The Range Potential of North American Tree Species in Europe

Round 1

Reviewer 1 Report (Previous Reviewer 1)

Comments and Suggestions for Authors

I reviewed the manuscript after the corrections made by the authors according to my recommendations. I believe that the manuscript is greatly improved and can be published.

Author Response

Thank you very much, R1, for your positive feedback. 

No changes were required, thus none made.

Reviewer 2 Report (New Reviewer)

Comments and Suggestions for Authors

The article is devoted to the actual problem of the climate change. The authors used modern methods and modeling approaches to provide insights into the suitability of six North American species in the introduced areas in 2070 (2061–2080) under different climate change scenarios (the representative concentration pathways (RCPs) scenarios: 4.5 - intermediate emission scenario, 8.5 - high emission scenario). The selection of North American species (Quercus Rubra L., Liriodendron tulipifera, Robinia pseudoacacia L., Pinus ponderosa P. Lawson & C. Lawson, Abies grandis (Douglas ex D. Don) Lindl., Pseudotsuga menziesii (Mirb.) Franco var. menziesii) is explained in the Materials and Methods. The authors selected ensemble SDMs (containing 5 algorithms: boosted regression trees, random forest, generalized linear models, generalized additive models and maximum entropy), multivariate environmental similarity surface (MESS) analysis to study the niche potential of tree species. The variables for the distribution models were obtained from various databases: “Climatologies at high resolution for the earth’s land surface areas” (CHELSA), LandGIS. The statistical analyses were performed with the software R (package BIOMOD2). The use of modern approaches determines the novelty of the study. The results obtained are of interest for environmental management in the context of climate change and the selection of plants for landscaping in Europe.

Introduction

In my opinion, it would be good to add more modern references. It is also worth emphasizing the importance of the study for the scientific community.

Materials and Methods

Methodological approaches are described quite fully.

Results

The results of the study are presented clearly and illustrated with four figures, three tables, as well as an appendix at the end of the article, which contains one table, two figures (including a diagram of ensemble modeling approach).

There are a few comments about the design of this section.

- The subsection title 3.4 (Line 369) is separated from the text. It should be moved after Figure 5 (Line 374). Table 4 should be moved after the first paragraph in subsection 3.4 or later.

- One figure is numbered incorrectly: the last figure should be 6 (Line 454). Accordingly, the reference to the figure in the text should be corrected.

Discussion

The authors discussed different hypotheses: limitations in niche transferability and ensemble model performance, north and east range shifts of all North American tree species, changes of the distribution potential and species with potential area gains. They also indicated strenghts and limitations of the study.

Conclusions

Conclusions follow from the results and are reasonable. In my opinion, the authors should emphasize the practical and theoretical significance of the research.

Author Response

Thank you for your positive feedback.

The requested changes were made:

Introduction: In my opinion, it would be good to add more modern references. It is also worth emphasizing the importance of the study for the scientific community.

Done. Added additional more recent references to the introduction in L31/32 and L62.

Puchałka et al. 2023 Predicted range shifts of alien tree species in Europe, AgrForMet

Pretzsch et al. 2023 Forest growth in Europe shows diverging large regional trends, Nature Scientific Reports

Martinez et al. 2022 Climate-change-driven growth decline of European beech forests, Natur Communications Biology

subsection title 3.4 (Line 369) moved to line 374

Table 4 moved after the first paragraph in subsection 3.4.

old figure 5 was renumbered to figure 6. Accordingly, the reference to the figure in the text was corrected.

Reviewer 3 Report (New Reviewer)

Comments and Suggestions for Authors

Dear authors and editors. I am grateful for the opportunity to review a scientific article. The article is devoted to an urgent and interesting topic. The article advises the subject of the scientific journal. 

There are a number of comments, the correction of which will improve the quality of the scientific article. 

1. Increase the size of geographical maps. Coordinate grids (geographical coordinates) should be represented on geographical maps. Each map should have a scale, an arrow pointing to the north, and a legend for the map. 

2. Bring all the cards to the same style. Why do you show the outlines of countries on some of them, but not on others?

3. In Figure 2, the names of the axes of the diagram are missing. 

4. Specify the limitations of using the input climate data. Have you used averaged values? Can you get different results if you compare the values from year to year? 

