Arrested Succession on Fire-Affected Slopes in the Krummholz Zone and Subalpine Forest of the Northern Limestone Alps

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Potentially interesting work, however, the scientific background is not sufficiently explored in the introduction (check bibliographic citations) and the aim of the work needs to be better explained. I have some concerns about the method. The conclusion paragraph is missing.

My notes are included in the margin of the paper in attachments.

Although I am not a native English speaker, the language is quite fluent, although some sentences have a somewhat complex construction.

Comments for author File: Comments.pdf

Author Response

Thank you for your detailed notes. We’ve transposed them here with our responses.

General Comments:

Potentially interesting work, however, the scientific background is not sufficiently explored in the introduction (check bibliographic citations) and the aim of the work needs to be better explained. I have some concerns about the method. The conclusion paragraph is missing.

Thank you for your clear commentary. We improved the literature, adding sentences in the introduction (LL32-35), connecting this work and this site with fire in other systems such as the subalpine in the Brooks range in Alaska, and the Corsican black pine forest. We have further clarified the aim of the work adding a couple of points that we initially considered moot in the final paragraph of the discussion (LL80-87).

We have also added a paragraph to the end of the discussion further elucidating several potential research outlooks as well as management recommendations, which are then contextualized and summarized in the new conclusion paragraph.

Inline Comments:

LL[55-56 + 74] Write the correct scientific name: Latin binomial (in italics) + author's name abbreviation (patronymic)

Corrected.

LL[95] Improve the figure in the appendix with a clearer map of the study area. Perhaps a vegetation map could be added?

There is no available vegetation map for the area to my knowledge. But the map has been updated to be clearer, please let us know what you think of the new version and what you would like to see improved further.

LL[119-123] Write the names of species correctly. Describe vegetation more precisely. What are the plant associations found? belonging to which classes? (Junipero sabinae-Pinetea sylvestris? Vaccinium-Picetea?). It is not enough to indicate the dominant species generically... you could refer to works by Mucina, e.g: Grabherr, G. & Mucina, L. 1993. Die Pflanzenge sell schaften & Oumlsterreichs, Teil II. Gustav Fischer, Stuttgart , DE .

The names of all species in the text have been corrected to Latin binomial + author’s name abbreviation. We have also described the vegetation more precisely incorporating the four main plant associations found in our study site, following Mucina, L., et. al. (2016). Vegetation of Europe: hierarchical floristic classification system of vascular plant, bryophyte, lichen, and algal communities. The two phytosociological classes present in the unburned plots are Piceion excelsae in the open spruce stands and Erico-Pinion mugo in the krummholz vegetation. These are clearly delineated, while the main identifiable classes in the burned areas are Seslerion caeruleae and Potentillion caulescentis (LL 124 & 129-131).

LL[162] Add citation: POWO (2024). "Plants of the World Online. Facilitated by the Royal Botanic Gardens, Kew. Published on the Internet; http:// www.plantsoftheworldonline.org/ Retrieved 17 May 2024."

Thank you for the reminder. The citation has been added.

LL[166] Insert bibliographic citation explaining the scale.... It is not used in all disciplines that study vegetation. One could use Braun-Blanquet....

This is a helpful note, we have added the citation for the original paper by Londo 1976 and added a line describing its benefits (LL167-168)

LL[168] Why did you use both Landolt and Ellenberg? Explain the pros and cons of the two systems.

As is now also included in the text (LL170-174), the Ellenberg system, while being more widespread is based on flora of the entirety of Central Europe may be biased towards lower elevation populations. The Landolt system, developed specifically for the flora of Switzerland provides nuance regarding species at higher elevations. We thought that it would be important to be able to compare the two – as we see with the temperature EIV (where we see a misalignment between the two systems) and thus cannot draw conclusive evidence for a difference between fire histories.

LL[173] Clarify how alpha diversity was calculated, with the Shannon index? Simpson?... you only talk about floristic richness, but richness is not biodiversity. Alpha biodiversity takes into account specific richness and equipartition (i.e. the percentage of occurrence of each species).

We clarified that the alpha diversity was calculated with the Shannon index (LL206-207) and corrected the paragraph in the methods section (LL173), stating that “We calculated the Shannon index (Hill, 1973) as alpha diversity metric to get a balanced weight of rare species (rather than the Simpson index) using the diversity() function in the vegan R package”.

