Comparison of Drivers of Soil Microbial Communities Developed in Karst Ecosystems with Shallow and Deep Soil Depths
Round 1
Reviewer 1 Report
Although the study of Guan et al. seems to be an interesting one there are two serious drawbacks. The first has to do with the language that needs to be revised by a native speaker. The second one concerns the description of the experimental design and the statistical analyses. It is too confusing and I think that there are some problems that need fixing such as the mixing of trees' and shrubs' leaves in a composite sample that used for the determination of its nutrient content or the fact that the type of ecosystem or otherwise vegetation (grassland, forests, plantation , abandonded land) were not taken into consideration. The samples summed in two categories no matter the ecosystem that they were originated. Also the main question that the microbial communities developed in the first 20 cm of the soil would be related to the final depth of the soil is not convincing enough. The confusing experimental design together with the difficulties in language makes the evaluation of the reliability of the article a difficult task.
I attach an annotated version of the article
Comments for author File: 
Comments.pdf
Author Response
(1) Although the study of Guan et al. seems to be an interesting one there are two serious drawbacks. The first has to do with the language that needs to be revised by a native speaker. The second one concerns the description of the experimental design and the statistical analyses. It is too confusing and I think that there are some problems that need fixing such as the mixing of trees' and shrubs' leaves in a composite sample that used for the determination of its nutrient content or the fact that the type of ecosystem or otherwise vegetation (grassland, forests, plantation, abandonded land) were not taken into consideration. The samples summed in two categories no matter the ecosystem that they were originated. Also, the main question that the microbial communities developed in the first 20 cm of the soil would be related to the final depth of the soil is not convincing enough. The confusing experimental design together with the difficulties in language makes the evaluation of the reliability of the article a difficult task.
I attach an annotated version of the article.
Thanks very much for reviewer’s suggestions.
Accept. The language has been revised by a native speaker professor Warwick Harris, showed in manuscript with tracking changes.
I agree that samples of trees' and shrubs' leaves are two categories. However, based on the research methods reported so far, the leaves of the dominant plant in the plant community can be used to represent the nutrient content of vegetation. Therefore, only the leaves of dominant plants in the subplot could be selected as plant samples. The sampling method for plant samples is described in Line 99-101. If tree species was dominant in the subplot, plant samples were selected from tree leaves. Otherwise, shrub leaves or aboveground part of herb were selected as plant samples.
For ecosystems developed in thick soil layers, the microbial communities developed in the first 20 cm of the soil would be related to the final depth of the soil is not convincing enough may be true. However, in karst areas that with severe soil erosion, the environmental factors of communities that developed in different soil thickness were quite different (Table 2). Therefore, we believe that soil microbial communities in ecosystems with different total soil depth are of comparative value.
(2) Line 12 What do you mean by thin and thick soil depth communities?
In our study, we defined communities with soil thickness less than 100 cm as thin soil depth communities, and thick soil depth communities are communities with soil depth at least 100 cm. We supplemented this explanation in the abstract in Line 13 of document with tracking changes.
(3) Line 16 “correlation between microbial community and plant-soil” microbial community and plant or microbial community and soil? It is not clear.
Accept. Modified as microbial community and plant-soil system in Line 18 of document with tracking changes.
(4) Line 17 “pure plant effect explained the 43.2% variance of microbial biomass” revised to pure plant effect explained the 43.2% of variance in microbial biomass.
Accept.
(5) Line 18 G+/G− and F/B, its the first time for these abbreviations and they need to be explained.
Accept. Revision in Line 20-23: ratio of gram positive bacteria to gram negative bacteria (G+/G−) and ratio of fungi to total bacteria (F/B)
Ratio of microbial PLFA cyclopropyl to precursors (Cy/Pr) and ratio of saturated PLFA to monounsaturated PLFA (S/M).
(6) Line 19 I think that dominated must be replaced by controlled.
Accept.
(7) Line 19 “but high pH was not conducive to microorganisms in this area.” what do you mean by that?
pH was positively related to Cy/Pr and S/M, which were indicators of microbial stress. I have modified this sentence to make it more explicit.
(8) Line 20 “indicating microorganisms were under environmental” revised into indicating that microorganisms
Accept.
(9) Line 29 reclamation is not an environmental factor. Delete “environmental” in Line 28.
Accept.
(10) Line 30 Delete “and”
Accept.
(11) Line 42 “nitrogen addition concentration (Yang et al., 2019) have regular gradient.” modified to nitrogen concentration (Yang et al., 2019) exhibit regular gradient.
