Ecological Stoichiometry Research Articles

Effects of stoichiometric ratio fertilization on leaf photosynthetic characteristics and fruit quality of blueberry

AimsThis study aims to accurately determine the fertilizer demand of blueberries during different developmental stages.MethodsThe ecological stoichiometry of C, N, P, and K in plant leaves is an important indicator of plant's ability to absorb and utilize its nutrient elements as well as mineral elements in soils. This work experimentally measured the theoretical NPK fertilizer requirement of seven-year-old rabbiteye blueberry 'Powderblue' according to their ecological stoichiometric ratios in leaves, along with photosynthetic rates and area. Calculations were obtained every ten days during flowering stage (S1), fruit setting stage (S2), young fruit stage (S3) and fruit expanding stage (S4). Different N, P, and K fertilizer gradients (1F, 5F, 10F, and 15F) were evaluated at four developmental stages to verify the fertilizer requirement of blueberry. The experimental observations were used to examine the effects of various NPK fertilizer amounts across growth stages on the photosynthetic characteristics of blueberry leaves as well as fruit yield and quality.ResultsFertilization significantly enhanced the plants' photosynthetic capacity. S1-5F, S2-10F, S3-15F, and S4-1F treatments largely increased the longitudinal and transverse diameters of fruits and the single fruit weight. Higher fertilization levels (15F) during each stage facilitated anthocyanin synthesis and increased soluble protein content.ConclusionsStoichiometric analysis revealed that blueberry during the flowering, fruit setting, young fruit, and fruit expansion periods required 4.85, 5.89, 3.21, and 12.63 g of N, 0.17, 0.18, 0.18, and 0.40 g of P, and 3.54, 3.24, 3.32, and 5.28 g of K, respectively. These nutrients were sourced from 22.88, 27.81, 15.13, and 59.60 g/plant of ammonium sulfate, 0.67, 0.72, 0.71, and 1.61 g/plant of superphosphate, and 7.90, 7.25, 7.43, and 11.80 g/plant of potassium sulfate.

C, N, P, and K Ecological Stoichiometry Characteristics of Different Organs of Tree Species in Dolomite and Limestone Karst Areas of Southwestern China

To explore environmental differentiation in the stoichiometric characteristics of carbon (C), nitrogen (N), phosphorus (P), potassium (K), and their ratios among tree species organs in different lithological karst regions of Guizhou, six common species were selected from the limestone karst area of Liping and the dolomite karst area of Shibing. The analysis focused on the differences in the contents of C, N, P, and K, as well as the ratios of C/N, C/P, C/K, and N/P, and the correlations among these elements in branches, leaves, and roots, with the aim of investigating the allocation distribution patterns of nutrient elements among organs in tree species under different lithological karst conditions. The results showed the following: In both dolomite and limestone karst regions, the tree species exhibited a distinct characteristic: their leaves exhibited high C levels, but relatively low N and P levels. Tree species in both karst regions showed high C/N, C/P, and C/K ratios, indicative of rapid C assimilation rates and efficient utilization of N, P, and K. Plant growth in the dolomite region was N-limited, while plant growth in the limestone region was P-limited. However, plant growth in neither region was K-limited. The nutrient characteristics and adaptation strategies of plants in dolomite and limestone karst regions were the result of multiple factors, such as lithology, plant organs, and interactions among elements. In conclusion, considering the differences in lithology during vegetation restoration and management in karst regions, targeted application of nitrogen or phosphorus fertilizers is expected to promote plant growth and further enhance the carbon sequestration capacity of both karst plants and soils.

The role of pyrogenic carbon addition after wildfires in the boreal forest of China: Impact on plant–soil–microbial ecological stoichiometry

The role of pyrogenic carbon addition after wildfires in the boreal forest of China: Impact on plant–soil–microbial ecological stoichiometry

Ecological stoichiometry of macroalgae from Sinop Peninsula coast of Black Sea, Türkiye: characterization of C:N:P.

