The response of plant functional diversity to external disturbances not only effectively predicts changes in the ecosystem but it also reflects how plant communities use external environmental resources.However,resear...The response of plant functional diversity to external disturbances not only effectively predicts changes in the ecosystem but it also reflects how plant communities use external environmental resources.However,research on how different herbivore assemblages affect plant functional diversity is limited.Therefore,this study systematically explored the effects of three typical herbivore assemblages(yak grazing,Tibetan sheep grazing,and mixed grazing by yaks and Tibetan sheep)on species richness,plant functional diversity,and soil physicochemical properties in alpine grasslands on the Qinghai-Tibet Plateau,China.This study further investigated the primary mechanisms driving the changes in plant functional diversity.The results indicate four key aspects of this system:(1)Grazing significantly enhanced plant functional diversity,particularly when the mixed grazing by yaks and Tibetan sheep was applied at a ratio of 1:2.This ratio showed the most substantial improvement in the functional dispersion index and Rao's quadratic entropy index.(2)Compared to enclosed treatments,grazing increased species richness andβ-diversity,contributing to higher plant functional diversity.(3)Grazing treatments affected various plant traits,such as reducing plant community height and leaf thickness while increasing specific leaf area.However,the impact on plant functional diversity was most pronounced under the mixed grazing by yaks and Tibetan sheep at a ratio of 1:2.(4)Speciesα-diversity was positively correlated with plant functional diversity.Changes in plant functional diversity were primarily regulated by variations in soil physicochemical properties.Specifically,increases in soil available nitrogen significantly promoted changes in plant functional diversity,while increases in soil available potassium and bulk density had a significant inhibitory effect on these changes.Long-term grazing significantly reduced the height of plant communities in alpine meadows,while a balanced mixture of yak and Tibetan sheep grazing,especially at a ratio of 1:2,enhanced plant functional diversity the most.This suggests that,under these conditions,the use of external environmental resources by the plant community is optimized.展开更多
The source region of the Yellow River, accounting for over 38% of its total runoff, is a critical catchment area,primarily characterized by alpine grasslands. In 2005, the Maqu land surface processes observational sit...The source region of the Yellow River, accounting for over 38% of its total runoff, is a critical catchment area,primarily characterized by alpine grasslands. In 2005, the Maqu land surface processes observational site was established to monitor climate, land surface dynamics, and hydrological variability in this region. Over a 10-year period(2010–19), an extensive observational dataset was compiled, now available to the scientific community. This dataset includes comprehensive details on site characteristics, instrumentation, and data processing methods, covering meteorological and radiative fluxes, energy exchanges, soil moisture dynamics, and heat transfer properties. The dataset is particularly valuable for researchers studying land surface processes, land–atmosphere interactions, and climate modeling, and may also benefit ecological, hydrological, and water resource studies. The report ends with a discussion on perspectives and challenges of continued observational monitoring in this region, focusing on issues such as cryosphere influences, complex topography,and ecological changes like the encroachment of weeds and scrubland.展开更多
The response of N_(2)O emissions to nitrogen(N)addition is usually positive,but its response to phosphorus(P)addition varies,and the underlying mechanisms for the changes in N_(2)O emissions remain unclear.We conducte...The response of N_(2)O emissions to nitrogen(N)addition is usually positive,but its response to phosphorus(P)addition varies,and the underlying mechanisms for the changes in N_(2)O emissions remain unclear.We conducted field studies to examine the response of N_(2)O emissions to N and P addition over two years in three typical alpine grasslands,alpine meadow(AM),alpine steppe(AS),and alpine cultivated grassland(CG)on the Qinghai-Tibet Plateau(QTP).Our results showed consistent increases in N_(2)O emissions under N addition alone or with P addition,and insignificant change in N_(2)O emissions under P addition alone in all three grasslands.N addition increased N_(2)O emissions directly in AM,by lowering soil pH in AS,and by lowering abundance of denitrification genes in CG.N and P co-addition increased N_(2)O emissions in AM and AS but only showed an interactive effect in AM.P addition enhanced the increase in N_(2)O emissions caused by N addition mainly by promoting plant growth in AM.Overall,our results illustrate that short-term P addition cannot alleviate the stimulation of N_(2)O emissions by N deposition in alpine grassland ecosystems,and may even further stimulate N_(2)O emissions.展开更多
