Of climate and its resulting tree growth: Simulating the productivity of temperate forests

Abstract

We parametrize the maintenance respiration of a single tree depending on reference climate parameters (light, temperature and precipitation) and the observed stem diameter increase resulting from that climate. The simulated biomass increment results from photosynthesis under the given climate scenario and is then reduced by maintenance and growth respiration. We incorporate this new carbon allocation algorithm into the established individual based gap model FORMIND to reproduce the biomass development of typical central European forest stands. Yield tables for northern Germany recorded over the last century are used for our parametrizations, along with the climate of the area at the time of recording. The model simulates eight tree species based on data on pine, spruce, beech, oak, ash, poplar, birch and robinia. The model dynamics emerge from tree competition, growth and mortality. These processes are calculated on an annual scale. The climate variables (global radiation, air temperature and precipitation) are entered into the model in daily resolution. This new version of FORMIND version reproduces the forest biomass development represented in the yield tables for northern Germany as well as those for western France. The modeled annual fluxes of gross primary production, woody net primary production and autotrophic respiration correspond with results from eddy flux measurements. Therefore, this version of FORMIND with the new carbon allocation is a suitable tool to investigate the carbon flux, biomass development and potential yield of forests at the individual tree level in the temperate climate zone. (C) 2014 Elsevier B.V. All rights reserved.