LL[229] I think it is too simplistic to refer to groups: forbs, graminoides, shrub, tree. Species should be grouped on the basis of their ecological-environmental and dynamic-evolutionary role. The classification and hierarchisation used by phytosociology (floristic-ecological science) is a more effective interpretative key. You could consult the European Vegetation Prodrome and similar works and group species according to their belonging to the same class/order/alliance/ association. i.e.: Mucina et al. Vegetation of Europe: hierarchical floristic classification system of vascular plant, bryophyte, lichen, and algal communities. https://doi.org/10.1111/avsc.12257

Thank you for sharing this insight with us. While looking at diversity at a functional type level may be a simplification of the system dynamics, we disagree that it is too simplistic. For the purpose of our hypotheses (i.e. that there is a different composition of species in burned communities and that the taxa that drive these differences are ‘invaders’ within this elevational range), studying the functional type level can help provide a detailed view of the functional changes in the community. The detail provided by this grouping allows us to identify whether growth forms favored by fire (e.g. graminoids and ruderal forbs) are still present at high levels 80 years after disturbance. While grouping by phytosociological association/class would provide insight into the types of communities present, it would provide less insight into the actual structural changes promoted by the disturbance.

LL[249-270] It is not clear. Is the Nardetum replaced by the Carici-Curvuletum? Or vice versa? Or have you not studied the associations? What changes in terms of rare and/or endangered species? Do competitive or ruderal or stress-tolerant species increase? I would say that it would be essential to also include qualitative aspects and not only quantitative ones.

While we agree that associations would have been an interesting addition to the analysis, we did not set out to study the phytosociology of the area. Rather we are looking more quantitatively at the diversity changes in fire affected areas. This being said, we have added the phytosociological associations in the initial descriptions of the vegetation (LL119-123).

We have reworded the paragraph and added a table to improve clarity and included some qualitative changes we observed in addition to the quantitative changes mentioned (LL249-256). Interestingly, there are fewer protected taxa in burned plots than in unburned plots, though slightly less than half the endangered species we observed were present in both. Though this could insinuate that burn plots house more ruderal species, the unique presence of Calamagrostis varia (a disturbance-phile) in unburned plots, seems to counter this train of thought. The difference between the burned and unburned plots lies mostly in the physical structure of the vegetation (read vegetation height), and community composition, rather than provenance (both elevational and ‘ruderal’) of the taxa. This is an important addition that we believe belongs in the discussion and has therefore also been highlighted better there.

LL[294-297] Explain why. Is this due to ecological factors or soil or climate or exposure or altitude or...? The fact that unburnt areas are richer in species does not mean that they are more biodiverse. Biodiversity is also a qualitative concept. If I have more species but they are all trivial, ruderal and widely distributed, it is a poor biodiversity.

This is a very important note- both in content and in clarification. Your question implies that we haven’t explained this portion of our results correctly as it is meant to study whether the community present in the burned sites differs in ‘elevational provenance’ from that in the unburned sites. As we touch upon in the discussion, this lack of difference is likely due to abiotic filters (such as temperature and humidity) preventing immigration. We would only expect a deviation of the unique species from the whole community if we observed immigration from plant communities outside the elevational niche- indicating an upward shift of valley-dwellers, or a downward shift of alpine-dwellers. Though we can postulate the potential causes of this absence of shift, we do not have any data providing a clear explanation, nor did we set out to.

Regarding the biodiversity section of your comment: we agree that pure species richness does not directly correspond to ‘better’ biodiversity and have made no attempt to claim that these burned areas are more biodiverse than the unburned areas. Rather, our inclusion of the count of unique species is meant to highlight the fact that the burned community is compositionally distinct from unburned community. Overall, while the burned plots have a slightly higher species richness (174 species vs 136 in unburned plots), the unburned plots are home to more protected species (35 species identified as threatened or higher by Red List standards vs only 30 in burned plots).

LL[375] Part of the discussion could be integrated into the sub-sections of the results section. A conclusion paragraph should be written with some of the arguments now in the discussion paragraph. What are the future developments of the research? What are the spin-offs in terms of nature conservation? Clarify.

Thank you for this suggestion. Though there are some elements of the discussion that could fit well in the results, we have chosen to keep the results section as simple as possible, attempting to avoid making too many interpretive statements, and thus have elected to maintain them in the discussion.

We have added a conclusion paragraph as you suggested, including future prospects and implications of this work in terms of management of these areas. To summarize:

Future work could focus on two separate parameters: understanding a) the regeneration failure of Pinus mugo in this site, through micrometereological data, physiological studies on P. mugo seedlings, and b) the potential filter of ungulate browsing.

Climate predictions for the Eastern Alps indicate increases in summer and autumn temperatures as well as an increase in frequency and severity of heatwaves (Beniston 2004, 2006). The northern Eastern Alps are predicted to have increases in winter precipitation coupled with increases in precipitation intensity but a shift from large summer events to spring and autumn heavy rainfall (Beniston 2003). Beniston (2003) also forecasts earlier snowmelt dates, exposing the vegetation to a longer ‘dry’ period. The coupling of these three factors could in fact lead to increased fire risk in many of these areas due to overall drier conditions by the end of the summer.

