plants expressing distinct strategies in response to pathogen pressures. Understanding trait-pathogen relationships can provide a more realistic understanding of global patterns of functional trait variation. We examined leaf intraspecific trait variability (ITV) in response to foliar disease severity, using Coffea arabica cv. Caturra as a model species. We quantified coffee leaf rust (CLR) severity-a fungal disease prominent in coffee systems-and measured key coffee leaf functional traits under contrasting, but widespread, management conditions in an agroforestry system. We found that coffee plants express significant ITV, which is largely related to shade tree treatment and leaf position within coffee canopy strata. Yet within a single plant canopy stratum, CLR severity increased with increasing resource conserving trait values. However, coffee leaves with visible signs of disease expressed overall greater resource acquiring trait values, as compared to plants without visible signs of disease. We provide among the first evidence that leaf traits are correlated with foliar disease severity in coffee, and that functional trait relationships and syndromes shift in response to increased disease prevalence in this plant-pathogen system. In doing so, we address a vital gap in our understanding of global patterns of functional trait variation and highlight the need to further explore the potential role of pathogens within established global trait relationships and spectra.

Arbuscular mycorrhizal fungi contribute to wheat yield in an agroforestry system with different tree ages

Intercropping achieved through agroforestry is increasingly being recognized as a sustainable form of land use. In agroforestry, the roots of trees and crops are intermingled, and their interactions and the production of exudates alter the soil environment and soil microbial community. Although tree–crop interactions vary depending on the stand age of the trees, how stand age affects beneficial microorganisms, including arbuscular mycorrhizal fungi (AMF), and whether changes in soil microorganisms feed back on crop growth in agroforestry systems are unknown. We therefore conducted a long-term field study to compare changes in the soil microbial and AMF communities in a jujube/wheat agroforestry system containing trees of different stand ages: 3-year-old jujube, 8-year-old jujube, and 13-year-old jujube. Our results showed that by changing soil moisture and available phosphorus content, the stand age of the trees had a significant effect on the soil microbial and AMF communities. Soil moisture altered the composition of soil bacteria, in particular the proportions of Gram-positive and Gram-negative species, and available phosphorus had significant effects on the AMF community. A network analysis showed that older stands of trees reduced both AMF diversity and network complexity. An ordinary least squares regression analysis indicated that AMF diversity, network complexity, and stability contributed to wheat yield. Finally, structural equation modeling showed that changes in edaphic factors induced by tree age brought about significant variation in the soil microbial and AMF communities, in turn, affecting crop growth. Our study highlights the crucial roles of soil microorganisms, in particular AMF, in supporting plant growth in agroforestry systems as well as the need to consider stand age in the establishment of these systems.

Tree diversity in a tropical agricultural-forest mosaic landscape in Honduras

Biodiversity decline in the tropics requires the implementation of comprehensive landscape management where agricultural systems are necessarily an integral element of biodiversity conservation. This study evaluates the potential for taxonomic biodiversity conservation within an intensive livestock-agricultural-forest mosaic landscape in Catacamas, Honduras. Tree sampling was performed in 448 plots set up within different forest and agricultural land uses: secondary forests, agroforestry coffee plantations, agriculture, pastures, live fences and riparian forest. All trees with a minimum diameter at breast height of 10 cm were identified and measured. We characterized their tree structure and diversity, and compared tree diversity between the different uses. The results indicate a high degree of tree species diversity: 375 species identified, belonging to 74 families among the 15,096 trees inventoried across 84.2 hectares, including many rare species (40% of the species registered three individuals or fewer). Biodiversity indices for agroforestry coffee were found equivalent to those for natural secondary forests in the Catacamas landscape. Combining biodiversity conservation and agricultural production is possible in human-pressured tropical landscapes through tree cover maintenance. Enrichment practices combining local producers and technical knowledge may improve tree diversity in agricultural landscapes by prioritizing a mix of forest and introduced tree species (rare and with multiple uses).

Catalyzing transformative futures in food and farming for global sustainability

This perspective article highlights the need for transformation in food and farming at three scales to promote a food system that meets UN Sustainable Development Goals. Food insecurity is still a persistent problem globally because of how food and farming sector is currently organized vs. how it should be organized if cultural traditions, environmental concerns, and nutritional needs of the world's growing population were foregrounded. The article argues that system-wide transformations are needed at different scales: landscape (macro), species (meso) and genes (micro). It suggests alternatives available for food and farming sector and identifies transformative pathways that are more sustainable in cultural, social and environmental terms. A better management of farming landscapes; diversification of the food system to include a wider range of species; and better use of neglected and underutilized species, varieties and cultivars of plants, and breeds of animals, in the food system can help to catalyze such a transformation. This can go a long way in promoting global sustainability by achieving three key UN Sustainable Development Goals: 2 (Zero Hunger), 3 (Good Health and Wellbeing) and 15 (Life on Land).

