Spatial–Temporal Dynamics of a Germinable Seed Bank of a Semi-Arid Vegetation in the Brazilian Northeast

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Overall the article is well written. The subject of the article is important in the application of dam observation data.

 

The deficiencies that need to be corrected in the article are as follows:

 

The word "Monphs" in Figure 1 is misspelled and should be corrected.

 

The full name of the word ANOSIM should be written. At the same time, it was written that ANOSIM analysis was performed, but there is no result related to the test in the results.

 

Acceptable after minor revision

Author Response

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files. Suggested modifications are highlighted in red in the manuscript.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

I have read the manuscript (ms) “Spatial-temporal dynamics of a germinable seed bank in a dry forest
area from Northeast Brazil”, by Santos et al. The ms has interesting information regarding a dry forest environment in Northeastern Brasil. Its main merit is that it has evaluated the seed bank around a plot located in the Caatinga region during seven consecutive years, twice each year. In this sense, it allows to follow the temporal changes in seed bank species richness, density, and composition. It also has assessed a spatial component, as it considered habitat influences on seed bank dynamics.

 

The ms has some deficiencies. The authors should recognize this in the ms. The main drawbacks are the following :

1) The scope is too large for the sample that was obtained: the samples were taken around a 1-ha plot. In this regard, I am a little concerned about the experimental design. The samples from a given year were obtained from a circumscribed space; there was no interspersion of samples that would allow me to say that differences between, for example, year 1 and year 5 are not due to spatial heterogeneity.

2) The study has evaluated seed bank using a proxy for it: the “seedling emergence method”, that is, the transient seed bank. Usually, seed banks are studied from the perspective of the permanent seed bank. To do this, sampling should be done maximizing the possibility of obtaining it (the permanent component, which is usually the most interesting one), i.e., selecting a month during the year when the transient seed bank has germinated, has been eaten or has rotten. What authors show is a mix of both components (transient and persistent). I would like to know if they have an estimate of how large the persistent seed bank in this Caatinga forest could be. Persistent seed banks are usually very important in desert ans semideserts, not in dry forests. In fact, seed numbers/m2 in the study region were very low indeed (Table 2), 1/5 to 1/10 of what is found in deserts and semideserts having the lowest seed numbers. Seed banks in deserts are mainly composed of seeds from annual species. How many of the 138 species found in the Caatinga were true annuals (each species name in the supplementary material should be accompanied by its life form). I guess very few, if any. This distinction is important to interpret the results, and because the authors use many references from deserts. I really think that a great deal of the variability in seed banks reflects simply differences in the transient component, i.e, is influenced by the quantity of seeds produced in the current year (precipitation could be a proxy for it) plus the effect of herbivores, which obviously introduces some noise in the interpretation of results. It is known that there is positive correlation between rainy years and fecundity, for example, and rainy years should be those with large herbivore populations affecting the seed bank.

 

3) The ms mentions three hypotheses, but these are really predictions. I think the study is more descriptive (and this is not at all a pejorative statement), and thus less amenable to including hypotheses.

Minor concerns (see in text)

 

Page 1, line35. Although the first sentence talks about dry forests, the citations refer to deserts.

P2 L52-53. I do not understand it. I would delete this sentence.

P2 L59-63. What life forms are better represented in the seed bank of Caatinga?

P2 L72. Insert a point after [37]. The first part of this paragraph is not very clear.

P2 L74. The “ciliary” microhabitat should be described from the beginning. Readers are not supposed to be experts on Caatinga.

P2 L79-83. These justifications for the study are not really a novelty. All dry regions have several michohabitats and a more or less irregular distribution of rainfall. By definition, all dry areas have low rainfall.

P2 L85-91. These are really predictions, not hypotheses.

P2 L87. Insert “that” before … determine the number …

P2 L92-98. In the Introduction I would keep the questions and omit the “hypotheses” (predictions).

P2. I would stress the major contribution of this study in the Introduction, which is the measurement of the seed bank during 7 years.

P2. The ms has a lot of citations of studies in deserts and semideserts. What is the relationship of Caatinga to these much more arid environments. I think they differ a lot.

 

P3 L113-114. Rewrite. It is not clear.

 

P4 Figure 2. Would it not have been better to intersperse the sampling units? I would expect year 1 and year 2, for example, to be more similar simply based on their proximity.

 

P5 L181. Change “which not flowered” by “which did not flower”.

 

P5 L211-212. If there are 138 species and each season has more than 100 exclusive species, something does not add up.

 

P8 L270. Erase “the” before “richness”.

