Soil, Topography and Forest Structure Shape the Abundance, Richness and Composition of Fern Species in the Fragmented Tropical Landscape of Xishuangbanna, Yunnan, China

Round 1

Reviewer 1 Report

This manuscript investigates the effect of several edaphological and other environmental variables such as size of forest fragments and topography on the diversity of terrestrial ferns. I enjoyed reading the manuscript. It is well written and presented. The methods are sound and appropriate (but see the comment 1 below). The analytic approach is interesting and the study innovative. The results are valuable and merit publication, but could be more detailed (e.g. soil variables). The discussion is perhaps still the weakest part of the manuscript and lacks some depth and more facts. The relevant literature is nearly completely covered (but see some exceptions below). I have only a few general comments that are more critical or indicate some gaps:

1.      Perhaps my main concern is the low sampling effort at each site (here called transect) of 3 plots of 100m2. Comparable studies often use 1000-1200 m2. This puts at risk the local completeness of data and overestimates the heterogeneity between sites, can also affect your tests on nestedness, and may explain why you could not detect differences in species richness between fragments of different sizes. On the other hand, the number of repetitions per fragment size is appropriate. Because the study is otherwise very complete and well executed, I suggest discussing this possible weakness in the manuscript.

2.      In the methods section, the authors mention that some sites were located in National Parks. Did these differ from the ones outside the Parks?

3.      Soil variables (pH, cations, etc.) are mentioned in the methods section, but neither presented in the results nor discussed. Resuming them into two PCA axes does not really help to understand possible correlations.

4.      The term transect is not appropriate for a discontinuous sampling of three square plots in a line and should be called differently.

In the following, I comment specifically on some lines of the manuscript:

Lines 29-32: Be cautious with this statement, because smaller fragments like disturbed environments tend to have increasing numbers of introduced and invasive species and for conservational purposes, you do not want to increase the plant diversity with these species. See for instance: https://0-doi-org.brum.beds.ac.uk/10.1007/s10530-018-1866-1

L55-56: This statement is misleading because fern diversity in the tropics has a mid-elevation peak. In other words, there is no linear increase with elevation until the mountain tops.

L65-67: The two statements are a bit too simple and require a backup with literature references. Ferns (depending on species and genera) are often abundant and diverse on poor soils! There are also fern species that specifically occur on soils with a different texture. See https://www.researchgate.net/publication/333419191_The_Role_Of_Soils_For_Pteridophyte_Distribution_In_Tropical_American_Forests

L77-91: This paragraph is of crucial importance and well presented, however, it would be helpful to clarify in the last concluding sentence (L88-91) “whether the small fragments…still… represent a subset of the plant communities found in larger fragments or whether their plant communities …diverged because of…

L96: species names in italics

L102: other crops such as… (give two examples)

L105: tree species composition is poorly explained by the size of forest fragments

L116: PPG I (2016) cite 11916 species of fern and lycophytes. Please cite your reference 29 according to the authors’ preference as PPG I.

L127-133: Please give the mean annual temperature and clearly state the minimum temperature (is there any frost during the year? And at which elevation?) This has an enormous effect on tropical ferns.

L133: clarify which type of tropical forest: lowland rain forest, montane forest, cloud forest…?

L139-141: Do not use the term “transect” if you have sampled individual quadratic plots. This is misleading. A transect is a continuous linear plot. Use simply “site” and explain that on each site you have sampled three plots.

L168: refer to the version and provider of the software.

L170-171: Unclear why you did not sample the first 0-10 cm of soil depth where ferns are rooted. Please explain the reasoning.

L187: What is the unit of AWC? %?

L203-205: The method to measure species composition is not a standard and should be described in more detail. Which axes were used, the first two axes? NMDS is not scaled (non-metric) so it does not have parametric values. How do you retrieve data from this ordination?

Many authors use species evenness within a community as an indicator of species composition.

L257: Mention the five species and if these are native or introduced because this changes your interpretation of the results.

