Soil stoichiometric characteristics and influencing factors in karst forests under micro-topography and microhabitat scales

Dang, Yi; Zhou, Hua; Zhao, Wenjun; Cui, Yingchun; Tan, Chengjiang; Ding, Fangjun; Wang, Yukun; Liu, Run; Wu, Peng

doi:https://doi.org/10.5194/egusphere-2025-3510

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https://doi.org/10.5194/egusphere-2025-3510

Preprints

29 Jul 2025

| 29 Jul 2025

Soil stoichiometric characteristics and influencing factors in karst forests under micro-topography and microhabitat scales

Yi Dang, Hua Zhou, Wenjun Zhao, Yingchun Cui, Chengjiang Tan, Fangjun Ding, Yukun Wang, Run Liu, and Peng Wu

Abstract. To quantitatively evaluate the stoichiometric characteristics of karst forest soils and their response mechanisms to complex microenvironments, the study systematically investigated soil stoichiometric traits and influencing factors across micro-topography and microhabitat scales in the Maolan karst forest. Key findings include: (1) Soil nutrients (organic carbon, total nitrogen, hydrolyzable nitrogen, available phosphorus, available potassium, total calcium, exchangeable calcium, and exchangeable magnesium) exhibited strong variability with significant spatial heterogeneity; (2) Microhabitat factors significantly influenced nutrient accumulation, though different elements showed distinct response patterns to microhabitat variations; (3) Micro-topographic parameters (slope gradient, aspect, and position) exerted indirect effects through gravity, light exposure, and erosion, driving the formation of gradient patterns in soil stoichiometry; (4) Differential response mechanisms of nutrients to abiotic factors, combined with the differential nutrient regulation and absorption strategies of various plant life forms, collectively shaped the complex stoichiometric characteristics. Synergistic interactions were observed among microhabitat-micro-topography-plant life form factors, with geomorphological abiotic factors playing predominant roles at this scale. Although biotic factors like plant life forms showed relatively weaker direct influences, their regulatory effects were closely interrelated with microhabitat-topographic factors. This multi-dimensional feedback mechanism between biotic and abiotic factors reflects the complexity of nutrient cycling in karst ecosystems.

Received: 21 Jul 2025 – Discussion started: 29 Jul 2025

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Yi Dang, Hua Zhou, Wenjun Zhao, Yingchun Cui, Chengjiang Tan, Fangjun Ding, Yukun Wang, Run Liu, and Peng Wu

Status: final response (author comments only)

RC1:
'Comment on egusphere-2025-3510', Anonymous Referee #1, 16 Sep 2025
The study investigates the drivers of stoichiometric relationships in soil properties in the Maolan karst region of southwest China. The researchers tie soil stoichiometry to microhabitats, topography, and vegetation, using multi-scale analysis of soil nutrients and plant life forms. The study provides strong ecological reasoning for observed nutrient patterns in karst systems, but there are some ways that the ms could be improved for readability and interpretability (in the figures and the text).
Specific Comments:
L20: The effects of the micro-topographic parameters were investigated through correlations, but it cannot be directly stated that gravity, light exposure, and erosion were the drivers since the study didn’t directly investigate those.

L70: The motivations for the study are presented as questions, but not listed in that format. I recommend re-wording accordingly.

L117-123: The microtopographic classes could instead be listed in a table format with the number of associated plots per class combination.

Fig. 2-5 axis labels are illegible because they are so small. Please increase text size.

What is the sample size per class? It is difficult to assess the strength of the statistical comparisons without the sample numbers. The paper mentions 120+ sampling sites and multiple samples per site, but sample number per stratum is needed.

Fig. 7 Suggest moving to supplementary material and increasing the size so the text is more legible.

Table 4 seems redundant with the correlation matrix presented in Fig. 7.

Perhaps the journal has its own guide on this point, but my preference to ease readability is to present percentages with only one significant digit after the decimal instead of two (both within the text and in tables).

Fig. 9 Consider a more colorblind-friendly color scheme and remove the “Vpa” title at the top since it’s described in the caption. Residuals could also be moved to the figure caption.

It seems that spaces are frequently missing between text and ellipses.

The statistical analyses seem appropriate to the data types and questions of interest, but there is a heavy reliance on presenting descriptive statistics in the results section. Consider ways to streamline the presentation of key results, and add the remainder to a supplemental section.

Pairwise comparisons should include confidence intervals when reported in the text.

The discussion is very long. While it does a good job putting the results of the distributions of plant nutrients in the context of biogeochemical conditions specific to karst regions, it is not necessary to discuss every single result in the discussion section. They should be grouped into broader categories for a more streamlined discussion.

The broader literature referenced is usually in relation to established biogeochemical relationships, but not those specific to other karst regions. The discussion would benefit from integrating connections to studies in other karst regions globally.

L 615: Is there a citation for this statement “arboreal species often fail to retain even their own litter around smooth trunk bases” or was it only a direct observation from the present study?

