Bark Stripping by Deer Was More Intensive on New Recruits than on Advanced Regenerants in a Subalpine Forest

Round 1

Reviewer 1 Report

As a zoologist who study evolution and ecology of deer, I will focus my attention on the ecological aspect of the relationship “deer – tree saplings” described in the manuscript entitled “Bark stripping by deer was more intensive on gap successors than on advanced regenerants in a subalpine forest”. The paper present interesting observations on influence of increased cervid density on the forest regeneration and describes how Cervus nippon alters the tree species composition in the observed subalpine forest zone. Human activity and human intervention in natural processes often upset balance in ecosystems, including forests regenerations, and the described in the present paper study reveals such a phenomenon (sika deer protection resulted an increase of population density that triggered the mechanism of alteration of forest regeneration). The only concern that I have about this study is the potential conflict between Cervus nippon protection measures and forest protection that is not addressed in the paper. I have just some questions in order to make more clear the context of the observed phenomenon. The correctly indicated context of the study will help to avoid the conflict between sika deer protection measures and forest regeneration protection.

1. Ecology of deer (including Cervus nippon) follow annual biological cycle that also include the seasonal change of forage (see, for instance: Feldhamer, G.A., 1980. Cervus nippon. Mammalian Species, (128), pp.1-7 and references therein). Usually, bark stripping occurs during winter season when other type of forage is unavailable. During which season (winter, springtime, summer or autumn?) your observations were made (please, indicate it in your research methods chapter) and during which season saplings were stripped by sika deer (please, indicate it in the description of discussion chapters)?
2. The second question issues from the previous ones: did sika deer were present during all seasons in the subalpine forests you observed? You mention in the Study site description 50 cm snow cover at the site from December to April. Since sika deer usually avoid deep snow cover, one can expect that this cervid species was not present in the subalpine forests you studied. Could you confirm or refute this statement in your paper?
3. If your observations were made during supper season, is it usual for Cervus nippon in the studied area to feed during summer in subalpine forests with poor understory moss-type vegetation or this is a consequence of overpopulation?
4. How seasonal change of forage sources in sika deer affected bark striping in the area you studied?

Even if you cannot give a detailed replies to the questions, better to mention in the discussion chapter the problem of cervid seasonal change of forage type and its potential influence on the sapling survivorship. You also can indicate those questions as directions for future research.

When the missing information will be included in the manuscript, I will be happy to recommend it for publication in the journal “Forests”.

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

This was a straightforward study on an interesting topic with a long-term data set.  The analysis was plainly described, but I have some questions about the conclusions drawn, and some other minor issues.

Please specify in the introduction that "gap successors" and "advanced regenerants" are both regeneration modes that can be used by a single species.  My first reaction was that this was a species-specific characterization.  The intro was otherwise very solid. 

Please end the intro with some specific hypotheses.

The dramatic increase of deer density was startling!  I think it needs to be further discussed in light of the results (see below).

Please indicate if sapling or tree death was recorded during each survey.

Please indicate that Table 2 is showing CI results.

In table 3, I believe the column heading should be "Exact Wilcoxon" rather than "Asymptotic"?

DISCUSSION

First paragraph was gripping.  Second paragraph introduces the terms as different regeneration modes.  Please state this in the intro as well.

I would like to see some discussion of the dramatic increase in deer density and how that may or may not have influenced the results.  It does not seem that bark stripping has a demographic influence on these species, based on the mortality data.  So, the conclusions don't seem to follow the data.   Yes, there was a difference in the degree of bark stripping, but not ultimately on mortality.

Author Response

Please see the attached file.

Author Response File: Author Response.docx