Fractal geometry is an important method in soil science,and many studies have used fractal theory to examine soil properties and the relationships with other eco-environmental factors.However,there have been few studi...Fractal geometry is an important method in soil science,and many studies have used fractal theory to examine soil properties and the relationships with other eco-environmental factors.However,there have been few studies examining soil particle volume fractal dimension in alpine grasslands.To study the volume fractal dimension of soil particles （D） and its relationships with soil salt,soil nutrient and plant species diversity,we conducted an experiment on an alpine grassland under different disturbance degrees：non-disturbance （N0）,light disturbance （L）,moderate disturbance （M） and heavy disturbance （H）.The results showed that （1） Ds varied from 2.573 to 2.635 among the different disturbance degrees and increased with increasing degrees of disturbance.（2） Shannon-Wiener diversity index,Pielou＇s evenness index and Margalef richness index reached their highest values at the M degree,indicating that moderate disturbance is beneficial to the increase of plant species diversity.（3） In the L and M degrees,there was a significant positive correlation between D and clay content and a significant negative correlation between D and soil organic matter （SOM）.In the H degree,D was significantly and positively correlated with total salt （TS）.The results suggested that to a certain extent,D can be used to characterize the uniformity of soil texture in addition to soil fertility characteristics.（4） For the L degree,there was a significant negative correlation between D and the Shannon-Wiener diversity index; while for the M degree,there was a significant negative correlation between D and Pielou＇s evenness index.展开更多
Using stat ic chamber technique, fluxes of CO 2 , CH 4 and N 2 O were measured in the alpine grassland area from July 2000 to July 2001, d eterminations of mean fluxes showed that CO 2 and N 2 O were gene rally releas...Using stat ic chamber technique, fluxes of CO 2 , CH 4 and N 2 O were measured in the alpine grassland area from July 2000 to July 2001, d eterminations of mean fluxes showed that CO 2 and N 2 O were gene rally released from the soil, while the alpine grassland accounted for a weak CH 4 sink. Fluxes of CO 2 , CH 4 and N 2 O ranged widely. The highest CO 2 emission occurred in August, whereas a lmost 90% of the whole year emission occurred in the growing season. But the variations of CH 4 and N 2 O fluxes did not show any clear patterns over the one-year-experim ent. During a daily variation, the maximum CO 2 emission occurred at 16:00, and then decreased to the minimum emi ssion in the early morning. Daily pattern analyses indicated that the variation in CO 2 fluxes was positively related to air temperatures (R 2 =0.73) and soil temperatures at a depth of 5 cm (R 2 =0.86), whereas daily variations in CH 4 and N 2 O fluxes were poorly explained by soil temperatures and climatic va riables. CO 2 emissions in this area were much lower than other grasslands in plain areas .展开更多
Methane （OH4）, carbon dioxide （CO2） and nitrous oxide （N2O） are known to be major greenhouse gases that contribute to global warming. To identify the flux dynamics of these greenhouse gases is, therefore, of gre...Methane （OH4）, carbon dioxide （CO2） and nitrous oxide （N2O） are known to be major greenhouse gases that contribute to global warming. To identify the flux dynamics of these greenhouse gases is, therefore, of great significance. In this paper, we conducted a comparative study on an alpine grassland and alpine wetland at the Bayinbuluk Grassland Eco-system Research Station, Chinese Academy of Sciences. By using opaque, static, manual stainless steel chambers and gas chromatography, we measured the fluxes of CH4, N2O and CO2 from the grassland and wetland through an in situ monitoring study from May 2010 to October 2012. The mean flux rates of CH4, N2O and CO2 for the experimental alpine wetland in the growing season （from May to October） were estimated at 322.4 μg/（m2.h）, 16.7 μg/（m2.h） and 76.7 mg/（m2.h）, respectively; and the values for the alpine grassland were -88.2 μg/（m2.h）, 12.7 μg/（m2.h）, 57.3 mg/（m2.h）, respectively. The gas fluxes showed large seasonal and annual variations, suggesting weak fluxes in the non-growing season. The relationships between these gas fluxes and environmental factors were analyzed for the two alpine ecosystems. The results showed that air temperature, precipitation, soil temperature and soil moisture can greatly influence the fluxes of CH4, N2O and CO2, but the alpine grassland and alpine wetland showed different feedback mechanisms under the same climate and environmental conditions.展开更多
Understanding the vertical distribution patterns of soil microbial community and its driving factors in alpine grasslands in the humid regions of the Tibet Plateau might be of great significance for predicting the soi...Understanding the vertical distribution patterns of soil microbial community and its driving factors in alpine grasslands in the humid regions of the Tibet Plateau might be of great significance for predicting the soil microbial community of this type of vegetation in response to environmental change. Using phospholipid fatty acids （PLFA）, we investigated soil microbial community composition along an elevational gradient （3094-4131 m above sea level） on Mount Yajiageng, and we explored the impact of plant functional groups and soil chemistry on the soil microbial community. Except for Arbuscular Mycorrhizal fungi （AM fungi） biomarker 18：2ω6,9 increasing significantly, other biomarkers did not show a consistent trend with the elevational gradient. Microbial biomass quantified by total PLFAs did not show the elevational trend and had mean values ranging from 1.64 to 4.09 ktmol per g organic carbon （OC）, which had the maximum value at the highest site. Bacterial PLFAs exhibited a similar trend with total PLFAs, and its mean values ranged from 0.82 to 1.81 μmol （g OC）-1. The bacterial to fungal biomass ratios had the minimum value at the highest site, which might be