This comprehensive ecological investigation systematically analyzed the temporal and spatial variations in carbon (C), nitrogen (N), and phosphorus (P) concentrations across diverse macroalgal assemblages inhabiting the upper infralittoral zone of the Sinop peninsula. The study encompassed seasonal sampling conducted at five distinct stations between October 2019 and July 2020, targeting nine prevalent macroalgal species representing three major taxonomic groups: Chlorophyta, Rhodophyta, and Phaeophyceae. Statistical analyses revealed statistically significant (p < 0.05) variations in mean elemental concentrations across seasonal, regional, and species-specific dimensions. The elemental concentration ranges demonstrated substantial diversity, with carbon concentrations spanning from 14.73% in Corallina officinalis to 43.04% in Pterocladiella capillacea. Nitrogen concentrations exhibited remarkable variability, ranging from 0.50% in C. officinalis to 5.14% in Ceramium spp., while phosphorus concentrations varied from 0.02% in Ceramium spp. to 0.32% in Ulva rigida. The elemental ratio analyses uncovered intricate inter-specific variations, with carbon/phosphorus ratios ranging from 157 in C. officinalis to 4255 in Laurencia obtusa, nitrogen/phosphorus ratios varying from 9 to 304, and carbon/nitrogen ratios spanning from 9 to 51. Taxonomic group-level analyses revealed nuanced nutritional characteristics, with nitrogen concentrations showing slight variations across green (1.98%), brown (1.76%), and red (2.20%) algae, and phosphorus concentrations exhibiting similar patterns across these taxonomic groups. The macroalgal community presented a mean C:N:P atomic ratio of 1187:57:1, with a median ratio of 859:41:1. These stoichiometric signatures predominantly indicate phosphorus limitation across the studied macroalgal assemblages along the Sinop coastal region, with C. officinalis emerging as a notable exception.

Response Characteristics of Farmland Soil Enzyme Activity and Microbial Nutrient Restriction Under Long-term Mulching Measures in the Loess Plateau

To study the response characteristics of long-term mulching measures on soil enzyme activity and the limitation of microbial nutrients in the Loess Plateau Region, the study adopted a random block design and setup based on the long-term field positioning experiment conducted in 2008. Four types of inter-field management measures were established, including conventional no-mulch （NM）, straw mulch （SM）, mulch mulch （PM）, and ridge mulch （RPM）. The changes in soil nutrients and extracellular enzyme activities, their ecological stoichiometry and influencing factors under different cover measures, were investigated using a one-way analysis of variance, a stoichiometric model of soil extracellular enzymes, and redundancy analysis （RDA）. The results showed that mulching significantly affected soil basal nutrients （P &lt;0.05） and that the dissolubility of organic carbon, available nitrogen （AN）, and available phosphorus （AP） showed significant dynamic changes with plant growth. The extracellular enzyme activity of C, N, and P cycles showed a positive response and increased or changed by 21.03%-161.14%, 1.11%-60.68%, and 17.55%-37.66%, respectively, with the effect of SM and RPM being more significant. During long-term tillage, soil microorganisms as a whole faced C and N nutrient limitations. Under the mulching treatment, the vector angle increased significantly by 11.52%-23.17% in the early growth stage of crops, indicating that the microbial nitrogen limitation was alleviated, while the overall vector length showed an increasing trend and increased by 10.38%-84.38%. Additionally, the level of C restriction became stronger over time. The RDA analysis showed that soil water content, AN, and AP content were the key factors affecting the enzyme activity and their measurement relationship in the Loess Plateau. In summary, the implementation of SM and RPM tillage practices in the Loess Plateau Region had a stronger impact on soil nutrient properties and enzyme activities and could be combined to achieve better results. In the meantime, the appropriate application of nitrogen fertilizer should be considered to mitigate nutrient limitations. The research results can help better understand the influence of mulch on soil microbial nutrient utilization strategies in agricultural land and its regulatory mechanisms. Moreover, it provides theoretical foundations for the long-term sustainable development of the Loess Plateau hilly area.

The Effects of Water and Nitrogen Addition on the Allocation Pattern and Stoichiometric Characteristics of C, N, and P in Peanut Seedlings.

