Global to local genetic diversity indicators of evolutionary potential in tree species within and outside forests

There is a general trend of biodiversity loss at global, regional, national and local levels. To monitor this trend, international policy processes have created a wealth of indicators over the last two decades. However, genetic diversity indicators are regrettably absent from comprehensive bio-monitoring schemes. Here, we provide a review and an assessment of the different attempts made to provide such indicators for tree genetic diversity from the global level down to the level of the management unit. So far, no generally accepted indicators have been provided as international standards, nor tested for their possible use in practice. We suggest that indicators for monitoring genetic diversity and dynamics should be based on ecological and demographic surrogates of adaptive diversity as well as genetic markers capable of identifying genetic erosion and gene flow. A comparison of past and present genecological distributions (patterns of genetic variation of key adaptive traits in the ecological space) of selected species is a realistic way of assessing the trend of intra-specific variation, and thus provides a state indicator of tree genetic diversity also able to reflect possible pressures threatening genetic diversity. Revealing benefits of genetic diversity related to ecosystem services is complex, but current trends in plantation performance offer the possibility of an indicator of benefit. Response indicators are generally much easier to define, because recognition and even quantification of, e.g., research, education, breeding, conservation, and regulation actions and programs are relatively straightforward. Only state indicators can reveal genetic patterns and processes, which are fundamental for maintaining genetic diversity. Indirect indicators of pressure, benefit, or response should therefore not be used independently of state indicators. A coherent set of indicators covering diversity–productivity–knowledge–management based on the genecological approach is proposed for application on appropriate groups of tree species in the wild and in cultivation worldwide. These indicators realistically reflect the state, trends and potentials of the world’s tree genetic resources to support sustainable growth. The state of the genetic diversity will be based on trends in population distributions and diversity patterns for selected species. The productivity of the genetic resource of trees in current use will reflect the possible potential of mobilizing the resource further. Trends in knowledge will underpin the potential capacity for development of the resource and current management of the genetic resource itself will reveal how well we are actually doing and where improvements are required

Tropical and subtropical Asia's valued tree species under threat

Tree diversity in Asia's tropical and subtropical forests is central to nature-based solutions. Species vulnerability to multiple threats, which affects the provision of ecosystem services, is poorly understood. We conducted a region-wide, spatially explicit vulnerability assessment (including overexploitation, fire, overgrazing, habitat conversion, and climate change) of 63 socio-economically important tree species selected from national priority lists and validated by an expert network representing 20 countries. Overall, 74% of the most important areas for conservation of these trees fall outside of protected areas, with species severely threatened across 47% of their native ranges. The most imminent threats are overexploitation and habitat conversion, with populations being severely threatened in an average of 24% and 16% of their distribution areas. Optimistically, our results predict relatively limited overall climate change impacts, however, some of the study species are likely to lose more than 15% of their habitat by 2050 because of climate change. We pinpoint specific natural forest areas in Malaysia and Indonesia (Borneo) as hotspots for on-site conservation of forest genetic resources, more than 82% of which do not currently fall within designated protected areas. We also identify degraded lands in Indonesia (Sumatra) as priorities for restoration where planting or assisted natural regeneration will help maintain these species into the future, while croplands in Southern India are highlighted as potentially important agroforestry options. Our study highlights the need for regionally coordinated action for effective conservation and restoration

Harnessing the diversity of wild relatives of tropical fruit tree species for sustainable livelihoods

South and Southeast Asia is the center of origin for many tropical fruit crops. This region is a prime habitat for in situ conservation of genetic diversity of long-lived, largely out-crossing wild/domesticated Tropical Fruit Tree (TFT) species. Wild TFT species in 36 project sites throughout India, Indonesia, Malaysia and Thailand were examined with an objective of documenting species richness and understanding their local uses and potential value in plant breeding/ecosystem services. Multiple methods such as participatory rural appraisal, baseline survey, focus group discussion on traditional knowledge documentation, fruit diversity fairs, community fruit catalogues and key informant surveys of custodian farmers were carried out focusing on wild species of Mangifera, Garcinia, Nephelium and Citrus. For the genus Mangifera, highest number of wild species (LSQUOsRSQUO) was recorded among the communities of Indonesia (11) and Malaysia (11), while it was 6 in Thailand and only one in India. Communities of Thailand also showed highest LSQUOsRSQUO value for Garcinia (14), while it was 8 for Malaysian, 5 in Indian and 3 for Indonesian communities. For the genus Nephelium, 7 species were used in Malaysia, 5 in Indonesia and 5 in Thailand. However, communities of India showed higher species richness of Citrus (8) and it was 2 for communities of Thailand. This study concludes that South and South East Asian countries are stunningly rich in wild fruit tree species diversity. However their principal economic value as genetic resources and the benefits derived from their associated cultural value is seldom demonstrated by public-sector research initiatives. It is also concluded that there are potentials for marketing of wild species of Mangifera viz. M. pajang, M. caesia, M. odorata, M. casturi; of Citrus viz. C. indica, C. macroptera, C. assamensis, C. ichangensis, C. megaloxycarpa (Sour Pummelo); of Garcinia viz. G. cowa, G. atroviridis, G. indica, G. xanthochymus, G. gummi-gutta and of Nephalium viz. N. ramboutan-ake

Indicators of the genetic diversity of trees – State, pressure, benefit and response. The State of the World’s Forest Genetic Resources – Thematic study

This study, prepared within the ambit of The State of the World’s Forest Genetic Resources, reviews issues related to the development of indicators for tree genetic diversity. It includes a historical account of the development of science-based indicators for tree genetic diversity that embrace ecological surrogates for genetic diversity, the genealogical approach, genetic monitoring of management units, the use of molecular markers, as well as relevant experience from other organisms and policy processes. It also includes a section on relevant data, data sources, and databases. Finally, the study proposes a set of four operational indicators for monitoring tree genetic diversity. The proposed indicators could support efforts towards sustainable forest management, as well as the development of indicators for the post-2020 global biodiversity framework