Study on the Extraction Method for Ecological Corridors under the Cumulative Effect of Road Traffic

Round 1

Reviewer 1 Report

The described method of separating ecological corridors is an interesting study, but with the attention that it concerns preliminary analyzes allowing for significant simplifications/generalizations. I find it valuable to show the possibility of using the available digital field data to describe the resistance function.

In my opinion, the following limitations of the presented method should be added in the summary:

1. omission of species diversity of birds. Such differentiation affects the formation of corridors for the movement of birds. Thus, resistance functions should be built taking into account specific groups of birds along with "their preferences"

2. rivers are usually natural ecological corridors for birds and this is not sufficiently taken into account in the described method. It is advisable to comment on this phenomenon.

3. The authors do not take into account the volume of traffic in the description of the impact of road location on the formation of ecological corridors. Although the article mentions that these data are not available, such a comment is not sufficient. The potential impact of traffic volume on changes in ecological corridors should be described.

It is good that the authors mention many limitations of the described method. However, a valuable supplement to the summary would be a synthetic presentation of the concept of the second stage of the method's development, so that it would be more universal.

Author Response

Thank you for your valuable suggestions and detailed comments.

We have summarized the changes in the attached document.

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

The paper is an important contribution to ecological network construction in urban areas which provides a method to extract ecological networks and the effects of road networks on them. 

The materials and methods utilised in this study are sufficiant for the purpose of the paper. 

The paper is well written and referenced. The results are throughly represented and outcomes are discussed in the relevant literature with some recommendations to future works. 

So I believe that the paper can be published in its present form. 

Best regards

 

Author Response

Thank you for your diligent review.

Reviewer 3 Report

The authors “propose an algorithm for superposition analysis of multiple road impacts and construct an ecological corridor extraction method that considers landscape pattern, habitat quality, remote sensing ecology and road traffic resistance to address the shortcomings of current ecological corridor extraction methods that underestimate the potential impacts of road traffic.”

“The results showed that the improved method was effective, with the proportion of ecological corridors not re-identified due to road traffic impacts being 0.45% and the proportion of ecological corridors with significant changes in spatial location, represented by regions far from roads or high road network density, being 22.15% in the whole Wuhan.”

These seem to be highly relevant results and the study approach is interesting and much needed for landscape planning. However, the manuscript would benefit from a more structured writing. The description of the methods, the results and the discussion bounce back and forth.

Here are detailed recommendations listed how to improve the structure of the manuscript and to guide the reader to interpreting the results:

·         In the introduction, the authors are discussing the topic of birds and factors that contribute to population decline, habitat loss and degradation. It would be easier to comprehend the study results if this subject was again taken up in the discussion.

·         A clear hypothesis in the introduction and the overall structure of methods, results and discussion would be of benefit to grasp the content of the study.

·         The sentence: “Of course, with the development of science and technology, respecting the laws of nature, more comprehensive consideration, finer quantification and other initiatives will ensure that the simulated resistance surface is constantly close to the real situation.” Seems to be a nice pivot point for the discussion, but is incomprehensible in the methods section.

·         The sentence “It can be seen that ecological corridors remain basically the same before and after the improvement of the extraction method, but there are still some obvious improvements.” belongs into the result section. As it is as well mentioned there, it can be simply deleted in the methods section.

·         The following parts belong to the methods section: “3.2. Data Collecting and Pre-Processing The land cover data were obtained from GlobeLand30, the 30-meter resolution global land cover data product, which was developed by China, and the latest version is GlobeLand30 2020. GlobeLand30 includes 10 classes of land cover: cultivated land, forest, grassland, shrubland, wetland, water bodies, tundra, artificial surfaces, bare land, permanent snow and ice. The remote sensing image data were obtained from Landsat8 L2 data product. This paper uses imagery from May 2020 to September 2020, and completes the fusion process and removes the impacts of clouds and noise before use. The road network data are obtained from OpenStreetMap, firstly extracting the high-grade roads of fclass as "primary", "motorway" or "trunk", then processing the adjacent parallel multi-road in a single line and the multi-segment roads without bifurcation in a single segment. The processed results are used as the basic data for road traffic resistance analysis. 3.3. Ecological corridor extraction and analysis First, the GlobeLand30, Landsat8 L2 and OpenStreetMap road network are analyzed and calculated using the method in subsection 2.2 to obtain landscape, habitat quality, remote sensing ecology and road traffic resistance of Wuhan, respectively. Then, the combined resistance is calculated using the weights and resistance values in Table 1 and the method in subsection 2.2.3. The calculation results of the combined resistance are detailed in Figure 4, where the resistance values gradually increase from blue to red. In the central city of Wuhan, the combined resistance is larger, and the further away from the city center, the resistance value is smaller. However, there is a general abrupt change in the resistance values, mainly due to the abrupt change from the artificial surface to the natural surface, and the ecological resistance values of these two surfaces differ greatly.”

·         Results: The discussion and sub-chapters of chapter 4 are actually the results. The sub-chapter “Difference between two methods” is the center piece of the results and should be the focus of the discussion later on. It is recommended to set this part upfront in the results section and explain the readers what the differences will implement in practical landscape planning in future. Table 2 and 3 are listing the results like described in the abstract. Thus, this part must be put into the results section.

·         Discussion: the following sentence is subject to the discussion. “In Figure 10, a long ecological corridor is emerging, which may be a coincidence. In the actual planning and construction process, if there are multiple ecological corridors with basically the same function in the extraction results, they can be further screened according to the constraints such as funding, and a final decision can be made to keep or delete some of them.”

·         But as a first step in the discussion the reader should be guided back to the problem or the example of the birds and receive the information why the results are relevant and how they could be changing future landscape planning. In the discussion section it would be recommendable to get some practice examples, on how the results of the study can help to better create ecological corridors and where the limitations of the studies are.

General other remark:

In this paper,…is often used for the start of chapters but is actually not needed. The authors should consider to simply delete this phrase (it will not change the content) or rephrase to “the study results”, “the hypothesis of this research”, “the approach of the research design”.

Author Response

Thank you for your valuable suggestions and detailed comments.

We have summarized the changes in the attached document.

Please see the attachment.

Author Response File: Author Response.docx