Influence of Urban Agglomeration Expansion on Fragmentation of Green Space: A Case Study of Beijing-Tianjin-Hebei Urban Agglomeration

Round 1

Reviewer 1 Report

This paper covers a relevant topic but needs significant improvements in a number of areas, especially in poor, unreadable maps and some confusing tables and graphs.

Please write in the past tense when describing what you did.

Line 63 When talking about drivers you may also refer to the DPSIR framework and the PESTEL factors

Lines 77 and 78 You introduce a number of models just with initials – please give them their full names at the first time they are used.

Section starting at Line 80 – needs some general definition or typology of Green Space and also perhaps, given the recent surge in research, also Blue Space. However, the use of the term and its derivation in the literature related to urban green spaces does not make sense later when you refer to key land cover classes. I suggest you rephrase this – and also the paper – to reflect the fact that you are looking at non-urban or green (blue?) land covers/uses at a regional scale and not the fine grain of urban green areas such as parks. Essentially you are studying the process and patterns of how non-built land cover transfers to built-up urban areas.

Line 109 You refer to BTH but this needs to be spelled out in full as the first mention. At this point you summarise methods but do not clearly state the goals, objective, hypotheses and/or research questions for which the chosen methods are suited.

The location map is not cited in the text (Fig 1) and the use of the elevation map is not useful at this point. Please replace with the provincial boundaries and locations of the main cities for better orientation of the reader.

Section 2.3.2 your selection of particular landscape metrics needs much more justification and a single numbered reference is insufficient. Please expand on why these were chosen and what they tell us. Section 2.3.3 has the same name as 2.3.2 – why? In this section the relationship of the factors to be correlated with the metrics measured in 2.3.2 is very unclear – in fact I can see no clear relationship between them, apart from mesh size. Please explain how the one feeds the other.

Do not use the term construction land. It is better to use “built up areas” in English. Construction land means land used for the activity of construction.

You refer to Fig which shows patterns and you explain in detail different patterns and trends in land use change by naming different cities and parts of the BTH area. This is impossible to relate to the maps due to size, resolution and lack of information such as names of the cities. Please think of a better way to show this and relate it to specific locations because at present it is meaningless.

Figure 3 is also meaningless as presented – why show the amounts as % when the total actual area changed – what is it showing? Are these the areas converted to built-up land or the remaining amounts after built-up areas have been removed? It is very confusing. Table 3 is also confusing – how is it showing transfer from one land use to another – there is no net reduction or addition as far as I can see, just a set of areas – it also states it is 2020 so is this transfer up to 2020 or in 2020?

Figure 4 is an interesting map but is so low resolution that it is impossible to see what transferred to what. Figure 5 clearly shows how the built-up areas have expanded but does not reveal what transferred from what to built-up. Figure 6 comes closest to something that can be understood but there is no idea of what time period it covers and the legend is really clumsy.

Figure 8 states it is the projected changes in the BTH but it focuses on Beijing and Tianjin – where is Hebei? You state in relation to this figure that it is clear that urban expansion is on farmland and grassland but it is not possible to see this from the low resolution of the maps. You also discuss different trends by naming places not marked on the maps, so this is not useful.

Your conclusions may be correct but it is not clear from the ways you have presented the work exactly how you deduced this.

Overall, you need to rethink the methods of presenting the results in ways that are easy to follow and clear in terms of what they are showing. Confusing tables, graphs and low-resolution maps with no locations do not help the reader to follow your narrative.

Author Response

Please see the attachment.

Author Response File: Author Response.zip

Reviewer 2 Report

This manuscript provides an interesting and clear empirical contribution to the study of urban expansion and land use change in the BTH area. Through the use of what seems to be appropriate and adequate methods, the authors show the land use changes and urbanization patterns over the last 20 years in the area. The assessment of green spaces fragmentation is presented as one of the main contributions of this paper. The extent and conversion of different land use categories are assessed, while there is a land use forecast using the FLUS model. 

General comments: 

While this is a highly relevant empirical contribution, it seems that there should be more attention paid to some of the policies and land management framework underlying these land use changes. I understand this is not the intend ot the authors to address primarily policy issues, but this would provide more depth to the analysis. 

The contribution is situated among other work on Chinese urbanization, but I believe a few more references on international urbanization processes should be cited to demonstrate a better grasp of international literature on the issue. 

Grees space fragmentation is one of the main consequences of current urbanization processes, yet this change does not seem to be sufficiently explained in the paper. The process is described, but we know little about the impacts or consequences of such fragmentation. 

Specific comments: 

Statements on page 1 and 2, should be removed or rewritten with caution, especially when saying "Under the background of new urbanization and ecological civilization construction, China is gradually transforming into green development". I understand this is citing a previous study, but such statement is highly contested regarding the currend development trend taken by China, along with most jurisdictions in the world. "Green development" remains largely a fiction. 

Statement on page 13 "but the encroachment  on farmland is relatively slow and that on grassland is intensified" seems interesting but not fleshed out sufficiently. Would it be possible to futher explain this trend, which would demonstrate that natural land conversion is sparing farmland due to policies or economic factors?

 

Author Response

Please see the attachment.

Author Response File: Author Response.zip

Round 2

Reviewer 1 Report

The authors have taken all my comments on board very well and now the confusion and  uncertainties which affected the original draft have been resolved. I still believe that there is space to look more closely at Hebei in order to make it logical to focus on the BTH area and I urge the authors to consider this for completeness sake . Many of the maps are still very small and difficult to read, especially when yellow is used for the land use colour - it is a difficult colour to see against a white background. Since Land imposes no restrictions on page length of a paper I suggest you consider making as many of the maps as possible as large as possible and maybe also consider adding a file of supplementary materials where the maps are larger and very clear. It is still frustrating to try to see the detail in a number of them.

Author Response

Dear Reviewer,

Thank you very much for your comments. Following your suggestions, we have revised the manuscript again.

We mainly made further modifications to the pictures according to your suggestions. We enlarged the contents of the figures, changed the colors, and split some figures. Our picture export resolution is 1000dpi, which is believed to be clear, but after being inserted into "Word", the picture becomes fuzzy, so this time we submitted an additional original picture. In addition, for example, as shown in figure 5, the transfer area may not be seen in individual drawings, perhaps because the area is too small to be ignored.

And in figure 7 and the manuscript, we revised it again, highlighting Hebei Province.

Here, we resubmitted this manuscript and original drawings. We hope this revision is closer to your expectation.

Author Response File: Author Response.zip