Surface soil cracking in alpine meadows signifies the transition of degradation from quantitative accumulation to qualitative deterioration.Quantitative research remains insufficient regarding changes in the mechanica...Surface soil cracking in alpine meadows signifies the transition of degradation from quantitative accumulation to qualitative deterioration.Quantitative research remains insufficient regarding changes in the mechanical properties of degraded meadow soils and the mechanical thresholds for cracking initiation.This study explored the relationships between surface cracking and the physical properties,tensile strength,and matrix suction of root-soil composites in alpine meadow sites with different stages of degradation(undegraded(UD),lightly degraded(LD),moderately degraded(MD),and heavily degraded(HD))under different water gradients(high water content(HWC),medium water content(MWC),and low water content(LWC))corresponding to different drying durations at a constant temperature of 40.0°C.The Huangcheng Mongolian Township in Menyuan Hui Autonomous County,Qinghai Province,China was chosen as the study area.The results indicated that as the degradation degree of alpine meadow intensified,both water content of rootsoil composite and the fine grain content of soil decreased.In contrast,the root-soil mass ratio and root area ratio initially increased and then decreased with progressive degradation.Under a consistent water content,the tensile strength of root-soil composite followed a pattern of MD>HD>LD>UD.The peak displacement of tensile strength also decreased as the degradation degree of alpine meadow increased.Both the tensile strength and matrix suction of root-soil composite increased as root-soil water content decreased.A root-soil water content of 30.00%-40.00%was found to be the critical threshold for soil cracking in alpine meadows.Within this range,the matrix suction of root-soil composite ranged from 50.00 to 100.00 kPa,resulting in the formation of linear cracks in the surface soil.As the root-soil water content continued to decrease,liner cracks evolved into branch-like and polygonal patterns.The findings of this study provide essential data for improving the mechanical understanding of grassland cracking and its development process.展开更多
In recent decades, global climate change and overgrazing have led to severe degradation of alpine meadows. Understanding the changes in soil characteristics and vegetation communities in alpine meadows with different ...In recent decades, global climate change and overgrazing have led to severe degradation of alpine meadows. Understanding the changes in soil characteristics and vegetation communities in alpine meadows with different degrees of degradation is helpful to reveal the mechanism of degradation process and take the remediation measures effectively. This study analyzed the changes in vegetation types and soil characteristics and their interrelationships under three degradation degrees, i.e., non-degradation(ND),moderate degradation(MD), and severe degradation(SD) in the alpine meadows of northeastern Qinghai-Xizang Plateau, China through the long-term observation. Results showed that the aggressive degradation changed the plant species, with the vegetation altering from leguminous and gramineous to forbs and harmful grasses. The Pielou evenness and Simpson index increased by 24.58% and 7.01%,respectively, the Shannon-Wiener index decreased by 17.52%, and the species richness index remained constant. Soil conductivity, soil organic matter, total potassium, available potassium, and porosity declined.However, the number of vegetation species increased in MD. Compared with ND, the plant diversity in MD enhanced by 8.33%, 8.69%, and 7.41% at family, genus, and species levels, respectively. In conclusion,changes in soil properties due to degradation can significantly influence the condition of above-ground vegetation. Plant diversity increases, which improves the structure of belowground network. These findings may contribute to designing better protection measures of alpine meadows against global climate change and overgrazing.展开更多
