Effect of Individual Selection Silvicultural Treatment on the Vertical Structure of a Pine-Oak Forest in Northern Mexico

Round 1

Reviewer 1 Report

Review for Rascon-Solano et al. – ecologies article

This paper seems to focus on an interesting topic, which is the impact of selective harvest systems on forest structure in a diverse pine-oak forest. However, the methods and data analysis are so poorly explained that it is impossible to assess the validity or meaning of the results. The data collection methods need significant improvement, including basic information such as how plots were located, how many plots were measured, how large the plots are, and what the minimium size of tree that was measured. Basic results around how many total trees were found per species, overall densities, and so forth are also missing. With significant revisions, however, I would be happy to review this paper again, as I believe the manuscript has the potential to make a valuable contribution to the literature.

Abstract:

--selection cutting – specify if single tree or group selection

--analyses methods are good to include, but what data were you analyzing with these methods? Basal area? Volume? Diameter? Species richness?

--what do you mean by stability in crown cover?

--lines 31-32 – this seems like a repetition of lines 28-30.

--stand level vs. plot level? This is a bit confusing

Introduction:

--line 40 – “relevant” an odd word choice here—maybe “important”. Also I would specify mixed temperate forests here, because just mixed forests is incredibly broad.

--lines 61-63 – this is methods, and this whole paragraph can be condensed to focus more on structure as relates to ecosystem services and resilience.

--paragraph in lines 64-72—this is again going back more to structure than to silviculture – would be good to have a bit more on silviculture here and move the forest structure part above to be all in one paragraph.

--line 73 – be more specific than selection silviculture – single tree selection? Diameter limit cutting? Group selection? There are many ways that “selection” can be implemented and can all have very different results. You also may want to draw on literature around the implementation of selection in temperate systems – there have been mixed results depending on where it has been implemented.

--hypothesis that selection system will lead to greater stratification – this can depend on how selection is implemented, and there are plenty of studies showing “selection” systems can turn into high-grading and lead to overall simplification and degradation. I’m not saying this is what happens in Mexico, but I think would be important to include this context for the research.

Methods:

--how were the plot locations selected?

--you say in the 2022 harvest site, but should specify what date these plots were established. Also how big are the plots? Are they square? Circular?

--section 2.3 – this should be broken up—some of this is about the context of the site and the details of harvest, and some is about the plot measurements. These should be in separate sections.

--for timber harvest, what is the volume that they are cutting? Do they cut each year or once over a 10 year period? Give more details here. What percentage of pine vs. oak do the harvest?

--for the plots – again, how did locate these? How many did you place? What is the size of plot? Did you measure DAP/DBH or only crown diameter? What was the minimum diameter of tree that you included in measurements? Did you record seedlings and saplings or only trees above a certain height or certain diameter? Did you include other measurements such as slope, elevation, or soil type? Based on the map, it seems like one of the plots is in a fairly different forest type dominated by oak while the others are in a more pine dominated system – do you account for this in your measurements or analyses?

Lines 109-118 – this is getting into results already and should not be in the methods section.

--Figure 3 – this figure is super confusing. Are these individual plots and trees? Are the trees mapped out in a spatially explicit way? What is the scale? Is this a summary of all plots? Is each dot an individual tree in a single plot? Are these different stands? You need to explain what this is and how you calculated it. Frequency of species also very confusing – what do you mean by frequency? Are these densities per hectare? Percentages of the total for a single plot or for all plots combined?

Overall you need to do way more in explaining of the methods in terms of plot layout and measurements, as well as in data analysis.

--lines 128 – 129 – homogeneity of variances for what? Height distributions? But again, is this based on individual trees? On plot aggregates? What is the data here? How many plots did you measure and how large were they?

--line 136 – ok so you must have measured tree diameter if you do height diameter analyses. Are these on a species level? You are giving us a lot of unnecessary information about the tests you use (i.e. you don’t need to explain the details of the Kruskal-Wallis statistic because that is a standard procedure) but not nearly enough information about what actual data you are analyzing.

--lines 155-158 – kernel density analysis—but again, what is this on? Individual plots? Do you have replication?

--Figure 3 – this should probably go in the appendix/supplemental materials. But again, you are giving details that we don’t really need and omitting details that we do! How many plots? How big? Also you have two figure 3s – this one and the one on pg. 4.

Results:

--Figure 4 – you need to include units on the y-axis (meters?) and also the x axis label seems to be off? What are the two large boxes with the capital letters vs. the small ones? I see on Fig. C the label but you should include this on all of them. Also, can you line up the species so that they are in the same column across all three figures? It is confusing to have P. chinensis as first, then 4^th then 5^th depending on the graph and would be much clearer to have them line up and then add new species to the far left as they appear. And again, you still haven’t told us your sample size anywhere? How many total trees did you measure? How many plots? How many trees per species? What were overall differences in tree density/basal area pre and post harvest?

