Variations and Factors Characterizing Ecological Niches of Understory Herbaceous Species in Plantation Forests
Round 1
Reviewer 1 Report
Your article contains valuable biodiversity information and its results can be used to manage similar forests.
You can use the following resources to improve the introduction of the article
Xu, H., Wang, X., Qu, Q., Yang, Z., Wang, M., Liu, G. and Xue, S., 2021. Variations and factors characterizing ecological niches of species in a stable grassland plant community. Ecological Indicators, 128, p.107846.
Dar, A.A. and Parthasarathy, N., 2022. Community associations and ecological drivers of understory vegetation across temperate forests of Kashmir Himalayas, India. Trees, Forests and People, 8, p.100217.
Su, X., Zheng, G. and Chen, H.Y., 2022. Understory diversity are driven by resource availability rather than resource heterogeneity in subtropical forests. Forest Ecology and Management, 503, p.119781.
In the materials and methods section, please provide more information on how to measure the canopy density (line 129)
I did not see any specific cases in other parts of the article for correction.
Author Response
Thank you very much for your valuable suggestions on my article. I fully agree with the suggestions and modifications. At the same time, it is my negligence to fail to refine the details of the measurement of plant canopy density. For canopy density, Sample line method was used to investigate canopy density, and canopy density was calculated according to the ratio of total diagonal length to total crown length，and add to article of the materials and methods section.
Thank you again.
Reviewer 2 Report
Comments for author File: 
Comments.pdf
Author Response
Thank you very much for your valuable suggestions on my article. I fully agree with the suggestions and modifications. I have revised your suggestions one by one：
Line 12: In abstract，I explained the research background of the study as follows：
Plant ecological niche characteristics are powerful representations of plant survival status. The understory herbaceous species in plantation forestsare sensitive to local ecological environment changes, the patterns of ecological niche changes of herbaceous plants under plantation forests are of great significance for maintaining the stability and sustainable development of plantation forest ecosystems.
Line 31: the “site type” all means the site fertility and site quality. Through the analysis, we understand that there are different emphases on the niche characteristics of understory herbaceous plants, but the guiding force of emphasis tends to the difference of site types. Therefore, we conclude that the difference of site types is the reason for the niche characteristics of understory herbaceous plants, and then elaborate the impact of the differences of environmental factors caused by different site types on the niche characteristics of understory herbaceous plants.
Line85: The full name of Pinus tabulaeformis has been changed.
Line 118: The number of repetitions of the experimental study is indeed only 2. On the one hand, we must consider the field operation, on the other hand, considering that the local environmental changes are generally small, and there is no extreme difference in nature between the physical and chemical properties of plantations, herbaceous plants or soil, so only 2 repetitions are set during the test planning.
Line 142: The category of the slope for 15° -25 ° is steep slope。
Line 159: Were RC is relative biomass, RH is relative height, RA is relative abundance.
Line 222: The proportions of different plant families are Gramineae 25.81%, Compositae 29.03%, Leguminosae 19.35%.
About replace the artificial forest by plantation forest, I have replaced this word from the whole manuscript. And In table 3, i have removed the color in the table.
Thank you again
Reviewer 3 Report
1. Can you provide more detail on how you surveyed and sampled your plots? For example, how did you sample or measure plant types, cover, and height? What was the purpose of the 1x1 m plot? Did you combine soil samples from the 5x5 m plots for analyses or examine each one separately? More description is needed to know what you actually did in the field and lab.
2. Relative dominance, etc is typically expressed as a % and IV would be an average of those relative %s, so a 0.25 should be 25% for an IV.
3. Explain your "analysis of nullity distribution of niche width index."
4. The analysis methods you mention in your results should be described in some detail in your section on "statistical analysis." For example, your use of CCA. What were the contents of the matrices? What scaling options did you use? Justify why you used CCA compared to say, NMS or Bray-Curtis.
5. Did you transform any of your environmental factors for the CCA? I ask this because CCA includes multiple regression, so it is subject to problems associated with statistical assumptions. Did you account for the possibility of species-environment relationships appearing stronger than they actually are as the number of environmental variables increases relative to the number of observations? As that is increasingly the case, CCA becomes more like CA, which isn't typically the best option for ordination.
6. Did you make any attempt to "control" for geographical factors? For example, by using a partial Mantel test.
The paper is well-written, but can be improved by providing more detail on their approach and some moderate English language editing.
Overall this paper is well-written, logical, and structured. I see no problem in publishing this article after some moderate editing.