L275: total basal area

L276: higher basal area values

L280-282: I expected two results about nestedness because the authors had three fragment sizes. Consequently, I would test the nestedness of small fragments within medium fragments and medium fragments within large fragments. The latter analysis should be expected to have increased nestedness.

L295-295: The logic behind these statements is unclear. The authors sampled 75x3 quadrats of 100 m2 summing up 22500 m2 and consequently must find more species than in the studies of smaller areas.

L299-301: Your results show a high percentage of rare species, which is a common phenomenon.

L307: clay, sand and silt (insert comma)

L312-319: species names in italics

Look for other explanations for the abundance of these fern species, e.g., vegetative reproduction?

L323: Section 4.2 is missing

L324-333: This part of the discussion needs to be enhanced. How old are the small fragments? Time plays an important role. Are some fragments recovering, secondary forests or are they all primary forest fragments? Which of your other variables were most related to fragment size? And if there was no correlation, fragment size indeed does not affect these variables in the short term but may still have consequences on gene pools, genetic drift etc. that were not measured.

L349: What do you mean with a lower species composition? This is unclear as the method was not sufficiently explained (see comment on L203-205). Species evenness can be lower or higher, but species composition? Under disturbed conditions, species in a community become more uneven. See Magurran 2004: https://books.google.com.mx/books/about/Measuring_Biological_Diversity.html?id=tUqzLSUzXxcC&redir_esc=y

L378-388

This discussion is weak and too superficial. Why did you expect nestedness? I assume because small fragments are just part of former larger fragments. If smaller fragments differ from larger fragments, something must have changed the composition over time. Some species were lost, and others may have established. Is a completely random distribution of species nested? Does a heterogenous landscape explain the lack of nestedness?

Small fragments are also worth being protected if their species composition is the same as in larger fragments!

L392-396

Conclusions about soil erosion and the protection of soil necessary for conservation (which they are without doubt) are neither covered nor supported by the study and should be avoided. Stick instead to your best results: the importance of different environmental variables on your three response variables.

L506: correct author abbreviations.

Fig. 1 Use a different color for small fragments to allow for a better distinction. Selected fragments should be numbered and indicated on the map. What are the triangles? The small fragments?

Fig. 1 – Appendix A: reduce the labels of sites to simple numbers and change them to a more transparent color to clearly distinguish the axes with the variables which are far more important.

Fig. 2 Use the same x-scale (and labeling) for all three figures to make them comparable.

Correct spelling errors: fragment (not frament), coefficients (not coefficiets)

Table 1- Appendix A:

Why do you list the median values? For parametric variables, the mean should be sufficient.

Order rows for each variable to increase readability: Min, Mean, SE, Max, or even better use only three rows: Min, Mean±SE, Max

Table 2 – Appendix B: could you insert the ΔAICc values for the variables (models), please?

Author Response

This manuscript investigates the effect of several edaphological and other environmental variables such as size of forest fragments and topography on the diversity of terrestrial ferns. I enjoyed reading the manuscript. It is well written and presented. The methods are sound and appropriate (but see the comment 1 below). The analytic approach is interesting and the study innovative. The results are valuable and merit publication, but could be more detailed (e.g. soil variables). The discussion is perhaps still the weakest part of the manuscript and lacks some depth and more facts. The relevant literature is nearly completely covered (but see some exceptions below). I have only a few general comments that are more critical or indicate some gaps:

DC: We would like to thank the reviewer for taking the time to review our manuscript and for the constructive feedback, which has helped us improve our study considerably. We have made a series of changes to address the concerns raised, which we explain in detail below. Additionally, we have edited our manuscript further to improve clarity and accuracy.

• Perhaps my main concern is the low sampling effort at each site (here called transect) of 3 plots of 100m2. Comparable studies often use 1000-1200 m2. This puts at risk the local completeness of data and overestimates the heterogeneity between sites, can also affect your tests on nestedness, and may explain why you could not detect differences in species richness between fragments of different sizes. On the other hand, the number of repetitions per fragment size is appropriate. Because the study is otherwise very complete and well executed, I suggest discussing this possible weakness in the manuscript.