Water and fertilizer application strategies seriously affect the healthy growth of peanuts. The stoichiometric ratio can directly reflect the elemental requirements for crop growth, which are very important for improving fertilizer utilization efficiency. In order to investigate the response of C (carbon), N (nitrogen), and P (phosphorus) allocation pattern and stoichiometric characteristics in peanut seedlings to water and nitrogen addition, we designed a greenhouse pot experiment which had different water treatments (W1, 75-80% field capacity; W2, 45-50% field capacity) and nitrogen addition treatments (N0, 0 kg hm-2; N1, 90 kg hm-2; N2, 180 kg hm-2). The distribution and content changes in C, N, and P in different organs were measured and analyzed by ecological stoichiometry. The results showed that drought stress significantly increased the N or P content of different organs. The average N/P value of peanut roots treated with W2 decreased by 13.02% compared to W1. Restoring irrigation relieved this stress while reducing the C/N and C/P of roots, stems, and leaves, as well as the N/P of roots and stems. The water treatment after rehydration showed significant differences in the C/N, C/P, and N/P ratios of peanut roots. The average values of the C/N, C/P, and N/P ratios of peanut roots in W2 treatment were reduced by 13.54%, 28.66%, and 16.34%, respectively, compared to W1 treatment. On the other hand, nitrogen application significantly increased the N content of stems and leaves, while reducing C/N. On the contrary, it significantly reduced the P content of roots and stems, and increased the N/P ratio of roots, stems, and leaves. Overall, there is a significant interaction between water and nitrogen treatment on the stoichiometric characteristics of C, N, and P in different organs, with water treatment playing a dominant role. In terms of nutrient distribution in organs, the average N content in leaves is the highest. The coefficient of variation (CV) of P content is greater than that of C and N content. The CV of N content, P content, and C/N and N/P ratios of the stem are all greater than those of the roots or leaves, while the stems are more sensitive to water and nitrogen conditions. And the N and P content of roots, stems, and leaves were positively correlated. Meanwhile, peanut seedlings have the phenomenon of ionic synergism that occurs between nitrogen and phosphorus ions. In summary, studying the stoichiometric ratios can reflect the water and fertilizer demand status of peanuts, thereby better improving water and fertilizer utilization efficiency.

Stress signaling, response, and adaptive mechanisms in submerged macrophytes under PFASs and warming exposure.

Stress signaling, response, and adaptive mechanisms in submerged macrophytes under PFASs and warming exposure.

Ecological Stoichiometry of Carbon, Nitrogen and Phosphorus in Coffee Leaves and Soil from Different Origins in Yunnan Province

Ecological Stoichiometry of Carbon, Nitrogen and Phosphorus in Coffee Leaves and Soil from Different Origins in Yunnan Province

Epigean-Hypogean Continuum concept

Subterranean streams represent unique heterotrophic ecosystems, usually supported by organicmatter imported fromthe surface. Traditionally, the biological communities from subterranean streams were characterized as simple associations, with low diversity and species abundance, comprising mostly aquatic invertebrates connected by few trophic links compared with those of the surface. However, these features have not yet been described in the wider context of fluxes of energy and nutrients through food webs along a gradual switch from autotrophy (dominated by photosynthesis) towards heterotrophy (dominated by detritus) following the surface−subterranean continuum. Combining the most recent predictions of Ecological Stoichiometry and theMetabolic Theory of Ecology, the Epigean-Hypogean Continuum concept (Pacioglu et al., 2021) provides a theoretical framework aiming to explain the patterns observed along the surface−subterranean continuum in streams.

Optical remote spectral acquisition of elemental stoichiometry

Optical remote sensing (RS) enables the study of the elemental composition of Earth’s surface over broad spatial extents by detecting reflected electromagnetic radiation. Covalent bonds of macromolecular structures often reflect electromagnetic radiation at specific wavelengths, and in some cases relate to bonds of specific elemental identity. In other cases, interfering optical properties greatly impact the ability of RS to measure elements directly, but advances in statistical methods and the theoretical understanding of optical properties expand the capacity to quantify diverse elements in many systems. When applied under the framework of ecological stoichiometry, spatially and temporally explicit measurements of elemental composition permit understanding of the drivers of ecological processes and variation over space and through time. However, the multitude of available technologies and techniques present a large barrier of entry into RS. In this paper we summarize the capabilities and limitations of RS to quantify elements in terrestrial and aquatic systems. We provide a practical guide for researchers interested in using RS to quantify elemental ratios and discuss RS as an emerging tool in ecological stoichiometry. Finally, we pose a set of emerging questions which integrating RS and ecological stoichiometry is uniquely poised to address.

