Fine-Scale Organization and Dynamics of Matrix-Forming Species in Primary and Secondary Grasslands

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Comments

This study applies the information theory model to the monitoring of grassland communities with centimeter-level resolution for many years, and systematically compares the "microscale vegetation matrix" formed by dominant species in primary and secondary grasslands and their regulatory effects on community dynamics, diversity and ecological functions. The topic selection is cutting-edge, data is scarce and the workload is huge, which can provide a new theoretical basis for grassland restoration and management. However, there are missing methodological details, unclear conceptual definitions, and format errors.

Firstly, the research methodology of this study is innovative, however, the sample size of your experiments is too small, and the combinations of the two samples with the two treatments lack sufficient persuasive power.

Secondly, there is actually quite a bit of research on the spatial entropy function; however, one crucial aspect of this method is the collection of data samples. In the methods section, you provide very little description regarding the scale and details of the data, only mentioning the years processed and the total length of the sample strips. Additionally, the figures S2-S6.2 in your supplementary materials do not display properly in Word, which prevents me from making any judgments regarding the details of your research from the accompanying figures.

 

1.Detailed description of baseline transect data elements in Materials and Methods mentioning the sample format and data volume would be clearer for non-technical readers.

2. figures S2-S6.2 isnot displayedcorrectly in Word, so it is recommended that you upload a PDF version. I have provided annotations for additional details that require modification or deletion in the PDF file of the manuscript.

Comments for author File: Comments.zip

Author Response

Detailed response to Referees:

 

Referee 1.

 

This study applies the information theory model to the monitoring of grassland communities with centimeter-level resolution for many years, and systematically compares the "microscale vegetation matrix" formed by dominant species in primary and secondary grasslands and their regulatory effects on community dynamics, diversity and ecological functions. The topic selection is cutting-edge, data is scarce and the workload is huge, which can provide a new theoretical basis for grassland restoration and management. However, there are missing methodological details, unclear conceptual definitions, and format errors.

Response: Thank you very much for your careful read and constructive comments. We thank also your comments in the annotated manuscript. When we refer line number, it refers the track of changes docx version of new revised manuscript.

Firstly, the research methodology of this study is innovative, however, the sample size of your experiments is too small, and the combinations of the two samples with the two treatments lack sufficient persuasive power.

Response: We agree with your comment, and we made explicit statements about this limitation in the manuscript. In L 581-584, we wrote: „We analyzed only two replicates of each grassland type. Therefore, our results (Table 1) are limited and preliminary. However, according to our knowledge, no similar long-term study is available, where the fine-scale spatiotemporal organization of primary and secondary grasslands has been compared.” In addition, we wrote (L 591-596): „These criteria resulted in laborious sampling protocols that constrained the number of sites we were able to study. Despite the limited number of replicates, our study contributes to filling an important gap in current knowledge. We are aware of only three similar data sets in grasslands, where high resolution spatial mapping was repeated in continuous, long-term study (37, 68, 69].”Due to the huge workload similar long-term studies have also small number of replicates. For example Herben et al (2017) analysed the high- resolution spatiotemporal patterns in four small 50 cm x 50 cm grids in a species poor mountain grassland. Chen at al. (2005) monitored and analysed two 400 long transects in open desert grassland vegetation. Our sample size (four 52 m long transects sampled over 15 years) is similar. However, we worked in species rich, close grasslands where the sampling is more laborious. We hope that more studies will use similar methodology in the future and after 10-15 years, comparative studies can use larger sample sizes.

References:

Herben, T.; Mayerová, H.; Skálová, H.; Hadincová, V.; Pecháčková, S.; Krahulec, F. Long-term time series of legume cycles in a semi-natural montane grassland: evidence for nitrogen-driven grass dynamics. Funct. Ecol. 2017, 31, 1430-1440.

Chen, X.; Li, B.; Collins, S.L. Multiscale monitoring of a multispecies case study: Two grass species at Sevilleta. Plant Ecol. 2005, 179, 149–154.

