Parallel functional and stoichiometric trait shifts in South-American and African forest communities with elevation
Marijn Bauters1,2, Hans Verbeeck2, Miro Demol2, Stijn Bruneel2, Cys Taveirne1, Dries Van der Heyden1, Landry Cizungu3, and Pascal Boeckx11Isotope Bioscience Laboratory – ISOFYS, Ghent University, Coupure Links 653, 9000 Gent, Belgium 2CAVElab, Computational and Applied Vegetation Ecology, Department of Applied Ecology and Environmental Biology, Ghent University, Coupure Links 653, 9000 Ghent, Belgium 3Faculty of Agronomy, Université Catholique de Bukavu, Avenue de la mission, BP 285, Bukavu, DR Congo
Abstract. Elevational gradients are an empirical tool to assess long-term forest responses to environmental change. We studied whether functional composition of tropical forest along elevational gradients in South America and in Africa showed similar shifts. We assessed community-weighted functional canopy traits and indicative δ15N shifts along two new altitudinal transects in the tropical forest biome of both South-America and Africa. We found that the functional forest composition response along both transects was parallel, with a species shift towards more nitrogen conservative species at higher elevations. Moreover, canopy and topsoil δ15N signals decreased with increasing altitude, suggesting a more conservative N cycle at higher elevations. This cross-continental study provides two empirical indications that both South-American and African tropical forest show a parallel response along altitude, driven by nitrogen availability along the altitudinal gradients, inducing a parallel shift in the functional forest composition. This highlights the importance of nutrient availability for tropical forest in a changing world. More standardized research, and more research on other elevational gradients is needed to confirm our observations.
Bauters, M., Verbeeck, H., Demol, M., Bruneel, S., Taveirne, C., Van der Heyden, D., Cizungu, L., and Boeckx, P.: Parallel functional and stoichiometric trait shifts in South-American and African forest communities with elevation, Biogeosciences Discuss., doi:10.5194/bg-2017-136, in review, 2017.