Timber growth, cacao yields, and financial revenues in a long-term experiment of cacao agroforestry systems in northern Honduras

Cacao in Honduras is cultivated under traditional shade tree species (Inga sp., Erythrina sp., Gliricidia sp.), fruit and timber species deliberately planted or selected and managed from natural regeneration. Typically, the shade canopy of these cacao plantations is poorly managed resulting in high tree density and heavy shading, thus affecting cacao yield performance overtime. We assessed 12 cacao plots made up of 15–35 useful timber shade trees with varying spacing 6 × 9, 9 × 9, 8 × 10, and 10 × 12 m. Initially, each plot consisted of three shade components plus cacao. Plantain (Musa x paradisiaca) and madreado (Gliricidia sepium) were used as temporary shade and timber species, were selected as permanent shade. Dasometric data were retrieved to assess growth rates of timber species and cacao yield per plant were recorded to explore the effects of shade cover yield performance and the incidence of main diseases. Specifically, we: a) calculated growth rates and build curves for diameter (DBH), total height (Ht), and commercial volume (Vc) and compared the growing performance with ANOVA and DGC tests; b) run a correlation analysis between shade cover, timber basal area, cocoa yields, and the incidence of monilia and black pod. Statistical differences were found in terms of growth rates among timber species evaluated. Mean annual growth rates were 2.25 cm in DBH, 1 m in Ht, and the standing commercial timber gained was 4.2 m3ha−1year−1. Cocoa yields ranged between 950 and 1,365 kg ha1year1 and were negatively affected by both increased tree cover and timber basal area. Cacao yields were reduced up to 25% when tree cover and tree basal area were over 40% and 10 m2ha−1, respectively. Regardless of timber tree species, no significant effect of tree cover was found on the incidence of cacao diseases. After 22 years, total revenues were determined by the proportion of incomes provided by each component of the agroforestry systems assessed. Five out of 12 timber-based cacao plantations accumulated more than U$95,000 of combined revenues, equivalent to incomes of US$3775 ha−1 year−1. Timber-based cacao plantations are a promising alternative for farm diversification in northern Honduras.

Tree diversity in agroforestry systems of native fine-aroma cacao, Amazonas, Peru

Cocoa cultivation is of considerable economic and social importance to the Amazonas region and is commonly associated with forest species in the region. However, the diversification level and composition of cacao agroforestry systems in Peru are poorly understood. The objective of this study is, therefore, to describe the diversity of tree species in cocoa AFS by plantation age. Accordingly, the number of species of 15 plots covering a total of 1.5 hectares was recorded. Moderately low levels of tree species diversity were reported (H´ ranged 0.89-1.45). In total 17 species were reported throughout the study area. The most abundant botanical family was represented by a single Musa sp. species. The dissimilarity indices show a moderate similarity between the age ranges evaluated (over 62%). Additionally, the IVI indicates that the most important species are used for food and timber apart from providing shade, additionally major of this species are introduced intentionally for the farmers. Based on the observations, it may be concluded that the farmer's interest in obtaining further benefits from the plot, mostly economic benefits affect the diversification of cocoa agroforestry systems.

The terroir of the finch: How spatial and temporal variation shapes phenotypic traits in DARWIN'S finches

The term terroir is used in viticulture to emphasize how the biotic and abiotic characteristics of a local site influence grape physiology and thus the properties of wine. In ecology and evolution, such terroir (i.e., the effect of space or “site”) is expected to play an important role in shaping phenotypic traits. Just how important is the pure spatial effect of terroir (e.g., differences between sites that persist across years) in comparison to temporal variation (e.g., differences between years that persist across sites), and the interaction between space and time (e.g., differences between sites change across years)? We answer this question by analyzing beak and body traits of 4388 medium ground finches (Geospiza fortis) collected across 10 years at three locations in Galápagos. Analyses of variance indicated that phenotypic variation was mostly explained by site for beak size (η² = 0.42) and body size (η² = 0.43), with a smaller contribution for beak shape (η² = 0.05) and body shape (η² = 0.12), but still higher compared to year and site‐by‐year effects. As such, the effect of terroir seems to be very strong in Darwin's finches, notwithstanding the oft‐emphasized interannual variation. However, these results changed dramatically when we excluded data from Daphne Major, indicating that the strong effect of terroir was mostly driven by that particular population. These phenotypic results were largely paralleled in analyses of environmental variables (rainfall and vegetation indices) expected to shape terroir in this system. These findings affirm the evolutionary importance of terroir, while also revealing its dependence on other factors, such as geographical isolation.

Spatial indicator of priority areas for the implementation of agroforestry systems: An optimization strategy for agricultural landscapes restoration

The ecological functions restoration in agricultural areas is a major challenge on a landscape scale. In the specific case of active restoration through Agroforestry Systems (AFS), the absence of a specific direction hinders ecological restoration processes, especially in regions that prefer intensive agriculture. Thus, this study aims to develop a Spatial Indicator of Priority Areas to guide Agroforestry Systems implementation in agricultural landscapes. A spatial multicriteria decision analysis (MDCA) was carried out based on environmental factors: soil, geology and slope (which determine the natural vulnerability of the land) and anthropogenic factors: land use and land cover, forest fragments, potential land use capacity and legal protected areas in rural properties (which reflects human pressure and land use suitability). Subsequently, four priority levels were classified for agroforestry interventions: (1) Low priority; (2) Average priority; (3) High priority; (4) Extreme priority. A final map was made to identify priority areas for landscape recovery in 9 cities located at the mouth of the Mogi Guaçu River Hydrographic Basin, State of São Paulo, Brazil. Considering the natural vulnerability of the land and the multifunctional aspects of the landscape, the scenarios projection allowed a consensus for forest conservation and agricultural suitability perspectives. A final combination of the explored aspects culminated in the spatial indicator, which model foresees 22,300 ha available for urgent actions for restoration, reforestation and sustainable exploitation through agroforestry systems. We emphasize the challenges in reconciling the socioeconomic and ecological functions in the agroecosystem, however, the metric provides a more inclusive and assertive management strategy for natural resources and advances towards the goal of reforestation and implementation of payment for environmental services (PES) schemes.