  --so from what I am understanding, you have a sample in 2012 before the first harvest (which was when?), then a sample in 2022 before the second harvest, and then there was a second harvest in 2022 and you have a sample in 2023 right after that second harvest? How much volume or BA did they remove in each harvest? What were the dates of harvesting? This needs to be explained way more explicitly in the methods.

--analysis of vertical profiles – lines 248- again, what data are you analyzing? Aggregates of all plots? How many trees are in your sample size for each species?

--lines 248 onward – this is getting into results interpretation, which should all be in the discussion section.

--line 261 – this is discussion. But also the term “recruitment” usually refers to new seedlings or regeneration, but it’s completely unclear what level of strata you are measuring. How big did trees need to be to enter into your plot measurements?

--lines 266 – again this is all discussion—any time you are talking about management implications or interpretation of what the results mean, this should be moved to the discussion.

Figure 5 – ok so now you have densities per hectare, but you still have not told us how many plots you measured and what the area per plot was or how you calculated any of this. You also seem to sometimes lump all conifers together and sometimes separate them out without any clear rationale behind these decisions. I think it is fine to sometimes group them and sometimes not, but it would be good to explain when and why you are doing each.

Figure 6 – I think it may make less sense to group all broadleaf species together as they can have pretty different ecological niches. Here you are grouping multiple genera together, whereas with conifers you are presumably only grouping different Pinus species together? I can see you have a smaller sample size, but then you maybe just pull out all oaks for analysis or only analyze groups that had big enough sample sizes.

Lines 338 – throughout all of this results section there is discussion mixed in.

Figure 7 – I’m unclear what the three things are here – three different stands? Three plots? You mention stand level in the abstract but then never explain what this means? And are the three areas combined in all other analyses but separated here?

Figure 8 – are each of these an actual spatially explicit map of trees or is this a model based on averages? What is this data from?

Figures 9 and 10 – you need a lot more explanation of what these represents. These are in percent of dominant height, not absolute measures? Again, need a lot more methods explanation of what the data is and how exactly you analyzed it.

I am not going to comment on the discussion section now because there are so many revisions that are needed in the methods and results before I can assess the paper fully.

Author Response

Author Response File: Author Response.docx

Reviewer 2 Report

This study systematically analyzes the effects of selection cutting on the vertical structure of a pine-oak mixed forest in Mexico through long-term permanent monitoring. The research is well-supported by data, methodologically rigorous, and employs a variety of statistical models and structural indices. It demonstrates that selection cutting plays a positive role in maintaining vertical complexity and forest functionality, offering valuable insights for the sustainable management of similar ecosystems. The manuscript is of high quality overall and is recommended for acceptance after minor revisions.

1. Methodology and Data Presentation Require Supplementation (Page 2, Section 3.1 & Figure 1):
   Figure 1 only shows the study area location and does not illustrate the specific plot design (e.g., plot size, shape, number of replicates). It is recommended to add a schematic diagram of the plot layout to enhance methodological reproducibility. Furthermore, the crown diameter data are underexplored in the vertical structure analysis; their relationship with stratification should be further elaborated in the Discussion.
2. Figure Readability Needs Improvement (Pages 8–9, Figure 4):
   The species abbreviations and functional group classifications (A, B, C) in Figure 4 are not clearly explained within the figure itself, requiring readers to refer to the main text for interpretation. It is advised to define the group classifications directly in the figure caption and simplify the caption by moving some explanatory text to the main body.
3. Results Presentation Could Be More Concise (Pages 10–13, Figures 5 & 6):
   Descriptions of conifer and broadleaf structure contain some repetition. It is suggested to consolidate the discussion of common trends and emphasize the differences between the two groups (e.g., strength of height-DBH relationship, distribution patterns) to avoid redundancy.
4. Results and Discussion Sections Should Be Clearly Distinguished (Pages 14–18, Sections 3.4–3.6):
   The Results section currently includes interpretive statements (e.g., "selection cutting effectively conserved trees of high structural and ecological value"). Descriptive results should be strictly separated from mechanistic interpretations and literature comparisons, with all explanatory content relocated to the Discussion chapter.
5. Discussion Section Should Be Reorganized and Deepened (Pages 19–21):
   The current subheadings in the Discussion mirror those in the Results and fail to synthesize core scientific questions. It is recommended to structure the Discussion around key findings, such as "Niche separation between tree species and its interaction with selection cutting" or "Structural indices as indicators of management sustainability," and to highlight the novelty and broader implications of this study.