related to temperature and soil total nitrogen （TN）. The ratios of Gram-negative to Gram-positive bacteria had a significantly negative correlation with soil TN and had the maximum value at the highest site. Leguminous plant coverage and soil TN explained 58% of the total variation in the soil microbial community and could achieve the same interpretation as the whole model. Other factors may influence the soil microbial community through interaction with leguminous plant coverage and soil TN. Soil chemistry and plant functional group composition in substantial amounts explained different parts of the variation within the soil microbial community, and the interaction between them had no impact on the soil microbial community maybe beeause long-term grazing greatly reduces litter. In sum, although there were obvious differences in soil microbial communities along the elevation gradient, there were no clear elevational trends found in general. Plant functional groups and soil chemistry respectively affect the different aspects of soil microbial community. Leguminous plant coverage and soil TN had important effects in shaping soil microbial community.展开更多
Fertilization has been shown to have suppressive effects on arbuscular mycorrhizal fungi(AMF) and root hemiparasites separately in numerous investigations, but its effects on AMF in the presence of root hemiparasites ...Fertilization has been shown to have suppressive effects on arbuscular mycorrhizal fungi(AMF) and root hemiparasites separately in numerous investigations, but its effects on AMF in the presence of root hemiparasites remain untested. In view of the contrasting nutritional effects of AMF and root hemiparasites on host plants, we tested the hypothesis that fertilization may not show strong suppressive effects on AMF when a plant community was infested by abundant hemiparasitic plants. Plants and soil samples were collected from experimental field plots in Bayanbulak Grassland, where N and P fertilizers had been applied for three continuous years for control against a spreading root hemiparasite, Pedicularis kansuensis. Shoot and root biomass of each plant functional group were determined. Root AMF colonization levels, soil spore abundance, and extraradical hyphae length density were measured for three soil depths(0 e10 cm, 10 e20 cm, 20 e30 cm). Partial 18 S r RNA gene sequencing was used to detect AMF diversity and community composition. In addition, we analyzed the relationship between relative abundance of different AMF genera and environmental factors using Spearman's correlation method. In contrast to suppressive effects reported by many previous studies, fertilization showed no significant effects on AMF root colonization or AMF species diversity in the soil. Instead, a marked increase in soil spore abundance and extraradical hyphae length density were observed. However, fertilization altered relative abundance and AMF composition in the soil. Our results support the hypothesis that fertilization does not significantly influence the abundance and diversity of AMF in a plant community infested by P. kansuensis.展开更多
Alpine grassland is the typical vegetation in the eastern Qinghai–Tibetan Plateau,which has important ecological service functions,and also supports the development of alpine stock farming.In recent years,under both ...Alpine grassland is the typical vegetation in the eastern Qinghai–Tibetan Plateau,which has important ecological service functions,and also supports the development of alpine stock farming.In recent years,under both the natural and human disturbance,alpine grasslands in this area have appeared to different degrees of desertification.A diagnosis of the desertification degree serves as the basis for grassland ecological restoration.This study constructs a comprehensive index based on remote sensing called alpine grassland desertification index(AGDI)to monitor the areas and degree of desertification.The most relevant indicators of desertification,namely,vegetation fraction,aboveground biomass,soil moisture,and land surface temperature,were selected to establish AGDI.The geographical detector is used to reselect and assess these indicators.The results show that the overall verification accuracy of AGDI is 82.05%.In particular,the accuracy of identifying severe desertification is the highest.Our study confirms that the desertification of alpine grasslands in the eastern Qinghai–Tibetan Plateau is characterized by fragmentation.Thus,Landsat-8 OLI data with a spatial resolution of 30 m is more suitable than MODIS data for alpine grasslands desertification monitoring.The research results can provide a methodological reference for monitoring desertification of alpine grasslands and other grassland regions in the world.展开更多
In this study, two different methods including Digital Camera and Reference Panel （DCRP） and traditional in situ fPAR observation for measuring the in situ point fPAR of very short alpine grass vegetation were compa...In this study, two different methods including Digital Camera and Reference Panel （DCRP） and traditional in situ fPAR observation for measuring the in situ point fPAR of very short alpine grass vegetation were compared, and the Moderate Resolution Imaging Spectroradiometer （MODIS） fPAR products were evaluated and validated by in situ point data on the alpine grassland over the Northern Tibetan Plateau, which is sensitive to climate change and vulnerable to anthropogenic activities. Results showed that the MODIS alpine grassland fPAR product, examined by using DCRP, and traditional in situ fPAR observation had a significant relationship at the spatial and temporal scales. The decadal MODIS fPAR trend analysis showed that, average growing season fPAR increased by 1.2 × 10^-4 per year and in total increased 0.86% from 2002 to 2011 in alpine grassland, when most of the fPAR increments occurred in southeast and center of the Northern Tibetan Plateau, the alpine grassland tended to recover from degradation slightly. However, climatic factors have influenced the various alpine grassland vegetation fPAR over a period of 10 years; precipitation significantly affected the alpine meadow fPAR in the eastern region, whereas temperature considerably influenced the alpine desert steppe fPAR in the west region. These findings suggest that the regional heterogeneity in alpine grassland fPAR results from various environmental factors, except for vegetation characteristics, such as canopy structure and leaf area.展开更多