DC: We appreciate this important comment. We could just say that following the reviewer’s comment, we now mention this limitation in the discussion.  The area of our sites is 300m², lower than other studies. For this reason, we tested with the sampling completeness, which gave us a 78%. It shows that we may have underestimated the true richness. To acknowledge this point we have included in the Discussion section, Lines 1454-1459, this following paragraph: “We recorded a total of 131 fern species corresponding to 78% sampling completeness. Among the 131 species, more than 50% have been recorded once or twice, demonstrating high levels of species richness with a low frequency of occurrence [51]”.

2. In the methods section, the authors mention that some sites were located in National Parks. Did these differ from the ones outside the Parks?

DC: Line 214: Only four sites were inside the national park, and the forest outside the protected area had only minor human disturbance since people are allowed to enter/use the protected areas (but not to log trees). We have modified the sentence to include information that describes better the forest in protected and non-protected areas. Lines 515-518 “When placing the sites, we avoided canopy gaps and areas with high levels of human disturbance. That said, large fragments outside National Parks showed minor level of disturbance, due to that local people are allowed to enter, but not to log trees. Moreover, only 4 sites out of 42 were inside national parks and hence these minor differences are unlikely to have influenced the results. Furthermore, we avoided edge effects by establishing the plots at least 50 m from the forest edge”.

3. Soil variables (pH, cations, etc.) are mentioned in the methods section, but neither presented in the results nor discussed. Resuming them into two PCA axes does not really help to understand possible correlations.

DC: We understand and agree with the reviewer’s point. The ordination allowed us to summarize the soil factors in two main axes and use them to discuss their role in understanding the species abundance, richness and composition. Indeed, we agree that with the ordination axis, we lose the information on each factor, however in the discussion, we have compared the role of soil in explaining the fern abundance and richness with other studies where soil was also presented with an axis from a similar ordination method.

4. The term transect is not appropriate for a discontinuous sampling of three square plots in a line and should be called differently.

DC: We understand and agree with the reviewer’s point. The term transect is now changed to site.

In the following, I comment specifically on some lines of the manuscript:

Lines 29-32: Be cautious with this statement, because smaller fragments like disturbed environments tend to have increasing numbers of introduced and invasive species, and for conservational purposes, you do not want to increase the plant diversity with these species. See for instance: https://0-doi-org.brum.beds.ac.uk/10.1007/s10530-018-1866-1

DC: Thank you for this comment. We agree. To address this issue, we have removed the final part of this sentence. Line 33, “and hence are also essential [small forest fragments] for preserving fern species diversity”.

L55-56: This statement is misleading because fern diversity in the tropics has a mid-elevation peak. In other words, there is no linear increase with elevation until the mountain tops.

DC: Thank you for pointing this out. We have edited this sentence to address this issue: “In general, terrestrial fern diversity in tropical regions have a hump shape distribution with its pick around 2000m a.s.l, with changes according to the local conditions [10]”. Lines 68-69.

L65-67: The two statements are a bit too simple and require a backup with literature references. Ferns (depending on species and genera) are often abundant and diverse on poor soils! There are also fern species that specifically occur on soils with a different texture. See https://www.researchgate.net/publication/333419191_The_Role_Of_Soils_For_Pteridophyte_Distribution_In_Tropical_American_Forests

DC: We have improved the paragraph by adding the following sentences: “Terrestrial fern species diversity tends to be richer in soils with a high level of organic nutrients. In contrast, sites with high concentrations of sand and clay have fern species that can be specifically adapted to those conditions [15]”. Line 80. The reference 15 is: Moulatlet, G.; Zuquim, G.; Tuomisto, H. The Role of Soils for Pteridophyte Distribution in Tropicalmerican Forests. Fern Gaz. 2019, 21, 1-21.

L77-91: This paragraph is of crucial importance and well presented, however, it would be helpful to clarify in the last concluding sentence (L88-91) “whether the small fragments…still… represent a subset of the plant communities found in larger fragments or whether their plant communities …diverged because of…

DC: Thank you for this point. We have modified the sentence as follows: “For conservation purposes, it is crucial to understand whether the fern communities in smaller fragments represent a subset of the communities found in larger fragments or whether they are different”. Lines: 100-103

L96: species names in italics

DC: We now provide the species names in italics.