L625-629: It’s great to have this plan, but it is more of a statement for a research proposal than an article. Perhaps something like “Future research directions should explore more dynamic approaches to characterizing karst microenvironments, potentially incorporating real-time environmental monitoring, continuous gradient analysis, and adaptive sampling strategies driven by ecological processes rather than predetermined spatial categories. This could enable better representation of the continuous nature of environmental variation in heterogeneous karst systems.”
Citation: https://doi.org/10.5194/egusphere-2025-3510-RC1
RC2:
'Comment on egusphere-2025-3510', Anonymous Referee #2, 03 Oct 2025
The authors studied the stoichiometric characteristics of a karst forest soil and the relationship with microtopography, microhabitat and plant life form at Maolan Nature Reserve, and found that stoichiometric characteristics are shaped by interactive effects of these three factors, especially microhabitat-micrography interactions. In general, the authors investigated complex relationships using various statistical analysis, as the effect on certain elements and stoichiometric ratios are often not uniform, it is difficult for readers to grasp the most relevant results and key messages. To improve the readability, I suggest the authors reduce the length and make descriptions on results and discussion more concise (see where to reduce in the specific comments below). In addition, more details are needed in figures or their captions so they are understandable stand alone.
Major comments
Consistence of terms needs to be improved. A few examples

Types of microhabitat were rock surface, rock groove, and soil surface (lines 125-144), but they were coded as stone surface, stong gully and soil surface from the method (lines 182) and used in the results and discussion. I believe ‘stong’ is a typo, but it appeared eight times in the texts and sometimes is capitalized and sometimes not.
Hyphen usage: e.g. microtopography and micro-topography both appeared in the text. Microenvironment, micro-environment, etc.
Slope degrees and slop gradients: stick to one term
Missing important information, for example

Lines 100-108: how many sites/plots were sampled and how many points were in each stratum? The authors neither report this in any tables nor figures.
Lines 145-149: The description of microhabitat showed soil layer thickness was less than 20 cm for rock surface, <20 cm for rock groove and has well-developed soil horizons for soil surface type, what was the sampling depth and how did the authors sample soils while thickness differs this much? Sampled the center of the layer with cut ring? Was the thickness of soil layer recorded? The comparability of analyzed properties and calculated stoichiometric ratios would be questionable if the sampling depths were not similar.

Specific comments
Line 18: specify the microhabitat factors

Lines 21-23: different instead of differential?

Line 22: specify abiotic factors to microtopographic and microhabitat instead of using abiotic factors alone. ‘Abiotic factors’ here may mislead readers to think about temperature and other commonly used climatic factors.

Lines 70-75: rephrase them into questions or aims?

Line 76: what multi-scale refers to? Is not this study at the hillslope scale?

It looks like space is often missing before each citation.

Line 96: section 2 study area and 3 study method can be combined into one

Lines 155-158: 0.149 mm sieve, the justification here is not convincing. Up to 2 mm is still considered as soil in commonly used soil particle size classification systems. What happened to the material not passing 0.149 mm sieve? Dropped or milled until passing the sieve? Add details about which properties were analyzed with fresh soil and which with dry soils.

Lines 172-173: explicitly list which ratios were calculated.

Table 1 caption, it is not a comparison, use soil properties instead of detection indicators. Is CV the coefficient variation? Add reference for which range is considered as weak, moderate and strong variability.

Lines 191-198: section 4.1.1 might not be needed at all. The only important information I see here is the variability of all samples and only TK and TP were normally distributed. Considering the authors used soil pH to explain the pattern of exchangeable Ca in the discussion, I suggest add soil pH column to table 1.

Section 4.1.2 Very long descriptive statistics, reduce the text to the most relevant. For example, describe the general trend, means or medians were highest on which slop degrees or increase in the order of …, which types had significant differences, and the interesting patterns to be discussed later. Similar reduction can be made throughout the sections under 4.2.

Figure 2: Add number of points for each slope degree type either in the figure or in the caption, same applies to figures 3-6.

Lines 229-231: wordy, can be reduced to e.g. Major soil nutrients were highest at flat land, followed by shady slopes and sunny slopes. There are many places like this can be shortened, consider using editing services or asking native speakers to improve language.

Lines 321-325: this is because the same variable was used in correlating that ratio, it does not make sense to report this type of correlation. Report only the most relevant parts.

I think section 4.4 does not need subsections, readers can see that one paragraph reporting results from RDA and the other from VPA.

Figure 8: space is enough to write environmental factors in full in the biplot, or add the abbreviations to the figure caption.

Line 336, and table 4: what type of correlation is used in correlating continuous variables and assigned ordinal variables? What is the correlation coefficient called in this case? I could not find details from the method either. It seems that results from Table 4 is not used from the results section, move to supplement instead?

Line 359-360: plant species and plant nutrient contents appeared first time here, describe them in the method.

Lines 360-367 and figure 9: What are stoichiometric traits and stoichiometric variation refer to? What is/are response variable(s) in VPA analysis?

Regarding the discussion part, the authors tended to begin paragraphs by stating the importance of the topics, this fits to introduction better and completely unnecessary in the discussion. I suggest the authors focus on their findings and then put them into a larger context (findings from other studies). As an example, take a look at https://doi.org/10.5194/bg-19-2171-2022. In addition, sometimes it is not clear whether the authors referring to their results or the results from other studies in the discussion, the clarity could be improved.

Lines 620-630: The limitation and outlook could be in a separate paragraph. No need to list detailed next steps, instead, point out the direction is sufficient.
Citation: https://doi.org/10.5194/egusphere-2025-3510-RC2

Yi Dang, Hua Zhou, Wenjun Zhao, Yingchun Cui, Chengjiang Tan, Fangjun Ding, Yukun Wang, Run Liu, and Peng Wu

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Short summary

The soil stoichiometric characteristics in the study area are predominantly governed by niche-microtopographic factors. Although plant life forms influence certain elements through processes such as nutrient return, their overall effect is relatively weak, and their impact is often contingent upon the microtopographic context. This combined action of biotic and abiotic factors reflects the complexity inherent in the karst soil nutrient cycling mechanism.


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