Knowledge of nitrous oxide(N_(2)O)exchanges through soils and atmosphere in various ecosystems has been of great importance in global climate change studies.However,the relative magnitude of surface and subsurface N_(...Knowledge of nitrous oxide(N_(2)O)exchanges through soils and atmosphere in various ecosystems has been of great importance in global climate change studies.However,the relative magnitude of surface and subsurface N_(2)O production sources from the alpine grassland ecosystem is unclear.In the present study,the N_(2)O concentration profile from 1.5 m in depth in soil to 32 m in height in air was measured from July 2000 to July 2001 in alpine grassland located in the permafrost area of the Qinghai-Xizang Plateau,which revealed that N_(2)O concentrations had a distinct variation pattern both in air and in soil during the study period.Mean N_(2)O concentrations in the atmosphere were significantly lower than those in the soil,which induced the N_(2)O emission from the alpine steppe soil into the atmosphere.Mean flux of N_(2)O in this alpine grassland experiment site was 0.05×10^(-4)μmol·m^(-2)·s^(-1).But the variation in N_(2)O emissions did not show any clear trends over the whole-year experiment in our study site.The highest N_(2)O concentration was found at the depth of 1.5 m in the soil while the lowest N_(2)O concentration occurred at the height of 8 m in the atmosphere.Mean N_(2)O concentrations in the soil increased significantly with depth.This was the influence of increasing soil moistures,which induced the increasing denitrification potential with depth.The mean N_(2)O concentrations at different heights in the air remained a more steady state because of the atmospheric negotiability.Seasonal variations of N_(2)O concentrations showed significant correlations between the neighbor layers both in the soil and in the atmosphere.The seasonal variations of N_(2)O concentrations at all horizons in the soil showed very clear patterns,with the highest concentrations occurring from the onset of frost to the freeze-thaw period and lowest concentrations occurring during the spring and the summer.Further analyses showed that the seasonal variations of N_(2)O concentrations in the soil were hardly explained by soil temperatures at any depth.Temporally,atmospheric N_(2)O concentrations at all heights exhibited almost the same seasonal pattern with the soil N_(2)O variations,while soil is believed to be the predominant natural source of atmospheric N_(2)O near the earth surface in this alpine grassland area.Also,a significant correlation was found between N_(2)O emissions and soil N_(2)O concentrations at 0.2 m in depth during the study period.This implied the variation of N_(2)O concentrations in the soil surface horizon was the most direct driving force of N_(2)O exchanges between the soil and the atmosphere.Soil atmospheric N_(2)O at surface layers is the main source of N_(2)O emissions from the soil surface to the atmosphere.Soil N_(2)O concentrations at deeper layers were all significantly higher than those at surface layers,which indicated that N_(2)O was diffused from the deeper layers to the surface layers in the soil,and finally was emitted to the atmosphere.展开更多
The Qinghai-Tibet Plateau(QTP)has the largest and highest alpine grassland ecosystem in the world,which is considered to be the most sensitive and vulnerable ecosystem to climate change.Its dynamic changes and driving...The Qinghai-Tibet Plateau(QTP)has the largest and highest alpine grassland ecosystem in the world,which is considered to be the most sensitive and vulnerable ecosystem to climate change.Its dynamic changes and driving mechanism have always been widely researched.The Qomolangma National Nature Preserve(QNNP),with the largest altitude difference in the world,was selected as the study area to analyse the spatial-temporal dynamics of grassland coverage and the different characteristics of elevation gradients at the southern slope(SS)and northern slope(NS)with MODIS MOD13Q1 NDVI and MOD11A2 land surface temperature data from 2000to 2019 using the Mann-Kendall trend test and Theil-Sen slope methods.Further,the response mechanism of grassland coverage to climate warming is discussed.The results revealed that from 2000 to 2019,the grassland coverage change in the study area is mainly stable.The increased area proportion of grassland coverage on the southern slope is significantly higher than that on the northern slope,and the decreased area proportion of grassland coverage on the northern slope is significantly greater than that on the southern slope.The change characteristics of grassland coverage in the QNNP exhibit an obvious elevation gradient;the higher the elevation,the greater the increased area proportion of grassland coverage,particularly on the SS.The land surface temperature can be used as a proxy for analysing the temporal and spatial variation trends of air temperature in the QNNP.With the increase of the altitude,the land surface temperature rise rate on both the southern slope and northern slope exhibited an increasing trend,and the sensitivity of grassland coverage to temperature rise was higher on the northern slope.The water condition was the decisive factor for the horizontal and vertical spatial heterogeneity of the dynamic change of grassland coverage,and the melting of glaciers and thawing of permafrost were important sources of water for grassland growth in the QNNP.Climate warming promotes the growth of grassland in areas with a sufficient water supply,but adversely affects the growth of grassland in areas with insufficient water supplies,which will be further intensified by human activities.展开更多