5. Specify more detailed theoretical ideas about the concept of an ecological niche that you use.

Author Response

1. Increase the size of geographical maps. Coordinate grids (geographical coordinates) should be represented on geographical maps. Each map should have a scale, an arrow pointing to the north, and a legend for the map. 

Done, figs 1, 3, 4 and 5 were modified and include coordinates, north arrows and a scale bar.

2. Bring all the cards to the same style. Why do you show the outlines of countries on some of them, but not on others?

Done, when redoing the maps we added country (EU) or state (North America) borders.

3. In Figure 2, the names of the axes of the diagram are missing. 

The axes names are included, we assume that R3 meant the lack of units. We added units to the x-axis.

4. Specify the limitations of using the input climate data. Have you used averaged values? Can you get different results if you compare the values from year to year? 

We added a short discussion of limitations using periodic means only, versus annual data in section 4.2 (LL558-62).

5. Specify more detailed theoretical ideas about the concept of an ecological niche that you use.

We actually did not develop any new concepts of an ecological niche. We indicated which concepts we applied (e.g. naturalized niche sensu [14], natural and fundamental niche as synonymous, sensu [65]). Since the objective of the manuscript is not to develop a new niche concept and the applied concepts are referenced and previously published, we did not add any text.

 

Round 2

Reviewer 3 Report (New Reviewer)

Comments and Suggestions for Authors

 Accept in present form

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

To cite Fig. 1 and in Materials and Methods, where it is placed - page 3

Include a brief comment on the indicators (d) winter precipitation (Bioclim 19) [mm], (e) Conrad's continentality index; (f) growing degree days >5°C; (g) sum of soil available water capacity in 0-30cm   soil depth (AWC) [mm], presented in fig. 2

In the caption of Fig. 2 for (e) Conrad's continentality index to be added (CCI); and for (f) growing degree days >5°C - (GGD)

Line 273 – Fig.2 to become Fig. 3 and to be cited as Fig. 3 on page 7

Line 323 – Fig. 3 to become Fig.4

Line 328 Fig. 4 to become Fig. 5

To correct the citation in the text of the figures after their renumbering

To consider whether to drop the current Fig. 5, since the gain and loss of suitability is clearly visible from the Table. 4

Author Response

Please see attached file

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript entitled “Exploring the range potential of North American tree species in Europe” is based on a study where the authors modeled the potential distribution of 5 North American tree species in Europe under different climate scenarios. While this may be an interesting idea, I found major issues with the manuscript:

-The main research question is not clearly stated. The authors refer to exploring the potential distribution of North American tree species in Europe, but it is unclear why they want to explore this. They mention climate change as a threat to the conservation of European tree species but then only suggest that European species could be replaced with North American species. With what goal would European species be replaced? Is it for conservation purposes (for example, to keep forested habitats which are key for animals’ species conservation) or is it for production purposes (for example, to keep producing wood from European forests?). Depending on the final goal different key aspects should be considered. From a conservation point of view, introducing non-native trees into European forests would further threaten native tree species through competition and many possible negative impacts of non-native species introductions in large scale. From a wood production point of view, climate adaptation does not guarantee good wood quality or high growth rates. Even when North American tree species could actually adapt to the climate in Europe, the authors are not considering biotic interactions in their work. This is key for two reasons, one is that negative interactions may hinder the successful naturalization of North American tree species in Europe. The second is that these non-native trees may produce negative impacts to native biota in Europe. 

-The methods section is missing key information. First, how was the initial pool of 37 species chosen? Second, how were the final 6 species selected from the initial list of 37? The authors only mention “5 disciplines (silviculture, yield, timber quality, ecosystem services, risk)”, but no further explanation is given for the selection procedure, which is a central part of this work. Third, where in Europe are the authors aiming to introduce these North American species? Are trees throughout all of Europe threatened by future climate scenarios? Since this work is focused in climate matching, not only the native ranges of the focal species should be described but also their future introduced range. Based on Figure 2, I would guess the authors are working with all of Europe as introduced range, however, this should be clearly stated early in the methods section.

-To be honest, this just seems like the use of species distribution models to find climate matching regions for five North American tree species in Europe, somewhat in the context of climate change. It may be an interesting idea, but without a conceptual framework that leads to a research question, a clearly defined goal and a full description of the methods this is not enough for a research paper.

 

Author Response

Please see attached file

Author Response File: Author Response.pdf