Effects of nutrient manipulation (NUMEX) on nutrient use and carbon allocation of Andean forests: Stand level response and the performance of single tree species

• Applicant: Dr. Jürgen Homeier
• Subject Area: Ecology and Biodiversity of Plants and Ecosystems
• Term: from 2007 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 29937865

Human activities will globally affect the cycles of N and P during the coming decades, both elements are of major importance for the productivity of plant communities. But it is not sufficiently understood how tropical forests will respond, particularly with regard to the expected increase of atmospheric N deposition. Although these forests store large amounts of carbon their quantitative role in the global carbon cycle remains uncertain, especially the contribution of montane tropical forests is unclear. This project combines experimental and descriptive studies along an elevational transect (1000 to 3000 m asl) of Andean forests to investigate (A) the natural variation of aboveground biomass and productivity related to nutrient availability and elevation, (B) the influence of tree functional traits on stand productivity, and, in the experimental part, the effects of continued nutrient addition (C) on the aboveground forest productivity and carbon allocation at the stand level, (D) on the tree seedling assemblage (establishment and species composition) and thereby the future species composition, and (E) on the growth performance and nutrient allocation of key species (mature trees and seedlings). The approaches (A) and (B) will be studied in the existing environmental matrix of 54 permanent forest plots, covering a wide range of site conditions. The effects of continued nutrient addition (C-E) will be investigated within the ongoing N and P addition experiment (Numex), that started in January 2008 (adding moderate amounts of N (50 kg ha-1 yr-1), P (10 kg ha-1 yr-1), and N and P to representative forest stands).

• DFG Programme: Research Units
• Subproject of: FOR 816: Biodiversity and Sustainable Management of a Megadiverse Mountain Ecosystem in Southern Ecuador
• International Connection: Ecuador
• Participating Person: Dr. Carlos Iván Espinosa