In recent years,many studies have focused on the effects of global climate warming and increased nitrogen deposition on the structure and function of grassland ecosystem.However,there are still significant uncertainti...In recent years,many studies have focused on the effects of global climate warming and increased nitrogen deposition on the structure and function of grassland ecosystem.However,there are still significant uncertainties in the response mechanism of stability of plant community biomass in alpine meadows of the Qinghai-Xizang Plateau,China to these two major climate factors.Given this,based on field control experiments,this study systematically evaluated the effects of different levels of climate warming(W0(no warming),W1(air temperature increased by 0.47℃ or soil temperature increased by 0.61℃),W2(air temperature increased by 0.92℃ or soil temperature increased by 1.09℃),W3(air temperature increased by 1.44℃ or soil temperature increased by 1.95℃)),nitrogen deposition(N0(0 kg N/(hm^(2)·a)),N16(16 kg N/(hm^(2)·a)),and N32(32 kg N/(hm^(2)·a))),and their interactions on plant community biomass and its temporal stability,and explored its potential regulatory mechanisms.The results showed that the biomass of total community,Gramineae,and dominant species increased significantly with increasing temperature,but the biomass of common and rare species decreased significantly.Nitrogen deposition also significantly promoted the biomass accumulation of community and gramineous plants.Under the treatment of W3N32,the biomass of plant community,Gramineae,and dominant species reached the highest values,indicating that there was a synergistic effect under this treatment.Structural equation model showed that increasing temperature significantly decreased the stability of plant community biomass by reducing the stability of grass and dominant species biomass and weakening species asynchronism.Interaction of increased nitrogen deposition and temperature increased the biomass fluctuation of grass functional group,thus amplifying its negative influence on community stability.More attention should be paid to the response and regulatory mechanisms of dominant species and functional groups under global climate change.This study provides a theoretical basis for revealing the stability maintenance mechanism of alpine grassland and also provides scientific support for the development of future grassland ecosystem management and assessment.展开更多
IS1921 VF-256 type ground object spectrometer was used to extract the spectral data of the meadow grassland and bare land to obtain their refleotivity spectral characteristics. The experiment was carried out on the lo...IS1921 VF-256 type ground object spectrometer was used to extract the spectral data of the meadow grassland and bare land to obtain their refleotivity spectral characteristics. The experiment was carried out on the low mountain meadow steppe in the Saiwundu Village, Hargentai Town, West Ujumqin Banner, Xilin Gol League, Inner Mongolia. The results showed that different ground objects had different reflectances. The spectral reflectance curve of the meadow steppe plant communities had obvious characteristics of peak and valley in the visible spectrum band, and had strong reflection in the near-infrared band. The reflection curve of the bare lands in the visible spectrum band was higher than that of the meadow grassland communities while inthe near-infrared band it was lower than that of the meadow grassland communities. Under different degradation gradients, the spectral reflectivity of the meadow steppe grassland communities increased with the enhancement of the degradation gradients. Under the same degradation gradient, the Stipa grandis communities had a lower visible light reflectivity than the Artemisia frigida communities but had a higher near-infrared reflectivity than the Artemisia frigida communities; different ground objects on the meadow steppe had different spectrum characteristic, and showed a certain discrepancies with the changes of the degradation level.展开更多
