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Ecol Appl. 2019 Mar;29(2):e01837. doi: 10.1002/eap.1837. Epub 2019 Feb 4.

The sensitivity of the forest carbon budget shifts across processes along with stand development and climate change.

Author information

1
National Research Council of Italy, Institute for Agriculture and Forestry Systems in the Mediterranean (CNR-ISAFOM), 87036, Rende, Cosenza, Italy.
2
Impacts on Agriculture, Forests and Ecosystem Services (CMCC-IAFES) Division, Foundation Euro-Mediterranean Centre on Climate Change, 01100, Viterbo, Italy.
3
Environmental Sciences Division and Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37830, USA.
4
Joint Research Centre, Directorate for Sustainable Resources, European Commission, Ispra, Italy.
5
Scuola di Scienze Agrarie, Forestali, Alimentari e Ambientali, Università degli Studi della Basilicata, Viale dell'Ateneo Lucano 10, Potenza, Potenza, 85100, Italy.
6
Department for Innovation in Biological, Agro-Food and Forest Systems (DIBAF), University of Tuscia, 01100, Viterbo, Italy.
7
IPSL-LSCE CEA CNRS UVSQ UPSaclay Centre d'Etudes Orme des Merisiers, 91191, Gif sur Yvette, France.

Abstract

The future trajectory of atmospheric CO2 concentration depends on the development of the terrestrial carbon sink, which in turn is influenced by forest dynamics under changing environmental conditions. An in-depth understanding of model sensitivities and uncertainties in non-steady-state conditions is necessary for reliable and robust projections of forest development and under scenarios of global warming and CO2 enrichment. Here, we systematically assessed if a biogeochemical process-based model (3D-CMCC-CNR), which embeds similarities with many other vegetation models, applied in simulating net primary productivity (NPP) and standing woody biomass (SWB), maintained a consistent sensitivity to its 55 input parameters through time, during forest ageing and structuring as well as under climate change scenarios. Overall, the model applied at three contrasting European forests showed low sensitivity to the majority of its parameters. Interestingly, model sensitivity to parameters varied through the course of >100 yr of simulations. In particular, the model showed a large responsiveness to the allometric parameters used for initialize forest carbon and nitrogen pools early in forest simulation (i.e., for NPP up to ~37%, 256 g C·m-2 ·yr-1 and for SWB up to ~90%, 65 Mg C/ha, when compared to standard simulation), with this sensitivity decreasing sharply during forest development. At medium to longer time scales, and under climate change scenarios, the model became increasingly more sensitive to additional and/or different parameters controlling biomass accumulation and autotrophic respiration (i.e., for NPP up to ~30%, 167 g C·m-2 ·yr-1 and for SWB up to ~24%, 64 Mg C/ha, when compared to standard simulation). Interestingly, model outputs were shown to be more sensitive to parameters and processes controlling stand development rather than to climate change (i.e., warming and changes in atmospheric CO2 concentration) itself although model sensitivities were generally higher under climate change scenarios. Our results suggest the need for sensitivity and uncertainty analyses that cover multiple temporal scales along forest developmental stages to better assess the potential of future forests to act as a global terrestrial carbon sink.

KEYWORDS:

autotrophic respiration; climate change; forest development; forest structuring; model sensitivity; model uncertainty; net primary productivity

PMID:
30549378
PMCID:
PMC6849766
DOI:
10.1002/eap.1837
[Indexed for MEDLINE]
Free PMC Article

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