Roeland Kindt

What is the relevance of smallholders’ agroforestry systems for conserving tropical tree species and genetic diversity in circa situm, in situ and ex situ settings? A review

Smallholders’ agroforests may be valuable for conserving tropical trees through three main mechanisms. First, trees planted and/or retained by farmers in agricultural landscapes where wild stands were once found may be circa situm reservoirs of biodiversity. Second, farmland trees may support conservation in situ by providing an alternative source of product to reduce extraction from forest, and by acting as ‘corridors’ or ‘stepping stones’ that connect fragmented wild stands. Third, the additional value that planting assigns to trees may result in greater interest in including them in seed collections, field trials and field ‘genebanks’ that support ex situ conservation. Here, we critically review the evidence for these mechanisms, and highlight areas for research and for intervention so that agroforestry practices can better support conservation in each setting, with an emphasis on often neglected genetic-level considerations. Based on current global challenges to diversity, conservation will need to rely increasingly on a smallholder-farm circa situm approach, but concerns on long-term effectiveness need to be properly quantified and addressed. Connectivity between widely dispersed, low density trees in agricultural landscapes is an important factor determining the success of the circa situm approach, while improving farmers’ access to a diversity of tree germplasm that they are interested in planting is required. The circumstances in which agroforestry plantings can support in situ conservation need to be better defined, and research on the stability of active tree seed collections (how long are species and populations retained in them?) as ex situ reservoirs of biodiversity is needed.

Tree diversity in western Kenya: using profiles to characterise richness and evenness

Species diversity is a function of the number of species and the evenness in the abundance of the component species. We calculated diversity and evenness profiles, which allowed comparing the diversity and evenness of communities. We applied the methodology to investigate differences in diversity among the main functions of trees on western Kenyan farms. Many use-groups (all trees and species that provide a specific use) could not be ranked in diversity or evenness. No use-group had perfectly even distributions. Evenness could especially be enhanced for construction materials, fruit, ornamental, firewood, timber and medicine, which included some of the most species-rich groups of the investigated landscape. When considering only the evenness in the distribution of the dominant species, timber, medicine, fruit and beverage ranked lowest (> 60% of trees belonged to the dominant species of these groups). These are also use-groups that are mainly grown by farmers to provide cash through sales. Since not all communities can be ranked in diversity, studies that attempt to order communities in diversity should not base the ordering on a single index, or even a combination of several indices, but use techniques developed for diversity ordering such as the Rényi diversity profile. The rarefaction of diversity profiles described in this article could be used in studies that compare results from surveys with different sample sizes.

Managing biological and genetic diversity in tropical agroforestry

The issues of biological and genetic diversity management in agroforestry are extremely complex. This paper focuses on genetic diversity management and its implications for sustainable agroforestry systems in the tropics, and presents an analysis of the role and importance of inter- and intra-specific diversity in agroforestry. Diversity within and between tree species in traditional agroforestry systems and modern agroforestry technologies in the tropics is assessed, with a view to understanding the functional elements within them and assessing the role and place of diversity. The assessment shows that although the practice of agroforestry has been a diversity management and conservation system, research in agroforestry over time has de-emphasized the diversity element; nevertheless farmers do value diversity and do manage agroforestry from that perspective. Based on a profiling of various traditional agroforestry systems and research-developed technologies, a strong case is made for increased species- and genetic diversity, at both inter- and intra-specific levels. The review and analysis point to the need for increased awareness, training/education, partnerships and collaborative efforts in support of genetic diversity in agroforestry systems; of special importance is increased cross-disciplinary research.All the flowers of all the tomorrows are in the seeds of today – A Chinese proverb

An ecoregion-based approach to protecting half the terrestrial realm

Abstract We assess progress toward the protection of 50% of the terrestrial biosphere to address the species-extinction crisis and conserve a global ecological heritage for future generations. Using a map of Earths 846 terrestrial ecoregions, we show that 98 ecoregions (12%) exceed Half Protected; 313 ecoregions (37%) fall short of Half Protected but have sufficient unaltered habitat remaining to reach the target; and 207 ecoregions (24%) are in peril, where an average of only 4% of natural habitat remains. We propose a Global Deal for Nature—a companion to the Paris Climate Deal—to promote increased habitat protection and restoration, national- and ecoregion-scale conservation strategies, and the empowerment of indigenous peoples to protect their sovereign lands. The goal of such an accord would be to protect half the terrestrial realm by 2050 to halt the extinction crisis while sustaining human livelihoods.