[Objective]The aim of this study is to explore the effects of grassland degradation on soil physical and chemical properties.[Method]The ratio of plant root to soil and soil texture on Alpine Meadow were investigated ...[Objective]The aim of this study is to explore the effects of grassland degradation on soil physical and chemical properties.[Method]The ratio of plant root to soil and soil texture on Alpine Meadow were investigated in this study,and soil available N,P,K,Cu,Zn,organic matter and pH value were also analyzed by routine analysis of soil nutrients in different degraded grasslands.[Result]With the intensification of degraded gradient and the soil depth,the ratio of plant root to soil was decreased gradually.The highest ratio of plant root to soil was in 0-10 cm depth of soil in grassland with different degraded gradients,while its ratio of plant root to soil changed from 0.001 to 0.040 with soil type of loam.Soil chemical characteristic changed in different degraded gradients.The content of available N,P,K reduced significantly with the soil depth and the intensification of degraded gradients.The content of Cu and Zn was relatively lack in degraded grassland.[Conclusion]There is no significant correlation between nutrition content or pH value and the succession degree of degraded grassland.展开更多
Using the measurement of stable carbon isotopes in leaves as a tool to investigate photosynthetic pathway of 102 plant species grown at an alpine meadow ecosystem, at the foot of the Qilian Mountain, Qinghai, China. T...Using the measurement of stable carbon isotopes in leaves as a tool to investigate photosynthetic pathway of 102 plant species grown at an alpine meadow ecosystem, at the foot of the Qilian Mountain, Qinghai, China. The results indicate that the delta C-13 values of plants have a narrow range from -28.24parts per thousand to -24.84parts per thousand, which means that none of the species examined belongs to C-4 and crassulaceous acid metabolism (CAM) photosynthetic pathway and all of these species perform photosynthesis through the C-3 pathway. This is likely due to a long-term adaptation to environments at the alpine meadow ecosystem.展开更多
[Objective] The aim was to explore the management mode on optimal re-sources al ocation of family ranch in meadow steppe. [Method] Three double repre-sentative family ranches were selected in meadow steppe of Hulunber...[Objective] The aim was to explore the management mode on optimal re-sources al ocation of family ranch in meadow steppe. [Method] Three double repre-sentative family ranches were selected in meadow steppe of Hulunber Old Barag Banner, and the study was carried out with the baseline survey. Three family ranches were selected as the demonstrative households for the corporation study, while other three family ranches with the similar conditions were looked as the non-demonstrative households for the comparison. Demonstrative households of the fami-ly ranches reduced the stocking rate, optimized the flock structure and took a winter feeding and other means to explore the different management models on plant com-munity characteristic of family ranch. [Result] The seasonal dynamic of community characteristic in family ranches showed the single-peaks curves. The seasonal dy-namics of community coverage, height and biomass in the demonstrative households showed higher compared with the non-demonstrative households, and community density in the experiment households was lower than that of the control experiment households. Community coverage, height and biomass of degraded grassland in family ranch have a great improve after optimization of management. Community coverage, height , density and biomass were increasing in fencing plot, but decreas-ing in free grazing area. Enclosure improved grassland coverage, vegetation height, density and forage yield. Leymus chinensis played an important role in plant com-munity. The important values of Leymus chinensis, Stipa baicalensis, Cleistogenes squarrosa, and Carex duriuscula were high. Leymus chinensis important value in the demonstrative households of optimal management was higher than that in the non-demonstrative households, and Carex duriuscula important value of the non-demon-strative households was significantly higher than that of the demonstrative house-holds. The indexes of Margalef richnes,Shannon-Wiener diversity, Simpson diversity and Pielou uniformity showed that the demonstrative households were higher than the non-demonstrative households. [Conclusion] The research provides theoretical ref-erences for sustainable development of pastures dominated by family ranch.展开更多
