Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Climate Analogues for Temperate European Forests –Forestry Practice Profits From Silvicultural Evidence in Twin Regions

Version 1 : Received: 26 March 2021 / Approved: 29 March 2021 / Online: 29 March 2021 (11:28:36 CEST)

How to cite: Mette, T.; Brandl, S.; Kölling, C. Climate Analogues for Temperate European Forests –Forestry Practice Profits From Silvicultural Evidence in Twin Regions. Preprints 2021, 2021030684 (doi: 10.20944/preprints202103.0684.v1). Mette, T.; Brandl, S.; Kölling, C. Climate Analogues for Temperate European Forests –Forestry Practice Profits From Silvicultural Evidence in Twin Regions. Preprints 2021, 2021030684 (doi: 10.20944/preprints202103.0684.v1).

Abstract

Climate analogues provide forestry practice empirical evidence of how forests are managed in “twin” regions, i.e. regions where the current climate is comparable to the expected future climate at a site of interest. But the uncertain future climate creates uncertainty in how to adapt the forests. We therefore investigate how the uncertainty in future climate affects tree species suitability and whether there is a common underlying pattern. Like most studies we employ different ensemble variants of RCP 4.5 and 8.5. But instead of focusing on a single point in future time, we resolve each variant in a climate trajectory from 2000 to 2100. We calculate climatic distances between the climate trajectories of our site of interest and the current climate in Europe, generating maps with twin regions from 2000 to 2100. Forest inventories from the twin regions allow us to trace the changes in the prevalence of 23 major tree species. We find that it is not the direction but rather the velocity of the change that differs between the scenarios. We use this pattern to propose a tree species suitability concept that integrates the uncertainty in future climate. Twin regions provide further information on silvicultural practices, pest management, product chains etc.

Subject Areas

climate analogue; climate change; model ensemble; twin region; analogue region; national forest inventories; species suitability; forest adaptation; forestry practice; Europe

Comments (1)

Comment 1
Received: 4 April 2021
Commenter: Patrick Grenier
The commenter has declared there is no conflict of interests.
Comment: This paper is very interesting, at it strives to produce down-to-earth and useful reflexions for forestry under climate change. From a climate science perspective, the methodology considers most technical aspects involved in the computation of spatial analog trajectories. Some suggestions would be the following : 1) The authors worried about interpretation, notably by quoting "The appropriateness of a specific analogy in a specific situation […] does not concern the number of similarities two objects share but rather the significance of the similarities." (Glantz, 1988). This is interesting, and I also encourage the authors to have a look at the related work of P. Bartha (https://plato.stanford.edu/entries/reasoning-analogy/). 2) Traditionnaly, climate analogs have been divided into two categories : spatial and temporal (Mearns et al., 2001, IPCC chapter 13, "Climate scenario development"). It would be interesting to see the paper connecting with this terminology. 3) The authors have used already-bias-adjusted EURO-CORDEX simulations. Because this adjustement is not necessarily done at the same temporal resolution as that of the indices used for assessing similarity (three-month JJA T and Pr averages), it would be worth verifying whether the spatial analog trajectory starts from the target itself (Roth) in 1991-2010. In a recent paper ("The issue of properly ordering climate indices calculation and bias correction before identifying spatial analogs for agricultural applications"; https://www.sciencedirect.com/science/article/pii/S2405880719300639), myself and colleagues proposed the "self-analog test" as a standard to verify that the bias adjustement details do not prevent from having a fully meaningful spatial analog trajectory. The authors mention in the Results section that "The 2000 twin regions (grey) cover the vicinity of Roth itself", and this is well supported by their figures. I guess this can count as an equivalent of the self-analog test, or maybe as a less stricter variant of it. But it would be interesting to verify whether Roth is its own best analog for the recent-past period. And by the way, I think there is a small error in the descriptions of the indices, as at some point "June-July-August" is associated with "meteorological winter". 4) The authors show that uncertainty on future climate change is reflected into uncertainty on the closest spatial analogs identified. For the urban context, Hallegatte et al., 2007 ("Using Climate Analogues for Assessing Climate Change Economic Impacts in Urban Areas") showed how uncertainty on analogs illustrates the uncertainty on the best way to adapt to a specific problematic. Macro-level methodological links with this paper would be interesting. 5) In the Discussion section, RCP8.5 was subjectively linked with "pessimist" and RCP4.5 subjectively linked with "optimist". Such subjective labels look reasonable to me, but it would be interesting to open the discussion to some "utopian" RCP2.6. If adjusted simulations of RCP2.6 had been used, what would we have obtained ? Maybe the same spatial direction of change, but just with a slower pace ? Maybe even a turnover of the trajectory at the end of the century ? This could suggest some impacts will occur and some adaptation will be needed, even with the most drastic CO2 reductions conceivable. 6) In the Introduction section, we see the following segment "And of not reaching forestry at its basis? We do not share this point of view as [...]". I guess this responds to some debate within the forest science community. But from outside this science, it is not clear what this debate refers to, or what exactly is at stake (?) I think some expansion or clarification on that matter would be welcome. Looking forward for an official publication.
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