Guiding Conservation for Mountain Tree Species in Lebanon

Round 1

Reviewer 1 Report

The authors have made several important changes and clarifications and the manuscript is greatly improved compared to the previous version. In particular, the methods and the conservation index are now much more transparent and easy to follow. The calculation of the climatic distance is clearer, and the logic for using terrain ruggedness is better justified. The discussion is shortened and more clearly focused, and there are new paragraphs that help give more general conclusions. I also appreciate the author’s rescaling of the genetic diversity index to 0.1-1.0 (instead of 0-1), which I agree provides a fairer range to consider and does not set any population to zero priority based on genetic diversity alone. All of my major concerns have been addressed and I believe the study will contribute to the discussion about conservation of these three species and provides a useful framework.

MINOR SUGGESTIONS

1. Line 284, Figure 5 caption. I would find it helpful to state the information about the units that was provided in the previous response to authors. Something like “… occurrence of Cedrus libani (in terms of predicted net primary productivity, gCm-2year-1) simulated under…” would address my confusion about why habitat suitability was measured in units of carbon.

2. I had made a previous comment about considering assisted migration to new areas. I appreciate the authors’ response that there could be concerns with that approach, and I recognize that planning assisted migration is outside the scope of the current project. However, it is widely recognized that assisted migration to new areas is one possible tool (in addition to in-situ protection of existing populations) for the conservation management of tree species, not just a theoretical exercise for vegetation modellers. Personally, I would still find it relevant to include one or two sentences acknowledging that planting new populations in new areas (e.g., higher elevations) predicted to be highly suitable under future climates could be an additional conservation action to potentially explore in future studies. This might help improve the big-picture relevance of the discussion and ensure that it considers an integrated approach to tree conservation and genetic management.

GRAMMAR

L108. “the question, whether” > “the question whether” or “the question of whether”

L302. “lowed CI” > “lower CI”

L302. “be interpreted as they should” > “be interpreted as suggesting that they should”

L337. “Cedar Nature Reserve” > “Cedar Nature Reserves” and L339 “Key Biodiversity Area” > “Key Biodiversity Areas”                             

L384. “suitable for it” > “suitable for them”

L392 and L395. Should “the Mount Lebanon” maybe be “the Mount Lebanon range”?

Author Response

MINOR SUGGESTIONS

Line 284, Figure 5 caption. I would find it helpful to state the information about the units that was provided in the previous response to authors. Something like “… occurrence of Cedrus libani (in terms of predicted net primary productivity, gCm-2year-1) simulated under…” would address my confusion about why habitat suitability was measured in units of carbon.

This has been corrected.

I had made a previous comment about considering assisted migration to new areas. I appreciate the authors’ response that there could be concerns with that approach, and I recognize that planning assisted migration is outside the scope of the current project. However, it is widely recognized that assisted migration to new areas is one possible tool (in addition to in-situ protection of existing populations) for the conservation management of tree species, not just a theoretical exercise for vegetation modellers. Personally, I would still find it relevant to include one or two sentences acknowledging that planting new populations in new areas (e.g., higher elevations) predicted to be highly suitable under future climates could be an additional conservation action to potentially explore in future studies. This might help improve the big-picture relevance of the discussion and ensure that it considers an integrated approach to tree conservation and genetic management.

Thank you for this comment. We have included it in the manuscript.

GRAMMAR

L108. “the question, whether” > “the question whether” or “the question of whether”

L302. “lowed CI” > “lower CI”

L302. “be interpreted as they should” > “be interpreted as suggesting that they should”

L337. “Cedar Nature Reserve” > “Cedar Nature Reserves” and L339 “Key Biodiversity Area” > “Key Biodiversity Areas”

L384. “suitable for it” > “suitable for them”

L392 and L395. Should “the Mount Lebanon” maybe be “the Mount Lebanon range”?

These grammar corrections were integrated into the manuscript. Thank you.