To understand the dynamics of added nitrogen (N) in alpine meadow and the role of alpine plants and soil microorganisms in the retention of deposited N, the fate of 15 N labeled nitrate and ammonium salts was...To understand the dynamics of added nitrogen (N) in alpine meadow and the role of alpine plants and soil microorganisms in the retention of deposited N, the fate of 15 N labeled nitrate and ammonium salts was determined in an alpine meadow for two months. Two weeks after 15 N application, total recovery of 15 N from NO - 3_ 15 N was 73.5% while it was 78% from NH + 4_ 15 N. More 15 N was recovered in plants than in soil organic matter or in microbial biomass, irrespective of forms of N added. After one month, 70.6% of added NO - 3_ 15 N and 57.4% of NH + 4_ 15 N were recovered in soils and plants. 15 N recovered in soil organic matter decreased greatly while that recovered in plants varied little, irrespective of the form N. Compared with the results of two weeks after 15 N application, more NO - 3_ 15 N than NH + 4_ 15 N was recovered in microbial biomass. Total recovery was 58.4% (six weeks) and 67% (eight weeks) from NO - 3_ 15 N, and 43.1% and 49% from NH + 4_ 15 N, respectively. Both plants and soil microorganism recovered more NO - 3_ 15 N than NH + 4_ 15 N. But plants recovered more 15 N than soil microorganisms. During the whole experiment plants retained more NO - 3_N and 15 N than soil microorganisms while 15 N recovered in inorganic N pool did not exceed 1% due to lower amount of inorganic N. This indicates that plants play more important roles in the retention of deposited N although microbial biomass can be an important sink for deposited N in early days after N application.展开更多
高寒草甸是青藏高原主要植被类型之一,全球气候变化背景下大气氮(nitrogen,N)沉降与降水格局改变对高寒草甸碳平衡产生显著影响。然而,这两种变化对土壤有机碳(soil organic carbon,SOC)的交互作用仍存在较大不确定性。本研究于2019—2...高寒草甸是青藏高原主要植被类型之一,全球气候变化背景下大气氮(nitrogen,N)沉降与降水格局改变对高寒草甸碳平衡产生显著影响。然而,这两种变化对土壤有机碳(soil organic carbon,SOC)的交互作用仍存在较大不确定性。本研究于2019—2021年以青藏高原东北部高寒草甸为研究对象,设置氮添加(包膜尿素,10 g N m^(-2)a^(-1))和降水变化(增雨50%和减雨50%)处理,每个处理设置3个重复,探究植物生物量和表层(0—10cm)土壤SOC含量的响应特征。结果表明,仅氮添加处理显著提高峰值地上生物量(aboveground plant biomass,AGB)达19.1%(83.8g/m^(2)),使AGB/BGB显著增加23.3%(0.057)。AGB和SOC含量在不同年份间存在显著差异。为排除年份效应,采用各处理与对照组的相对变化量(ΔAGB、ΔBGB和ΔSOC)进行分析,发现这些相对变化量对处理同样不敏感。随机森林模型和结构方程模型结果均显示,SOC和ΔSOC含量主要受气温变化的调控,而非植物碳输入(AGB和BGB或ΔAGB和ΔBGB)驱动。研究证实气候变化对高寒草甸SOC积累的正向效应,可能缘于过去数十年气温持续升高的主导作用,而非大气氮沉降和降水格局改变。年份而非处理产生的显著效应表明,亟需开展长期多因子实验以揭示高寒草甸土壤固碳能力对气候变化的复合响应及其机理。展开更多
基金funded by the National Natural Science Foundation of China(42062019,42002283)。
文摘Surface soil cracking in alpine meadows signifies the transition of degradation from quantitative accumulation to qualitative deterioration.Quantitative research remains insufficient regarding changes in the mechanical properties of degraded meadow soils and the mechanical thresholds for cracking initiation.This study explored the relationships between surface cracking and the physical properties,tensile strength,and matrix suction of root-soil composites in alpine meadow sites with different stages of degradation(undegraded(UD),lightly degraded(LD),moderately degraded(MD),and heavily degraded(HD))under different water gradients(high water content(HWC),medium water content(MWC),and low water content(LWC))corresponding to different drying durations at a constant temperature of 40.0°C.The Huangcheng Mongolian Township in Menyuan Hui Autonomous County,Qinghai Province,China was chosen as the study area.The results indicated that as the degradation degree of alpine meadow intensified,both water content of rootsoil composite and the fine grain content of soil decreased.In contrast,the root-soil mass ratio and root area ratio initially increased and then decreased with progressive degradation.Under a consistent water content,the tensile strength of root-soil composite followed a pattern of MD>HD>LD>UD.The peak displacement of tensile strength also decreased as the degradation degree of alpine meadow increased.Both the tensile strength and matrix suction of root-soil composite increased as root-soil water content decreased.A root-soil water content of 30.00%-40.00%was found to be the critical threshold for soil cracking in alpine meadows.Within this range,the matrix suction of root-soil composite ranged from 50.00 to 100.00 kPa,resulting in the formation of linear cracks in the surface soil.As the root-soil water content continued to decrease,liner cracks evolved into branch-like and polygonal patterns.The findings of this study provide essential data for improving the mechanical understanding of grassland cracking and its development process.