 

P9 Table 2. For the rocky substrate, do the calculations of seed density include the rocky substrate, or only the microhabitats inside it that would be capable of containing seeds?

 

P12 L329-333. What if we compare the samples from the dry season between each other, and the same for those from the wet season. Maybe we will find that they may be very different from one another.

 

P12 L334-338. Rewrite. Not understandable.

 

P12 L344-348. Years with much rain can have many predators in these subequatorial environments, possibly much more than in true deserts. In deserts, additionally, there is practically no litter in the open spaces (which cover most of the community). How should this affect seed bank abundance, composition and dynamics?

 

P12 L345. Almost all these citations are from desert/semidesert environments.

 

P12 L377-379. I think most of the sampled seed bank had a transient component, even in the soil.

 

P13 L380-383. How much do samples from the same microhabitat differ from each other?

 

P13 L 404. I do not think that humidity would favor the presence of a seed bank. Fungi would invade the seeds or else they would germinate.

 

P13 L 405-407. This sentence is not true. The permanent seed bank was not determined. Most of what you sampled is very likely a transient seed bank. When do you think that sampling should be performed in order to maximize the permanent seed bank component?

 

 

P13 L428. Is it not exaggerated to extrapolate your results to the entire Caatinga region?

 

Comments on the Quality of English Language

The English was not bad, but can be improved. I gave some suggestions.

Author Response

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files. Suggested modifications are highlighted in green in the manuscript.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The MS conveys the main points about seed bank dynamics in dry tropical forests. It states the hypothesis that seasonal and annual variations in precipitation, along with spatial variations, affect the soil seed bank. The presentation of hypotheses and research questions is well-organized.

Additionally, the authors use relevant citations to support their claims. Please provide the following additional recommendations as well, as they reinforce your work and the literature: 

1. Cogoni, D., Fenu, G., & Bacchetta, G. (2013). Effects of timing of emergence and microhabitat conditions on the seedling performance of a coastal Mediterranean plant. Ecoscience, 20(2), 131-136.

2. de Souza, A. C., Donohue, K., & de Mattos, E. A. (2022). The effect of seed-dispersal timing on seedling recruitment is modulated by environmental conditions that vary across altitude in a threatened palm. Annals of Botany, 129(7), 839-856.

3. Metz, J., Freundt, H., & Jeltsch, F. (2018). Stable germination behavior but partly changing seed–seed interactions along a steep rainfall gradient. Basic and applied ecology, 28, 5-16.

Line 78- 82: It would have been better to incorporate Caatinga's introduction with the theories.

Line 87: A seven-year research timeline is suggested by the study. What are the possible constraints on this duration to capture the impacts of long-term precipitation on seed banks? To make the methods part stronger, it would be helpful to bring up this issue.

In the discussion section, the MS highlights variations in seed bank attributes across space and time. Expanding on how these variations influence plant community regeneration in different contexts would be valuable.

Also, the focus of discussion is on precipitation and microhabitats. But there are other factors influencing the seed bank (e.g., herbivory): it could be briefly discussed.

Pease, including a concluding sentence that reiterates the significance of understanding seed bank dynamics in dry tropical forest conservation and restoration.

 

Also, the concluding statements could be strengthened by highlighting the study's key findings and their contribution to understanding Caatinga seed banks.

Author Response

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files. Suggested modifications are highlighted in blue in the manuscript.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Editors,

The manuscript has substantially improved and it could be published once a few aspects are clarified. I mention them below.

In the Abstract, “ciliary” should be changed by “riverside”, a terms the authors suggested themselves.

In line 34. ·”dry environment seed bank” should be changed by “the seed banks of dry environments”

L 73-79. I do not think that low rainfall, irregular distribution of this rainfall, and spatial heterogeneity are particular aspects of Caatinga, but of all dry regions in the world. So, they should not be used as justification for this study. I think it would suffice to say that this study addresses how the seed bank varies according to these two scales (spatio-temporal). We know that the seed bank is supposed to change as a function of microhabitat and time (this is quite obvious). The interesting thing to discover is how it does in this particular environment, which could be similar in other forests of this type. I think the main contribution of this study is its temporal aspect: the seed bank was sampled during seven years, and so it is an example of Caatinga seed bank dynamics in the long run.

Finally, I would like to know if the system contains true therophytes (annuals), that is, semelparous plants that complete their life cycles in a few months. Based on what they report, it would seem that what they call annuals are indeed short-lived perennials. I would like to see some reference to this.

Comments on the Quality of English Language

None

Author Response

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files. Suggested modifications are highlighted in green in the manuscript.

Author Response File: Author Response.pdf