Accept.
(12) Line 43 heterogeneity modified to heterogeneous
Accept.
(13) Line 44-46 Needs rephrasing
Accept. We modified that statement in Line 49-52 in document with tracking changes. Showed as follows:
This makes it more difficult to explore the driving factors of microbial community in this these areas on a regional scale, as the scale is complicated by the interactions among biogeography, climate, and soil abiotic conditions
(14) Line 51 I am not sure that the terms "thin and thick soil depth' are appropriate.
Thank you very much for your advice. I am looking for a more appropriate expression, but I’m not sure whether thin soil thickness or shallow soil layer would be more appropriate?
(15) Line 51 “serious karst rocky desertification” modified to “serious karst rocky desertified areas”
Agree the modification, and I revised as “areas with serious karst rocky desertification”
(16) Line 52 “communities with thick soil” modified to “communities developed in thick soil”
Accept.
(17) Line 52 what this abbreviation means?
karst rocky desertification (KRD).
(18) Line 54 need a further research，delete a
Accept.
(19) Line 56 “the impact factors of microorganism” it is not clear what this sentence mean?
Accept. The language has improved and revision in Line 61-62: Further, previous studies in karst regions have not distinguished the differences between communities with different soil depth when exploring the impact factors of microorganisms.
(20) Line 58 composition? structure? function?
Thank you very much for your revision. Accept and revise: microbial community composition and structure.
(21) Line 59 “in karst communities with different soil depth” modified to in karst communities developed in different soil depths
Accept.
(22) Line 66 what about the community in thick soil depth
Thank you very much for your advice. I have revised to: soil microbial community in thin-SDC would be more strongly driven by plant and edaphic factors than in thick-SDC.
(23) Line 67 what kind of stress? please describe
We use microbial stress indicators including Cy/Pr and S/M to represent the stress to the microbial community. These indicators increased under stress like nutrient deficiency, soil acidification, high temperature and other unfavorable conditions for survival. Thus, these indicators dose not respond to a particular environmental pressure, so I think it is not appropriate to describe stress here.
(24) Line 76 “the soil is mainly developed of limestone” modified to developed on limestone
I agree with your advice, and I think “developed from limestone” is more appropriate.
(25) Line 86 “are” modified to is an
Thank you very much for your revision. I have revised this sentence and made it clearer in Line 93-97 in document with tracking changes.
(26) Line 88 what kind of community? “natural community” modified to plant natural community.
Thank you very much for your revision. I have revised in Line 100: Plant community. Therefore, natural community could represent natural community of plant obviously.
(27) Line 90 Delete “ecological”.
Disagree. Ecological forest represents the forest planted for ecological restoration that would not be destroyed, which is different to forest.
(28) Line 90 it is not clear. what kind of ecosystems?
Thank you very much for your suggestion. I have revised in Line 101-104: Twenty-one karst ecosystems were divided into two groups, one included 10 ecosystems with soil depth less than 100 cm and another included 11 ecosystems with soil depth at least 100 cm (Figure 1).
(29) Line 99-101 leaves from shrubs and trees exhibit diffrent nutrient concentrations, I don’t think that you are allowed to mix them and used it as a composite sample.
I am very sorry for the misunderstanding caused by my improper English writing. I have revised to: “Leaves of shrubs or trees in the quadrat were collected from at least 6 dominant plants and mixed, combined to form one composite plant sample per plot.”
According to the present prescribed sampling method, whether it’s trees or shrubs, only the dominant plants in the subplot are selected as samples, for they are representative of the entire plant community.
(30) Line 111 the description of the experimental design is not adequate. I cann;t get an idea how the establishmnet of the design took place. You mentioned 21 sites, you discuss about 10 ecosystems, then you sampled 63 samples (I think 21x3) and these were mixed by at least 6 soil cores. It is very confusing. It is not clear what you want to evaluate by this design. In all cases you collected sample from the first 20 cm of the soil?
I am very sorry for the misunderstanding caused by my improper English writing.
In our study, twenty-one sites were selected. We divided these twenty-one sites into two groups according to their total soil depth. Group A consists of ten sites developed in thin soil depth, group B consists of 11 sites developed in thick soil depth. The purpose of our design is to compare the characteristics of soil microbial communities in communities developed in different soil depths.
In every site, 3 plots were selected. Soil samples collected from every plot were mixed with at least 6 soil cores.
In all cases we collected sample from the first 20 cm of the soil.
(31) Line 115 cm? Line in which depth? 5 cm or 0-20 cm?