Secondly, there is actually quite a bit of research on the spatial entropy function;

Response: Thank you very much for this important comment. We are interested in these models developed in geography, landscape ecology and in other research fields. We already published a paper where we applied our information theory models at landscape scale: Konrád, K.D.; Bede-Fazekas, A.; Bartha, S.; Somodi, I. Adapting a multiscale approach to assess the compositional diversity of landscapes. Landscape Ecology 38(11), 2731-2747. Exploring applicability of the suggested models in community ecology is a challenging task. However, now it is out of the scope of our present paper. The model family of Juhász-Nagy that we used here has been developed in community ecology and it is an established approach with many methodology papers and case studies in the last 40 years. The major advantage of this model family is that particular models representing the basic coenological phenomena have additive relationships. Calculating mutual, multiple, partial and conditional entropy measures it is possible to quantify various relationships between dominant and subordinate species. In this paper we used relatively simple models. For further exploring our data, we plan to apply the more advanced models of Juhász-Nagy in the future.

however, one crucial aspect of this method is the collection of data samples. In the methods section, you provide very little description regarding the scale and details of the data, only mentioning the years processed and the total length of the sample strips.

Response: Thank you for this important comment. We added more details in the methods section about data volume of the baseline data and the secondary computerized sampling. The related new texts:

L 209-213: “In each sampling campaign we sampled 4 × 1,040 = 4,160 microquadrats. This resulted 62,400 microquadrats over the 15 years of monitoring. For the present study we used a subset, 29,120 microquadrats of this large database. The time series of baseline transect data were resampled with computerized sampling for further analyses.”

L 232-238: “Hx is a function of sampling unit size (Figure S3.1). Therefore, Hx was estimated across a range of scales (at changing sampling unit sizes) from 5 cm × 5 cm to 5 cm × 1,875 cm by merging two, then three, then four, …., and finally 375 consecutive microquadrats by subsequent computerized sampling in 48 spatial steps [36, 49]. Significance of spatial aggregations was tested against a null model of complete spatial randomness of species presences along transect. The randomization was repeated 999 times for each test. Significance was expressed as a probability of the observed Hx under the null model.”

L 273-281: “As shown in Figure S4, Temporal Associatum is a scale-dependent variable. Therefore, Temporal Associatum was estimated across a range of scales (at changing sampling unit sizes) from 5 cm × 10 cm to 5 cm × 990 cm by merging two, then three, then four, …., and finally 198 consecutive microquadrats by subsequent computerized sampling in 13 spatial steps [36, 49]. Significance of association was tested against a null model of complete spatial randomness of species presences along transects. The randomization was repeated 999 times for each test. Significance was expressed as a probability of the observed Temporal Associatum under the null model (for more details see Supplementary S4).”

 

 

Additionally, the figures S2-S6.2 in your supplementary materials do not display properly in Word, which prevents me from making any judgments regarding the details of your research from the accompanying figures.

Response: We revised our Supplementary Material by adding more details and providing more statistical tests. We checked the Word format of our text and contacted the journal editor if we could submit our Supplementary Material in pdf format.

2. Detailed description of baseline transect data elements in Materials and Methods mentioning the sample format and data volume would be clearer for non-technical readers.

Response: Thank you for this comment. We added details about the data volume of the baseline data, and we added more information about the secondary computerized sampling in Materials and Methods section. Examples of data formats can be found in the Supplementary Materials. The related new texts:

L 209-213, L 232-238, L 273-281 (see the related new text above).

2. figures S2-S6.2 is not displayed correctly in Word, so it is recommended that you upload a PDF version. 

Response: We revised our Supplementary Material by adding more details of data and analyses. We also provided more statistical tests. We checked the Word format of our text and contacted the journal editor if we could submit our Supplementary Material in pdf format.

I have provided annotations for additional details that require modification or deletion in the PDF file of the manuscript.

Response: Thank you for your comments in the annotated manuscript. Herewith, we are responding to these suggestions point by point. (The line numbers below refer to the original annotated manuscript version.)

 

L58-63: There is excessive description regarding forests; it is recommended to supplement the current research status of grasslands.

 

Response: Thank you for your suggestion. However, we respectfully disagree and prefer keeping this text. As we pointed out, studies comparing primary and secondary forests are numerious while similar studies in grasslands are missing (L 71-72). Therefore, we had to review the related research background from forest ecology.

 

L86-89 What does this mean? Does it mean that asexual reproduction is so widespread in grasslands that it is impossible to distinguish how many individuals there are in the community or how large the size of the individuals is? If there is a clear article pointing out this point, I recommend that you cite it.

 

Response: Thank you. We added the appropriate reference to here [53].