L102: other crops such as… (give two examples)

DC: Two species are now provided. We have also added a new reference to document the expansion of tea and pineapple (The Situation and Challenges of Pineapple Industry in China; Shu et al. 2019). The new sentence is: “However, the collapse of the rubber price in 2012 curtailed the expansion of rubber and slowed deforestation. Nonetheless, other crops, such as tea (Camellia sinensis) and pineapple (Ananas comosus), are still expanding in the area, albeit at slower rates [26,28]”. Lines: 290-294

L105: tree species composition is poorly explained by the size of forest fragments

DC: We have corrected the sentence: “Moreover, tree species composition appears to be poorly explained by the size of the forest fragments [30]”.

L116: PPG I (2016) cite 11916 species of fern and lycophytes. Please cite your reference 29 according to the authors’ preference as PPG I.

DC: We apologize, the preference was mentioned in the paper, but we overlooked it. We now use the authors’ preference. The sentence has been changed to ‘nearly 12,000 species… “and the citation modified accordingly”.

L127-133: Please give the mean annual temperature and clearly state the minimum temperature (is there any frost during the year? And at which elevation?) This has an enormous effect on tropical ferns.

DC: The paragraph now has three new sentences, providing all information: “The annual mean temperature ranges from 21.7ºC at 550 m to 15.1ºC at 1980 m. The hottest month is June with a mean temperature of 17.9ºC at 1980 m, and 25.3ºC at 550 m, while the coldest month is January with a mean temperature ranging from 8.8ºC to 15.6ºC. In March and April temperature can exceed 38ºC with relative humidity below 40%”. Lines: 330-335

L133: clarify which type of tropical forest: lowland rain forest, montane forest, cloud forest…?

DC: Following the temperature information above, we have modified the sentence about the forest classified. The new sentence is: “The vegetation is generally classified as tropical forest, with variations from lowland to mountain sites [35].” Line:335-336

L139-141: Do not use the term “transect” if you have sampled individual quadratic plots. This is misleading. A transect is a continuous linear plot. Use simply “site” and explain that on each site you have sampled three plots.

DC: We appreciate the comment, the term “transect” has been replaced with “site” throughout the manuscript.

L168: refer to the version and provider of the software.

DC: The sentence now provides the following information: “(GLA 21, Care Institute of Ecosystem Studies)”. Line 579

L170-171: Unclear why you did not sample the first 0-10 cm soil depth where ferns are rooted. Please explain the reasoning.

DC: We apologize for not being clear. We did remove the leaves layer and then collected the soil within the interval of 0 up to 15 cm depth. The sentence is now: “We collected soil samples (100 g each) from each plot at a depth of 0-15 cm in the uppermost mineral soil layer …”  Lines: 580-581

L187: What is the unit of AWC? %?

DC: AWC is expressed in %. Sorry for the omission. We added a new sentence explaining the unit where AWC was first introduced. “Due to the variation in forest structure and microclimatic conditions, which can significantly impact water availability, we measured the soil’s Availability of Water Content (AWC), expressed in percentage…” Line 591

L203-205: The method to measure species composition is not a standard and should be described in more detail. Which axes were used, the first two axes? NMDS is not scaled (non-metric) so it does not have parametric values. How do you retrieve data from this ordination?

Many authors use species evenness within a community as an indicator of species composition.

DC: We use the first axis of the NMDS, which has been also used in other studies as a measure of species composition in regression models.

Two references are used as an example for this point.

Dayananda, S.K.; Mammides, C.; Lee, M.B.; Liu, J.J.; Pasion, B.O.; Sreekar, R.; Yasuda, M.; Quan, R.C.; Slik, J.W.F.; Tomlinson, K.W.; et al. Topography and Soil Type Are Critical to Understanding How Bird and Herpetofaunal Communities Persist in Forest Fragments of Tropical China. Biol Conserv 2017, 215, 107–115, doi:10.1016/j.biocon.2017.08.034.