Thank you very much for your scrupulous work. I have revised in Line 132-133: Soil temperature at 5 cm soil depth (Ts) was determined by a portable soil thermometer. In the laboratory, gravimetric soil water content (SWC) and bulk density (BD) at 0-20 cm were determined by drying soil samples at 105 °C for 48 h in a 100 cm3 soil core.
(32) Line 142 what does "DMA" describe?
DMA, dimethylacetamide. I added this note in Line 159.
(33) Line 144 “assigned 6 microbial species” modified to: assigned to six microbial groups
Accept.
(34) Line 147 what H mean? what S mean?
Accept. Modified to microbial abundance and microbial diversity.
(35) Line 148-149 “ratio of cyclopropyl/precursors as calculated by (cy17∶0+cy19∶0)/(16∶1ω7+18∶1ω7) (Cy/Pr), ratio of saturated PLFA to monounsaturated PLFA (S/M)” what these indices show?
The precursor compound of soil microbial PLFA will convert to stable cyclopropyl when suffering environmental stress, and monounsaturated PLFA will also convert to saturated PLFA under adverse environment. Therefore, S/M and Cy/Pr can be used to indicate the degree of environmental stress suffered by soil microorganisms.
For example, the precursors of cyclopropyl 17 is 16∶1ω7.
(36) Line 151 “Species diversity” modified to Plant species diversity
Accept. And I added the method of calculating microbial diversity in Line 188-195.
(37) Line 167-168 “one” modified to individuals, “all” modified to individuals of.
Accept.
(38) Line 169 Delete “statistical”
Accept.
(39) Line 172 “profiles parameters” revised to variables
Accept.
(40) Line 177 please explain “indexes with the maximum weight and over 90% of the maximum in each PC “
We use Table S3 as an example to explain the selection process of minimum data set.
In PC-1, total bacterial PLFA is the index with the maximum weight (0.974), so total bacterial PLFA was selected.
90% of the maximum weight (0.974*90% = 0.877) is 0.877.
Therefore, indexes with the weight over 0.877 in PC-1 were selected, showed in bold font.
Table S3 Principal components analysis of soil PLFA indices
|
Principal components |
PC–1 |
PC–2 |
PC–3 |
|
Eigenvalues |
6.715 |
3.135 |
1.303 |
|
Variation (%) |
47.967 |
22.394 |
9.308 |
|
Cumulative (%) |
47.967 |
70.361 |
79.669 |
|
Total PLFA |
0.971 |
0.187 |
0.141 |
|
Total bacterial PLFA |
0.974 |
0.173 |
0.124 |
|
General bacterial PLFA |
0.953 |
0.064 |
.186 |
|
G- |
0.946 |
0.252 |
0.018 |
|
G+ |
0.953 |
0.128 |
0.228 |
|
Fungal PLFA |
-0.428 |
0.673 |
0.475 |
|
Actinomycic PLFA |
0.946 |
0.161 |
0.171 |
|
Eucaryotic PLFA |
0.465 |
0.168 |
-0.158 |
|
G+/G- |
-0.421 |
-0.406 |
0.571 |
|
F/B |
-0.633 |
0.490 |
0.450 |
|
Cy/Pr |
-0.286 |
0.719 |
-0.190 |
|
S/M |
.003 |
0.668 |
-0.456 |
|
Microbial S |
-0.386 |
0.751 |
0.276 |
|
Microbial H |
-0.108 |
0.739 |
-0.228 |
Note: PC–1, PC–2 and PC–3 indicate the first to third principal component, respectively. Bold factors are considered highly weighted.
(41) Line please rephrase Line 179-181.
Accept. Modified to: When more than one high loading indicators in a single PC and highly correlated (>0.6) with each other, only the indicator with the highest eigenvector was selected (Bastida et al., 2006) in Line 206-208.
(42) Line 185 this belongs to the previous paragraph.
Accept.
(43) Line Line 187-188 “Major factors that significantly affect microbial community were analyzed with forward selection (alpha=0.05).” what kind of analysis you applied in this case?
Factor analysis by the method of forward selection (alpha=0.05). I added this state in Line 214.
(44) Line 204 which is the number of samples in the two categories? It is not mentioned in the experimental design
Thank you very much for your conscientious in work. I added the experimental design in Line 97-98: “Sites 3, 4, 5, 6, 10, 11, 12, 13, 14 and 19 developed in thin soil depth, the others developed in thick soil depth.”
