Linking tree above- and belowground traits across gradients of elevation and climate in highly diverse tropical montane forests

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Functional traits are a highly useful tool (i) to describe the response of species and communities to their environment, (ii) to quantify how single traits or trait combinations are related to ecosystem functioning, and (iii) to predict how future species assemblages and their trait spectrum will affect ecosystem functioning under altered environmental conditions. In the proposed second phase, the project will continue to analyse the relation between aboveground and belowground traits in trees of highly diverse tropical mountain forests in a systematic way. A large number of leaf, stem and root traits of 24 native dry forest tree species will be examined with a replicated sampling design in the RESPECT (FOR2730) plot network. Target species have been preselected which systematically cover the co-existing plant functional types (PFTs) at each elevation level. In addition, we will sample traits of less abundant-tree species (about 300 species) present in the RESPECT plot network. Through forest plot inventories, we will quantify tree species’ abundances and their contribution to biomass production on the stand level, testing our hypotheses on functional trait variation of tropical montane forest trees along elevation and climate gradients. The approach to cover all tree species in our study plots will (i) improve our understanding of trait variation in species-rich communities, (ii) improve trait-based modelling of biogeochemical fluxes in the research group, and (iii) allow conclusions on the functional importance of rare tree species in tropical forests, a topic that has rarely been addressed before.The data will be analysed for linkages between above- and belowground traits on the species-level, PFT-level and stand level, and the relative importance of interspecific and intraspecific trait variation. Based on the wide range of tree species investigated, we further examine the importance of the phylogenetic signal for trait variation. Using the environmental co-variates (soil properties, climate) recorded by cooperating projects, we will analyse which tree response traits are sensitive to environmental changes and how tree effect traits determine tropical montane forest stand biomass and productivity. This subproject is also responsible for identifying the sample trees investigated by RESPECT and it contributes actively to parameterizing the LSM. Stand-level data recorded by the subproject on biomass and productivity will be used to calibrate the LSM.