Author Response
Thank you very much for your valuable suggestions on my article. I fully agree with the suggestions and modifications. I have revised your suggestions one by one：
1.The initial consideration of this paper is the impact of geographical types on the niche characteristics of herbaceous plants under artificial forests, its emphasis is on the accurate understanding of herbaceous plants under Pinus tabulaeformis plantations and measurement of quantitative ecological indicators. First, try not to damage the original ecological environment,the identification of herbaceous plants is mainly through field confirmation and collection of samples to consult experts.As for the coverage rate of herbaceous plants, due to the fragile and complex geological environment in the test area, and in order to reduce vegetation damage, this study mainly uses the visual method to calculate.Herbaceous plant heights were measured directly on site.The reason for selecting 1 x 1 m quadrat, on the one hand is to provide a sample for the investigation of understory herbaceous plants, on the other hand is to consider a comprehensive investigation of herbaceous plants.
For soil sample collection, considering regional environmental factors in the early stage should change its soil texture greatly, therefore, soil samples were collected at the center of each 5 × 5 m sample plot for analysis. But later by detecting the soil found that the same geographical type of soil between small changes,therefore, the average value of soil samples from each 5x5 m plot of the same geographical type was used in the environmental factor gradient analysis.
2.About Relative dominance, etc is typically expressed as a %，I've made changes.
3.We calculated the occurrences of species generated by simulating 1000 permutations (quasiswap permutation algorithms) performed using the EcolUtils R package. The null distribution of niche breadth indices of these herbaceous plants was calculated through spaaa R package.
4.Contents of the matrix are the niche width and niche overlap of herbaceous plants under the forests of six different geographical types and the environmental factors selected by the plantations of six geographical types, the matrix size is 6 * 31~6 * 11.This paper uses the data composed of species and related environmental factors to sort at the same time. At present, CCA (canonical responsibility analysis) and RDA (redundancy analysis) are often used to sort species and environmental factors, the difference between them is that RDA is based on linear model and CCA is based on unimodal model.Generally, we will choose CCA for direct gradient analysis.However, the selection principle of RDA or CCA is: first, use the species-sample data for RDA analysis to see the size of the first axis of lengths of gradient in the analysis results,If it is greater than 4.0, CCA should be selected. If it is between 3.0-4.0, RDA and CCA can be selected. If it is less than 3.0, RDA should be selected.In this paper, the results of species analysis show that the size of the first axis of length of gradient is between 3-4, and RDA and CCA can be selected. However, in this paper, the ranking effect of CCA and the degree of interpretation of environmental factors are slightly higher than RDA, so CCA analysis is selected.
5.(correspondence analysis, CA) is a typical unconstrained sort, the purpose is to show as many changes as possible on as few axes, and to allow quadrats or species to be displayed visually in the sequence diagram without entering any environmental variable factors.The purpose of constrained ordering is to find the changes of species on the environmental gradient. In this regard, as the number of environmental variables increases relative to the number of observations, the relationship between species and the environment is stronger than they actually are,however, this paper tests the sorting method used before sorting analysis, that is, linear model and unimodal model. The meaning of linear model means that a plant species changes linearly with the change of an environmental factor, which is called linear response. The implication of the unimodal model is that the number of individuals in a plant species increases with the value of an environmental factor. When the environmental factor increases to a certain value, the number of individuals of the plant species reaches the maximum, and the value of the environmental factor at this time is called the optimum of the species; Then, when the value of environmental factors continues to increase, the number of individuals of species gradually decreases. Based on the detection analysis and the results show that the number of environmental factors and the number of species selected in this paper are ranked and analyzed, CCA performs best.
6.The autocorrelation of environmental factors does affect the analysis results. The environmental factors selected in this paper are screened based on previous studies and the unique geographical environment of the test area. Many research conclusions show that the selected environmental factors meet the requirements of data analysis. References:
1.YANG Zhenqi et al. Environmental interpretation of herb species diversity under different site types of Hippophae rhamnoides forest in feldspathic sandstone region[J]. Acta Ecologica Sinica, 2018, 38(14).
2.Chendi Shi. Study on the effect of Arsenic sandstone and sand mixed soil on natural vegetation restoration in Mu Us Sandy Land[J]. Scientific Journal of Intelligent Systems Research, 2021, 3(12).
3.Wang Ruijie and Yan Feng and Wang Yanjiao. Vegetation Growth Status and Topographic Effects in the Pisha Sandstone Area of China[J]. Remote Sensing, 2020, 12(17) : 2759-2759.
Thank you again.