And Line 101-104: Twenty-one karst ecosystems were divided into two groups, one consists of 10 ecosystems with soil depth less than 100 cm and the other consists of 11 ecosystems with soil depth at least 100 cm (Figure 1).
And Line 121: Soil at depths of 0–20 cm was collected from three plots per site, providing a total of 63 plots.
(45) Line 221-222: These 63 samples samples from different ecosystems; abandoned land, grassland, forest, plantation etc. By summing samples independently on the ecosystem type and use them as replicates, you hypothesize that the soil microbial community is independent on the ecosystem type which is wrong since the type of vegetation controls soil microbial communities.
I agree that when analyzing the effects of total soil depth on soil microbial community, choosing the same vegetation type is more convincing. However, there are advantages to choosing different ecosystems. The ecosystem selected in our study are the typical vegetation type in this study area, which can represent the vegetation in karst area of Guizhou province. Therefore, our findings can explain the universal phenomenon of microorganisms in karst areas, rather than being confined to a single vegetation type.
Physical and chemical properties of plant and soil in different vegetation types of community would be different. We have taken these factors into consideration in analysis of driver factors for soil microbial community.
The purpose of our study was to compare microbial drivers in two groups of community developed in different soil depths, so it would be more appropriate to select different ecosystems that with different plant and soil characteristics than to select the same ecosystem.
(46) Line 319 “VPA” what is this?
variance partitioning analysis (VPA). We have mentioned it in the statistical analysis Line 216.
(47) Line 352 “resource-ecology” modified to resource- ecological
Accept.
(48) Line 352 “dominated” revised as controlled
Accept.
(49) Line 386-387 “On the other hand, most microorganisms prefer weakly acidic soil” who said that? alkalinity or acidity acts selectively to the members of the microbial community.
Accept. We removed this inaccurate description.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The study of Guan et al. looks into changes in the microbial community (making use of PLFA analyses) in karst ecosystems between "thin" and "thick" soil depths. Even though the research can be interesting for the community, I think some major issues need to be solved first. For instance:
- After rereading the article, I still do not now what a thin and thick soil depth is. I think this is not a general description in soil-related research and thus should at least already be described in the introduction + repeated in the materials and methods section.
- The introduction is quite limited. Information on karst ecosystems should be included to show the importance of this study. Also the researchers refer to studies looking into karst ecosystems befor, but on physicochemical changes, but they do not give a lot of information on their findings.
- In your research hypotheses: why would you expect that thin SDC is more driven by plant and edaphic factors?
- The headings of the material and methods section or often not clear. For instance: does species diversity refer to microbial species or plant species? Why did you do this calculation, what is the benefit?
- Also the description of the statistical analysis is quite limited. On page line 183 you speak of microbial properties. What are these? If you make use of a two sample t-test, did you than check normal distribution of your data? Were the variances between the groups equal or not? You describe significant differnces of PLFA markers, but they are not described in your statistical analysis. These should at least be done by Kruskal wallis/anova and you also should take into account correcting for multiple comparisons.
- I think the article needs to be read and corrected by a native English speaker, as sometimes the messages seems quite weird, probably by applying the wrong words.
- Discussion should include a small introduction paragraph where you include your research hypotheses again + why these are important!
- The discussion needs a lot of rephrasing. You often use very long sentences which makes it hard to understand what you are saying. I also can't find the major points you want to show here. Please try to build up your discussion according to the hypotheses you have stated.
- I find the conclusion more a wrap up of the discussion. I really want to see here the major findings of the study and what this means to the community
Minor comments:
- G+/G-, I suppose you here refer to gram positive and gram negative BACTERIA. Please include the word bacteria throughout the manuscript
- page line 43-47: this sentence is not clear to me
- line 56-61: a bit of repetition with the sentences above. Shorten this down + rephrase
- line 73: accumultated temperature: is this value not really high? Normally this is expressed in degree-days
- line 76: I think developed here should be consisting?
- figure 1: this si a nice figue, but maybe better to even zoom in more on the sampling area
- line 87: what is community investigation? I cannot find this back in the description below
- line 90: so soil depth less than 100 cm is than thin ?
- I would put table 1 in the supplementary
- line 152: include a bit of an introduction in this paragraph. Is this part on PLFA? or plant species?
- line 183: what do you mean with microbial properties?
- line 203: so S, H, D and J are calculated on plant species? This is not clear so far
Author Response
The study of Guan et al. looks into changes in the microbial community (making use of PLFA analyses) in karst ecosystems between "thin" and "thick" soil depths. Even though the research can be interesting for the community, I think some major issues need to be solved first. For instance:
(1) After rereading the article, I still do not know what a thin and thick soil depth is. I think this is not a general description in soil-related research and thus should at least already be described in the introduction + repeated in the materials and methods section.
