Too Warm and Too Dry—Decline and Threat of the Subarctic-Subalpine Liverwort Hygrobiella laxifolia in a Low Mountain Range in Central Europe under the Conditions of Climate Change

Round 1

Reviewer 1 Report

Please elaborate on the field methods used for the ecological sampling.  See document.

I find that the study on systematics and that on the ecology target two different audiences.  I would prefer to see this as two papers. I could only justify the combination if the ecological study supported the speies separations, but it doesn't since only one species was in the ecological study.

Comments for author File: Comments.pdf

The paper is well written, but does have a few minor corrections needed.

Author Response

Responses to the reviewer's comments of reviewer 1:

Please elaborate on the field methods used for the ecological sampling.  See document. Line 105-110: Were all rocks/boulders sampled?  How many?  If not all, what was the sampling design?  How was colonized area determined?  Did you include boulders with no Hygrobiella?  How were boulders relocated?  (numbered, markers, or what?)

We have clarified the section on field methods. The corresponding paragraph is now as follows: 

At each record site, during the initial survey carried out in 2014–2018 and the follow-up survey carried out in 2023, all microhabitats suitable for colonization by the species were searched. These microhabitats were generally boulders in the creek bed and we recorded the presence of the species at the record site and the number of boulders colonized by the species. On each boulder, the area colonized by the species was measured with a ruler and a total sum of the area colonized by the species was determined for each record site. GPS coordinates, photos and handwritten sketches of the colonized microhabitats of the record sites were taken during the initial survey in order to ensure that the occurrences could be reliably located. To determine changes of the habitat, a photo comparison was carried out at selected sites, in which photos were taken at approximately the same time of year and using the same perspective and the same section. Thus, photos from the year 2023 were compared with those from the period 2015–2018.

I find that the study on systematics and that on the ecology target two different audiences.  I would prefer to see this as two papers. I could only justify the combination if the ecological study supported the species separations, but it doesn't since only one species was in the ecological study.

In chapters 3.1 to 3.3, some basic aspects of the distribution, taxonomy and habitat requirements of the studied species in the study area are presented first, followed by the results on changes in occurrence and population size in chapter 3.4, which takes up the main part of the manuscript. These chapters are important in order to characterize the initial state. The section on taxonomy is important because the recent splitting of H. laxifolia and the morphological peculiarities of the populations in the study area meant that their exact taxonomic classification had to be clarified first. We therefore do not wish to split the manuscript into two manuscripts.

The paper is well written, but does have a few minor corrections needed.

We have taken up and implemented all the linguistic changes suggested by the reviewer.

Line 18: the reviewer recommends to insert Czech Republic behind Elbe Sandstone Mountains.

The study area is situated in both, Germany and Czech Republic. Therefore, we changed this passage as follows: The study area is the Elbe Sandstone Mountains in Germany and the Czech Republic, where …

Line 26-29: What does "this" refer to? What is meant by "in this dimension"?

We have changed the sentence as follows:

The severe bark beetle infestation and the large-scale forest fire of 2022 both represent events that led to the almost complete deforestation of large parts of the study area, which was previously unknown on this scale. Since both, the bark beetle infestation and the forest fire, are strongly intensified by climate change, we assume that climate change is the main reason for the decline of Hygrobiella laxifolia in the area.

Line 36: we have added ecology in the Keywords

Line 76: Do you mean subalpine?  I can't find a definition for dealpine.

Yes, subalpine is better. We have changed it accordingly.

Line 85: insert to between due and forest.

The desired change has been made.

Line 133: reference for Sanger method should be included

We included a reference: ….(Sanger et al. 1977)

Sanger F., Nicklein S., Coulson A.R. (1977) DNA sequencing with chain-terminating inhibitors. Proc. Natl. Acad. Sci. U.S.A., Biol. Sci. 1977, 74, 5463–5467.

Line 165: Why are the places in italics?

We have put the locations in italics to emphasize them better. As this is unusual in Diversity, we set them in normal font.

Line 299: Remove extra l.

We have deleted the extra l in laxifolia.

Line 333: We have changed Twenty one to Twenty-one.

Line 349: we have changed occured by occurred

Line 470: insert to between due and bark.

The desired change has been made.

Line 483:  insert to between due and thinning.

The desired change has been made.

Line 540: We changed the sentence according the suggestion of the reviewer. The sentence is now:

The site Koutský potok, already severely impacted by dying of spruces, was directly affected by the forest fire in 2022.

Line 553: We have changed dead to death.

Line 566: What dimension? I don't know what you mean here.

We have adopted this sentence.

Since such bark beetle infestations as well as large-scale forest fires as in 2022, which led to a complete loss of the forest in large parts, have not been observed in the region in previous times, and since both events are favoured by climate change, we argue that climate change has a strong amplification effect and is thus the main cause of the decline of H. laxifolia in the Elbe Sandstone Mountains.

Line 576: Periods and commas go inside the quotes.

We have changed “cellar effect”. to “cellar effect.”

Line 604: change occurrence to occurrences.

The desired change has been made.

Line 617: Is this CR?

Yes, this is the Red List category CR. We have included the abbreviation in the text.

Line 621: Are you referring to Czech Republic, or a category in the Red List.  If the latter, you need to define it.

We have written out the Red List category and put the abbreviation of the category in brackets behind it.

Line 644: Where or whose is herbarium B?  This is not standard notation for any herbarium.

The acronym B is the standard notation of the herbarium of Botanical Garden and Botanical Museum Berlin, see Index Herbariorum https://sweetgum.nybg.org/science/ih/herbarium-details/?irn=124103

Line 686 ff.: Don't capitalize titles of journal articles unless they would be capitalized in a sentence.

We have adopted this.

Line 713: Abbreviate journal name.

The desired change has been made.

Reviewer 2 Report

A few minor commentss in the manuscript and a couple of misspellings highlighted

Comments for author File: Comments.pdf

Author Response

Responses to the reviwer's comments of reviewer 2:

Line 155: The reviewer has pointed out that the species also occurs in Nova Scotia and Quebec in eastern North America.

We have changed the information of the distribution as follows: … and in the east from Quebec, Newfoundland, Labrador, Nova Scotia to Greenland

Figure 1: seems to be localities in Czechia that is not marked on the map.

We have checked the records in Czech Republic cited in the text and compared it with the marked records on the map. All known localities are shown. Some sites are very close to each other, so that they do not appear as separate points on the map or the circles of the sites overlap.

Line 299: H. llaxifolia is corrected in H. laxifolia

Line 376: ommitted is corrected to omitted

Round 2

Reviewer 1 Report

I accept your argument for keeping this as one paper.

In reference 26, Bryophyta should be capitalized because it is the name of a phylum.  It is also part of a book title, which also should be capitalized.