Using land-use history and multiple baselines to determine bird responses to cocoa agroforestry

Agroforests can play an important role in biodiversity conservation in complex landscapes. A key factor distinguishing among agroforests is land-use history - whether agroforests are established inside forests or on historically forested but currently open lands. The disparity between land-use histories means the appropriate biodiversity baselines may differ, which should be accounted for when assessing the conservation value of agroforests. Specifically, comparisons between multiple baselines in forest and open land could enrich understanding of species' responses by contextualizing them. We made such comparisons based on data from a recently published meta-analysis of the effects of cocoa (Theobroma cacao) agroforestry on bird diversity. We regrouped rustic, mixed shade cocoa, and low shade cocoa agroforests, based on land-use history, into forest-derived and open-land-derived agroforests and compared bird species diversity (species richness, abundance, and Shannon's index values) between forest and open land, which represented the 2 alternative baselines. Bird diversity was similar in forest-derived agroforests and forests (Hedges' g* estimate [SE] = -0.3144 [0.3416], p = 0.36). Open-land-derived agroforests were significantly less diverse than forests (g* = 1.4312 [0.6308], p = 0.023) and comparable to open lands (g* = -0.1529 [0.5035], p = 0.76). Our results highlight how land-use history determined the conservation value of cocoa agroforests. Forest-derived cocoa agroforests were comparable to the available - usually already degraded - forest baselines, but entail future degradation risks. In contrast, open-land-derived cocoa agroforestry may offer restoration opportunities. Our results showed that comparisons among multiple baselines may inform relative contributions of agroforestry systems to bird conservation on a landscape scale.

The Coffee Compromise: Is Agricultural Expansion into Tree Plantations a Sustainable Option?

In tropical regions, land-use pressures between natural forest, commercial tree plantations, and agricultural land for rural communities are widespread. One option is to increase the functionality of commercial plantations by allowing agroforestry within them by rural communities. Such land-sharing options could address wider societal and environmental issues and reduce pressure on natural forest. To investigate the trade-offs involved, we used InVEST to model the ecosystem services provided by growing coffee under commercial pine plantations in Indonesia against other land-use options. Pine–coffee agroforestry provided worse supporting and regulating services (carbon, sediment and nitrogen retention, catchment runoff) than natural forest; however, it provided greater provisioning services (product yield) directly to smallholders. Converting pine monoculture into pine-coffee agroforestry led to increases in all ecosystem services, although there was an increased risk to water quality. Compared with coffee and root crop monocultures, pine–coffee agroforestry provided higher levels of supporting and regulating services; however, product yields were lower. Thus, opening up pine plantations for agroforestry realises additional income-generating opportunities for rural communities, provides wider ecosystem service benefits, and reduces pressure for land-use change. Lower smallholder yields could be addressed through the management of shade levels or through Payments for Ecosystem Services schemes.

Ecosystem Services from Ecological Agroforestry in Brazil: A Systematic Map of Scientific Evidence

(1) Brazil has great potential to expand the area under agroforestry, and thereby simultaneously enhance multiple ecosystem services. However, divergent interests are currently polarized between drastic environmental deregulation and public resource allocation to chemical-intensive land use versus conservation and sustainable agriculture. This highlights an urgent need for a comprehensive overview of the evidence of the benefits to society generated by agroforestry across Brazil. (2) We present a systematic map of the scientific evidence related to the effects of agroforestry on ecosystem services in Brazil. (3) Reviewing 158 peer-reviewed articles, published in international scientific journals (database: Web of Science), we identified a disproportionate emphasis on the Atlantic Forest. Very little research has been published on the Cerrado savanna, Pampa grasslands and Pantanal wetlands. Regulating services were much more frequently studied (85%) than provisioning (13%), while cultural services represent a major gap. A consistent positive effect of agroforestry was demonstrated for soil quality, habitat and food provisioning. Trade-offs were demonstrated for soils and habitats. (4) Our analysis identifies high-priority gaps given their critical importance for human well-being which should be filled: agroforestry effects on water provision and regulation. Moreover, they should assess other ES such as erosion control, flood protection and pest control to enable a more reliable inference about trade-offs.

Contributions of Agroforestry Systems to Food Provisioning of Peasant Households: Conflicts and Synergies in Chiapas, Mexico

Traditional agroforestry systems are widely recognized for their contributions to provisioning, support, regulation, and cultural services. However, because of the advancement of industrial agriculture and a corporative food system, peasants' food systems are rapidly undergoing transformation. We identify the contributions of four types of agroforestry systems (AFS)—shade cocoa agroforest, shade coffee agroforest, milpas and homegardens—to food provisioning in peasant families and discuss conflicts between traditional food systems and the contemporary industrial model of production and consumption confronted by peasants and semi-proletarian migrants. We carried out research in 17 peasant communities in Chiapas, Mexico, and conducted 97 semi-structured interviews and agroecological inventories with peasant families, and 15 interviews with semi-proletarian families laboring in shade-grown coffee plantations. Thirty-nine weekly food diaries were applied in two communities. We recorded 108 plant species belonging to 49 botanic families. These species play an important role as sources of carbohydrates, protein, vitamins, minerals, and fatty acids. Despite the extraordinary agrobiodiversity of peasant agroecosystems, peasant families (PF) are changing their AFS' structure, composition and functions due to the influence of agribusiness, global markets, and public policies that orient changes in production and marketing, which in turn devalue local food, agrobiodiversity, and knowledge. Changing perceptions regarding the value of “good food” vs. “food of the poor” and competition over land use between traditional and modern systems are driving changes in diet, food sources, and health of PF who are including industrialized foods in their diets, driving changes in consumption patterns and affecting human health. For semi-proletarian migrants laboring in coffee plantations, land access in and outside of the plantation and strengthening social networks could mean access to healthier and culturally appropriate foods. While peasants have historically responded to market and household needs, articulating both activities to satisfy family needs and provide income is limited. This work highlights the urgent need to acknowledge the non-monetary value of local foods, agrobiodiversity, local knowledge, community building, and the need to work towards securing land access for landless workers in Latin America.