Author Response

Comments 3:  The presentation of results could be more concise (pages 10-13, figures 5 and 6):

The descriptions of the structure of conifers and broadleaves show some repetition. It is suggested that the discussion of common trends be consolidated and the differences between the two groups be emphasized (e.g., the strength of the height-DBH relationship, distribution patterns) to avoid redundancies.

Response 3: [Examination of the vertical structure shows a shift in the center of the height dis-tribution towards greater values between 2012 and 2022, accompanied by a widening of the interquartile range, indicating greater heterogeneity. In parallel, there is a redis-tribution of density from intermediate classes towards the extremes of the profile (lower strata with recent recruits and upper strata with persistent dominants), while mid-height classes lose weight after intervention. In terms of canopy occupancy, the crown-density envelope suggests an increase in effective vertical overlap between young and dominant cohorts, with a more marked transition zone around 12–18 m. At the species level, tall conifers (e.g., Pinus durangensis, P. arizonica) support the upper end of the profile, whereas recent cohorts contribute mainly to the subdominant strata, consolidating the stand’s vertical continuity under individual-selection management. Taken together, these patterns reflect greater structural variability and retention of dominance, consistent with the maintenance of canopy functionality and spatial het-erogeneity in the forest.]

Comments 4: The Results and Discussion sections should be clearly differentiated (pages 14-18, sections 3.4-3.6):

The Results section currently includes interpretive statements (e.g., "selective felling effectively conserved trees of high structural and ecological value"). Descriptive results should be strictly separated from mechanistic interpretations and bibliographic comparisons, and all explanatory content should be relocated to the Discussion chapter.

Response 4: [The analysis of vertical structure using Pretzsch’s A index shows that individual selection management has favoured a stable and functional vertical complexity in the forest. In 2012, following the first harvest, the A index was 2.34, with an Amax of 3.40, resulting in an Arel of 68.75%. By 2022, prior to the second harvest, A increased to 3.50 and Arel to 68.79%, reflecting structural advancement driven by advanced regenera-tion. In 2023, after the second harvest, A remained at 3.50 with an Arel of 77.53%, in-dicating that the intervention did not reduce the achieved vertical stratification. These values confirm that selective management allowed the maintenance of a multi-layered structure, promoting a balance between timber extraction and the conservation of key ecological functions.

Regarding the analysis of stratified vertical structure with the Pretzsch index, it was found that between 2012 and 2023 the upper stratum showed a moderate increase in its structural contribution, rising from 4.77% in 2012 to 7.37% in 2022 and remain-ing stable in 2023. P. durangensis consistently emerged as the dominant species, with secondary contributions from P. strobiformis and Q. sideroxyla. This pattern demon-strates that selection silviculture has been effective in conserving emergent trees of structural and ecological value, without compromising upper canopy cover after har-vesting, as shown in Table 1.]

Comments 5: The Discussion section should be reorganized and expanded (pages 19-21):

The current subheadings of the Discussion reflect those of the Results and do not summarize the fundamental scientific questions. It is recommended that the Discussion be structured around key findings, such as "Niche Separation among Tree Species and its Interaction with Selective Cutting" or "Structural Indices as Indicators of Management Sustainability," and that the novelty and broader implications of this study be highlighted.

Response 5: [Notably, the recruitment observed in 2022 translated in 2023 into vertical ad-vancement of previously established individuals, particularly among mid-height coni-fers. This process evidences a functional cohort turnover, whereby individuals from intermediate diameter classes progressively attain dominant positions, strengthening the structural continuity of the forest.

From a management perspective, the results indicate that the application of the individual selection system between 2012 and 2023 has effectively maintained the structural and ecological integrity of the stand. This system has promoted the conser-vation of dominant trees, particularly emergent individuals of high ecological and commercial value such as P. durangensis and P. arizonica, which act as seed sources, structural elements, and biodiversity refuges. At the same time, the selective removal of intermediate, subdominant, or defective trees has reduced competition for re-sources, facilitating the vertical progression of previously established individuals in lower classes. This pattern suggests a silvicultural strategy aimed at the progressive improvement of the forest in terms of both productivity and structural complexity.

Analysis of vertical profiles across the three evaluated stages revealed clear and persistent stratification, confirming the presence of a complex, multi-layered forest structure in this temperate conifer–broadleaf ecosystem. This structural pattern is characteristic of advanced successional stages and reflects functional coexistence among species with distinct ecological requirements.]

Author Response File: Author Response.docx