A Study of the Effects of Wetland Degradation on Soil-Microbial-Extracellular Enzyme Carbon, Nitrogen, and Phosphorus and Their Ecological Stoichiometry

Due to the unique geographic location of A’er Xiang, there is a natural landscape where sandy land and lake-marsh wetlands coexist. However, the wetland degradation caused by the disturbance of anthropogenic activities has led to the change in land use. In this study, the spatial-temporal substitution method was used to select five sample plots: the original wetland converted to forest land for reuse area of five years and ten years; the original wetland converted to cropland for reuse area of five years and ten years; and the native wetland. It aims to investigate the variations in carbon, nitrogen, and phosphorus and their stoichiometric characteristics of soil-microorganisms-extracellular enzymes before and after reuse, and to analyze potential interactions among these elements. The results indicated that following wetlands degradation, changes in land use for five years did not significantly affect the content of soil organic carbon (TOC), total nitrogen (TN), or total phosphorus (TP). However, after ten years, both TOC and TN, except for TP, decreased significantly. Microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) contents in cropland were consistently higher than those in WL, showing a trend of first increasing and then decreasing with longer conversion periods. In contrast, forest land values were lower than in WL and increased as the conversion period lengthened. The microbial biomass phosphorus (MBP) content was ranked across the five sample sites as follows: 10 CL &gt; 5 CL &gt; 5 FL &gt; 10 FL &gt; WL. β-1,4-glucosidase (BG) activity was significantly increased after conversion to forest land and significantly decreased after conversion to cropland. β-1,4-N-glucosidase (NAG) and L-leucine aminopeptidase (LAP) activities were ranked as follows among the five sites: 5 FL &gt; WL &gt; 5 CL &gt; 10 FL &gt; 10 CL. Phosphatase (PHOS) activity showed no significant changes post-conversion, though it was consistently lower compared to WL.

Seeing through the gray box: an integrated approach to physiological modeling of phytoplankton stoichiometry

The ‘black boxes’ of ecological stoichiometry, planktonic microbes, have long been recognized to have considerable effects on global biogeochemical cycles. Significant progress has been made in studying these effects and expanding our understanding of microbial stoichiometry. However, the ‘black box’ has not been completely cracked open; there remain gaps in our knowledge of the fate of elements within the phytoplankton cell, and the effect of external processes on nutrient fluxes through their metabolism and into macromolecules and biomass - the eponymous ‘gray box’. In this review paper, we describe the development of an integrative modeling approach that involves a stoichiometrically explicit model of Macromolecular Allocation and Genome-scale Metabolic Analysis (MAGMA) to gain insights into the intra- and extracellular fluxes of nutrients using the cyanobacterium Parasynechococcus marenigrum WH8102 as a target model organism. We then describe an example of the genome-scale resources for P. marenigrum that can be used to build such an integrated modeling tool to see through the gray box of phytoplankton stoichiometry and improve our understanding of the effects of resource supplies and other environmental drivers, especially temperature, on C:N:P demand, acquisition, and allocation at the cellular level.

Soil ecological stoichiometry in varied micro-topographies of an alluvial fan at eastern Helan Mountains, Northwest China

Soil ecological stoichiometry in varied micro-topographies of an alluvial fan at eastern Helan Mountains, Northwest China

Mixotrophic protists and ecological stoichiometry: connecting homeostasis and nutrient limitation from organisms to communities

