Making Way for Trees? Changes in Land-Use, Habitats and Protected Areas in Great Britain under “Global Tree Restoration Potential”

Round 1

Reviewer 1 Report

I have the pleasure to review the MS:

 Making way for trees? Changes in land-use, habitats 2 and protected areas in Great Britain under “global 3 tree restoration potential - The idea of the paper is original and timely –The MS reads very well.   I advise to accept the paper with minor revisions / it will be important to add in the discussion a main issue on reforestation, that is the selection of species as much of tree planting is based on exotic species with industrial interest; thus the impact is even further on the habitat quality. It will be important to add some few references and a good paragraph on this important component of reforestation.

Another issue will be to improve Table 1 – links are not active, perhaps it will be important to enter full link – the table caption does not make any sense “Table 1. – Descriptions and sources of spatial data included in the study. “We combined the supra-100 littoral sediment and littoral sediment classes.” Please correct / clarify

After corrections are introduced, I think the MS could be accepted  

Author Response

We thank the reviewer for their kind and constructive comments. We have now added a paragraph on species choice under the biodiversity sub-heading of the discussion, noting the adverse impacts of exotic monocultures. In Table 1, we have inserted the requested hyperlinks. We have also added “(see [17])” to the caption so that the reader may follow-up if interested about our decision to combine sediment categories. In any case, Figure 3 shows that this decision has negligible impact on the results as sediments occupy a far smaller area than other habitat types.

Reviewer 2 Report

An excellent paper, looking at the ramifications of large scale land cover changes.

Author Response

Thank you to the reviewer for such positive comments.

Reviewer 3 Report

The paper by Wilkes et al is timely, an appropriate test of the hypothesis regarding tree planting climate claims, and is well written. I had only minor suggested edits and a few comments to consider. Most importantly, the authors need to discuss how the tree potential was derived for their study - it's not enough to point to the Bastion et al. paper in Science (which has a pay wall). Add a few descriptive sentences on how the potential was mapped (criteria used). In addition, a better discussion of potential tree mapping limitations (assumptions) is warranted including problems in Bastion et al noted by other researchers that commented unfavorably about their original study (e.g., https://forestsnews.cifor.org/62487/trees-and-water-dont-underestimate-the-connection?fnl=). A section on data limitations would be helpful so the reader understands that tree potential may not equate to actual trees surviving in those localities under a changing climate, soil impacts from land use, tree mortality etc. Additionally, if tree planting were even a viable option in places, a discussion of the benefits of native vs non natives would provide some guidance to those wanting to do this and a discussion about how other strategies may prove more important - such as storing more carbon in native forests (primary forests in the rare places those remain) and proforestation (Moomaw et al 2019) - allowing degraded forests to recover stocks. In Ireland and Scotland, for instance, one of the most heavily deforested places in Europe - they are planting Douglas fir and spruce because of commercial value in plantations. That has negative effects on biodiversity that could be further discussed in an expanded tree planting implications section. I made additional comments in the comments feature of the pdf. Otherwise, this is a very important study. 

Author Response

We thank the reviewer for their well-considered and constructive comments. As suggested, we have added a brief description of the modelling process used by Bastin et al. in the introduction. We have covered the main criticisms of the Bastin et al model and now follow this up with more critical content in the biodiversity section of the discussion. This includes information on tree survival under climate change, the question of native vs. non-native tree species, and the potential adverse consequences of “tree restoration” on food and water security. We have stopped short of engaging with the proforestation literature in this case since we do not want to detract from the main message of paper, which by definition focuses on tree planting rather than management of existing forests. However, we have now offered more specific information about impacts associated with the type of commercial plantations mentioned by the reviewer (see biodiversity section of the discussion).