Climate change and tree genetic resource management: maintaining and enhancing the productivity and value of smallholder tropical agroforestry landscapes. A review

Anthropogenic climate change has significant consequences for the sustainability and productivity of agroforestry ecosystems upon which millions of smallholders in the tropics depend and that provide valuable global services. We here consider the current state of knowledge of the impacts of climate change on tree genetic resources and implications for action in a smallholder setting. Required measures to respond to change include: (1) the facilitated translocation of environmentally-matched germplasm across appropriate geographic scales, (2) the elevation of effective population sizes of tree stands through the promotion of pollinators and other farm management interventions; and (3) the use of a wider range of ‘plastic’ species and populations for planting. Key bottlenecks to response that are discussed here include limitations in the international exchange of tree seed and seedlings, and the absence of well-functioning delivery systems to provide smallholders with better-adapted planting material. Greater research on population-level environmental responses in indigenous tree species is important, and more studies of animal pollinators in farm landscapes are required. The development of well-functioning markets for new products that farmers can grow in order to mitigate and adapt to anthropogenic climate change must also consider genetic resource issues, as we describe.

Innovation in input supply systems in smallholder agroforestry: seed sources, supply chains and support systems

Institutional innovation in providing inputs and services is a central element for smallholder development. Agroforestry is an important income generating activity for millions of smallholders in the tropics, yet access to quality planting material—germplasm—of valuable tree species remains a major hurdle for improving farm productivity. We discuss requirements and possibilities for institutional innovation in developing more efficient delivery systems for tree germplasm as one aspect of improved input supply. We describe a simple model for delivery to farmers that identifies the major types of germplasm sources and discuss how this model can be used to identify relevant interventions to address bottlenecks in current systems. Our analysis leads to eight input supply configurations for smallholder agroforestry, typified by three major models. Lessons from the evolution of smallholder crop seed delivery systems can be applied to tree germplasm supply and indicate that a commercial, decentralised model holds most promise for sustainability. However, current emphasis in agroforestry on government and NGO models of delivery hinder the development of this approach. The application of prevailing classification approaches may also create a barrier to the development of appropriate supply systems that effectively service smallholders. An important implication of our analysis is that current actors in agroforestry input supply systems must redefine their roles in order for effective delivery to take place. We chose a case study from Kenya to illustrate our points.

Do Farm Characteristics Explain Differences in Tree Species Diversity among Western Kenyan Farms

With the objective of planning diversification of on-farm tree species composition, a survey was conducted in western Kenya involving a complete tree census (trees were defined as all woody or ligneous plants, including shrubs and lianas) and collection of ethnobotanical information on 201 farms. Differences between farms in diversity of the 12 most frequent use-groups were analysed by species richness, Shannon, Simpson and Berger-Parker diversity indices, and Shannon evenness and equitability. A large range of values was detected among farms and use-groups. Multiple linear regression of diversity statistics on household characteristics indicated significant relationships. However, these relationships generally explained low percentages of variation (ranging 2-44%). The connection between household characteristics and use-group diversity allows targeting specific household types with lower diversity. Farm size had a positive relationship with diversity of most use-groups. However, accumulation curves revealed that the same area carried a larger abundance and diversity when it was composed of a greater number of smaller farms. If the pattern of further subdivision of farmland in the survey area continues and the same differences between smaller and larger farms prevail, then larger diversity per unit area can be expected. Because smaller farms contain smaller diversity, however, diversification with the aim of enhancing or stabilising productivity of individual farms may become an important priority in the survey area. The results presented allow for the identification of individual farms, use-groups, and household types for which diversification is more relevant, and at the same time allow for impact monitoring.