 

L 169-172 You have already mentioned the consistency of the environmental background of the sample plot before, and there is no need to repeat it in the method section

 

Response: Thank you. We agree and removed the redundant text from the Introduction. We kept the related text in the Method section and added more information about sites and sampling conditions (as Referee#2 suggested).

 

L 317 In Figure 4, the maximum value of the 'Mean rate of changes' does not exceed 0.7, and many values are below 0.4, which is inconsistent with your description that 'the average rate of gains and losses was between 0.5 and 0.7'.

 

Response: Thank you. We carefully checked and corrected these values in the text.

 

L 341 The data presented in this article, as well as in the charts, do not include the results of significance tests, such as p-values or F-values. I suggest you add significance marks in your figures.

 

Response: Thank you. We carefully checked and improved the related text. Detailed test statistics described in the Supplementary Materials. We revised all related texts and these results now have been shown more explicitly with p values in the main text. Some new analyses have been added as well.

 

All other small format errors have been corrected at L 50, L 66, L 123-124, L 163, L 220, L 247, L249, L 337, L 367.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This paper, based on long-term monitoring data and information-based models, examines the spatial organization and dynamic changes of dominant matrix-forming species in native and secondary grasslands. Overall, the research questions addressed in this article are of some relevance to the evolution of ecology, the methods are relatively innovative, and the results provide valuable insights. However, the article contains some points that need to be improved.

1. The abstract does not explicitly quantify important results (e.g., the specific range or magnitude of spatial aggregation indices). For example, H1 hypothesizes that secondary grasslands are more patchy, but the summary does not specify the average difference in Iaggr values (e.g., whether Iaggr values in secondary grasslands are significantly higher than those in native grasslands). It is recommended to add important numerical values to improve quantifiability.
2. The authors describe the sampling sites in the Methods section as 52-meter-long permanent transects, but do not elaborate on the criteria used to select the transect sites (e.g., whether they were selected randomly or based on habitat heterogeneity). This may lead to bias, especially as the secondary grasslands (S1 and S2) are more than 400 meters apart. However, the potential impact of site differences on the results (e.g. microclimate variability) was not assessed. It is recommended to complement the study with a flow chart or a justification for the selection of transects.
3. The results describe a high spatio-temporal variability, but important results such as the changes in the spatial aggregation index (Iaggr) (Figure 2) are not sufficiently quantified. For example, the authors state that ‘Alopecurus pratensis showed significantly higher aggregation in secondary grasslands', but Figure 2 shows large differences in Iaggr values between S1 and S2 (e.g. Alopecurus in S1 ≈ 1.8 vs. P1 ≈ 1.2 in 2025) without providing average differences or confidence intervals. It is recommended to include numerical summaries in the text.
4. Figure 4 shows interannual rates of change, but does not take into account the impact of climate events (e.g. the drought of 2022). The results mention that the ‘drought of 2022' led to a decline in Poa angustifolia, but Figure 4 does not show outliers for drought years (e.g. the 2022–2023 rate of change). It is recommended to label the event points in the figure or refer to Supplementary S10 in the discussion.
5. The discussion correctly states that secondary grasslands have a stronger spatioand temporal dependence (which supports H2), but H4 is misinterpreted. The authors assume that primary grassland has higher variability in subordinate species richness, but the results (Figure 6) show higher variability in secondary grassland, which is however interpreted in the Discussion as ‘stronger filtering of the microhabitat'. This is contradictory: if the filtering is stronger, why is the variability higher? It is recommended to reinterpret the mechanism or revise H4.

Author Response

Detailed response to Referees:

 

Referee 2.

This paper, based on long-term monitoring data and information-based models, examines the spatial organization and dynamic changes of dominant matrix-forming species in native and secondary grasslands. Overall, the research questions addressed in this article are of some relevance to the evolution of ecology, the methods are relatively innovative, and the results provide valuable insights. However, the article contains some points that need to be improved.

Response: Thank you very much for your careful read and constructive comments. Herewith, We respond your comments point to point. When we refer line number, it refers the track of changes docx version of new revised manuscript.

 

1. The abstract does not explicitly quantify important results (e.g., the specific range or magnitude of spatial aggregation indices). For example, H1 hypothesizes that secondary grasslands are more patchy, but the summary does not specify the average difference in Iaggr values (e.g., whether Iaggr values in secondary grasslands are significantly higher than those in native grasslands). It is recommended to add important numerical values to improve quantifiability.