基金supported by the National Forage Industry Technology System Program (CARS-34)Grassland Ecological Restoration and Management Science and Technology Support Project of Gansu Forestry and Grassland Bureau (GSAU-TSYF-2021-011)。
文摘In recent decades, global climate change and overgrazing have led to severe degradation of alpine meadows. Understanding the changes in soil characteristics and vegetation communities in alpine meadows with different degrees of degradation is helpful to reveal the mechanism of degradation process and take the remediation measures effectively. This study analyzed the changes in vegetation types and soil characteristics and their interrelationships under three degradation degrees, i.e., non-degradation(ND),moderate degradation(MD), and severe degradation(SD) in the alpine meadows of northeastern Qinghai-Xizang Plateau, China through the long-term observation. Results showed that the aggressive degradation changed the plant species, with the vegetation altering from leguminous and gramineous to forbs and harmful grasses. The Pielou evenness and Simpson index increased by 24.58% and 7.01%,respectively, the Shannon-Wiener index decreased by 17.52%, and the species richness index remained constant. Soil conductivity, soil organic matter, total potassium, available potassium, and porosity declined.However, the number of vegetation species increased in MD. Compared with ND, the plant diversity in MD enhanced by 8.33%, 8.69%, and 7.41% at family, genus, and species levels, respectively. In conclusion,changes in soil properties due to degradation can significantly influence the condition of above-ground vegetation. Plant diversity increases, which improves the structure of belowground network. These findings may contribute to designing better protection measures of alpine meadows against global climate change and overgrazing.
基金supported by the Key Research and Development and Transformation Plan of Qinghai Provincial Science and Technology Department(2024-NK-137)the Qinghai Province Science and Technology Commissioner Special Project(2024-NK-P28).
文摘In recent years,many studies have focused on the effects of global climate warming and increased nitrogen deposition on the structure and function of grassland ecosystem.However,there are still significant uncertainties in the response mechanism of stability of plant community biomass in alpine meadows of the Qinghai-Xizang Plateau,China to these two major climate factors.Given this,based on field control experiments,this study systematically evaluated the effects of different levels of climate warming(W0(no warming),W1(air temperature increased by 0.47℃ or soil temperature increased by 0.61℃),W2(air temperature increased by 0.92℃ or soil temperature increased by 1.09℃),W3(air temperature increased by 1.44℃ or soil temperature increased by 1.95℃)),nitrogen deposition(N0(0 kg N/(hm^(2)·a)),N16(16 kg N/(hm^(2)·a)),and N32(32 kg N/(hm^(2)·a))),and their interactions on plant community biomass and its temporal stability,and explored its potential regulatory mechanisms.The results showed that the biomass of total community,Gramineae,and dominant species increased significantly with increasing temperature,but the biomass of common and rare species decreased significantly.Nitrogen deposition also significantly promoted the biomass accumulation of community and gramineous plants.Under the treatment of W3N32,the biomass of plant community,Gramineae,and dominant species reached the highest values,indicating that there was a synergistic effect under this treatment.Structural equation model showed that increasing temperature significantly decreased the stability of plant community biomass by reducing the stability of grass and dominant species biomass and weakening species asynchronism.Interaction of increased nitrogen deposition and temperature increased the biomass fluctuation of grass functional group,thus amplifying its negative influence on community stability.More attention should be paid to the response and regulatory mechanisms of dominant species and functional groups under global climate change.This study provides a theoretical basis for revealing the stability maintenance mechanism of alpine grassland and also provides scientific support for the development of future grassland ecosystem management and assessment.