To our knowledge the NPA does not have fire management actions in place for the Arnspitze massif. While in the past this may not have been necessary, seeing the potential increase in fire risk due to the predicted climatic changes, as well as the arrested succession we observe here, we would recommend resource allocation to such a project to prevent the complete eradication of the Krummholz ecotone in this area.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The research “Arrested Succession on Fire Affected Slopes in Krummholz Zone and Subalpine Forest of the Northern Limestone Alps” presented a phytosociological analysis in burned and unburned areas to identify the post-burn pattern.

The research used standard phytosociological analysis techniques, with a clear and objective introduction and methodology. The results and discussions addressed all the questions described in the objectives and brought important observations about the ecological pattern of the area.

As suggestions, I identified some points that could be better addressed by the authors to make the text easier to read.

*Based on the references indicated in the text, especially 35-38 or other studies, can it be confirmed that the areas analyzed had similar phytophysiognomic characteristics in the pre-fire period? This did not seem so clear when reading the text.

*The figures in the appendix were very important for understanding the location of the plots and the geographic pattern of the area. In my opinion, they could be included throughout the text, facilitating comparisons for readers.

*I suggest expanding the discussions on two points: according to the climate change forecast models for the area, is there a possibility of a drier climate? This could be analyzed by connecting the possibility of larger fires in the area with their impact; I suggest further detailing how the study can help in decision-making for the ecological management of the area. As it is a Nature Protection Area, are there fire prevention or fire management actions in the area? Or if they do not exist, would it be recommended given the researchr esults?

Author Response

The research “Arrested Succession on Fire Affected Slopes in Krummholz Zone and Subalpine Forest of the Northern Limestone Alps” presented a phytosociological analysis in burned and unburned areas to identify the post-burn pattern.

The research used standard phytosociological analysis techniques, with a clear and objective introduction and methodology. The results and discussions addressed all the questions described in the objectives and brought important observations about the ecological pattern of the area.

As suggestions, I identified some points that could be better addressed by the authors to make the text easier to read.

Thank you for your insightful commentary. Please find below our responses to your suggestions.

 

Suggestion 1: Based on the references indicated in the text, especially 35-38 or other studies, can it be confirmed that the areas analyzed had similar phytophysiognomic characteristics in the pre-fire period? This did not seem so clear when reading the text.

Thank you for highlighting this necessary clarification. Yes, the areas analyzed can be confirmed to have had similar phytophysiognomic characteristics – pictures taken a couple of years before the fire (one seen in Figure 3a) show an even cover of krummholz vegetation on the entire burned slope and reference 37 goes into depth about the historical evidence photographic as well as written of the vegetation of the studied slopes. We have added this detail to the methods (LL128).

Suggestion 2: The figures in the appendix were very important for understanding the location of the plots and the geographic pattern of the area. In my opinion, they could be included throughout the text, facilitating comparisons for readers.

The figures were initially placed in the appendix to limit the number of figures in the main text but have now been appropriately included in the main text, as suggested.

Suggestion 3: I suggest expanding the discussions on two points: according to the climate change forecast models for the area, is there a possibility of a drier climate? This could be analyzed by connecting the possibility of larger fires in the area with their impact; I suggest further detailing how the study can help in decision-making for the ecological management of the area. As it is a Nature Protection Area, are there fire prevention or fire management actions in the area? Or if they do not exist, would it be recommended given the research results?

These are interesting suggestions that we have taken into account and added to our discussion (see lines 438-444), and which I will paraphrase below:

Climate predictions for the Eastern Alps indicate increases in summer and autumn temperatures as well as an increase in frequency and severity of heatwaves (Beniston 2004, 2006). The northern Eastern Alps are predicted to have increases in winter precipitation coupled with increases in precipitation intensity but a shift from large summer events to spring and autumn heavy rainfall (Beniston 2003). Beniston (2003) also forecasts earlier snowmelt dates, exposing the vegetation to a longer ‘dry’ period. The coupling of these three factors could in fact lead to increased fire risk in many of these areas due to overall drier conditions by the end of the summer.

To our knowledge the NPA does not have fire management actions in place for the Arnspitze massif. While in the past this may not have been necessary, seeing the potential increase in fire risk due to the predicted climatic changes, as well as the absence of full recovery, we would recommend resource allocation to such a project.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Dear Editors and kind Authors,

I have reread the text and I believe that all the changes requested have been made.

The quality of the images has improved, the quality of the work has definitely improved. I believe it can be published.

Thank you kind regards.