 

Response: Thank you for your suggestions. We improved the Abstract by adding more details. The related new text:

L 34-38: “Alopecurus pratensis and Poa angustifolia had coarse-scale patchiness with stronger aggregations in secondary grasslands. The spatial patterns of Festuca valesiaca were nearly random in both types of grasslands. Strong associations were found among the spatial patterns of each species across different years, with stronger dependence in secondary grasslands.”

According to the rules of  journal LAND (see journal template and Instructions to Authors) the maximum length of the Abstract should be 200 words. Our Abstract was 226 words in the original version and now it became longer 261 words. By adding numerical values (in this case not only about Iaggr but also to other analyses) the text of Abstract would be too long.

Behind each statements in the Abstract, there were statistical tests and our statements were based on the related results. We highlighted more the related statistical tests in the Results section and added some new tests in the revised version.

 

1. The authors describe the sampling sites in the Methods section as 52-meter-long permanent transects, but do not elaborate on the criteria used to select the transect sites (e.g., whether they were selected randomly or based on habitat heterogeneity). This may lead to bias, especially as the secondary grasslands (S1 and S2) are more than 400 meters apart. However, the potential impact of site differences on the results (e.g. microclimate variability) was not assessed. It is recommended to complement the study with a flow chart or a justification for the selection of transects.

 

Response: We improved the Method section.The primary grasslands were homogeneous at patch scale, at the extent of the transects. Monitoring transects were selected in early old field succession in secondary grasslands when these fields were 2 years old, remarkably homogeneous, dominated by Tripleurospermum inodorum. The patchwork we detected in later stages (when field ages changed from 10 to 16 years) were the result of spontaneous self organization of vegetation and it could not be predicted in advance. (Please, see Fig.1. for additional details). The rate of succession is variable between old fields and even within fields. According to our experiences, the differences found between S1 and S2 can be attributed to stachastic factors (dispersal limitation, different arrival time of species) and not to microclimatic or other environmental factors. We added the following new text:

L 177-180: “Selected sites were open flat areas (without shrubs or trees) with similar elevation (99 m a.s.l.). They were physiognomically homogeneous without microtopographical or microclimatic differences. Disturbed areas (e.g. old roads) and small depressions were avoided during site selection.”

L 189-190: “At each monitoring site, one 52 m long permanent belt transect was selected randomly within a homogeneous area.”

In the original text we already stated that other factors (species pool, soil, weather, landuse) were the same or very similar between fields (L 180-182).

 

1. The results describe a high spatio-temporal variability, but important results such as the changes in the spatial aggregation index (Iaggr) (Figure 2) are not sufficiently quantified. For example, the authors state that ‘Alopecurus pratensis showed significantly higher aggregation in secondary grasslands', but Figure 2 shows large differences in Iaggr values between S1 and S2 (e.g. Alopecurus in S1 ≈ 1.8 vs. P1 ≈ 1.2 in 2025) without providing average differences or confidence intervals. It is recommended to include numerical summaries in the text.

 

Response: Thank you for your suggestions. We improved the related text with adding numerical values to the main text in the Result section. The related new text:

L 336-351: “In the secondary grassland sites, Poa angustifola showed very strong but temporally decreasing spatial aggregations in this period (Figure 2) (median Iaggr=1.65). Aggregation of Alopecurus pratensis was also strong (median Iaggr=1.39) but slightly lower and it increased over time. The aggregation index of Festuca valesiaca decreased and converged to one, i.e. its fine-scale spatial variability did not deviate from the random null model. The spatial pattern of Festuca valesiaca was random or close to random in the primary grassland sites. Here, Alopecurus pratensis showed the highest degree of aggregation, which remained relatively stable over the study period (median Iaggr=1.18). In the primary grassland sites the aggregation index of Poa angustifolia did not deviate from the null model in the early period of our study but then it started to increase (median Iaggr=1.08). Evaluating the overall temporal patterns, we can conclude that the spatial aggregation of Alopecurus pratensis and Poa angustifolia showed significantly higher values in secondary grassland sites than in primary grassland sites all over the years (Friedman test, p < 0.001; Supplementary Table S7), while Festuca valesiaca showed lower aggregation values in all years, with no difference between secondary and primary grasslands (Friedman test, p=0.542; Supplementary Table S7).”