Characteristics of plant species diversity of two types of grassland communities (alpine meadow and alpine grassland) was examined and the relationship between species diversity and community dynamics was determined u...Characteristics of plant species diversity of two types of grassland communities (alpine meadow and alpine grassland) was examined and the relationship between species diversity and community dynamics was determined using GPS positioning and in situscrutinization of community of alpine grassland in Nakchu prefecture of Tibet Autonomous Region. The result indicated that: ① there was an unobvious difference between grassland communities in terms of richness index of plant, evenness index, dominant index and diversity index. The species diversity index followed the order Kobresia humilis meadow >Stipa purpurea steppe>K. littledalei meadow; ② the original community created high diversity, while the degenerative community suffering from serious disturbance was of low diversity; ③ the diversity of community plants was closely related to changes of species biomass, and the growth and decline of species in the community; ④ grazing disturbance is a key factor of community dynamics, leading to coexistence of various secondary successions of communities, diversified suitable habitats and species diversity. improvements展开更多
The change of freeze-thaw pattern of the Tibetan Plateau under climate warming is bound to have a profound impact on the soil process of alpine grassland ecosystem;however,the research on the impact of the freeze-thaw...The change of freeze-thaw pattern of the Tibetan Plateau under climate warming is bound to have a profound impact on the soil process of alpine grassland ecosystem;however,the research on the impact of the freeze-thaw action on nitrogen processes of the alpine grassland ecosystem on the Tibetan Plateau has not yet attracted much attention.In this study,the impact of the freezing strength on the soil nitrogen components of alpine grassland on the Tibetan Plateau was studied through laboratory freeze-thaw simulation experiments.The 0–10 cm topsoil was collected from the alpine marsh meadow and alpine meadow in the permafrost region of Beilu River.In the experiment,the soil samples were cultivated at –10℃,–7℃,–5℃,–3℃ and –1℃,respectively for three days and then thawed at 2℃ for one day.The results showed that after the freeze-thaw process,the soil microbial biomass nitrogen significantly decreased while the dissolved organic nitrogen and inorganic nitrogen significantly increased.When the freezing temperature was below –7℃,there was no significant difference between the content of nitrogen components,which implied a change of each nitrogen component might have a response threshold toward the freezing temperature.As the freeze-thaw process can lead to the risk of nitrogen loss in the alpine grassland ecosystem,more attention should be paid to the response of the soil nitrogen cycle of alpine grasslands on the Tibetan Plateau to the freeze-thaw process.展开更多
In this paper, the CO2 concentrations profile from 1.5 m depth in soil to 32 m height in atmosphere were measured from July 2000 to July 2001 in an alpine grassland ecosystem located in the permafrost area on the Tibe...In this paper, the CO2 concentrations profile from 1.5 m depth in soil to 32 m height in atmosphere were measured from July 2000 to July 2001 in an alpine grassland ecosystem located in the permafrost area on the Tibetan Plateau, which revealed that CO2 concentrations varied greatly during this study period. Mean concentrations during the whole experiment in the atmosphere were absolutely lower than the CO2 concentrations in soil, which resulted in CO2 emissions from the alpine steppe soil to the atmosphere. The highest CO2 concentration was found at a depth of 1.5 m in soil while the lowest CO2 concentration occurred in the atmosphere. Mean CO2 concentrations in soil generally increased with depth. This was the compositive influence of the increasing soil moistures and decreasing soil pH, which induced the increasing biological activities with depth. Temporally, the CO2 concentrations at different layers in air remained a more steady state because of the atmospheric turbulent milking. During the seasonal variations, CO2 concentrations at surface soil interface showed symmetrical patterns, with the lowest accumulation of CO2 occurring in the late winter and the highest CO2 concentration in the growing seasons.展开更多
