Evaluation of the Potential Seed Dispersal Effectiveness of Malus sieversii (Lebed.) M. Roem. by Cattle

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

General Comments

The authors studied (potential) frugivores feeding on Malus sieversii fruits, their movements, dispersal distances of Malus seeds, and their germination rates after passing the intestinal tract of cattle. For quantification of offered Malus fruits removed from the ground by frugivores three camera traps at three mother trees were utilized. Movements and distances were evaluated based on three adult cattle tracked with GPS electronic collars (earlier fed with Malus; without additional feeding for six days). And finally, germination trials were performed with collected seeds after passage through the cattle’s digestive tract, including (undigested) control seeds (i.e. 25 seeds each).

I see problems with explanatory power due to the small number of replicates per experimental setting (n = 3 mother trees; n= 3 tracked cattle; n = 25 germinated seeds); however, the testing and analysing of the different consecutive processes all relevant for the dispersal and germination of Malus seeds somehow compensate for the small Ns within each step. In a way, I would leave it to the editor to decide whether the generated amount of data fulfills Journal criteria.

Therefore, my main point is regarding the question, how representative the environmental setting is indeed for native Malus sieversii, and therefore, for the chance that the results obtained indeed reflect a situation comparable to a natural situation in the wild. So, if I understood correctly, the study site was a Botanic Garden, and I wonder whether the short description given about co-occurring plants (page 3) reflect a natural or more an artificial (= Botanic Garden) setting. A related question in this context is: How relevant could cattle be as diaspore disperser for Malus sieversii under natural conditions? In which natural vegetation types is this Malus tree species native, and those vegetation types commonly characterised by the occurrence of cattle?

If the authors intended to answer their research questions for an artificial context, by design; this needs to be worked out more clearly. And of course, then the question will arise whether such an artificial setting is indeed relevant for native, natural populations of Malus sieversii. Therefore, also information about the size of the Botanical Garden, whether it is fenced or not, if cattle is used to keep the Botanic Garden open anyway, etc. should be provided.

On the other hand, a typical natural habitat of Malus sieversii might be described and explained how different such natural habitats are from the situation in the study site, i.e. the Ili Botanic Garden. For instance, on page 9 (line 319) the authors speak about “a wide range of movement in natural environments” and about “cattle” grazing – this sounds as a contradiction, because landscapes grazed by cattle are per definition “cultural landscapes”, which might nevertheless include some semi-natural habitats. And this leads to the next question: Is Malus sieversii (only) part of this semi-natural elements? In summary, I recommend describing the present situation more precisely, with respect to naturalness.

One final remark (and maybe I missed this by mistake…): I somehow miss the aspect, that Malus seeds in/on cattle feces will likely benefit from the nutrient matter in these feces. So, this might be an additional supportive factor of cattle positively influencing reproductive success of Malus sieversii, although not studied here, specifically.

 

Specific/Minor Comments:

p.2, l.63: As this is a general introductory part, I would suggest using “plant” instead of “tree”, here.

p.3, l.130: “bias” instead of “errors”?

p.3, l.118-122 and 131-133: There is some potentially misleading redundancy, because in the first mentioned lines there are “three mother trees” as well as “infrared cameras”, and the second mentioned lines stated “infrared cameras were placed to three mother trees…”. I guess, these are the same three mother trees and not additional ones summing up to six trees…?! Please, clarify.

p.5, l.174-176: Text should not be centred.

p.6, l.234: “obtained by” instead of (just) “obtained”.

Table 3, column “Fruits removed (%)”: How is it possible that the strikingly smaller mean value for Equus (76.67) is significantly different from the lower values marked with “b”, while the clearly second-highest mean value of Sus (93.33) is not significantly differentiated from the obviously much lower “b” values of Capreolus and Meles (and furthermore, given similar SE-values)?

p.7, l.242: What are “relevant data”? Do you mean “corresponding raw data”?

p.7, l.252: Add a blank after “Figure 5”.

p.8, l.264: Add “final germination rate (after 30 days)”.

p.8, l.267ff: Why “additionally”? In the sentence before, the “higher germination rate” was already stressed…

p.8, l.271: “Figure 6” instead of “Figure 5”.

p.8, l.271: Blank missing before “CK”.

p.8, l.272: Why “n = 3”? From the M&M I thought 25 seeds were sown for each treatment – was this replicated three times? Please, clarify.

p.9, l.275: “terms of” instead of (just) “terms”.

p.9, l.277: “renewal” instead of “renwal”.

p.9, l.279: “can contribute that” instead of (just) “contribute”.

p.9, l.284: “reproduction” instead of “regeneration”.

p.9, l.285: “visiting” instead of “visited”.

p.9, l.306: I do not agree with this first statement. Why, for instance given very small diaspores, should not wind be the most common vector for long-distance dispersal? And even if perhaps rarely successful in terms of establishment, oversea water dispersal might hold world records of geographical distances of LDD!? Therefore, at least a strong citation is needed here for the first part of the sentence!

p.9, l.320: “In our study” instead of “In this study” (because “this” might wrongly refer to citation 62).

p.10, l.357: I would say that the “significant role” can only be “significant” in the wild. And the present setting needs to be worked out more clearly (see my comments above).

p.10, l.367/368: The same is true for the last sentence: In the present context, it is not clear whether the cattle’s role for “biodiversity conservation and maintaining ecosystem functioning” is just relevant “within the Ili Botanical Garden”.

p.11, l.391: “our” instead of “my”.

Table S1 and S2: Provide the scientific animal species names in italics.

Table S2, headline: “Number of fruits removed” instead of “Number of remove fruits”.

Comments on the Quality of English Language

The manuscript reads quite well. I found only a small number of mistakes (see above).

