A Demographic Imbalance of Tree Populations in the Managed Part of Białowieża Forest (NE Poland): Implications for Nature-Oriented Forestry

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Overall Assessment

Brzeziechi et al. aim to address the question: What are the population structure characteristics of foundation species in an intact forest ecosystem? To this end, they established 1,373 forest plots in the Białowieża Forest and constructed an equilibrium/sustainable tree size distributions model to assess the gap between current and expected DBH class distributions. They further estimated the regeneration area needed to meet recovery requirements for these populations. I believe that their large dataset provides robust support for the results and conclusions. However, there are significant issues with the manuscript’s logic, writing quality, and clarity, as well as insufficient explanations for some key indices. I recommend major revision before further consideration.

Introduction

The introduction provides a good description of the Białowieża Forest but does not sufficiently present current methodologies for population viability analysis, nor does it clearly state hypotheses leading to the research questions. A rewrite is needed to make the study’s motivation clearer.

Lines 33–43: These two paragraphs can be merged. The authors should explicitly state the main biodiversity maintenance challenges faced by Central Europe and link these directly to their study.

Lines 47–59: While the functional traits and ecological value of foundation species are well explained, the core issue is missing—what is the precise definition of “foundation species” and what is the research gap in their population structure studies?

Lines 55–64: The discussion of the biocentric value of foundation species appears tangential to the main theme of population dynamics.

Lines 65–79: Excessive background on Białowieża Forest is unnecessary; instead, this section should be linked to the current research status and gaps concerning foundation species populations in this forest.

Lines 81–88: The research questions appear abruptly. What are the hypotheses? How are they logically constructed? These points are missing in the introduction.

Lines 89–90: The criterion mentioned should be explained briefly.

Regarding the four research questions:

Lines 85–89: This is not scientific questions; it could be discussed later in the discussion section.

I suggest the core scientific questions be reframed as:

1. In a stable forest state, what DBH class distribution of trees is needed to sustain both ecosystem functions and long-term regeneration/production?
2. Compared with an ideal equilibrium structure, how many surplus or deficit trees exist for each species and DBH class, and what regeneration area is needed to restore the structure?

Materials and Methods

Lines 102–156: This section should be reorganized as a subsection under Materials and Methods. Soil, topography, and geomorphology details can be condensed. In contrast, details on the forest plots (Lines 133–138) should be expanded: census frequency, plot establishment, species identification, and how newly recruited individuals are recorded—these details are essential to link with later metrics used in Lines 170, 180, and in natural mortality and growth function calculations.

Line 141: Clarify the basis for DBH class division. Since life history traits differ among species, the DBH threshold for adulthood varies; should classes be species-specific?

Lines 148–176: My understanding is that in a stable state, the number of trees entering a DBH class (in-growth) equals the number leaving that class (out-growth + mortality + harvesting). If this is correct, it should be stated concisely. Too many citations here are distracting; focus on the core calculation and specify the software used.

Lines 177–197: Provide more calculation details, ideally as equations.

Line 187: Clarify the data used—according to Line 130, the model is based on 2018 data, but the mortality and growth functions are derived from 1936–2012 data. Is there a mismatch? Given that population sizes fluctuate, this could affect the validity of the model.

Lines 170 and 218: Equation labels are duplicated.

Line 196: Table 3 is not found in the Supplementary Information.

Results

The results section is overly detailed. Instead of presenting all outputs, focus on those that directly address the core scientific questions—particularly Lines 302–320 and 359–366.

Other results, such as Tables 1–3 and Figures 1, 3–5, could be moved to supplementary materials.

Line 290: “omparison” should be “comparison.”

Discussion

Line 396: Table 3 is again referenced but missing.

Lines 422–438: I agree with the points made but note that they lack specific data or statistical modeling to support them.

The forest appears to be secondary; similarly, Lines 439–450 describe a single-species dominance, which is common in secondary forests. The explanations provided may not be entirely convincing.

Summary and Conclusions

This section should be rewritten. Lines 595–605 should not appear in the conclusions. Summarize key findings, significance, and forest management implications concisely.

Minor Issues

1.Each main heading should be numbered.

2.The reference format does not follow Forests journal requirements.

 

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

1. The list is not formatted according to the MDPI Forests rules.
2. The sources are quite old; only 13 out of 81 were published in 2021 or later.
3. The authors' articles appear 11 times in the reference list
4. References in Polish must be duplicated in English.
5. Reference Ngugi MR, Neldner VJ, Dowling RM, Li J (2021) must be after Muys et al. 2022 (if alphabetically)
6. The climate description is given according to a source from 1986 (Faliński 1986). During this time, the climate has changed. This needs to be shown.
7. The research attempts to answer four questions. Respective results must be presented in the Conclusions and the Abstract.
8. The distribution of trees of different species by diameter was calculated based on a huge amount of material. Various biodiversity indices could be calculated from these data and used to compare territories with various management in the same woodland community types.

The supplement table 2 BULiGL (2021) shows the representation of tree species in various woodland community types. Within one woodland community, it is necessary to compare the diversity of tree species at different levels of forest management.

9. Tree species differ in the frequency of fruiting, lifespan, and interactions with neighboring tree species in the community. It is difficult to consider these features when mechanically comparing the diameter distribution by age with model data.
10. It is certainly interesting to compare the distribution of diameters of oak and pine, the dominant species, in Figs 2 and 6. Unfortunately, these figures are separated by text....
11. Proposed biodiversity conservation strategies should be tailored to specific woodland community types and differ across different management areas. This should be reflected in the conclusions.
12. Supplement Fig. 1. map legend – “scrict reserve” – must be “strict reserve”

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

I am very satisfied with the revisions. I believe it can be accepted in its current form.

Reviewer 2 Report

Comments and Suggestions for Authors

The authors took into account all the comments from the first review and improved the manuscript.