Accept. We have described it in the introduction in Line 68-72, and repeated in the materials and methods section in Line 119-120 and Line 125-126.
(2) The introduction is quite limited. Information on karst ecosystems should be included to show the importance of this study. Also, the researchers refer to studies looking into karst ecosystems before, but on physicochemical changes, but they do not give a lot of information on their findings.
Accept. We added the information of karst ecosystems in Line 53-75: The karst area in southwest China is one of the three major continuous karst areas and is the largest in the world (Wang et al., 2015). Carbonate rocks are not able to produce much soil for their extremely slow soil formation rate, resulting in shallow soil in this karst area (Jiang et al. 2014). Also, the carbonate rocks have developed the broken karst surface in the long-term hydro-chemical process due to the highly soluble carbonate rocks, strong vertical and horizontal flow exchange of groundwater and surface water and the steep landforms in southwest China, leading to serious soil loss (Bai et al., 2019; Yan et al., 2018; Zhou et al., 2017a). In addition, this area is densely populated with poor counties and people mainly work in agriculture that cause serious vegetation destruction (Ma et al., 2020). This karst area has obvious regional characteristics for its different natural foundations (topography, climate, etc.) and are exposed to the influence of different human social conditions (economy, population, etc.) (Ma et al., 2020). Therefore, different degrees of soil erosion prevail in the karst area of southwest China, and subsequently has resulted in surface rock exposure and uneven distribution of soil depth in the karst area. In areas with severe karst rocky desertification (KRD) the soil is shallow and in areas with light or no KRD the soil layer is thick. Soil is the foundation of terrestrial ecosystems. It is well known that poorer plant and soil characteristics are always found in communities developed in thin soil than in communities developed in thick soil (Cheng et al., 2016; Liu and Liu, 2012; Sheng et al., 2018). Rocky desertification and shallow soil has become the primary ecological disaster in Southwest China, which has seriously hindered the economic growth and has a direct and significant impact on the 1.7 million people living in this karst region (Jiang et al. 2014).
We added the information of previous findings in Line 76-81: Microbial communities play an important role in soil fertility and plant succession (Vazquez et al. 2020). Therefore, it is necessary to study the driving factors of soil microbial communities in karst areas, which is beneficial for ecological restoration of this area. Previous studies found that communities with thick soil depth are rich in soil organic matter, and have higher fungal and bacterial diversity and microbial biomass than communities with thin soil depth (Li et al. 2020; Liu et al. 2019; Zhang et al 2019; Hu et al. 2016).
(3) In your research hypotheses: why would you expect that thin SDC is more driven by plant and edaphic factors?
For the reason that poorer plant and soil characteristics are always found in communities developed in thin soil than in communities developed in thick soil. Soil microbial community in thin SDC would more demand for nutrients supply, and parts of nutrients in thick SDC may reach saturation. Thus, we expect that plant and edaphic factors have stronger effects on soil microbial community in thin SDC than in thick SDC.
(4) The headings of the material and methods section or often not clear. For instance: does species diversity refer to microbial species or plant species? Why did you do this calculation, what is the benefit?
Thanks very much for your revision. We modified the headings to distinguish the microbial diversity from the plant diversity in Line 190-221. Plant species diversity indexes are important indexes of plant community. Plant diversity affects litter quality and plant community habitat and has a direct impact on the growth of microorganisms.
(5) Also, the description of the statistical analysis is quite limited. On page line 183 you speak of microbial properties. What are these? If you make use of a two sample t-test, did you than check normal distribution of your data? Were the variances between the groups equal or not? You describe significant differences of PLFA markers, but they are not described in your statistical analysis. These should at least be done by Kruskal wallis/anova and you also should take into account correcting for multiple comparisons.
Thanks very much for your revision. We modified “microbial properties” to indexes of soil microbial community in Line 236.