Oliveira-Filho Ary T.; Kyle G. Dexter; R. Toby Pennington; Marcelo F. Simon; Marcelo L. Bueno; Danilo M. Neves On the Floristic Identity of Amazonian Vegetation Types. Biotropica 2021, 53, 767–777.

Also, to makes this clearer, we have edited the sentence as follows: “Fern composition was measured using the first axes of a non-metric multidimensional scaling (NMDS), calculated from species abundance values [40], a standard approach used in the literature to assess species composition in regression models [29].”  Lines: 761-764

L257: Mention the five species and if these are native or introduced because this changes your interpretation of the results.

DC: This is an important point. We had mentioned the name of the five species in the discussion (Line 1488). However, we agree that it is helpful to mention the words in the results. The sentence now reads: “Those five species were, from higher to lower total cover values, Woodwardia japonica (L. f.) Sm., Cibotium barometz (L.) J. Sm., Arachniodes cavaleriei (Christ) Ohwi, Athyrium dissitifolium (Baker) C. Christensen, Tectaria herpetocaulos Holttum. All five species are native to China”. Lines: 1041-1046

L275: total basal area

DC: Edited as suggested.

L276: higher basal area values

DC: Edited as suggested.

L280-282: I expected two results about nestedness because the authors had three fragment sizes. Consequently, I would test the nestedness of small fragments within medium fragments and medium fragments within large fragments. The latter analysis should be expected to have increased nestedness.

DC: The categories mentioned in the text (i.e., small, medium, and large) were only used to select a representative sample of the fragments based on their different sizes in Xishuangbanna. In all subsequent analyses, we used the actual size in km² of each fragment since that is more informative and consumes fewer degrees of freedom for example in the regression models. Similarly, for the nestedness analysis, we only ran one Spearman correlation test with all fragments included in the analysis. Indeed, we could have run two nestedness analyses comparing small to medium and medium to large, but those would be based on smaller sample sizes. Also, we believe that the results would not change considerably because of the low overall correlation value (Spearman’s rank correlation = −0.09, p-value = 0.3).

L295-295: The logic behind these statements is unclear. The authors sampled 75x3 quadrats of 100 m2 summing up 22500 m2 and consequently must find more species than in the studies of smaller areas.

DC: Indeed, this statement was confusing since the sampling effort varied between the studies. We have removed the sentence to avoid confusion.  

L299-301: Your results show a high percentage of rare species, a common phenomenon.

DC: Yes, we agree. It is a common phenomenon. We believe it is useful to mention that out of 131 species, more than 50% have been found once or twice, while the rest were found more often.

L307: clay, sand and silt (insert comma)

DC: Edited as suggested.

L312-319: species names in italics

DC: The names are now given in italics, and the sentences have been modified to include that all the species are native to China (none of them is invasive or introduced). Line 1044

Look for other explanations for the abundance of these fern species, e.g., vegetative reproduction?

DC: We agree with the comment. A sentence has been added, and the other sentences have been partially modified, the new paragraph: “Their abundance can be explained by their vegetatively propagation, via rhizome, which facilitates the cover of large surface. Therefore, the abundance and biomass were driven by a subset of species, and these common species have a broad altitudinal range, with source and sink populations (Cicuzza personal observation) [53]. In contrast, some of them, like Woodwardia japonica and Cibotium barometz, tend to occur also in sites with higher light availability. The broad ecological adaptation of these species, vegetative propagation, distribution from lowland to mountain sites and with different degrees of light availability, could have determined their dominance across the range of a fragmented landscape.”. Lines 1478-1486

L323: Section 4.2 is missing

DC: We apologize for the mistake. We renamed section 4.3 to 4.2.

L324-333: This part of the discussion needs to be enhanced. How old are the small fragments? Time plays an important role. Are some fragments recovering, secondary forests or are they all primary forest fragments? Which of your other variables were most related to fragment size? And if there was no correlation, fragment size indeed does not affect these variables in the short term but may still have consequences on gene pools, genetic drift etc. that were not measured.

