Research aims - This project will deliver some of the first information about the role that the high diversity of tropical forests plays in supporting their functioning and stability. The project will also have specific applications by influencing tropical forest enrichment planting policy.
Forest biodiversity as an insurance against global change – We will use experimental plots of a large forest biodiversity experiment of the Sabah Biodiversity Experiment (SBE) (Hector et al., 2011b) and additional comparative study plots at the Borneo site to analyse patterns of tree mortality in 25 species to investigate whether differences in survival in the face of drought increase system stability in the context of the more frequent and intense El Nino droughts predicted for this century. The species belong to the genus Shorea of the dominant tree family in SE Asian rainforests, the Dipterocarpaceae. The influence of abiotic environmental drivers such as climate and soil conditions as well as biotic drivers such as competition and pathogens on differential mortality between species will be tested with novel statistical approaches and in collaboration with project 7. The biodiversity within the forest ecosystem resulting from these mortality patterns will be predicted, and information from the experiment will be used to infer the consequences of biodiversity change for ecosystem functioning and services. Ecosystem services such as timber yield and carbon storage will be predicted under different land-use scenarios at policy-relevant scales. A satellite study will be carried out using data from another large forest biodiversity experiment in Southeast China (BEF-China, Bruelheide et al. 2011) to test predictions made with the Borneo data in a subtropical ecosystem
Genome-wide polymorphism, phenotypic diversity and effects on forest ecosystem functioning – The SBE provides an ideal and unique opportunity to study effects of genetic diversity on ecosystem functioning. Genomic data for many Dipterocarpaceae species and the draft genome of Shorea leprosula are available and will be used as a scaffold to study genome-wide polymorphism. For each of four target species, Shorea leprosula, S. parvifolia, S. beccariana, 40 individuals from the SBE and 10 individuals from the surrounding natural forests will be initially surveyed by microsatellites (Ng et al. 2009). The genome size of Shorea species is relatively small (about 450 Mb). To survey the genome-wide polymorphism, 5-fold coverage of the 50 individuals of each species will be obtained using NGS in the Functional Genomics Center Zurich (FGCZ). The level of genome-wide polymorphism, population structure and demography will be estimated, with comparison among other species in the region. The polymorphism data will be used to test whether genetic diversity affects community- and ecosystem-level processes. Moreover, we will measure phenotypes that are relevant for feedback, such as phenology and carbon-related traits. The common environment for the transplanted trees combined with the polymorphism data provides an ideal opportunity to isolate genes responsible for those traits by using an emerging technique called genome-wide association studies (Atwell et al. 2010).
Expected contributions to research theme – Ecology, especially in the tropics, requires robust field workers with good biological and practical skills. At the same time, to get the most out of the data collected requires complex, modern computation and statistical analyses. This collaboration will achieve added value through the synergies between tropical field community and ecosystem ecology, computational modelling of plant growth and development and spatio-temporal statistical analysis (project 7). To our knowledge nothing is known about the effects of the genetic diversity of tropical trees on community and ecosystem level processes making this a novel contribution with relevance for both basic science and policy. The data on genetic diversity will reveal whether trees in the Sabah Biodiversity Experiment are genetically impoverished or not, and could have implications for the whole enrichment planting idea.