Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
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Volume 15, issue 18
Biogeosciences, 15, 5699-5713, 2018
https://doi.org/10.5194/bg-15-5699-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Biogeosciences, 15, 5699-5713, 2018
https://doi.org/10.5194/bg-15-5699-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 25 Sep 2018

Research article | 25 Sep 2018

Legacies of past land use have a stronger effect on forest carbon exchange than future climate change in a temperate forest landscape

Dominik Thom1,2, Werner Rammer1, Rita Garstenauer3, and Rupert Seidl1 Dominik Thom et al.
  • 1Institute of Silviculture, Department of Forest- and Soil Sciences, University of Natural Resources and Life Sciences (BOKU) Vienna, Peter-Jordan-Straße 82, 1190 Vienna, Austria
  • 2Rubenstein School of Environment and Natural Resources, University of Vermont, 308i Aiken Center, Burlington, VT 05405, USA
  • 3Institute of Social Ecology, Department of Economics and Social Sciences, University of Natural Resources and Life Sciences (BOKU) Vienna, Schottenfeldgasse 29, 1070 Vienna, Austria

Abstract. Forest ecosystems play an important role in the global climate system and are thus intensively discussed in the context of climate change mitigation. Over the past decades temperate forests were a carbon (C) sink to the atmosphere. However, it remains unclear to which degree this C uptake is driven by a recovery from past land use and natural disturbances or ongoing climate change, inducing high uncertainty regarding the future temperate forest C sink. Here our objectives were (i) to investigate legacies within the natural disturbance regime by empirically analyzing two disturbance episodes affecting the same landscape 90 years apart, and (ii) to unravel the effects of past land use and natural disturbances as well as the future climate on 21st century forest C uptake by means of simulation modeling. We collected historical data from archives to reconstruct the vegetation and disturbance history of a forest landscape in the Austrian Alps from 1905 to 2013. The effects of legacies and climate were disentangled by individually controlling for past land use, natural disturbances, and future scenarios of climate change in a factorial simulation study. We found only moderate spatial overlap between two episodes of wind and bark beetle disturbance affecting the landscape in the early 20th and 21st century, respectively. Our simulations revealed a high uncertainty about the relationship between the two disturbance episodes, whereas past land use clearly increased the impact of the second disturbance episode on the landscape. The future forest C sink was strongly driven by the cessation of historic land use, while climate change reduced forest C uptake. Compared to land-use change the two past episodes of natural disturbance had only marginal effects on the future carbon cycle. We conclude that neglecting legacies can substantially bias assessments of future forest dynamics.

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Over the past decades temperate forests were a carbon (C) sink to the atmosphere. Yet the drivers of C uptake and how these affect the future carbon cycle remain uncertain. Our simulation and study revealed that the future C sink of central European forest landscapes is strongly driven by historic land use, while climate change reduces forest C uptake. Compared to land-use change, past natural disturbances (wind and bark beetles) have only marginal effects on the future carbon cycle.
Over the past decades temperate forests were a carbon (C) sink to the atmosphere. Yet the...
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