Agroecosystem diversification with legumes or non-legumes improves differently soil fertility according to soil type

Plant diversification through crop rotation or agroforestry is a promising way to improve sustainability of agroecosystems. Nonetheless, criteria to select the most suitable plant communities for agroecosystems diversification facing contrasting environmental constraints need to be refined. Here, we compared the impacts of 24 different plant communities on soil fertility across six tropical agroecosystems: either on highly weathered Ferralsols, with strong P limitation, or on partially weathered soils derived from volcanic material, with major N limitation. In each agroecosystem, we tested several plant communities for diversification, as compared to a matching low diversity management for their cropping system. Plant residue restitution, N, P and lignin contents were measured for each plant community. In parallel, the soil under each community was analyzed for organic C and N, inorganic N, Olsen P, soil pH and nematode community composition. Soil potential fertility was assessed with plant bioassays under greenhouse controlled climatic conditions. Overall, plant diversification had a positive effect on soil fertility across all sites, with contrasting effects depending on soil type and legumes presence in the community. Communities with legumes improved soil fertility indicators of volcanic soils, which was demonstrated through significantly higher plant biomass production in the bioassays (+18%) and soil inorganic N (+26%) compared to the low diversity management. Contrastingly, communities without legumes were the most beneficial in Ferralsols, with increases in plant biomass production in the bioassays (+39%), soil Olsen P (+46%), soil C (+26%), and pH (+5%). Piecewise structural equation models with Shipley's test revealed that plant diversification impacts on volcanic soil fertility were related to soil N availability, driven by litter N. Meanwhile, Ferralsols fertility was related to soil P availability, driven by litter P. These findings underline the importance of multifactorial and multi-sites experiments to inform trait-based frameworks used in designing optimal plant diversification in agroecological systems.

Envisioning the Future of Mosaic Landscapes: Actor Perceptions in a Mixed Cocoa/Oil-Palm Area in Ghana

The future and benefits of mosaic landscapes have been a source of scientific and societal concern due to increasing population growth, climate change, urbanization, and expanding agricultural commodities. There is a growing call for integrated landscape approaches in which landscape actors discuss trade-offs between different land uses with a view to reaching a negotiated decision on the allocation of land uses. Yet, the operationalization of such approaches is still in its infancy, and integrated methodologies to visualize actors' landscape visions are still scarce. This study therefore presents a participatory spatial scenario-building methodology that uncovers local perceptions of landscape dynamics and needed actions in a mixed cocoa-oil-palm landscape in Ghana's Eastern Region. The methodology visualizes landscape actors' perceived plausible changes and desired future landscapes, and is designed to trigger discussions on actions needed to achieve these desired futures. Findings show that farmers and institutional actors are aware of their landscapes with future preferences coming close to actual landscape composition and spatial configuration, and that-contrary to common assumptions-only those in the oil-palm-dominated landscape who already experienced the drawbacks of increasing landscape homogenization desire a mosaic landscape. The paper concludes that the collective mapping process makes actors aware of challenges at landscape level and increases farmers' negotiation power through active engagement in the process and visualization of their knowledge and visions. Application of the methodology requires dedicated funding, political will, and capacity to apply it as an ongoing process, as well as monitoring feedback loops.

Genome-edited tree crops: mind the socioeconomic implementation gap

The discussion about CRISPR/Cas genome editing is focused mostly on technical aspects to improve productivity and climate resilience in major tree crops such as cocoa, coffee, and citrus. We suggest a solution to the largely ignored socioeconomic impacts for farmers, when new genome-edited varieties are introduced from the laboratory to the field.

Does the Presence of Shade Trees and Distance to the Forest Affect Detection Rates of Terrestrial Vertebrates in Coffee Home Gardens?

Complex agroforestry systems can host similar biodiversity levels to adjacent continuous forests and can offer important ecosystem services for wildlife. Species inhabiting adjacent forests, as well as species that prefer agroforestry systems, can benefit from this habitat matrix. It is necessary, however, to understand the species-specific adaptability to such a complex matrix. Indonesia is a biodiversity hotspot and hosts many endemic species that are threatened with extinction. Its human population relies heavily on agriculture, meaning that finding a balance between crop productivity and biodiversity is key for the long-term sustainability of local communities and wildlife. We aim to determine the influence of the presence of shade trees and distance to the forest on the detection rates of wildlife in coffee home gardens. In West Java, Indonesia, we monitored 23 gardens between April 2018 and March 2021 via camera traps, totalling 3856 days of monitoring in shade-grown and 3338 days in sun-exposed gardens. We also collected data in the nearby montane rainforest, totalling 1183 days of monitoring. We used Generalized Additive Models to estimate the influence of shade cover and distance to the forest on the detection rates of wildlife. The Sunda leopard cat Prionailurus javanensis was found more frequently in shade-grown gardens and used both the forest and agroforest matrix. Wild boars Sus scrofa mostly occurred in gardens adjacent to the forest, while barred buttonquails Turnix suscitator were associated with gardens far (>1 km) from the forest. Several species (civets Viverricula indica and Paradoxus musangus javanicus, Horsfield’s treeshrew Tupaia javanica, Javan ferret badger Melogale orientalis, Javan mongoose Herpestes javanicus) were not influenced by shade cover and distance to the forest, suggesting they are well adapted to the agroforestry system. Still, species of high conservation importance, such as Javan leopard Panthera pardus melas, Sunda porcupine Hystrix javanica, and grizzled langur Presbytis comata, were present in the forest but not in the agroforest, suggesting that the replacement of the forest by the agroforestry matrix is still detrimental. Nevertheless, it is important to maintain the complexity of the agroforestry system and connectivity with the neighbouring continuous forest to favour the long-term sustainability of this environment and the conservation of endemic species.