Reviewer 2 Report

The article “Guiding conservation for mountain tree species in Lebanon” deals with an interesting topic applicable in other territories. However, the organization and presentation of the article must be profoundly improved, in order to correspond to the high quality standard of the journal Forests.

In the Introduction, the authors adequately present the importance of the study of some spontaneous trees in Lebanon. However, I would like to see more information about the latest studies on the conservation status of these forests and their threats. In the last paragraph, the objectives must be presented clearly, if possible by topics, in order to improve the reading of the document.

In the topic 2. The authors must clearly separate what methods of what is the information about the species, through the creation of subtopics. The figures presented in bibliography should also be referenced in the caption and the data produced by the authors must be transferred to the topic Results.

Line 96 - " and produce seeds at 20 to 30 years of age." Requires a reference.

The results topic is very small, and should be more worked. All results production should be moved to this topic.

The Discussion topic should also be greatly improved. Some sentences, by the way they are written, seem to be a continuation of the results. The purpose of a discussion is to compare the results obtained with other similar studies, in order to validate or highlight the results obtained. Still, I recognize that some ecological information added in this topic is relevant to the interpretation of the results. Authors should also be aware of claims that do not come from the results. Opinions must be substantiated with bibliographic references.

The Conclusions are generally consistent with the data presented throughout the article and do not raise major doubts.

I also see that the authors did not properly read the Forests journal guidelines. Bibliographic references must be reformulated, using an automatic organization system, as indicated by the journal.

Author Response

The article “Guiding conservation for mountain tree species in Lebanon” deals with an interesting topic applicable in other territories. However, the organization and presentation of the article must be profoundly improved, in order to correspond to the high quality standard of the journal Forests.

In the Introduction, the authors adequately present the importance of the study of some spontaneous trees in Lebanon. However, I would like to see more information about the latest studies on the conservation status of these forests and their threats.

We have added a section into the introduction

In the last paragraph, the objectives must be presented clearly, if possible by topics, in order to improve the reading of the document.

We have reworded the last paragraph of the introduction

In the topic 2. The authors must clearly separate what methods of what is the information about the species, through the creation of subtopics.

We have added titles for the tow subtopics

The figures presented in bibliography should also be referenced in the caption

This is a formatting problem in our PDF. We have reformatted figure 2 so that it fits a smaller space and move it upward. The caption of figure 4 was also altered. We have corrected these issues.

This is the case for the other figures. We have moved them and their captions as well.

Line 96 - " and produce seeds at 20 to 30 years of age." Requires a reference.

We removed this statement because there contrasting studies.

The results topic is very small, and should be more worked. All results production should be moved to this topic.

We have extended a bit the results section and moved figure 4 and its caption into it.

The Discussion topic should also be greatly improved. Some sentences, by the way they are written, seem to be a continuation of the results. The purpose of a discussion is to compare the results obtained with other similar studies, in order to validate or highlight the results obtained. Still, I recognize that some ecological information added in this topic is relevant to the interpretation of the results. Authors should also be aware of claims that do not come from the results. Opinions must be substantiated with bibliographic references.

We added two sections with new references

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The authors read and significantly improved the manuscript. However, I have just one more point to suggest.

All scientific names must be accompanied by the respective classifier at least the first time they appear in the text.

In addition, the authors once again did not respect the editing rules of journal Forests. I advise authors to read the citation guidelines.

As all other questions were answered clearly, I consider that the manuscript can continue with the process for publication in the journal Forests after these improvements.

Congratulations to the authors.

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

This study focused on the conservation of three conifer species in Lebanon, including the well-known Lebanon cedar. Historical human activities have led to serious damage and fragmentations to native forests of three species. Now, many conservation measures have been taken to restore forests, such as establishing national parks or nature reserves, artificial planting. Although, these actions have recovered the forests to some extent, it is difficult to predict how climate change will affect different populations of the three species in the near future. Thus, it is important to identify the populations have more potential, and set priorities for conservation. This study is important, and has the potential to contribute to the area. The manuscript is written with clarity. My suggestions to improve the manuscript are as follows.

