Estimation of Forest Stand Volume in Coniferous Plantation from Individual Tree Segmentation Aspect Using UAV-LiDAR
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe authors have performed a very straightforward and easy to follow methodological approach, to estimate the forest stand volume in a Coniferous plantation forest in China. They achieved this by implementing various individual tree segmentation methods, to detect trees positions, tree heights and DBH, subsequently comparing their results with field measurements.
The “Introduction” part is well-written, providing a comprehensive overview of the field sample surveys, the LiDAR technology and particularly the UAV-LiDAR with pros & cons.
The “Materials & Methods” part is generally well-presented but requires some clarifications. Why was the IDW method chosen to generate the DEM instead of other methods such as TIN? Was this tested?
Additionally, in line 181, the correct model acronym should be CHM, not CMM.
Figure 4 is well-conceived but needs to be improved as it appears pixelated.
In lines 278 to 283, the basis for selecting a 2m threshold is unclear. Is there related literature supporting this value, and is it optimal?
Similarly, Figure 5 and all subsequent figures in the document need quality enhancements as they are pixelated.
The “Results” and “Conclusions” parts are well-presented and sufficiently elaborated.
Considering the arguments presented, in the reviewer’s opinion, the article needs minor revisions regarding figures, and further explanations. Also, moderate editing of English language required is also suggested.
Comments on the Quality of English Language-
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsGeneral Assessment
The manuscript presents research on estimation of forest stand volume, and is well-structured and logically sound. However, there are several significant areas where the manuscript could be improved.
1. Limited Contribution
The manuscript presents a study with limited contribution to the field. The chosen study area, a homogeneous coniferous plantation, inherently simplifies the task of individual tree segmentation. This choice limits the generalizability and robustness of the proposed algorithm when applied to more complex and heterogeneous forest environments.
Although the proposed individual tree segmentation algorithm shows improvements over previous methods, the existing methods, such as GMM have already demonstrated satisfactory performance in similar conditions. Therefore, the practical application of the algorithm improvements may not be significant.
2. Generalizability
The results appear to be highly context-specific, reducing their applicability to broader contexts. It would strengthen the manuscript if the authors could discuss how their findings can be applied to different forests or suggest ways to extend the applicability of their research. Providing a more comprehensive analysis of the potential limitations and implications of the study's generalizability would also be beneficial.
3. Clarity of Description
The manuscript's readability is hindered by the overly long sentences, some extending four to five lines. It would be helpful if the authors could review the manuscript to make complex sentences simplified, or rephrased.
Details:
1. L84 “raster data … have wider applications in coniferous forests” Please provide references to support this conclusion. Alternatively, consider removing this statement.
2. L279 Why is the threshold set to 2 m?
3. L291-L295, some descriptive terms are used here, such as "small trees", " closely connected between canopies", "tree spacing is small", can these descriptions be quantified to illustrate the applicability of the algorithm?
4. Section 4.1
Are the algorithms compared representative? The text mentions that raster-based algorithms are affected by raster resolution. Was this impact considered when comparing accuracy? Is the proposed algorithm always optimal under different resolutions, or there was a certain strategy selection when performed?
Comments on the Quality of English LanguageNo comments
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsSee many comments inserted in the pdf document. The manuscript need to be improved substantially before it can be considered for publication.
Comments for author File: Comments.pdf
Language precision is required here and there in the manuscript, see comments in the pdf document.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsNo comments
