Forest disturbances and climate constrain carbon allocation dynamics in trees. (13th April 2022)

• Record Type: Journal Article
• Authors: Gea‐Izquierdo, Guillermo; Sánchez‐González, Mariola
• Is Part Of: Global change biology. Volume 28:Number 14(2022)
• Page Start: 4342
• Page End: 4358
• Publication Date: 2022-04-13
• Subjects: carbon dynamics -- carbon partitioning -- carbon sink -- dendroecological plots -- global change -- vegetation models; Climatic changes -- Environmental aspects -- Periodicals; Troposphere -- Environmental aspects -- Periodicals; Biodiversity conservation -- Periodicals; Eutrophication -- Periodicals; 551.5
• DOI: 10.1111/gcb.16172
• Languages: English
• ISSNs: 1354-1013

Abstract

Abstract: Forest disturbances such as drought, fire, and logging affect the forest carbon dynamics and the terrestrial carbon sink. Forest mortality after disturbances creates uncertainties that need to be accounted for to understand forest dynamics and their associated C‐sink. We combined data from permanent resampling plots and biomass oriented dendroecological plots to estimate time series of annual woody biomass growth (ABI) in several forests. ABI time series were used to benchmark a vegetation model to analyze dynamics in forest productivity and carbon allocation forced by environmental variability. The model implements source and sink limitations explicitly by dynamically constraining carbon allocation of assimilated photosynthates as a function of temperature and moisture. Bias in tree‐ring reconstructed ABI increased back in time from data collection and with increasing disturbance intensity. ABI bias ranged from zero, in open stands without recorded mortality, to over 100% in stands with major disturbances such as thinning or snowstorms. Stand leaf area was still lower than in control plots decades after heavy thinning. Disturbances, species life‐history strategy and climatic variability affected carbon‐partitioning patterns in trees. Resprouting broadleaves reached maximum biomass growth at earlier ages than nonresprouting conifers. Environmental variability and leaf area explained much variability in woody biomass allocation. Effects of stand competition on C‐allocation were mediated by changes in stand leaf area except after major disturbances. Divergence between tree‐ring estimated and simulated ABI were caused by unaccounted changes in allocation or misrepresentation of some functional process independently of the model calibration approach. Higher disturbance intensity produced greater modifications of the C‐allocation pattern, increasing error in reconstructed biomass dynamics. Legacy effects from disturbances decreased model performance and reduce the potential use of ABI as a proxy to net primary productivity. Trait‐based dynamics of C‐allocation in response to environmental variability need to be refined in vegetation models. Abstract : Forest disturbances affect carbon dynamics. We used time series of woody biomass growth (ABI) to benchmark a vegetation model where carbon allocation of assimilated photosynthates is dynamically calculated as a function of temperature and moisture. Bias in tree‐ring reconstructed ABI increases back in time and with increasing disturbance intensity. Disturbances, species life‐history strategy and climatic variability modify carbon‐partitioning patterns in trees. Environmental variability explained much variability in woody biomass allocation. Effects of stand competition on C‐allocation were mediated by changes in leaf area except after major disturbances. Divergence between tree‐ring estimated and simulated ABI was independent of the model calibration approach. Higher disturbance intensity produced greater modifications of the C‐allocation pattern, increasing error in reconstructed biomass dynamics. Legacy effects from disturbances reduce the potential use of ABI as a proxy to net primary productivity. Trait‐based dynamics of C‐allocation in response to environmental variability need to be refined in vegetation models.