1. My major concern is the rationality of using terrain ruggedness index (Tr) to represent microclimate. The terrain ruggedness index quantifies topographic heterogeneity, however, it does not directly represent microclimate of forests. In forests, other factors (e.g. canopy height) also influence microclimate, indexes related to forests microclimate such as, temperature differences inside vs. outside forests (De Lombaerde et al., 2022), soil temperature (Lembrechts et al., 2022), or plant available soil water (Zhang et al., 2018) maybe better fit.

References

De Lombaerde, E., et al. (2022). Maintaining forest cover to enhance temperature buffering under future climate change. Science of the Total Environment 810: 151338.

Lembrechts, J., et al. (2022), Global maps of soil temperature. Global Change Biology. Accepted Author Manuscript. https://doi.org/10.1111/gcb.16060

Zhang, Y., et al. (2018). A high‐resolution global map of soil hydraulic properties produced by a hierarchical parameterization of a physically based water retention model. Water Resources Research 54: 9774-9790.

2. The authors used genetic diversity as a predictor of survival potential for future climate change. It is true that populations have larger effective population size will be better adaptive to future climate change. However, populations with low genetic diversity but high genetic uniqueness (e.g. have more private alleles within the species) also require special attention for conservation. The authors may also consider adding the number of private alleles into the equation.

3. Line 118, ambiguous in “where the three species can potentially survive for long-term conservation”. Whether the three species coexists or survive separately?

4. Line 301-305, “either because they are ….. climatic niche”. The contents are better placed in Discussion section. The Results section is tangled with Discussion.

Reviewer 2 Report

This study attempts to create a decision tool for identifying areas and populations of three conifer species with the highest diversity for conservation. The intention as to map microrefugia with suitable conditions under a changing climate. The manuscript is well written. Below I provide a few suggestions for its improvement.

1. In the abstract, change the word ‘including’ to ‘of’. When we use the word including, this suggests that there are other species included in the study.
2. In the background, it would be nice to explain the following: what is a suitable topography and why? Why is genetic diversity important for the resilience of a population and a species?
3. In the methods, the lines 79-88, concerning the species should be taken to the introduction
4. Change the word ‘modern’ to ‘current’ (line 158 and elsewhere)
5. Explain how was the normalization of genetic diversity was done.
6. In results, lines 296-299 can be taken to methods
7. Change title for section 2, from materials and methods to ‘study area and methods’
8. In methods, please explain how you determined that a terrain was favourable to the survival of a species and how you determine that it can support a species under a changing climate
9. Scenario building under a changing climate is not explained. Please do so.
10. Line 318, please use scientific names for the species.

Discussion

1. Some of the text under discussion should be moved to results e.g. lines 349-351 (and similar text). The lines 257-360 and similar text should be moved to study area and methods.
2. The CI (very high, high) what is their association with species and population viability? How do Gds and TRI differ/resemble? What makes them resemble?
3. I am not sure that lines 480-483 should not go to the background. Please check.

Reviewer 3 Report

The authors establish a Conservation Index (CI) to guide conservation efforts of three endangered / rare montane conifers in Lebanon. The CI is used to prioritize populations for protection given limited conservation resources, and combines measures of microhabitat availability (chance to persist), genetic diversity (ability to adapt), and climatic stability (future habitat suitability). Several populations with high CI are identified, but are spread throughout Lebanon suggesting a network of smaller protected areas would be the optimal strategy. While the CI provides a simple method for guiding conservation of these conifers and could perhaps serve as a useful tool, several aspects of the CI are not fully justified or methodologically explained, making it difficult to assess my level of confidence in the conclusions. I would suggest that the CI needs greater transparency in the paper, and the authors may wish to consider whether some simple modifications to the index might result in more robust conclusions.