(a) We use two independent samples T test and check normal distribution of data by Kolmogorov-Smirnov. If the significance > 0.05, data is normal distribution. For example, the Table 1 below is generated by using SPSS to check normal distribution of data in thick soil depth community.
|
Table 1 Normality test c |
||||||
|
|
Kolmogorov-Smirnova |
Shapiro-Wilk |
||||
|
統計資料 |
df |
Sig |
統計資料 |
df |
Sig |
|
|
general |
.145 |
33 |
.076 |
.953 |
33 |
.164 |
|
GN |
.199 |
33 |
.002 |
.839 |
33 |
.000 |
|
GP |
.163 |
33 |
.027 |
.923 |
33 |
.022 |
|
FUNGI |
.148 |
33 |
.065 |
.880 |
33 |
.002 |
|
ACTI |
.151 |
33 |
.055 |
.886 |
33 |
.002 |
|
Eucaryotic |
.103 |
33 |
.200* |
.942 |
33 |
.076 |
|
GG |
.215 |
33 |
.000 |
.823 |
33 |
.000 |
|
FB |
.095 |
33 |
.200* |
.974 |
33 |
.601 |
|
Cy/Pr |
.106 |
33 |
.200* |
.963 |
33 |
.311 |
|
SM |
.170 |
33 |
.016 |
.915 |
33 |
.013 |
|
MicroH |
.092 |
33 |
.200* |
.967 |
33 |
.413 |
|
MicroS |
.109 |
33 |
.200* |
.948 |
33 |
.115 |
|
SOC |
.153 |
33 |
.048 |
.882 |
33 |
.002 |
|
TN |
.166 |
33 |
.022 |
.948 |
33 |
.118 |
|
TP |
.228 |
33 |
.000 |
.815 |
33 |
.000 |
|
SCN |
.145 |
33 |
.075 |
.955 |
33 |
.190 |
|
SCP |
.128 |
33 |
.185 |
.939 |
33 |
.066 |
|
SNP |
.173 |
33 |
.014 |
.909 |
33 |
.009 |
|
Ts |
.214 |
33 |
.001 |
.892 |
33 |
.003 |
|
pH |
.127 |
33 |
.194 |
.943 |
33 |
.086 |
|
SWC |
.171 |
33 |
.016 |
.945 |
33 |
.093 |
|
BD |
.185 |
33 |
.006 |
.921 |
33 |
.019 |
|
NH4 |
.177 |
33 |
.010 |
.769 |
33 |
.000 |
|
NO3 |
.266 |
33 |
.000 |
.588 |
33 |
.000 |
|
SAP |
.306 |
33 |
.000 |
.619 |
33 |
.000 |
|
ASAK |
.108 |
33 |
.200* |
.962 |
33 |
.298 |
|
SoilTK |
.139 |
33 |
.105 |
.958 |
33 |
.232 |
|
SoilCa |
.240 |
33 |
.000 |
.590 |
33 |
.000 |
|
SoilMg |
.126 |
33 |
.200* |
.922 |
33 |
.021 |
|
sand |
.153 |
33 |
.048 |
.917 |
33 |
.015 |
|
silt |
.148 |
33 |
.063 |
.915 |
33 |
.013 |
|
clay |
.232 |
33 |
.000 |
.840 |
33 |
.000 |
|
Elevation |
.240 |
33 |
.000 |
.855 |
33 |
.000 |
|
MAP |
.236 |
33 |
.000 |
.890 |
33 |
.003 |
|
MAT |
.171 |
33 |
.015 |
.906 |
33 |
.008 |
|
S |
.154 |
33 |
.044 |
.927 |
33 |
.028 |
|
H |
.199 |
33 |
.002 |
.890 |
33 |
.003 |
|
D |
.321 |
33 |
.000 |
.729 |
33 |
.000 |
|
J |
.376 |
33 |
.000 |
.679 |
33 |
.000 |
|
WOODY |
.270 |
33 |
.000 |
.672 |
33 |
.000 |
|
HERB |
.198 |
33 |
.002 |
.798 |
33 |
.000 |
|
LITTER |
.204 |
33 |
.001 |
.606 |
33 |
.000 |
|
LeafC |
.087 |
33 |
.200* |
.986 |
33 |
.940 |
|
LeafN |
.241 |
33 |
.000 |
.789 |
33 |
.000 |
|
LeafP |
.173 |
33 |
.014 |
.932 |
33 |
.040 |
|
leafCN |
.123 |
33 |
.200* |
.948 |
33 |
.115 |
|
leafCP |
.188 |
33 |
.004 |
.836 |
33 |
.000 |
|
leafNP |
.106 |
33 |
.200* |
.947 |
33 |
.107 |
|
LitterC |
.097 |
33 |
.200* |
.948 |
33 |
.117 |
|
litterN |
.207 |
33 |
.001 |
.734 |
33 |
.000 |
|
litterP |
.197 |
33 |
.002 |
.871 |
33 |
.001 |
|
litterCN |
.126 |
33 |
.200* |
.952 |
33 |
.151 |
|
litterCP |
.141 |
33 |
.096 |
.808 |
33 |
.000 |
|
litterNP |
.112 |
33 |
.200* |
.938 |
33 |
.059 |
|
LitterK |
.171 |
33 |
.015 |
.909 |
33 |
.009 |
|
LitterCa |
.093 |
33 |
.200* |
.978 |
33 |
.713 |
|
LitterMg |
.146 |
33 |
.072 |
.912 |
33 |
.011 |
|
leafK |
.117 |
33 |
.200* |
.942 |
33 |
.076 |
|
leafCa |
.113 |
33 |
.200* |
.968 |
33 |
.418 |
|
leafMg |
.110 |
33 |
.200* |
.964 |
33 |
.326 |
|
*. 這是 true 顯著的下限。 |
||||||
|
a. Lilliefors 顯著更正 |
||||||
|
c. depth 是常數。已省略它。 |
||||||
(b) Then, T test is used to check for difference significance. Variances between the groups equal or not is tested by Levene test. If the significance of F in Table 3 is greater than 0.05, we select the significance of T test in the first row (equal), and vice versa, we use the significance of the second row (unequal) (Table 5).