Farm Rejuvenation-Induced Changes in Tree Spatial Pattern and Live Biomass Species of Cocoa Agroforests in Central Cameroon: Insights for Tree Conservation Incentives in Cocoa Landscapes

Cocoa agroforests sustain ecosystem services (ESs) to varying degrees. These services are otherwise mostly provided by other non-cocoa shade or companion trees. However, the density of shade trees is associated with services and/or disservices that drive farm-specific tree management successions. Considering the growing impacts of climate crisis on farm productivity and the need for adaptation strategies, the ESs are increasingly provisional and contingent on the prevailing vegetation, land tenure, and management successions, amongst others social and ecological factors. To assess the temporal changes in shade management, we surveyed an age gradient of “family farms” in cocoa agroforests created from forest (fCAFS) and savannah (sCAFS) land cover. We evaluated the temporal changes in farm structure, relative tree abundance, and live aboveground biomass of the major canopy strata. We used a spatial point process and linear mixed effect analysis to assess the contributions of associated perennial trees (AsT) on farm rejuvenation patterns. The density of cocoa trees was inconsistent with farm age; this was significantly high on farms in sCAFS (1544 trees ha−1) with spatially random configuration across farm age. On farms in fCAFS, we observed a transition of the cocoa tree configuration in the order regular, random, and clustering from young (with highest density of 1114 trees ha−1) to old farms. On a temporal scale, there is no clear distinction of farm structure and biomass between fCAFS and sCAFS. However, the cycle of tree species and structural composition of the canopy strata are dissimilar; the live biomass allocation for the considered use groups of tree species was different with farm age. The observed dynamics in canopy tree structure and live biomass provide insights into farmers’ temporal allocation of uses and prioritization of different tree species with farm age. We recommend the consideration of such landscape-specific, tree management dynamics in proposing on-farm tree conservation incentives. Our results are also conducive to reliable estimates of the ecosystem services from CAFS in the national implementation of conservation mechanisms such as REDD+.

Elucidating Pathways and Discourses Linking Cocoa Cultivation to Deforestation, Reforestation, and Tree Cover Change in Nicaragua and Peru

Cocoa cultivation is labeled as a driver of both deforestation and reforestation, yet the extent of the phenomena varies at farm and landscape level and as a response to national and local contexts. In this study, we documented the main pathways and contexts behind cocoa cultivation in two sites with different histories of cocoa cultivation. We combined official statistics, land-use trajectory, satellite imagery, and the Q-analysis to explore the discourses of country experts in Nicaragua and Peru. The Q-statements were based on an analysis of a set of legal, institutional, social, and technical guidelines that the cocoa cultivation/sector influences or is influenced by. Based on the responses of national experts to 31 statements we found four discourses linking cocoa cultivation and reforestation and deforestation in each country-case study. The enabling and limiting conditions driving tree cover change were a combination of landscape configuration, governance, management/commercialization models, and farmer's knowledge. Overall, between 60 and 64% of the variance was explained by four discourse factors in each country. In Nicaragua, the conditions associated with reforestation were the cocoa-agroforestry model promoted by local organizations/NGOs, the existence of incentives, degree of technical knowledge, access to safe market, and availability of improved genetic material. The circumstances associated with deforestation were the age of the farmers, fluctuation of cocoa beans prices, low productivity of cocoa plantations, and weak legal environmental frameworks. Whereas, in Peru, the main factors connecting cocoa cultivation to reforestation were access to market, degree of experimentation in cocoa, the economic weight of cocoa on family's income, certification processes, the existence of incentives, and the level of organization/association of cocoa farmers. The elements linking cocoa farming to deforestation were the influence of stakeholders in the cocoa value chain, weak legal environmental frameworks, fluctuation of cocoa prices, the existence of private investors, and insecure land tenure rights. This article demonstrated the utility of discourse analysis, through its application to two contrasting country case-studies, to elucidate the conditions that might minimize the deforestation footprint of cocoa cultivation and maximize its role as an agent for reforestation/restoration in the agricultural landscape of cocoa-growing areas in Latin America.

Wild Food Harvest, Food Security, and Biodiversity Conservation in Jamaica: A Case Study of the Millbank Farming Region

Harvesting wild food is an important coping strategy to deal with food insecurity in farming households across the Caribbean. The practice is tightly connected to the region's unique agrarian history, food heritage, traditional cuisine, and local knowledge of wild or semidomesticated plants. In Jamaica, small-scale farmers are the chief stewards of agrobiodiversity, and their food security and well-being are often dependent on wild food harvest. Yet, there is a paucity of empirical research on the relationship between wild food use, food security, and biodiversity conservation. In this paper, we use the knowledge and lived experience of rural farmers in a remote community (Millbank) at the edge of the Blue and John Crow Mountains National Park (BJMNP) to explore the relationship between wild food harvest and food insecurity within the context of protected area management. Specifically, we seek to (1) characterize different patterns of wild food harvest; (2) examine the relationship between food insecurity and wild food harvest, and (3) explore the implications of forest conservation measures for wild food harvest. Detailed interviews were conducted with 43 farmers to capture data on food insecurity, wild food collection, livelihood satisfaction, household characteristics, farming activities, livelihood strategies, and forest resource interaction. The Food Insecurity Experience Scale (FIES) was used to characterize food insecurity, while participatory techniques were used to develop indicators to assess the well-being of farmers. The results show strong evidence of a relationship between wild food harvest and food insecurity (p &lt; 0.001). Overall, the findings support the importance of wild foods to the well-being of rural households and provide empirical evidence for its inclusion in food security, poverty, and biodiversity conservation policies.