I have questions about all three of the components of the CI:

1. It was not clearly explained why higher terrain ruggedness (Tr) increases the CI, due to providing microsites. Does habitat only occur today in areas of high Tr? (If so, is that because Tr is necessarily required to create particular microclimates, or only because the conifers tend to occur at high-elevation climates and elevation is correlated with Tr?) Alternatively, is this a bet-hedging strategy, where the species do not necessarily required high Tr to survive, but you assume that if the terrain is very heterogeneous, then it is more likely by chance that some microsites will be suitable in the future?

2. Is normalizing the genetic diversity indices from 0 to 1 the best way to compare genetic diversity across studies? I can see two potential problems. Firstly, if the population with the lowest genetic diversity is scaled to zero (Table 1), this results in a CI of zero, so it is never possible to consider the lowest-diversity sites for conservation. This seems inappropriately strict. Secondly, and related to the first point, different species may have a different range of diversity. For example, imagine Species A has heterozygosity ranging from 0.01 to 0.50, and Species B has heterozygosity from 0.49 to 0.50. Clearly, in Species A some populations are much better for prioritization than others, while in Species B almost all populations are about the same priority. But if you convert the scale from 0 to 1 for both, then you lose the distinction that in Species B any population is approximately equally important and it could misguide your conclusions. One suggestion how to account both these issues is instead of converting from 0 to 1, you might consider dividing the raw values by the maximum value for each species, so that 1 is the maximum but the minimum will differ among species and is always scaled relative to the max.

3. I could not understand the calculation of the Di (climatic distance) component. Is this Euclidean distance calculated in only two dimensions (mean annual temperature and mean annual precipitation) or in eight dimensions (4 seasonal temperatures and four seasonal precipitations, Fig. 3)? Calculated separately for each of the three species (most logical), or for the climate combined across species as suggested in Fig. 3? Furthermore are the temperature and precipitation standardized to a single scale before calculating (otherwise the signal will be dominated by seasonal precipitation which is on a larger scale than temperature)? Finally, why is the distance from the “mean” modern climate used? This seems a very crude measure, and could introduce bias if the suitable modern climate envelope is not a symmetrical envelope in all dimensions around the mean (as suggested in Fig. 3), because a small distance in one direction might remove the population from the climate envelope, whereas a large distance in a different direction might allow the population to stay within the current climate envelope. A method that could account for a non-symmetrical shape of the climate envelope would be more robust. For example, the distance the edge of an ellipse containing 95% of the points if the population is outside the ellipse, and distance of zero if within the 95% ellipse.

Some additional further comments:

4. Is a uniform 2ºC temperature increase and 20% precipitation reduction reasonable across the entire study area and for all seasons? Wouldn’t different elevations, longitudes, and seasons be predicted to have different changes? It’s unclear why this simple approximation was chosen instead of using the actual predictions from one or more Global Circulation Models (GCMs) for a given time period.

5. Line 81. Why is Juniperus excelsa suddenly included? It was not previously mentioned (is it also locally endangered or ecologically important in Lebanon?).

6. Line 85. Conifers do not have flowers, perhaps better wording: “They reproduce in spring, with the male and female cones growing on separate branches…”

7. Fig. 5. The caption and scale are not clear. Is the scale (gCm-2year-1) supposed to represent habitat suitability?

8. Describing the conservation priority areas as “spots” is quite informal; I would suggest “area” or another less colloquial term.

9. Lines 347-448. Most of the detailed description of the conservation spots was unrelated to the rest of the study. This could be greatly shortened and instead focus on the key insights provided by the modelling study. For example, one really interesting key insight is L455 where you discover that a network of smaller sites is likely the best strategy. For example, this could connect to a broader literature on whether or not small populations and microsites are critical for conservation, the optimal conservation strategy for reserve design, etc., and make the paper more relevant to a global audience.

10. A comment: the study assumes that populations must be protected in situ, yet the introduction mentions many trees are planted for regeneration in Lebanon. One interesting caveat or future direction might be to consider whether there are other areas likely to have suitable future climates but not currently inhabited by the study species. These could be candidates for establishing new populations and assisted migration.