In this article, we mainly analysis the soil carbon storage of the alpine grassland under different land uses in Qinghai-Tibet Plateau. The samples of this investigation include six experimental fields which are fence...In this article, we mainly analysis the soil carbon storage of the alpine grassland under different land uses in Qinghai-Tibet Plateau. The samples of this investigation include six experimental fields which are fenced mowing grassland, artificial grassland, winter and spring grazing meadowland, summer and autumn mild grazing land, summer and autumn moderate grazing pasture and summer and autumn severe grazing land and seven soil layers included 0 cm-5 cm, 5 cm-10 cm, 10 cm-20 cm, 20 cm-30 cm, 30 cm-50 cm, 50 cm-70 cm and 70 cm-100 cm. The results show that the soil carbon storage in different soil layers will gradually reduce and the difference was remarkable （P 〈 0.05）. What is more, the soil carbon storage of alpine grassland under different land uses has following sequence： winter and spring grazing grassland 〉 summer and autumn mild grazing land 〉 artificial grassland 〉 summer and autumn moderate grazing meadowland 〉 summer and autumn severe grazing pasture 〉 fenced mowing meadow, and the significant difference between them is remarkable （P 〈 0.05）.展开更多
Soil organic carbon(SOC)and total nitrogen(TN)stocks are usually calculated with samples collected using core samplers.Although the calculation considers the effects of gravel in soil samples,other coarse fragments su...Soil organic carbon(SOC)and total nitrogen(TN)stocks are usually calculated with samples collected using core samplers.Although the calculation considers the effects of gravel in soil samples,other coarse fragments such as stones or boulders in soil may not be collected due to the restricted diameter of core samplers.This would cause an incorrect estimation of soil bulk density and ultimately SOC and TN stocks.In this study,we compared the relative volume of coarse fragment and bulk density of fine earth determined by large size soil sampler with three core samplers.We also investigated the uncertainties in estimation of SOC and TN stocks caused by this soil sampler procedure in three typical alpine grasslands on the northeast edge of the Qinghai-Tibetan Plateau(QTP),China.Results show that(1)the relative volume and size of coarse fragment collected by large size sampler were significantly(p<0.05)higher and larger than those of core samplers,while bulk density of fine earth,SOC and TN stocks show opposite patterns in all grassland types;(2)SOC and TN stocks determined by core samplers were 17%-45%and 18%-46%higher than larger size sampler for three typical alpine grasslands;and(3)bulk density of fine earth,SOC and TN stocks exponentially decreased with the increasing of coarse fragment content.We concluded that core sampler methods significantly underestimated the volume occupied by coarse fragment but overestimated SOC and TN stocks.Thus,corrections should be made to the results from core samplers using large size samplers on regions with gravel and stone-rich soils in future studies.展开更多
At first,the ecological restoration technology of abandoned mines is summarized,and the paths and models of mine ecological restoration in Zoige grassland area under the background of carbon neutrality are analyzed.Mo...At first,the ecological restoration technology of abandoned mines is summarized,and the paths and models of mine ecological restoration in Zoige grassland area under the background of carbon neutrality are analyzed.Moreover,the problems and deficiencies in the current research on mine ecological restoration in Zoige grassland area are initially identified,and the future research trend is prospected to provide a reference for the path of carbon reduction by mine ecological restoration in Zoige grassland area and other alpine grassland areas in the future.展开更多
High-precision models enable the visualization of spatiotemporal patterns of soil microorganisms in the Qinghai-Xizang Plateau,a region highly sensitive to global change.However,large-scale,high-resolution data on soi...High-precision models enable the visualization of spatiotemporal patterns of soil microorganisms in the Qinghai-Xizang Plateau,a region highly sensitive to global change.However,large-scale,high-resolution data on soil bacterial and fungal communities,particularly in relation to the ecological impacts of fencing,remains relatively scarce,thereby limiting studies on the spatiotemporal distribution patterns of soil fungi and bacteria.This study constructed models of soil fungal and bacterial abundance andα-diversity(total abundance,major phylum abundance,primary functional group abundance,and species/phylogenetic/functionalα-diversity)in the alpine grasslands of the Qinghai-Xizang Plateau,based on observational data and utilizing the random forest method.Under fencing conditions,the variations in soil fungal and bacterial abundance andα-diversity were collectively explained by temperature,precipitation,and radiation,accounting for 46%-88%of the variation;while under grazing conditions,the inclusion of NDVI allowed these four factors to explain 47%-92%of the variation.The relative biases between simulated and observed values for fungal and bacterial abundance andα-diversity were lower than 10.83%,and the simulated values explained the variation in observed values ranging from 75%to 100%.The slopes of the linear regressions between observed and simulated values ranged between 0.81 and 1.00.Consequently,the random forest models constructed in this study demonstrated high accuracy and they can predicted the total abundance,major phylum abundance,primary functional group abundance,andα-diversity of soil microorganisms in alpine grasslands.These models can serve as a robust foundation for future related research.展开更多