DC: Thank you for this comment. Unfortunately, we do not know the age and since when each fragment was isolated from the main large closer forest patch. Studies from Atlantic Forest (Brazil) have reported that time can determine the homogenization of tree species composition. We have added two more sentences, in which we explain the possibility of homogenization and its effect on gene pools.

Modified paragraph: “Long-term isolation of tropical forest fragments with continuous human disturbance, as in the Atlantic Forest, for example, has produced a homogenization of the tree species community [57]. The conversion of forests in Xishuangbanna is recent, but a similar phenomenon could be seen, with a negative impact on the fern species richness and the genetic pool of the community”. Lines: 1494-1499

L349: What do you mean with a lower species composition? This is unclear as the method was not sufficiently explained (see comment on L203-205). Species evenness can be lower or higher, but species composition? Under disturbed conditions, species in a community become more uneven. See Magurran 2004: https://books.google.com.mx/books/about/Measuring_Biological_Diversity.html?id=tUqzLSUzXxcC&redir_esc=y

DC: Thank you for pointing out this issue. Indeed, the phrase “lower species composition” was inaccurate. We have edited this section to make our results clearer. The new sentence: “This indicates that in mature forests, where the ecological conditions are stable, the species composition varied compared to disturbed sites where the community involves species with broader ecological traits.” Lines: 1693-1696

Moreover, we have removed the following portion of the sentence in Line 1707 in the last part of the paragraph, since as it can be confusing to compare directly the R²_marginal values of different studies. (Portion removed: and other studies in which it reaches 0.50)

This discussion is weak and too superficial. Why did you expect nestedness? I assume because small fragments are just part of former larger fragments. If smaller fragments differ from larger fragments, something must have changed the composition over time. Some species were lost, and others may have been established. Is a completely random distribution of species nested? Does a heterogenous landscape explain the lack of nestedness? Small fragments are also worth being protected if their species composition is the same as in larger fragments!

DC: Thank you for bringing this issue to our attention. Indeed, one of the major conclusions of our study is that small fragments are also worth being protected. We have improved the discussion underling that our results can be interpreted by several factors. First because most of the species assessed in every sites are unique of that area, second this can be justified by the hilly topography of the landscape has heterogeneous niche availability. The low frequency and the ecotonal zone of Xishuangbanna could explain this great distribution of species. Perhaps with larger sites (>then 300m²) we could be able to see nestedness. This is also explained by the need of further research.  The new paragraph, Lines 1724-2034.

“Fern species composition was found to not be significantly nested within the forested landscape of Xishuangbanna. This result suggests that species composition in small fragments is not a subset of the communities found in larger fragments and that the fern community appears to be highly diverse within the different sizes of forest fragments. Our findings could be explained by several factors. The changes in species composition among the different sites are not determined by fragment size because a large proportion of species have low frequency and are distributed within fragment from large to small fragments. The hilly topography of the Xishuangbanna landscape, can preserve local ecological condition that suite numerous fern species. We found an average of 6 species per site, while over 50% of the species are recorded once, suggesting that each site, from small to large fragments, harbor species with specific ecological requirements. The presence of these dissimilar species in the smaller fragments highlights the importance of preserving small forest patches for fern conservation. From a conservation perspective, this result suggests that small fragments are important for the preservation of ferns. However, more research is needed to understand how the community composition changes among the different forest patches”.

Conclusions about soil erosion and the protection of soil necessary for conservation (which they are without doubt) are neither covered nor supported by the study and should be avoided. Stick instead to your best results: the importance of different environmental variables on your three response variables.

DC: For the conclusion we have underlined the topography and soil properties are important for fern abundance and species richness. Furthermore, we have edited those part where conclusion was not supported by our results, i.e. soil erosion. The final part of the conclusion is now as follows: “Moreover, our study suggests that the distribution of the terrestrial ferns, with regards to their abundance, richness, and composition, is not explained by the same environmental factors. This finding is important because it shows that the different aspects of fern diversity are the result of the interaction with different environmental factors”. Lines: 2040-2044

L506: correct author abbreviations.