In recent decades, there has been a growing recognition that mixotrophy, the ability to utilize both phototrophy and phagotrophy, is more common among plankton than previously assumed. Even though mixotrophs can become highly abundant, especially under nutrient limitation, and significantly alter nutrient cycling and food-web dynamics due to their dual nutritional modes, a comprehensive synthesis from a stoichiometric perspective is still lacking. We conducted a systematic literature review in which we identified over 130 studies that directly relate nutrient ratios to mixotrophic protists at the organism to community scale. By conceptually linking mixotrophy with the concept of ecological stoichiometry, we provide insights into (1) the role of mixotrophic metabolism and nutrient limitation in regulating cellular homeostasis, (2) mixotroph abundance and community scale responses to nutrient limitation, and (3) the specific case of harmful algal bloom forming mixotrophs. On the organism scale, the existing literature points towards a stabilizing effect of mixotrophic metabolism on elemental composition, and the use of grazing as a compensation mechanism under stoichiometric imbalances in the water and prey. At the community scale, mixotrophs were found to increase in abundance relative to strict autotrophs and heterotrophs in nutrient-limited communities, and provide beneficial food for zooplankton grazers by maintaining relatively low and stable stoichiometry. Furthermore, global-scale models and studies of harmful algal blooms reveal the increasing importance of mixotrophs under climate change – highlighting the need for continued research addressing the interactions between mixotrophs and dynamic stoichiometry to understand the impacts of mixotrophs on global nutrient cycles.

Effects of grassland degradation on soil ecological stoichiometry and soil microbial community on the South of the Greater Khingan Mountains.

Grassland which covers 40% of terrestrial land is an important ecosystem having a multitude of functions, which has suffered various degrees of degradation with the interaction between global climate change and unreasonable human utilization (e.g., grazing and reclamation). Improved understanding of soil and microbial community diversity during meadow steppe degradation is crucial for predicting degradation mechanisms and restoration strategies. Here, we used Illumina sequencing technology to investigate the patterns of soil microbial community structure and the driving factors of its change across different degradation degrees of meadow steppe [i.e., non-degraded grasslands (NDG), lightly degraded grasslands (LDG), moderately degraded grasslands (MDG), and severely degraded grasslands (SDG)] south of the Greater Khingan Mountains. Our results showed a significant variation in soil properties, enzyme activity, and soil metal elements across the degraded meadows. Soil available phosphorus (AP), urease (UE), and cellulase (CL) in soils increased with the intensity of grassland degradation. Grassland degradation significantly decreased soil bacterial and fungal richness. In addition, grassland degradation significantly increased the relative abundance of Firmicutes (from 1.65% to 5.38%) and Myxococcota (from 2.13% to 3.13%). Degradation considerably increased the relative abundance of Ascomycota (from 66.54% to 75.05%), but decreased Basidiomycota (from 18.33% to 9.92%). The relative abundance of nitrogen fixation and cellulolysis decreased significantly due to grassland degradation. For fungal functional guilds, the relative abundance of pathotrophs increased while saprotrophs decreased significantly with increasing severity of degradation. Total nitrogen (TP), AP, available potassium (AK), manganese (Mn), lead (Pb), UE, sucrase (SC), and alcalase protease (ALPT) were the main drivers of soil bacterial community composition, while TP, AP, AK, Pb, UE, and SC were the main drivers of soil fungal community composition in the degraded grassland. Our findings demonstrated that severe grassland degradation has an enormous effect on soil microbial communities and soil physicochemical dynamics. These findings improve our theoretical understanding of the interactions between soil microbial populations and soil environmental variables in degraded grassland.

Ecological stoichiometry in leaves, branches, and soils of Pinus tabuliformis at different stand ages in the Taihang Mountains, China.

To understand the changes and relationship of plant-soil eco-stoichiometric characteristics of Pinus tabuliformis plantations with stand ages, we investigated P. tabuliformis plantations of different stand ages (10, 23, 39, and 47 years old) in the Taihang Mountains. We measured the concentration and stoichiometry of carbon (C), nitrogen (N), and phosphorus (P) in leaves, branches, and soils at different layers. We analyzed the relationship between leaf, branch nutrient characteristics and soil physicochemical properties. The results showed that soil C and N contents decreased after an initial increase with increasing stand ages, being the maximum at the 39 years old stand, while P content was the maximum at 47 years old stand. Soil C:P and N:P of the 23 years old stand were significantly higher than that of other stand ages, indicating that P was the limiting factor for P. tabuliformis growth. With increasing soil depth, the concentration of C, N, P, C:P and N:P in soils of different stand ages decreased, while the C:N increased, suggesting an enhanced N limitation. The stoichiometric characteristics of soils at different depths varied significantly among different stand ages, particularly in the upper soil layers (0-20 cm). The N content in leaves and branches increased first and then decreased, while the P content decreased first and then increased. The C:P and N:P in leaves and branches were higher at 23 years old, indicating a synergistic effect of nutrient acquisition between leaves and branches. Soil C concentration was significantly positively correlated with leaf N, while soil C:N was significantly positively correlated with branch C:N. There was a stronger correlation in the deeper soil layers (20-60 cm) than the upper soil layers. Soil sand content and N:P were key factors influencing nutrients in leaves, while soil P and C contents were the main factors influencing nutrients in branches. Soil water content (SWC), soil N content, and soil C:N jointly regulated nutrient variations in leaves and branches. Compared to the upper soil layers, the deeper soil layers showed a more pronounced N limitation. The impact of SWC on nutrient availability was relatively minor. Soil C:N (17.0) was higher than the national average, while the N:P in both leaves (8.2) and branches (8.3) were lower than 14, indicating increasing N limitation with increa-sing stand ages. To ensure the development of P. tabuliformis plantations and improve nutrient cycling, P and N fertilizers could be applied during the mid to late growth stages of P. tabuliformis plantations.