We screened 161 eligible papers of experimental data across the Tibetan Plateau for meta-analysis,in order to systematically assess and validate potential application of plant resource allocation strategies,such as th...We screened 161 eligible papers of experimental data across the Tibetan Plateau for meta-analysis,in order to systematically assess and validate potential application of plant resource allocation strategies,such as the optimal allocation hypothesis,the isometric allocation hypothesis,and the allometric allocation hypothesis under environmental changes,and to explore the effects of environmental factors(temperature change,grazing intensity)on plant resource allocation strategies in alpine grassland ecosystems on the Tibetan Plateau.Overall,we found that the aboveground and belowground growth relationship in alpine grasslands follows the allometric growth hypothesis,which was unaffected by warming,grazing and their interactions.In addition,the biomass transferred between aboveground and belowground,the former was decreased,while the latter was increased under warming conditions in alpine steppe implies that the resource allocation strategy in alpine steppe grassland may potentially follow the optimal allocation hypothesis.We further found that the effect of soil properties on biomass,not the biomass allocation,was different under warming and grazing conditions in alpine grasslands,which further confirms the above conclusion.In addition,warming helped to mitigate the negative effects of grazing,which indicated that the interaction between warming and grazing is important in alpine grassland ecosystems.Overall,the results of this study are of theoretical significance for understanding how moderate grazing affects the growth of plants in alpine grasslands under changing climate.展开更多
基金financially supported by the National Natural Science Foundation of China(U20A2007 and 32160343)the Open Project of Key Laboratory of the Alpine Grassland Ecology in the Three Rivers Region(Qinghai University),Ministry of Education of China(2023-SJY-KF-02)the West Light Foundation of the Chinese Academy of Sciences。
文摘The response of plant functional diversity to external disturbances not only effectively predicts changes in the ecosystem but it also reflects how plant communities use external environmental resources.However,research on how different herbivore assemblages affect plant functional diversity is limited.Therefore,this study systematically explored the effects of three typical herbivore assemblages(yak grazing,Tibetan sheep grazing,and mixed grazing by yaks and Tibetan sheep)on species richness,plant functional diversity,and soil physicochemical properties in alpine grasslands on the Qinghai-Tibet Plateau,China.This study further investigated the primary mechanisms driving the changes in plant functional diversity.The results indicate four key aspects of this system:(1)Grazing significantly enhanced plant functional diversity,particularly when the mixed grazing by yaks and Tibetan sheep was applied at a ratio of 1:2.This ratio showed the most substantial improvement in the functional dispersion index and Rao's quadratic entropy index.(2)Compared to enclosed treatments,grazing increased species richness andβ-diversity,contributing to higher plant functional diversity.(3)Grazing treatments affected various plant traits,such as reducing plant community height and leaf thickness while increasing specific leaf area.However,the impact on plant functional diversity was most pronounced under the mixed grazing by yaks and Tibetan sheep at a ratio of 1:2.(4)Speciesα-diversity was positively correlated with plant functional diversity.Changes in plant functional diversity were primarily regulated by variations in soil physicochemical properties.Specifically,increases in soil available nitrogen significantly promoted changes in plant functional diversity,while increases in soil available potassium and bulk density had a significant inhibitory effect on these changes.Long-term grazing significantly reduced the height of plant communities in alpine meadows,while a balanced mixture of yak and Tibetan sheep grazing,especially at a ratio of 1:2,enhanced plant functional diversity the most.This suggests that,under these conditions,the use of external environmental resources by the plant community is optimized.
基金supported by the National Natural Science Foundation of China for Distinguished Young Scholars (Grant No.42325502)the 2nd Scientific Expedition to the Qinghai–Tibet Plateau (Grant No.2019QZKK0102)+3 种基金the West Light Foundation of the Chinese Academy of Sciences (Grant No.xbzg-zdsys-202215)the Science and Technology Research Plan of Gansu Province (Grant Nos.23JRRA654 and 20JR10RA070)the Youth Innovation Promotion Association of the Chinese Academy of Sciences (Grant No.QCH2019004)iLEAPS (integrated Land Ecosystem–Atmosphere Processes Study)。
文摘The source region of the Yellow River, accounting for over 38% of its total runoff, is a critical catchment area,primarily characterized by alpine grasslands. In 2005, the Maqu land surface processes observational site was established to monitor climate, land surface dynamics, and hydrological variability in this region. Over a 10-year period(2010–19), an extensive observational dataset was compiled, now available to the scientific community. This dataset includes comprehensive details on site characteristics, instrumentation, and data processing methods, covering meteorological and radiative fluxes, energy exchanges, soil moisture dynamics, and heat transfer properties. The dataset is particularly valuable for researchers studying land surface processes, land–atmosphere interactions, and climate modeling, and may also benefit ecological, hydrological, and water resource studies. The report ends with a discussion on perspectives and challenges of continued observational monitoring in this region, focusing on issues such as cryosphere influences, complex topography,and ecological changes like the encroachment of weeds and scrubland.