|
Table 2 群組統計資料 |
|||||
|
|
depth |
N |
平均數 |
標準偏差 |
標準錯誤平均值 |
|
Cy/Pr |
>= 99.00 |
33 |
1.0858 |
.35138 |
.06117 |
|
< 99.00 |
30 |
1.4423 |
.32048 |
.05851 |
|
|
Table 3 獨立樣本檢定 |
||||||||||
|
|
Levene 的變異數相等測試 |
針對平均值是否相等的 t 測試 |
||||||||
|
F |
sig |
T |
df |
sig（雙尾） |
平均差異 |
標準誤差 |
95% 差異數的信賴區間 |
|||
|
下限 |
上限 |
|||||||||
|
Cy/Pr |
採用相等變異數 |
.537 |
.466 |
-4.193 |
61 |
.000 |
-.35647 |
.08502 |
-.52649 |
-.18645 |
|
不採用相等變異數 |
|
|
-4.211 |
60.999 |
.000 |
-.35647 |
.08465 |
-.52573 |
-.18721 |
|
|
Table 4 群組統計資料 |
|||||
|
|
depth |
N |
平均數 |
標準偏差 |
標準錯誤平均值 |
|
Fungi |
>= 99.00 |
33 |
.4571 |
.30740 |
.05351 |
|
< 99.00 |
30 |
.8310 |
.60313 |
.11012 |
|
|
Table 5 獨立樣本檢定 |
||||||||||
|
|
Levene 的變異數相等測試 |
針對平均值是否相等的 t 測試 |
||||||||
|
F |
sig |
T |
df |
sig（雙尾） |
平均差異 |
標準誤差 |
95% 差異數的信賴區間 |
|||
|
下限 |
上限 |
|||||||||
|
Fungi |
採用相等變異數 |
23.558 |
.000 |
-3.142 |
61 |
.003 |
-.37390 |
.11899 |
-.61184 |
-.13595 |
|
不採用相等變異數 |
|
|
-3.054 |
42.182 |
.004 |
-.37390 |
.12243 |
-.62094 |
-.12686 |
|
(c) Independent samples T test in nonparametric test is used for data that do not satisfy normal distribution.
Significant differences of PLFA markers were only compared between two independent samples (thin and thick SDC), so ANOVA was not used.
(6) I think the article needs to be read and corrected by a native English speaker, as sometimes the messages seem quite weird, probably by applying the wrong words.
Thanks very much for your suggestions.
Accept. The language has been revised by a native speaker professor Warwick Harris, showed in manuscript with tracking changes.
(7) Discussion should include a small introduction paragraph where you include your research hypotheses again + why these are important!
The discussion needs a lot of rephrasing. You often use very long sentences which makes it hard to understand what you are saying. I also can't find the major points you want to show here. Please try to build up your discussion according to the hypotheses you have stated.
Thanks very much for your suggestions. Accept. We modified discussion according to the hypotheses +why in Line 324-333, Line 386-387 and Line 415-418 in manuscript with tracking changes.
The language has rephrased in discussion in manuscript with tracking changes.
(8) I find the conclusion more a wrap up of the discussion. I really want to see here the major findings of the study and what this means to the community
Thanks very much for your suggestions. Accept. We revised the conclusion in manuscript with tracking changes.