Organic Farming Practices and Shade Trees Reduce Pest Infestations in Robusta Coffee Systems in Amazonia

Coffee agroforestry systems could reconcile agricultural and environmental objectives. While pests and diseases can reduce yield, their interactions with shade and nutrition have been rarely researched, and are particularly lacking in perennial systems. We hypothesized that intermediate shade levels could reduce coffee pests while excess shade could favor fungal diseases. We hypothesized that organic rather than mineral fertilization would better synchronize with nutrient uptake and higher nutrient inputs would be associated with reduced pest and disease damage due to higher plant vigor, yet effects would be less obvious in shaded plots as coffee growth would be light-limited. Using three-year-old trees of Coffea canephora var. Robusta (robusta coffee) in the Ecuadorian Amazon, we compared a full-sun system with four shading methods creating different shade levels: (1) Myroxylon balsamum; (2) Inga edulis; (3) Erythrina spp.; or, (4) Erythrina spp. plus Myroxylon balsamum. Conventional farming at either (1) moderate or (2) intensified input and organic farming at (3) low or (4) intensified input were compared in a split-plot design with shade as the main plot factor and farming practice as the sub-plot factor. The infestation of the following pests and disease incidences were evaluated monthly during the dry season: brown twig beetle (Xylosandrus morigerus), coffee leaf miner (Leucoptera coffeella), coffee berry borer (Hypothenemus hampei), anthracnose disease (Colletotrichum spp.), thread blight (Pellicularia koleroga), and cercospora leaf spot (Cercospora coffeicola). Coffee berry borer and brown twig beetle infestation were both reduced by 7% in intensified organic treatments compared to intensified conventional treatments. Colonization of coffee berry borer holes in coffee berries by the entomopathogenic fungus Beauveria bassiana was also assessed. Brown twig beetle infestation was significantly higher under full sun than under Inga edulis, yet no other shade effects were detected. We demonstrate for the first time how intensified input use might promote pest populations and thus ultimately lead to robusta coffee yield losses.

Simulating Agroforestry Adoption in Rural Indonesia: The Potential of Trees on Farms for Livelihoods and Environment

In recent years, agroforestry has gained increasing attention as an option to simultaneously alleviate poverty, provide ecological benefits, and mitigate climate change. The present study simulates small-scale farmers’ agroforestry adoption decisions to investigate the consequences for livelihoods and the environment over time. To explore the interdependencies between agroforestry adoption, livelihoods, and the environment, an agent-based model adjusted to a case study area in rural Indonesia was implemented. Thereby, the model compares different scenarios, including a climate change scenario. The agroforestry system under investigation consists of an illipe (Shorea stenoptera) rubber (Hevea brasiliensis) mix, which are both locally valued tree species. The simulations reveal that farmers who adopt agroforestry diversify their livelihood portfolio while increasing income. Additionally, the model predicts environmental benefits: enhanced biodiversity and higher carbon sequestration in the landscape. The benefits of agroforestry for livelihoods and nature gain particular importance in the climate change scenario. The results therefore provide policy-makers and practitioners with insights into the dynamic economic and environmental advantages of promoting agroforestry.

Towards sustainable agroforestry management: Harnessing the nutritional soil value through cocoa mix waste

Climate change and environmental degradation have contributed in compromising the soil nutrient integrity of cocoa farmlands, yet sustainable nutrient recycling innovation in cocoa waste management has received less research attention. Utilizing experimentation methodology in an agroforestry system composed of cocoa (Theobroma cacao L.) and a Nitrogen-fixing Gliricidia sepium (Jacq. Kunth ex Walp.), the study examines how the soil nutritional level of farmland can be enhanced. The study confirms the proposition that the rate of decomposition and nutrients release from an innovative mixed waste sample (60% cocoa waste and 40% gliricidia waste in this case) is significantly higher in comparison with the traditional cocoa waste only sample. The results further established that innovative mixed waste sample had a faster decomposition rate (no biomass left at 216 days after laying) as compared to traditional cocoa waste which fully decomposed at 277 days after laying. A difference of 51 days after laying justifies the waste mixture decomposition as a sustainable nutrient recycling innovation within cocoa agroforestry waste management context. These results have implications for agroforestry waste management, soil nutrient recycling and cocoa industry performance.

