Details

Autor(en) / Beteiligte

• Meyerholt, Johannes
• Zaehle, Sönke

Titel

role of stoichiometric flexibility in modelling forest ecosystem responses to nitrogen fertilization

Ist Teil von

• The New phytologist, 2015-12, Vol.208 (4), p.1042-1055

Ort / Verlag

England: Academic Press

Erscheinungsjahr

2015

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The response of the forest carbon (C) balance to changes in nitrogen (N) deposition is uncertain, partly owing to diverging representations of N cycle processes in dynamic global vegetation models (DGVMs). Here, we examined how different assumptions about the degree of flexibility of the ecosystem's C : N ratios contribute to this uncertainty, and which of these assumptions best correspond to the available data. We applied these assumptions within the framework of a DGVM and compared the results to responses in net primary productivity (NPP), leaf N concentration, and ecosystem N partitioning, observed at 22 forest N fertilization experiments. Employing flexible ecosystem pool C : N ratios generally resulted in the most convincing model–data agreement with respect to production and foliar N responses. An intermediate degree of stoichiometric flexibility in vegetation, where wood C : N ratio changes were decoupled from leaf and root C : N ratio changes, led to consistent simulation of production and N cycle responses to N addition. Assuming fixed C : N ratios or scaling leaf N concentration changes to other tissues, commonly assumed by DGVMs, was not supported by reported data. Between the tested assumptions, the simulated changes in ecosystem C storage relative to changes in C assimilation varied by up to 20%.