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

Thom, Dominik; Rammer, Werner; Garstenauer, Rita; Seidl, Rupert

doi:https://doi.org/10.5194/bg-15-5699-2018

Articles | Volume 15, issue 18

https://doi.org/10.5194/bg-15-5699-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/bg-15-5699-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 15, issue 18

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 Thom, Werner Rammer, Rita Garstenauer, and Rupert Seidl

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Final revised paper (published on 25 Sep 2018)
Supplement to the final revised paper
Preprint (discussion started on 03 Apr 2018)
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Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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RC1: 'reviewer comments', Anonymous Referee #1, 01 May 2018
- AC1: 'response', Dominik Thom, 29 May 2018
RC2: 'Review for Disturbance legacies have a stronger effect on future carbon exchange than climate in a temperate forest landscape  ', Anonymous Referee #2, 02 May 2018
- AC2: 'response', Dominik Thom, 29 May 2018
RC3: 'Review of : Disturbance legacies have a stronger effect on future carbon exchange than climate in a temperate forest landscape', Anonymous Referee #3, 04 May 2018
- AC3: 'response', Dominik Thom, 29 May 2018

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

ED: Reconsider after major revisions (11 Jun 2018) by Sebastiaan Luyssaert

AR by Dominik Thom on behalf of the Authors (21 Jul 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (08 Aug 2018) by Sebastiaan Luyssaert

RR by Anonymous Referee #2 (09 Aug 2018)

Suggestions for revision or reasons for rejection

I appreciate the efforts that the authors made to make the manuscript clearer and to elucidate some confusing points. The revised manuscript addressed many of my concerns and results more persuasive. The additional analyses bring new and interesting information to the study. However, I am not convinced by some of the authors’ edits.

1-I understand that the use of a pattern-oriented modeling approach (Grimm et al., 2005) is used to argue for a qualitative and multi-indicator description of model results. Maybe my comment was not clear. It is not a question of finding a single concise value, but simply to give the values that lead to the interpretation of the results that is currently presented in some parts of the results section. Statements such as « well able», «good match » do not describe the results but your interpretation of the results. Such statements would be acceptable in the discussion section but the objective description of the results is an important part of any scientific work, which I find sometimes missing still in the revised manuscript and relates to my prior comment on the shallowness of the results and discussion section. Statements such as « Good match » mean different things for different people which is not what is expected in the presentation of scientific results that should state objectively state what was found and allow the reader to judge for him/herself if the match is good/sufficient. The interpretation can then be discussed later on. I notice that this is actually done well in most part of the results section.

In brief, I do not agree that using a variety of indicators prevents the quantified description of the observed patterns. In particular, this argument hardly applies to the displayed results which are shown ad one-variable figures so it is merely a question of writing out in text what is displayed in the figure. In this case, stating in the text the numbers shown in the figure does not undermine the multi-criteria facet of your analysis.

In particular, please address these statements :
- « The results from the legacy spin-up revealed a good match with the  species composition and growing stock expected from the historic records for the year 1905  (see Section S2, including Fig. S5, Fig. S6).   » Fig S5 shows the variable species share in simlated versus reference state, Fig S6 shows the growing stock for simulated versus reference state. A more rigorous presentation of the results would read something in the line of «The species composition from the legacy spinup diverged by XX%, YY%, ZZ% from the reference state for species X, Y and Z respectively while the simulated growing stock average was 207, 4% lower than the reference state ».
- « ABE was well able (fig S7) » Here Fig S7 again only shows one variable, hampering the multi-indicator justification for not expliciting the results.
- "small overestimation", refers only to simulated harvest. Please quantify the variable described.
- "corresponded well" referes to the disturbed growing stock only, please give in the text the numbers shown in the figure.
- « Climate change weakened the carbon sink strength …» by how much ? by reducing the growing stock by XX%, YY%, ZZ% etc for species X,Y and Z resp. ?
- « climate change effects on NEE were more variable compared to disturbance legacy effects, with increasing uncertainty  over time as a result of differences in climate scenarios ». Give standard deviation to average ratio for each factor.

2 - Figure 4 that results from the merging of Fig 5, 6, S14 is an improvement and make the results easier to grasp. However, the use of this figure in the text is not only to describe the evolution of each factor but to support the main result of the study stated in the title : the largest importance of land use effects over disturbances. This result is not easy to read from the different scales on the current figure. Please consider adding to Fig. 4 a panel with all 4 factors displayed on the same scale which would make obvious the main result.

3 – « Based on our simulations we found only a moderate positive effect of the first disturbance episode on the volume disturbed during the  second episode (+8,181 m , p=0.401). In contrast, land use had a considerable impact on the  second disturbance episode. On average, land use increased the volume disturbed by +28.927  m (p<0.001).   »
This result of the new analyses is important but not clear. Which display items does it refer to and why is the unit « m » ?

Details :
L425 of track change documents. The colon is followed by a capital.

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RR by Anonymous Referee #3 (21 Aug 2018)

ED: Publish subject to minor revisions (review by editor) (22 Aug 2018) by Sebastiaan Luyssaert

AR by Dominik Thom on behalf of the Authors (04 Sep 2018) Author's response Manuscript

ED: Publish as is (05 Sep 2018) by Sebastiaan Luyssaert

AR by Dominik Thom on behalf of the Authors (05 Sep 2018) Author's response Manuscript

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Short summary

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.