Minor comments:
(9) G+/G-, I suppose you here refer to gram positive and gram negative BACTERIA. Please include the word bacteria throughout the manuscript
Thanks very much for your suggestions. G+/G- refer to gram positive and gram negative bacteria, but I think G+/G- is an appropriate abbreviation. Numerous previous studies have used this abbreviation, such as
Liu, M.H., Sui, X., Hu, Y.B. & Feng, F.J. (2019). Microbial community structure and the relationship with soil carbon and nitrogen in an original Korean pine forest of Changbai Mountain, China. BMC Microbiol., 19, 14.
Li, Q.X., Feng, J., Wu, J.J., Jia, W., Zhang, Q., Chen, Q. et al. (2019). Spatial variation in soil microbial community structure and its relation to plant distribution and local environments following afforestation in central China. Soil & Tillage Research, 193, 8-16.
(10) page line 43-47: this sentence is not clear to me
Thank you very much for pointing out the error. We rephrased this sentence Line 49-52: This makes it more difficult to explore the driving factors of microbial community in these areas on a regional scale, as the scale is complicated by the interactions among biogeography, climate, and soil abiotic conditions.
(11) line 56-61: a bit of repetition with the sentences above. Shorten this down + rephrase
Thank you very much for your revision. We modified in Line 85-90: Consequently, we still lack knowledge of the effects of environmental factors on the microbial community composition and structure in different soil depth communities. These combined factors and the definition of the proportion of each factor in karst communities developed in different soil depths limits our ability to understand the importance of soil microbial communities in regulating ecosystem structure and function.
(12) line 73: accumultated temperature: is this value not really high? Normally this is expressed in degree-days
Thank you very much for your scrupulous work. We modified this mistake in Line 105: mean accumulated temperature (> 0°C) of 8.9 ~20.5°C.
(13) line 76: I think developed here should be consisting?
Accept.
(14) figure 1: this is a nice figure, but maybe better to even zoom in more on the sampling area
Accept.
(15) line 87: what is community investigation? I cannot find this back in the description below
Community investigation refers to the work descripted in Line 132-142.
(16) line 90: so soil depth less than 100 cm is than thin ?
Yes. We defined the community developed in total soil depth less than 100 cm as thin soil depth community. We have modified this sentence to make it clearer in Line 125-126: thin-SDC consists of 10 ecosystems with soil depth less than 100 cm and thick-SDC consists of 11 ecosystems with soil depth at least 100 cm.
(17) I would put table 1 in the supplementary
Thank you very much for your suggestion. I think the contents in Table 1 are important experimental results and important references for data analysis, which should be included here.
(18) line 152: include a bit of an introduction in this paragraph. Is this part on PLFA? or plant species?
Thanks very much for your revision. We added an introduction in this paragraph in Line 190 and Line 213-214, and modified the headings to distinguish the microbial diversity from the plant diversity in Line 190-221.
(19) line 183: what do you mean with microbial properties?
Thanks very much for your revision. We modified “microbial properties” to indexes of soil microbial community in Line 236.
(20) line 203: so S, H, D and J are calculated on plant species? This is not clear so far
Thanks very much for your revision. Plant species diversity indexes include plant S, H, D and J, soil microbial diversity indexes include microbial S and H, we modified the sentence to distinguish the microbial diversity from the plant diversity in Line 190-221.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Dear Authors
Although this new version has been improved, however I believe that the language needs further editing. This became obvious even from the title of the paper that says " Drivers of soil microbial communities in karst ecosystems developed in different soil depth". The authors examined soil microbial attributes in the first 0-20 cm in soils with a total depth lower than 100 cm and in soils with total depth higher than 100 cm. So what they presented wasn't microbial communities developed in differnt soil depths. This kind of phrasing exist all over the text and must be change. Also I believe that some of the differences recorded in this study is due to the fact that since the total depth in thin SDC is lower compare to thick-SDC even the same amount of nutrients are diluted in lower soil volume resulting in increased nutrient concentration in thin soils supporting higher microbial diversity or biomass.
Author Response
Thank you very much for your suggestions. Your understanding is very reasonable. We accept your proposal and modify the title and language of this manuscript. The modifications we made are in the document with tracking changes.
Author Response File: Author Response.docx
Reviewer 2 Report
I thank the authors for the extensive review of the manuscript. Overall, the article has improved sufficiently and is now easy to follow.
Author Response
Thank you very much for your review. We have modified the language to make it more readable in document with tracking changes
Author Response File: Author Response.docx