DC: Edited as suggested

Fig. 1 Use a different color for small fragments to allow for a better distinction. Selected fragments should be numbered and indicated on the map. What are the triangles? The small fragments?

DC: The triangles in the Figure are the locality where the plots were conducted. We have modified the figure with different sets of colors; unfortunately, in most of the cases we have had even more confusing results compared with the present version. If we use black and white it is not clear either.

We have added a sentence in the Fig caption: “The triangles represent the study sites”.

Fig. 1 – Appendix A: reduce the labels of sites to simple numbers and change them to a more transparent color to clearly distinguish the axes with the variables which are far more important.

DC: We understand this comment from the reviewer, however the important factor which are aligned with Axis one and two of the PCA are visible.

Fig. 2 Use the same x-scale (and labeling) for all three figures to make them comparable.

Correct spelling errors: fragment (not frament), coefficients (not coefficiets)

DC: We apologize for these mistakes. We have corrected the spelling errors in all three graphs and used the same scale. Moreover, we have reduced the space between the factors (the coefficient estimates and the CI) to have a better image.

Table 1- Appendix A:

Why do you list the median values? For parametric variables, the mean should be sufficient.

Order rows for each variable to increase readability: Min, Mean, SE, Max, or even better use only three rows: Min, Mean±SE, Max

DC: We appreciate the advice, we have modified the table with three rows with: Min, Mean±SE, Max.

Table 2 – Appendix B: could you insert the ΔAICc values for the variables (models), please?

DC: We have included the ΔAICc. The table starts with R² marginal = 0.391; R² conditional = 0.646; ΔAICc 3.66.

Reviewer 2 Report

This manuscript studies how topography and selected soil properties shape ferns presence in the studied area. As ferns are part of forest and this topic is important for biology conservation I found it falling into the scope of Forest Journal.

It has good, informative title, abstract contains key information and good keywords.

First sentence of the abstract is written with smaller font. The same is in lines 75-76, 98-102 (introduction). There are such fragments in methods (L135-136, 138-139, 151, 170, 179-182, 189-192, 210-212, 218, 231), results (250-256, 290-293), discussion (296-300, 312, 278-288) and in conclusions too.

Methodology and design are well done including models used.

Results present obtained data quite well with good quality figures and tables. Data are discussed what eventually led to clear conclusions.

Author Response

Review two

Comments and Suggestions for Authors

This manuscript studies how topography and selected soil properties shape ferns presence in the studied area. As ferns are part of forest and this topic is important for biology conservation I found it falling into the scope of Forest Journal.

It has good, informative title, abstract contains key information and good keywords.

DC: We would like to thank the reviewer for taking the time to review our manuscript. We have changed the manuscript according to the concerns raised, and we believe that the manuscript is now much improved.

First sentence of the abstract is written with smaller font. The same is in lines 75-76, 98-102 (introduction). There are such fragments in methods (L135-136, 138-139, 151, 170, 179-182, 189-192, 210-212, 218, 231), results (250-256, 290-293), discussion (296-300, 312, 278-288) and in conclusions too.

DC: We apologize for this mistake. We have edited the text and the reference number which, in many cases, had a different font size.

Methodology and design are well done including models used.

Results present obtained data quite well with good quality figures and tables. Data are discussed what eventually led to clear conclusions. 

DC: We appreciate that the reviewer finds the results and discussion appropriate and well presented.

Reviewer 3 Report

Forests-1868318

Title of ms:

Soil and topography shape the abundance, richness and 2 composition of fern species in the fragmented tropical 3 landscape of Xishuangbanna, Yunnan, China

To the Editor in Chief

Journal of Forests

Dear Sir/Madam.

Thanks for sending the manuscript for review. The authors have carried our interesting study. Authors have collected good data and hope this study to be published in the Journal. However, my suggestions are given following for the quality of manuscript and its wide readership.

Comments

Abstract:

·         Few last line in the abstract should clearly indicated for outcome.