Attenuated asymmetry of above- versus belowground stoichiometry to a decadal nitrogen addition during stand development.

Deciphering the linkage between ecological stoichiometry and ecosystem functioning under anthropogenic nitrogen (N) deposition is critical for understanding the impact of afforestation on terrestrial carbon (C) sequestration. However, the specific changes in above- versus belowground stoichiometric asymmetry with stand age in response to long-term N addition remain poorly understood. In this study, we investigated changes in stoichiometry following a decadal addition of three levels of N (control, no N addition; low N addition, 20 kg N ha-1 year-1; high N addition, 50 kg N ha-1 year-1) in young, intermediate, and mature stands in three temperate larch plantations (Larix principis-rupprechtii) in North China. We found that low N addition had no impact on both above- (leaf and litter) and belowground (soil and microbe) stoichiometry. In contrast, high N addition resulted in significant asymmetry in above- versus belowground stoichiometry, which then diminished during stand development. Following 10 years of N inputs, the young and intermediate plantations transitioned from a state of relative N limitation to co-limitation by both N and phosphorus (P), whereas the mature plantation continued to experience relative N limitation. Conversely, soil microorganisms exhibited relative P limitation in all three plantations. Broader niche differentiation (N limitation for trees, but P limitation for microorganisms) under long-term N input may have been responsible for the faster attainment of stoichiometric homeostasis in mature plantations than in young plantations. Our findings provide stoichiometric-based insight into the operating mechanisms of large C sinks in young forests, particularly above- versus belowground C stock asymmetry, and highlight the need to consider the role of flexible stoichiometry when forecasting future forest C sinks.

Nutritional thermal ecology: investigating the combined influence of temperature and nutrient availability on plant‐ectotherm trophic interactions

Many primary consumers in freshwater, marine and terrestrial systems are ectotherms (e.g. zooplankton and insects), whose metabolisms, and therefore nutritional demands, are modulated by temperature. Further, nutrient availability largely influences the quality of resources consumed by these organisms, and hence affects whether nutritional demands of consumers are fulfilled. From these considerations, a crucial question arises: how do temperature and nutrient availability together modulate trophodynamics at the basis of food webs? Addressing this question for zooplankton and insects is essential since these consumers are the most abundant metazoans on Earth, and they link primary production to higher trophic levels. Here, we synthesize the existing literature and offer avenues to guide future scientific endeavours. We highlight that the vast majority of studies on the combined influence of temperature and nutrient availability published to date focus on at least one of the following research topics: 1) metabolic requirements of ectotherms; 2) feeding behaviour; 3) eco‐evolutionary processes; and 4) trophodynamics. We pose that further advances in this field of research may provide a robust understanding of how modulations of consumer metabolic requirements and resource quality define consumer–producer interactions across marine, freshwater and terrestrial ecosystems. This research effort would enable to combine the fields of Ecological stoichiometry and of Metabolic theory of ecology, and create an integrated approach, which we propose to call Nutritional thermal ecology.