基金Supported by Inner Mongolia Meteorological Brueau Technology ResearchProject(200618)~~
文摘IS1921 VF-256 type ground object spectrometer was used to extract the spectral data of the meadow grassland and bare land to obtain their refleotivity spectral characteristics. The experiment was carried out on the low mountain meadow steppe in the Saiwundu Village, Hargentai Town, West Ujumqin Banner, Xilin Gol League, Inner Mongolia. The results showed that different ground objects had different reflectances. The spectral reflectance curve of the meadow steppe plant communities had obvious characteristics of peak and valley in the visible spectrum band, and had strong reflection in the near-infrared band. The reflection curve of the bare lands in the visible spectrum band was higher than that of the meadow grassland communities while inthe near-infrared band it was lower than that of the meadow grassland communities. Under different degradation gradients, the spectral reflectivity of the meadow steppe grassland communities increased with the enhancement of the degradation gradients. Under the same degradation gradient, the Stipa grandis communities had a lower visible light reflectivity than the Artemisia frigida communities but had a higher near-infrared reflectivity than the Artemisia frigida communities; different ground objects on the meadow steppe had different spectrum characteristic, and showed a certain discrepancies with the changes of the degradation level.
基金Supported by National Natural Science Foundation of China(30700563)the Middleaged Fund in Qinghai University(2009-QN-07)~~
文摘[Objective]The aim of this study is to explore the effects of grassland degradation on soil physical and chemical properties.[Method]The ratio of plant root to soil and soil texture on Alpine Meadow were investigated in this study,and soil available N,P,K,Cu,Zn,organic matter and pH value were also analyzed by routine analysis of soil nutrients in different degraded grasslands.[Result]With the intensification of degraded gradient and the soil depth,the ratio of plant root to soil was decreased gradually.The highest ratio of plant root to soil was in 0-10 cm depth of soil in grassland with different degraded gradients,while its ratio of plant root to soil changed from 0.001 to 0.040 with soil type of loam.Soil chemical characteristic changed in different degraded gradients.The content of available N,P,K reduced significantly with the soil depth and the intensification of degraded gradients.The content of Cu and Zn was relatively lack in degraded grassland.[Conclusion]There is no significant correlation between nutrition content or pH value and the succession degree of degraded grassland.
文摘Using the measurement of stable carbon isotopes in leaves as a tool to investigate photosynthetic pathway of 102 plant species grown at an alpine meadow ecosystem, at the foot of the Qilian Mountain, Qinghai, China. The results indicate that the delta C-13 values of plants have a narrow range from -28.24parts per thousand to -24.84parts per thousand, which means that none of the species examined belongs to C-4 and crassulaceous acid metabolism (CAM) photosynthetic pathway and all of these species perform photosynthesis through the C-3 pathway. This is likely due to a long-term adaptation to environments at the alpine meadow ecosystem.
基金Supported by Special Fund for Agro-scientific Research in the Public Interest(201003019,201003061,201303060)the National Natural Science Foundation of China(41201199)+1 种基金International Science and Technology Cooperation Project(2012DFA31290)Modern Agricultural Technology System of Special Funding~~
文摘[Objective] The aim was to explore the management mode on optimal re-sources al ocation of family ranch in meadow steppe. [Method] Three double repre-sentative family ranches were selected in meadow steppe of Hulunber Old Barag Banner, and the study was carried out with the baseline survey. Three family ranches were selected as the demonstrative households for the corporation study, while other three family ranches with the similar conditions were looked as the non-demonstrative households for the comparison. Demonstrative households of the fami-ly ranches reduced the stocking rate, optimized the flock structure and took a winter feeding and other means to explore the different management models on plant com-munity characteristic of family ranch. [Result] The seasonal dynamic of community characteristic in family ranches showed the single-peaks curves. The seasonal dy-namics of community coverage, height and biomass in the demonstrative households showed higher compared with the non-demonstrative households, and community density in the experiment households was lower than that of the control experiment households. Community coverage, height and biomass of degraded grassland in family ranch have a great improve after optimization of management. Community coverage, height , density and biomass were increasing in fencing plot, but decreas-ing in free grazing area. Enclosure improved grassland coverage, vegetation height, density and forage yield. Leymus chinensis played an important role in plant com-munity. The important values of Leymus chinensis, Stipa baicalensis, Cleistogenes squarrosa, and Carex duriuscula were high. Leymus chinensis important value in the demonstrative households of optimal management was higher than that in the non-demonstrative households, and Carex duriuscula important value of the non-demon-strative households was significantly higher than that of the demonstrative house-holds. The indexes of Margalef richnes,Shannon-Wiener diversity, Simpson diversity and Pielou uniformity showed that the demonstrative households were higher than the non-demonstrative households. [Conclusion] The research provides theoretical ref-erences for sustainable development of pastures dominated by family ranch.