Introduction:

·         In this section some of sentences to be reduced especially old citations, which are not relevant to the present study area.

·         Scientific name of the plants to be given in italic;

·         Authors have given only research questions but not objectives of present study.

Methods:

Soil properties

·         This section need to be strengthen by giving detailed methods of each estimated parameters such as pH, SOC, Soil texture etc.

·         How AWC is calculated their also should be detailed information.

·         The detailed methods of abundance, species richness, and composition to be given.

Results:

·         Why the map is given in the results section. Actually, this should be part of study area.

·         Latitude and longitude in the map of the study area to be given.

Discussion:

·         There are number of sections here to be discussed with more related studies.

4.1 Fern species abundance

·         Scientific name of the species to be given in italic

Conclusion:

·         This section can be improved using estimated data.

Author Response

Review Three

Comments and Suggestions for Authors

Forests-1868318

Title of ms:

Soil and topography shape the abundance, richness and composition of fern species in the fragmented tropical landscape of Xishuangbanna, Yunnan, China

To the Editor in Chief

Journal of Forests

Dear Sir/Madam.

Thanks for sending the manuscript for review. The authors have carried our interesting study. Authors have collected good data and hope this study to be published in the Journal. However, my suggestions are given following for the quality of manuscript and its wide readership.

DC: We would like to thank the reviewer, we have followed the concerns and the manuscript is now improved considerably, compared with the previous version.

Comments

Abstract:

• Few last line in the abstract should clearly indicated for outcome.

DC: The Abstract is now changes in several sentence due to the concern raised, also, from other reviewers. The outcomes that the research suggests are now: “Our results suggest also that soil properties play an important role in maintaining fern abundance and diversity and therefore protecting soil can help conserve ferns in fragmented landscapes” Lines: 31-34

Introduction:

• In this section some of sentences to be reduced especially old citations, which are not relevant to the present study area.

DC: We have modified and reduced the introduction. The new version has all the changes tracked and it is possible to see how the Introduction has been edited. For example, the sentence in italics has been removed including the reference. “In fragmented forested landscapes, the plant community composition changes with different degrees of nestedness between the least and most fragmented forests [22]”.

• Scientific name of the plants to be given in italic;

DC: We now provide all species names in italics

• Authors have given only research questions but not objectives of present study.

DC: In the introduction we have modified a sentence as: “In this study, we investigated the factors influencing the abundance, species richness, and composition of ferns in the fragmented landscape of Xishuangbanna, China”. Lines: 305-309

Methods:

Soil properties

• This section need to be strengthen by giving detailed methods of each estimated parameters such as pH, SOC, Soil texture etc.
• How AWC is calculated their also should be detailed information.
• The detailed methods of abundance, species richness, and composition to be given.

DC: We have improved the methods sections with more information about some of the factors that were not clear. The description of how we estimated some of the parameters are now explained better and we provide reference for further information for the readers who are interested to understand in more details.   

Results:

• Why the map is given in the results section. Actually, this should be part of study area.
• Latitude and longitude in the map of the study area to be given.

DC: We have moved the map into the Methods, study area, section. We think that adding the Latitude and Longitude on the map will make the figure more difficult to read. Please note that we have provided the coordinates in the description of the study area.

Discussion:

• There is number of sections here to be discussed with more related studies.

DC: Following the comments from the other reviewers as well we have now expanded our discussion and added new references with related studies.

4.1 Fern species abundance

• Scientific name of the species to be given in italic

DC: The name of all species is now given in italics.

Conclusion:

• This section can be improved using estimated data.

DC: We refer to the importance of how different factors explain the fern cover, richness and composition. For example, the following sentence relates to the results obtained: “Moreover, our study suggests that the distribution of the terrestrial ferns, with regards to their abundance, richness, and composition, is not explained by the same environmental factors”.

Round 2

Reviewer 3 Report

 My earlier comments on the manuscript, I found that authors have addressed most of the comments and improved the quality of manuscript. Based on the inputs of the authors, I recommend that the manuscript can be accepted for publication in the Journal.