Limited Impacts of Activated Carbon and Mycorrhizal Amendments for Pinus echinata Reforestation on Strip-Mined Soils

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

General Comment

This study is based on the context of ecological restoration in an abandoned mining site, with an experimental design including four treatments: activated carbon (AC), mycorrhizal amendment (MA), a control, and a combination of AC and MA (A×M). Overall, the experimental setup is appropriate to evaluate the effects of these treatments on soil and vegetation recovery in the post-mined landscape. This study offers practical implications for ecological restoration in post-mined landscapes, although the results suggest that these soil amendments did not achieve the desired restoration outcomes, the study still provides valuable insights. Some minor comments are listed below.

Introduction

The introduction provides a comprehensive background on forest restoration challenges in post-mined lands, particularly in the southeastern United States, and presents a clear rationale for testing activated carbon (AC) and mycorrhizal amendments (MA) in shortleaf pine restoration. The structure is logical, and the transition from problem identification to study objectives is smooth. However, there are areas where the clarity, conciseness, and precision of writing could be improved.

 

Specific Comments:

1. The introduction section cites sufficient references, but further clarification of the differences between activated carbon (AC) and biochar, particularly in terms of production processes, physical properties, and costs (lines 47–61), may help to highlight the unique characteristics of AC in restoration. The characteristics of AC mentioned in lines 50–52 are also shared by biochar. However, since biochar has been studied more extensively, emphasizing the unique contributions of activated carbon will help to reinforce the validity of the research.
2. Additionally, the ecological context for using MA could be expanded slightly to include more recent literature on its effectiveness in forest systems.
3. Line 47: “One restoration methods is…” → should be “One restoration method is…”
4. Line 73: “utilizing A×M and are needed” → “utilizing A×M are needed”

 

 

Materials and Methods

The Materials and Methods section provides detailed and comprehensive information, which is commendable. However, the current structure lacks subheadings, making it difficult for readers to quickly navigate the different components of the methodology. To improve clarity and readability, I recommend organizing this section using appropriate second-level subheadings. For example:

• 2.1 Study Area
• 2.2 Field Experimental Design
• 2.3 Soil and Plant Characteristics
• 2.4 Statistical Analysis

Such a structure would enhance the logical flow and make the methodology easier to follow, especially for readers who may want to refer back to specific parts of the experimental approach.

Results

To better visualize and synthesize the multivariate responses of different treatments, I suggest including a Principal Component Analysis (PCA). PCA is a useful tool for reducing the dimensionality of complex datasets and identifying patterns or groupings across multiple variables simultaneously. In this case, incorporating a PCA plot could help illustrate how the treatment groups differ in terms of overall soil properties and plant growth characteristics.

Specifically, I recommend presenting two PCA plots:

• One based on baseline (pre-treatment) data,
• Another based on data from the final growing season (e.g., from 2023).

This approach would provide a clearer picture of how treatment effects evolved over time and whether certain treatments produced distinct shifts in overall soil–plant system properties. Including such visual summaries could substantially enhance the interpretability and impact of the results.

 

Line 223,224, please ensure that "P" is consistently formatted as lowercase "p", in line with standard statistical reporting and the rest of the manuscript.

 

Line 223-224, It is unclear to me how the conclusion about the differences in EC among groups was derived.

Discussion

 Line276-277, 288-289, I do not believe the conclusion regarding the negative effect of MA is appropriate in this context. The data do not indicate a significant difference between the MA treatment and the control (CT); instead, the significant difference is observed between MA and AC treatments. This distinction is important—while MA may be less effective than AC, this does not necessarily imply that MA has a detrimental effect. Therefore, that just can reflect that MA was less effective than AC, rather than suggesting it had a negative impact compared to the control.

 

Line309-312, It is unclear whether similar herbaceous plant communities commonly co-occur with shortleaf pine in the southeastern U.S., as suggested. More importantly, the experimental design did not include a control to assess the specific influence of herbaceous vegetation on pine growth. Therefore, the inference regarding the potential impact of herbaceous plants on tree performance should be carefully qualified or reconsidered, unless further justification or supporting evidence is provided.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Colleagues!

I read with interest your MS regarding the effect of biochar and mycorrhiza soil treatments on shortleaf pine (Pinus echinata) plantings in the southeastern US. In my opinion, I recommend that you consider the following comments in the revised version of the MS:

1) Please indicate the doses of soil treatment agents in the Abstract.

2) Please clarify who recommends the dose of 1.12 g/m² for biochar (activated carbon).

3) Please consider in the discussion and conclusions the most probable, in my opinion, hypothesis about the absence of a statistically significant effect of biochar treatment, namely, the extremely low dose that you used. If you add biochar at a dose of 3.36 g/m² (line 119 of the MS) and then distribute it in a 25 cm layer (line 121) in soil with a dry bulk density of about 1.5 g / cm³ or 1500 kg/m³ (Fig. 3), then the concentration of biochar will be less than 100*(3.26/1000)/ (1500*0.25*1)= 0.001% !!! This is an insignificantly small value that is not able to directly affect either the carbon content, or pH or EC, or the dry bulk density of the soil. I think that in the future experiments you need to greatly (100-1000 times) increase the doses of biochar to get any significant effect. And in this MS, it seems to me that it makes sense to say that the doses recommended (by whom?) of several grams per m² are obviously too small to expect a direct effect on the soil and an indirect effect on the survival and growth of forest crop seedlings.

June 26, 2025

With best wishes, Your Reviewer

Author Response

Please see the attachment.

Author Response File: Author Response.pdf