Synergistic impacts of anthropogenic fires and aridity on plant diversity in the Western Ghats: Implications for management of ancient social-ecological systems

Identifying the impacts of anthropogenic fires on biodiversity is imperative for human-influenced tropical rainforests because: i) these ecosystems have been transformed by human-induced fires for millennia; and ii) their effective management is essential for protecting the world's terrestrial biodiversity in the face of global environmental change. While several short-term studies elucidate the impacts of fires on local plant diversity, how plant diversity responds to fire regimes over long timescales (>100 years) is a significant knowledge gap, posing substantial impediment to evidence-based management of tropical social-ecological systems. Using wet evergreen forests of the Western Ghats of India as a model system, we discuss the synergistic effects of anthropogenic fires and enhanced aridity on tropical plant diversity over the past 4000 years by examining fossil pollen-based diversity indices (e.g., pollen richness and evenness, and temporal β-diversity), past fire management, the intervals of enhanced aridity due to reduced monsoon rainfall and land use history. By developing a historical perspective, our aim is to provide region-specific management information for biodiversity conservation in the Western Ghats. We observe that the agroforestry landscape switches between periods of no fires (4000-1800 yr BP, and 1400-400 yr BP) and fires (1800-1400 yr BP, and 400-0 yr BP), with both fire periods concomitant with intervals of enhanced aridity. We find synergistic impacts of anthropogenic fires and aridity on plant diversity uneven across time, pointing towards varied land management strategies implemented by the contemporary societies. For example, during 1800-1400 yr BP, diversity reduced in conjunction with a significant decrease in the canopy cover related to sustained use of fires, possibly linked to large-scale intensification of agriculture. On the contrary, the substantially reduced fires during 400-0 yr BP may be associated with the emergence of sacred forest groves, a cultural practice supporting the maintenance of plant diversity. Overall, notwithstanding apparent changes in fires, aridity, and land use over the past 4000 years, present-day plant diversity in the Western Ghats agroforestry landscape falls within the range of historical variability. Importantly, we find a strong correlation between plant diversity and canopy cover, emphasising the crucial role of maintenance of trees in the landscape for biodiversity conservation. Systematic tree management in tropical social-ecological systems is vital for livelihoods of billions of people, who depend on forested landscapes. In this context, we argue that agroforestry landscapes can deliver win-win solutions for biodiversity as well as people in the Western Ghats and wet tropics at large.

Moult of overwintering Wood Warblers Phylloscopus sibilatrix in an annual-cycle perspective

Wood Warblers, an Afro-Palearctic migrant species, are declining steadily in Europe likely due to mortality outside their breeding grounds. However, little is known about their overwintering, and records about the sensitive life-cycle stage of moult in Africa are practically absent. To fill this gap, we report on moult of Wood Warblers captured over two winters (January-February) in 2019-2020 in Cameroon. We caught 14 individuals, of which 12 were monitored for flight feather moult. All inspected individuals showed advanced stages of flight feather renewal. Despite low sample sizes, Underhill-Zucchini moult models aptly explained variation in primary and secondary moult (R ² = 0.61). Estimated moult onset date was 26 December, completion date was 25 February, and moult duration was 61 days. These findings fit well with experimental data on the annual cycle and the timing of recently published migration tracks of Wood Warblers. Jointly, the data suggest that moult timing is set by an internal programme, which enables Wood Warblers to organise their multi-stage migration such that they reach suitable moulting habitat in time, and can depart in time with a fresh plumage for the breeding grounds. In our study, moult occurred during the peak of the dry season, which in Cameroon nonetheless shows high relative humidity. During our mist-netting on 28 cocoa plantations of varying shade cover, Wood Warblers were caught on 6 farms whose canopies were comparatively open. These data suggest that the birds encounter in Cameroon relatively stable climatic conditions for moult, and do not measurably prefer closed-canopy forests. Our findings are important, because successful moult increases survival prospects and because moult needs to be safely embedded in a migratory life cycle. Hence, information on moult timing and location is essential for identifying year-round vulnerabilities of Wood Warblers.

Behavioral Ecology of the Coffee White Stem Borer: Toward Ecology-Based Pest Management of India's Coffee Plantations

India is the seventh largest producer of coffee with 395,000 tons of coffee exports that earn 10 billion US dollars annually. Two varieties of coffee are grown in India, Coffea arabica (arabica) and Coffea canephora (robusta). Xylotrechus quadripes, commonly known as Coffee White Stem Borer (CWSB), is a major pest of arabica, causing yearly crop damage of 17–40 million dollars. Management strategies, over 100 years in development, have provided successful, yet inconsistent solutions due to differences in local climate, elevation, natural enemies, grower diligence, and other factors. In addition, increased pesticide use affects both pests as well as their natural enemies, which has severe negative impacts on the biodiverse regions where coffee is grown. As a result, our goal is to develop an ecology-based solution for long term management of CWSB that reduces the use of pesticides and focuses on the importance of natural enemies and native hosts. In situ behavioral experiments were performed to examine the preferences of CWSB for various local species under field conditions. We found that CWSB beetles were attracted to both healthy arabica and robusta plants, and host plant volatiles played a key role in host selection. In addition, the beetles were attracted to the leaves of these coffee plants and also two species of cut stems from common shade trees; Spathodea campanulata (nandi flame) and Grevillea robusta (silver oak). Beetles were not attracted toward cut stems of Tectona grandis (teak) or Coffea arabica. GC-EAD and EAG experiments were then performed to identify host plant volatiles for these species, and these compounds were tested in field conditions to assess their effectiveness against the known chemical attractant pheromone. We found that the CWSB was attracted to our identified host volatile blend as much as the pheromone lure, although trap catches in general were very low. Having an understanding of the behavioral ecology of this pest can form the basis for new methods that use natural attractant and repellent plants to control the pests, reduce the cost of plantation pest management, and avoid the extensive use of insecticides.