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This study aims to evaluate the seed dispersal effectiveness of cattle by assessing visiting rate, fruit removal, movement range and germination rate of seeds of Malus sievesi in a site in northwest China. The authors combine camera traps, GPS tracking and seed germination trials with ingested and control seeds. The objectives of this study are relevant and the combination of different methodologies is interesting.

However, I do have some doubts and concerns that in my opinion must be addressed before publication.

1)      I’m not sure that you evaluated effectiveness (sensu Schupp et al. 2010 – New Phytologist) because the two main components are missing, that is the number of seeds dispersed and the probability a dispersed seed produces a new adult in the field. For example, you measured the distance of cattle movement, but not the real seed dispersal distance, habitat/microhabitat seed rain, neither showing quantity of seeds dispersed per feces or seed fate/recruitment in situ. This mismatch is also evident in the discussion headings once effectiveness is a combination of quantity and quality, and highlighted in the conclusions. Additionally, in Table 1 and along the ms you say seed predation, which is antagonist of effective seed dispersal. Thus, I would reorganize the ms downsizing the focus to frugivory and seed dispersal services (showing some quantitative data) rather than effectiveness, rewriting where needed and avoiding over-speculation.

I suggest to check these studies on seed dispersal including domestic animals (Malo et al. 2000 - J. Range. Management; Escribano-Avila et al. 2012 - Plos ONE and 2014 J. of Applied Ecology; Miguel et al. 2018 – Oikos; Bueno et al. 2021 - Glob. Eco. and Conservation) that might be useful to better frame your study and support discussion.

2)      Germination trials were done after cold stratification, which is a common nursery protocol but do not reflect the field conditions. Actually, gut passage is generally the natural stratification. In my opinion the authors must better discuss this point, for example whether this treatment somehow influenced the differences in relation to field conditions.

3)      Camera trapping was done on 2 months (L 123), but the fruit experiment (20 fruits per day) was done at the end of the fruiting season and repeated for seven days (L 133-134). Thus, it is not clear if the results, particularly in table 1 refers to the whole period, to these seven days or both. Please clarify including a metric of the sampling effort (e.g. hours) beyond the total photos and videos.

4)      The cameras were set up with a 30 second interval between trigger. Did the visiting rates consider every 30 sec intervals as a separate observation? This must be clarified once visiting rate might be inflated due to several observations of the same individual that remained for several minutes (e.g. resting as in table 1), which may be expected for cattle or a horse, but less for a fox or a badger.

5)      You say that ANOVA was used in the statistical analysis, but in L 224 a non-parametric Kruskal Wallis test is mention. And in table 1 in the footnote is mentioned “Different lowercase letters in the same line indicate significant difference”. I imagine that the comparison is between species, thus in the same column, and that a post-hoc test was used (e.g. Tukey HSD).  Please clarify and add the coefficients of the tests other than p values.

6)      It is not clear for me the empirical link of the detailed hourly movement/peak activity/speed information, including figure 5, with frugivory and seed dispersal, also considering the gut retention times up to 6 days (L 152) Please give more details on how to establish such link. Also check captions of the figures 5 and 6, that show a n=3.

Comments on the Quality of English Language

I’m not a native English speaker, but I think that an overall revision of the language and standardization and proper use of terminologies (e.g. predation, ground fruit visitors, seed dispersal effectiveness, long distance seed dispersal sensu Jordano 2017 – Journal of Ecology; the relevant data in supplementary) is desirable to improve clarity.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

In this revised version, the authors now show data regarding the germination trial of the seeds and recruitment of seedlings in field conditions. I still think that seed dispersal effectiveness was not fully accessed once the real quantification of the seed rain in the field is still lacking, with the revised ms just reporting a fixed value of seeds dispersed per feces (6.5 seeds per 100 g of feces) in the methods.

I would then include a “potential” in the title: Evaluation of the potential Seed Dispersal Effectiveness of Malus sieversii (Lebed.) M. Roem. by cattle.

There still some typos and confusing sentences, below just some examples:

L 95 – “found that recovery rate of M.sieversii seeds … was as high as 54.05%”.

What is recovery rate? Intact seeds?

L 157-160 – “nonconsecutive records of individuals of different species, nonconsecutive records of individuals of the same species, consecutive records of individuals of different species, or consecutive records of individuals of the same species with a time interval exceeding 10 min”.

If you consider consecutive visits of different species, or at 10min of same species, this confusing nonconsecutive interval is not needed.

L 227 - …”found that dispersal range of M. sieversii seed rain mainly concentrated under the crown of mother tree”.

This means lack of seed disperser?

L 231 – “Therefore, we have carried out the following processing”.

What do you mean by processing?

L 237 – “The treatment W was placed in three habitats (forest edges, gaps, and understory) and the treatment of each habitat was replicated three times”.

Three replicates of treatment W per habitat, for a total of how many seeds? 30 x 3 x 3?

Section 3.4 is not clear.  If treatment C was only in understory (L 240-241) how this comparison was possible? For example, in table 2 there are two forest understory and one forest edge and forest gap.

L 425 – “Furthermore, this study found that compared to the seedling emergence rate and survival rate of M. sieversii seeds dispersed to the forest understory through seed rain, those dispersed to the forest edges and gaps by cattle are significantly higher, while those dispersed to forest understory by cattle have no significant difference”.

You did not access seed rain in your study, but made a simulation to test seed emergence and seedling survival. Quantitative aspects of the real seed rain can vary a lot between habitats and consequently change the outcomes of the subsequent stages.

In figures and tables caption you must show the number of seeds/seedlings per treatment with which you performed the statistical test, not the number of replicates (N = 3)

Comments on the Quality of English Language

There still some typos and confusing sentences as some examples above

Author Response

Please see the attachment.

Author Response File: Author Response.pdf