文摘To understand the dynamics of added nitrogen (N) in alpine meadow and the role of alpine plants and soil microorganisms in the retention of deposited N, the fate of 15 N labeled nitrate and ammonium salts was determined in an alpine meadow for two months. Two weeks after 15 N application, total recovery of 15 N from NO - 3_ 15 N was 73.5% while it was 78% from NH + 4_ 15 N. More 15 N was recovered in plants than in soil organic matter or in microbial biomass, irrespective of forms of N added. After one month, 70.6% of added NO - 3_ 15 N and 57.4% of NH + 4_ 15 N were recovered in soils and plants. 15 N recovered in soil organic matter decreased greatly while that recovered in plants varied little, irrespective of the form N. Compared with the results of two weeks after 15 N application, more NO - 3_ 15 N than NH + 4_ 15 N was recovered in microbial biomass. Total recovery was 58.4% (six weeks) and 67% (eight weeks) from NO - 3_ 15 N, and 43.1% and 49% from NH + 4_ 15 N, respectively. Both plants and soil microorganism recovered more NO - 3_ 15 N than NH + 4_ 15 N. But plants recovered more 15 N than soil microorganisms. During the whole experiment plants retained more NO - 3_N and 15 N than soil microorganisms while 15 N recovered in inorganic N pool did not exceed 1% due to lower amount of inorganic N. This indicates that plants play more important roles in the retention of deposited N although microbial biomass can be an important sink for deposited N in early days after N application.
文摘高寒草甸是青藏高原主要植被类型之一,全球气候变化背景下大气氮(nitrogen,N)沉降与降水格局改变对高寒草甸碳平衡产生显著影响。然而,这两种变化对土壤有机碳(soil organic carbon,SOC)的交互作用仍存在较大不确定性。本研究于2019—2021年以青藏高原东北部高寒草甸为研究对象,设置氮添加(包膜尿素,10 g N m^(-2)a^(-1))和降水变化(增雨50%和减雨50%)处理,每个处理设置3个重复,探究植物生物量和表层(0—10cm)土壤SOC含量的响应特征。结果表明,仅氮添加处理显著提高峰值地上生物量(aboveground plant biomass,AGB)达19.1%(83.8g/m^(2)),使AGB/BGB显著增加23.3%(0.057)。AGB和SOC含量在不同年份间存在显著差异。为排除年份效应,采用各处理与对照组的相对变化量(ΔAGB、ΔBGB和ΔSOC)进行分析,发现这些相对变化量对处理同样不敏感。随机森林模型和结构方程模型结果均显示,SOC和ΔSOC含量主要受气温变化的调控,而非植物碳输入(AGB和BGB或ΔAGB和ΔBGB)驱动。研究证实气候变化对高寒草甸SOC积累的正向效应,可能缘于过去数十年气温持续升高的主导作用,而非大气氮沉降和降水格局改变。年份而非处理产生的显著效应表明,亟需开展长期多因子实验以揭示高寒草甸土壤固碳能力对气候变化的复合响应及其机理。