Genetic structuring of important medicinal species of genus Warburgia as revealed by AFLP analysis

The genus Warburgia (Canellaceae) contains four tree species that are of valuable medicinal importance and are all found in Africa. Genetic diversity present in wild populations of these species is under great threat due to unsustainable harvesting for medicines and indiscriminate felling for timber and agricultural expansion. There is therefore an urgent need for conservation of these species. Some authors disagree about the taxonomy of the genus and list different species as synonyms. Amplified fragment length polymorphism (AFLP) technique was used to determine the genetic relationships between three species to resolve the taxonomic confusion. The amount of genetic variation within and among populations was assessed to guide strategies for their conservation and sustainable utilization. Four AFLP primer pairs (EcoRI/MseI) generated a total of 185 amplification products. Analysis of molecular variance revealed most variation among individuals within populations (63%, P < 0.0001), but variation among populations (37%, P < 0.0001) was highly significant as well. Constrained analysis of principal coordinates based on the Jaccard distance confirmed the separation among populations (38.2%, P < 0.0001). A phenetic tree and ordination graphs showed a clear distinction of W. ugandensis from W. salutaris and W. stuhlmannii. W. ugandensis populations from Uganda and western Kenya formed a subgroup that clustered away from the rest of the W. ugandensis populations. W. salutaris and W. stuhlmannii populations showed little genetic differentiation. An implication of the data to genetic management and taxonomic clarification is discussed.

Patterns of species richness at varying scales in western Kenya: planning for agroecosystem diversification

Agroforestry tree domestication research is geared at promoting diversification of on-farm tree species composition. A survey was conducted in western Kenya with the objective of exploring possibilities for diversification for a particular agroecosystem, involving a complete tree census, tree measurement and collection of ethnobotanical information in 201 small-scale farms. Various approaches to landscape diversification were explored, including random distribution of trees to increase alpha richness and species richness at higher scales in the landscape, and random distribution of species composition over villages to increase the average richness of villages. The results showed that random distribution would result in increments of average species richness in the landscape, without requiring increments of total and average abundance. A new, fast and exact method of calculating site-based species accumulation curves was presented. The method yielded results that were extremely close to classical algorithms using 10,000 randomisations. Four use-groups (beverage, fodder, charcoal and soil fertility enhancement) were identified as use-groups with alpha richness smaller than one species, but only beverage and fodder had lowest richness at all scales (fruit and construction wood joined the four use-groups of lowest average species richness at higher scales in the landscape). The novel approaches used in this study could be used in future biodiversity studies on species accumulation patterns, or on spatial distribution patterns of species richness in a landscape.

Climate modelling for agroforestry species selection in Yunnan Province, China

Changing climate is likely to impact on both tree species and agroforestry systems in a variety of ways. A multi-model ensemble approach based on ecological niche modelling was used to understand the impact of climate on distribution of agroforestry trees in Yunnan Province of China. Future changes in distribution of 10 agroforestry tree species were projected using an ensemble of climate projections derived from the results of 19 Earth System Models provided by the Coupled Model Inter-comparison Project-Phase 5. Our model explained suitable habitat, and identified potential locations for mixed agroforestry using selected species. The model suggested west and southwest Yunnan as important location for tea and alder-based agroforestry, while southern parts of Yunnan are better suited for tea and hog plum, and northern parts could support walnut-based agroforestry options. Agroforestry is an important adaptation option for climate change, which could benefiting farmers and enhancing environmental conservation and restoration of the landscape. Display Omitted The ensemble model shows where we are most certain that the species is suitable.The tuning procedure with weighted AUC chose a specific number of best models for ensemble.Based on sensitivity analysis of spatially nested predictions where all sub-models agree that the species is suitable.A multi-model ensemble approach identified suitable habitat for agroforestry tree species.Mixed agroforestry choices for future climate recommended using consensus map outputs.