The Effects of Forest Gaps on the Physical and Ecological Stoichiometric Characteristics of Soil in Pinus densiflora Sieb. and Robinia pseudoacacia L. Forests

Forest gaps alter the environmental conditions of forest microclimates and significantly affect the biogeochemical cycle of forest ecosystems. This study examined how forest gaps and non-gap areas affect soil’s physical properties and eco-stoichiometric characteristics. Relevant theories and methods were employed to analyze the impact of forest gaps on nutrient cycling in Pinus densiflora Sieb. (PDS) and Robinia pseudoacacia L. (RPL) forests located in the Taishan Mountains. The results revealed that (1) forest gaps significantly enhanced the soil physical properties of PDS and RPL forests compared to non-gap areas (NPs). Notably, the bulk density of the soil decreased by 53%–12%, particularly in the surface layer (0–20 cm). Additionally, its non-capillary porosity increased by 44%–65%, while the clay and silt content rose by 39%–152% and 24%–130%, respectively. Conversely, the sand content decreased significantly, by 24%–32% (p &lt; 0.05). (2) The contents of C, N, and P in the gap soil of PDS forests showed a significant increase compared to those in non-gap soil, with increases of 56%–131% for carbon, 107%–1523% for nitrogen, and 100%–155% for phosphorus. There was a significant drop of 10%–33% and 39%–41% in their C:N and C:P ratios, respectively (p &lt; 0.05). The contents of C and P in the gap soil of the Robinia pseudo acacia L. Forest increased significantly, by 14%–22% and 34.4%–71%, respectively. Its C:P and N:P ratios significantly increased, by 14% to 404% and 11% to 41%, respectively (p &lt; 0.05). (3) Compared with NPs, the forest gap significantly reduced the soil electrical conductivity and increased the soil pH. Additionally, compared to the soil at the gap’s edge, the surface soil in the gap’s center had noticeably higher concentrations of C, N, and P. (4) Key variables affecting the soil pH, silt content, bulk density, and overall porosity in forest gaps include the concentrations of carbon (C), nitrogen (N), and phosphorus (P) present and their ecological stoichiometric ratios. The findings showed that forest gaps had a considerable impact on the soil’s physical characteristics and ecological stoichiometry. They also had a high potential for providing nutrients, which might aid in the establishment of plantation plants.

Characteristics and Drivers of Soil Carbon, Nitrogen, and Phosphorus Ecological Stoichiometry at the Heavy Degradation Stage of the Alpine Meadow

An in-depth understanding of the soil nutrient status and balance relationship can help the effective recovery and management of alpine degraded meadows. In order to study the balance relationship among soil carbon, nitrogen, and phosphorus nutrients during the heavy degradation stage of meadows, field sampling and investigation, indoor analysis, and mathematical statistics were used to explore the characteristics and driving factors of changes in soil carbon, nitrogen, and phosphorus content, storage, and ecological stoichiometry during the heavy degradation stage of alpine meadows in the Sanjiangyuan region. The results showed that in the heavy degradation stage, miscellaneous grass plants occupied absolute dominance, soil C∶N∶P was approximately 32.83∶3.87∶0.67, and there was certain nitrogen limitation. The coefficients of variation of soil carbon, nitrogen, and phosphorus content were in the following order： organic carbon （1.09） &gt; total nitrogen （0.63） &gt; total phosphorus （0.29）. The organic carbon content and the carbon and nitrogen ratio showed a significant linear decreasing trend with the increase in the grassland degradation index （GDI）, while the total phosphorus content and organic carbon storage showed a significant non-linear change, in which the total phosphorus content showed a significant gentle U-shaped distribution, and the organic carbon storage decreased more gently at the beginning of the heavy degradation stage and then decreased sharply when the GDI was 57.9. The results of Mantel correlation analysis showed that the soil carbon to nitrogen ratio, carbon to phosphorus ratio, and nitrogen to phosphorus ratio showed significant correlation with organic carbon content and storage and total nitrogen storage. The results of structural equation modeling indicated that soil water content had direct effects as well as indirect through vegetation factors, soil carbon, nitrogen, and phosphorus ecological stoichiometry ratios, and soil water content and vegetation factors （height, cover, and biomass） were key environmental factors affecting soil ecological stoichiometry. The research results can provide scientific basis and practical guidance for the restoration of heavily degraded grassland in alpine meadows.