Does Sentinel-1A Backscatter Capture the Spatial Variability in Canopy Gaps of Tropical Agroforests? A Proof-of-Concept in Cocoa Landscapes in Cameroon

A reliable estimation and monitoring of tree canopy cover or shade distribution is essential for a sustainable cocoa production via agroforestry systems. Remote sensing (RS) data offer great potential in retrieving and monitoring vegetation status at landscape scales. However, parallel advancements in image processing and analysis are required to appropriately use such data for different targeted applications. This study assessed the potential of Sentinel-1A (S-1A) C-band synthetic aperture radar (SAR) backscatter in estimating canopy cover variability in cocoa agroforestry landscapes. We investigated two landscapes, in Center and South Cameroon, which differ in predominant vegetation: forest-savannah transition and forest landscape, respectively. We estimated canopy cover using in-situ digital hemispherical photographs (DHPs) measures of gap fraction, verified the relationship with SAR backscatter intensity and assessed predictions based on three machine learning approaches: multivariate bootstrap regression, neural networks regression, and random forest regression. Our results showed that about 30% of the variance in canopy gap fraction in the cocoa production landscapes was shared by the used SAR backscatter parameters: a combination of S-1A backscatter intensity, backscatter coefficients, difference, cross ratios, and normalized ratios. Based on the model predictions, the VV (co-polarization) backscatter showed high importance in estimating canopy gap fraction; the VH (cross-polarized) backscatter was less sensitive to the estimated canopy gap. We observed that a combination of different backscatter variables was more reliable at predicting the canopy gap variability in the considered type of vegetation in this study—agroforests. Semi-variogram analysis of canopy gap fraction at the landscape scale revealed higher spatial clustering of canopy gap, based on spatial correlation, at a distance range of 18.95 m in the vegetation transition landscape, compared to a 51.12 m spatial correlation range in the forest landscape. We provide new insight on the spatial variability of canopy gaps in the cocoa landscapes which may be essential for predicting impacts of changing and extreme (drought) weather conditions on farm management and productivity. Our results contribute a proof-of-concept in using current and future SAR images to support management tools or strategies on tree inventorying and decisions regarding incentives for shade tree retention and planting in cocoa landscapes.

Shade-Tree Rehabilitation in Vanilla Agroforests is Yield Neutral and May Translate into Landscape-Scale Canopy Cover Gains

Agroforestry can contribute to an increase in tree cover in historically forested tropical landscapes with associated gains in biodiversity and ecosystem functioning, but only if established on open land instead of underneath a forest canopy. However, declines in yields with increasing shade are common across agroforestry crops, driving shade-tree removal in forest-derived agroforests and hindering tree regrowth in open-land-derived agroforests. To understand trajectories of change in tree cover in forest- and open-land-derived agroforests, and the impacts of tree cover on vanilla yields, we studied 209 vanilla agroforests along an 88-year chronosequence in Madagascar. Additionally, we used remotely sensed canopy cover data to investigate tree cover change in the agricultural landscape. We found yields to vary widely but independently of canopy cover and land-use history (forest- vs. open-land-derived), averaging at 154.6 kg ha−1 year−1 (SD = 186.9). Furthermore, we found that forest- and open-land-derived vanilla agroforests gained canopy cover over time, but that only open-land-derived agroforests gained canopy height. Canopy cover increased also at the landscape scale: areas in the agricultural landscape with medium initial canopy cover gained 6.4% canopy cover over 10 years, but canopy cover decreased in areas with high initial canopy cover. These opposing trends suggest tree cover rehabilitation across areas covered by vanilla agroforests, whereas remnant forest fragments in the agricultural landscape were transformed or degraded. Our results indicate that yield-neutral tree rehabilitation through open-land-derived agroforestry could, if coupled with effective forest protection, provide benefits for both ecosystem functions and agricultural production in a smallholder-dominated agricultural landscape.

Veteran trees are a source of natural enemies

Predation of invertebrate pest by natural enemies is a critical contribution of nature to people, because invertebrate pests cause a vast amount of economic damage and pesticides use has many long-term costs. Veteran trees are keystone structures and hotspots for biodiversity, and are a potential source of natural enemies. To explore this, we used a balanced experimental design where we measured predatory beetle diversity and attack marks on three colors of artificial caterpillars placed around 20 veteran oaks and 20 nearby young oaks, in Southern Norway. We predicted that around the veteran oaks there would be a greater diversity of predatory beetles and more invertebrate attacks on artificial caterpillars. Sampling for predatory beetles was conducted in summer 2017 and 2018, and invertebrate attacks were measured in 2018. We found support for the predictions: diversity of predatory beetles was higher around veteran trees and there were more arthropod attack marks on artificial caterpillars placed around veteran trees. Our results indicated that veteran trees are a source of natural enemies. Valuing and protecting veteran trees and their communities is an essential step towards a more sustainable system of management that has the possibility of promoting both the wellbeing of people and biodiversity.

Legacy Effects Overshadow Tree Diversity Effects on Soil Fungal Communities in Oil Palm-Enrichment Plantations

Financially profitable large-scale cultivation of oil palm monocultures in previously diverse tropical rain forest areas constitutes a major ecological crisis today. Not only is a large proportion of the aboveground diversity lost, but the belowground soil microbiome, which is important for the sustainability of soil function, is massively altered. Intermixing oil palms with native tree species promotes vegetation biodiversity and stand structural complexity in plantations, but the impact on soil fungi remains unknown. Here, we analyzed the diversity and community composition of soil fungi three years after tree diversity enrichment in an oil palm plantation in Sumatra (Indonesia). We tested the effects of tree diversity, stand structural complexity indices, and soil abiotic conditions on the diversity and community composition of soil fungi. We hypothesized that the enrichment experiment alters the taxonomic and functional community composition, promoting soil fungal diversity. Fungal community composition was affected by soil abiotic conditions (pH, N, and P), but not by tree diversity and stand structural complexity indices. These results suggest that intensive land use and abiotic filters are a legacy to fungal communities, overshadowing the structuring effects of the vegetation, at least in the initial years after enrichment plantings.