 

1. Figure 4 shows interannual rates of change, but does not take into account the impact of climate events (e.g. the drought of 2022). The results mention that the ‘drought of 2022' led to a decline in Poa angustifolia, but Figure 4 does not show outliers for drought years (e.g. the 2022–2023 rate of change). It is recommended to label the event points in the figure or refer to Supplementary S10 in the discussion.

 

Response: Thank you very much for this important and insightful suggestion. In a separate paper, we plan to analyse the relationship between weather variability and the rate of local species turnovers (gains and losses) with specific attention to the extreme climatic effects. This problem requires a lot more analyses and we could not include it to the present paper.

 

1. The discussion correctly states that secondary grasslands have a stronger spatio and temporal dependence (which supports H2), but H4 is misinterpreted. The authors assume that primary grassland has higher variability in subordinate species richness, but the results (Figure 6) show higher variability in secondary grassland, which is however interpreted in the Discussion as ‘stronger filtering of the microhabitat'. This is contradictory: if the filtering is stronger, why is the variability higher? It is recommended to reinterpret the mechanism or revise H4.

 

Response: Thank you for your careful read and highlighting the illogical aspects in the related text. We developed our fourth hypothesis before seeing the results. Our hypotheses were based on published results about the increasing structure and increasing constraints to coexistence in succession. Our hypothesis stated: „higher fine-scale spatial variability of subordinate species richness is expected in the primary grassland.” This was the pattern we could test and we found interesting results that contradicted to our expectation. However, we do not think that we should artificially change our original hypothesis and fitting it the results. We agree that the logic was not clear in our text. Now, we completely changed this section, improving the logic and we toned down the interpretation (L 554-565). In fact, we found some interesting results but our analyses were phenomenological and we could not test the mechanisms behind these patterns. In Discussion we provide our opinion about potential mechanisms. We believe that we are free to provide our opinion in Discussion if otherwise the analyses and results were correct. For better understanding the assembly mechanism behind these patterns we plan additional studies in the future.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The work has been very well prepared and presents the results of long-term research conducted on a 52 m long permanent belt transect between 2019 and 2025. As the Authors emphasise, despite the large number of studies on grasslands, there is a lack of systematic research comparing the spatial organisation, structure and dynamics between primary and secondary grasslands. Detailed hypotheses are formulated at the beginning of the work. The methods are described in details. The results are clearly presented. The discussion is comprehensive and refers to the hypotheses put forward at the beginning of the paper. The Authors also refer to limitations as prospects for future research.
I have marked my minor comments in the manuscript, which I am attaching.

 

Comments for author File: Comments.pdf

Author Response

Detailed response to Referees:

 

Referee 3.

The work has been very well prepared and presents the results of long-term research conducted on a 52 m long permanent belt transect between 2019 and 2025. As the Authors emphasise, despite the large number of studies on grasslands, there is a lack of systematic research comparing the spatial organisation, structure and dynamics between primary and secondary grasslands. Detailed hypotheses are formulated at the beginning of the work. The methods are described in details. The results are clearly presented. The discussion is comprehensive and refers to the hypotheses put forward at the beginning of the paper. The Authors also refer to limitations as prospects for future research.
I have marked my minor comments in the manuscript, which I am attaching.

Response: Thank you very much for your careful read and positive evaluations. We thank your comments in the annotated manuscript. Herewith, we are responding to these suggestions point by point. (The line numbers refer to the original annotated manuscript version.)

 

 

L 158 maybe graminoids should be used instead of grasses Carex praecox is a sedge

 

Response: Thank you. Corrected.

 

L 264 … between primary and secondary grasslands

 

Response: Corrected

 

Fig 5 Explain abbreviations of species in combination

 

Response: We added the following text to the caption of Figure 5.: Matrix species combinations: --- empty microsite; F—only Festuca valesiaca is present; -A- only Alopecurus pratensis is present; --P only Poa angustifolia is present; FA- Festuca valesiaca and Alopecurus pratensis are present; F-P Festuca valesica and Poa angustifolia are present; -AP Alopecurus pratensis and Poa angustifolia are present; FAP all three species are present.

 

L 556 Fig A1 explain green and blue symbols:

 

Response: Corrected. We added the following text to the caption of Figure A1.:

Blue colour shows rivers and lakes. Green circle marks the location of study area near the town Battonya.

 

All other small format errors have been corrected at L 176, L 430, L 437.

 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The author has already answered all the questions I raised very well.