基金funded by the National Key R&D Program of China(2021YFE0112400 and 2023YFF1304303)the National Natural Science Foundation of China(32361143870 and 32101315)。
文摘The response of N_(2)O emissions to nitrogen(N)addition is usually positive,but its response to phosphorus(P)addition varies,and the underlying mechanisms for the changes in N_(2)O emissions remain unclear.We conducted field studies to examine the response of N_(2)O emissions to N and P addition over two years in three typical alpine grasslands,alpine meadow(AM),alpine steppe(AS),and alpine cultivated grassland(CG)on the Qinghai-Tibet Plateau(QTP).Our results showed consistent increases in N_(2)O emissions under N addition alone or with P addition,and insignificant change in N_(2)O emissions under P addition alone in all three grasslands.N addition increased N_(2)O emissions directly in AM,by lowering soil pH in AS,and by lowering abundance of denitrification genes in CG.N and P co-addition increased N_(2)O emissions in AM and AS but only showed an interactive effect in AM.P addition enhanced the increase in N_(2)O emissions caused by N addition mainly by promoting plant growth in AM.Overall,our results illustrate that short-term P addition cannot alleviate the stimulation of N_(2)O emissions by N deposition in alpine grassland ecosystems,and may even further stimulate N_(2)O emissions.
基金financially supported by the National Basic Research Program of China(2009CB825103)
文摘Fractal geometry is an important method in soil science,and many studies have used fractal theory to examine soil properties and the relationships with other eco-environmental factors.However,there have been few studies examining soil particle volume fractal dimension in alpine grasslands.To study the volume fractal dimension of soil particles （D） and its relationships with soil salt,soil nutrient and plant species diversity,we conducted an experiment on an alpine grassland under different disturbance degrees：non-disturbance （N0）,light disturbance （L）,moderate disturbance （M） and heavy disturbance （H）.The results showed that （1） Ds varied from 2.573 to 2.635 among the different disturbance degrees and increased with increasing degrees of disturbance.（2） Shannon-Wiener diversity index,Pielou＇s evenness index and Margalef richness index reached their highest values at the M degree,indicating that moderate disturbance is beneficial to the increase of plant species diversity.（3） In the L and M degrees,there was a significant positive correlation between D and clay content and a significant negative correlation between D and soil organic matter （SOM）.In the H degree,D was significantly and positively correlated with total salt （TS）.The results suggested that to a certain extent,D can be used to characterize the uniformity of soil texture in addition to soil fertility characteristics.（4） For the L degree,there was a significant negative correlation between D and the Shannon-Wiener diversity index; while for the M degree,there was a significant negative correlation between D and Pielou＇s evenness index.
基金National Key Project for Basic Research,No.G1998040800
文摘Using stat ic chamber technique, fluxes of CO 2 , CH 4 and N 2 O were measured in the alpine grassland area from July 2000 to July 2001, d eterminations of mean fluxes showed that CO 2 and N 2 O were gene rally released from the soil, while the alpine grassland accounted for a weak CH 4 sink. Fluxes of CO 2 , CH 4 and N 2 O ranged widely. The highest CO 2 emission occurred in August, whereas a lmost 90% of the whole year emission occurred in the growing season. But the variations of CH 4 and N 2 O fluxes did not show any clear patterns over the one-year-experim ent. During a daily variation, the maximum CO 2 emission occurred at 16:00, and then decreased to the minimum emi ssion in the early morning. Daily pattern analyses indicated that the variation in CO 2 fluxes was positively related to air temperatures (R 2 =0.73) and soil temperatures at a depth of 5 cm (R 2 =0.86), whereas daily variations in CH 4 and N 2 O fluxes were poorly explained by soil temperatures and climatic va riables. CO 2 emissions in this area were much lower than other grasslands in plain areas .
基金funded by the National Basic Research Program of China (2009CB825103)the National Natural Science Foundation of China (41340041)the West Light Foundation of the Chinese Academy of Sciences (XBBS201206)
文摘Methane （OH4）, carbon dioxide （CO2） and nitrous oxide （N2O） are known to be major greenhouse gases that contribute to global warming. To identify the flux dynamics of these greenhouse gases is, therefore, of great significance. In this paper, we conducted a comparative study on an alpine grassland and alpine wetland at the Bayinbuluk Grassland Eco-system Research Station, Chinese Academy of Sciences. By using opaque, static, manual stainless steel chambers and gas chromatography, we measured the fluxes of CH4, N2O and CO2 from the grassland and wetland through an in situ monitoring study from May 2010 to October 2012. The mean flux rates of CH4, N2O and CO2 for the experimental alpine wetland in the growing season （from May to October） were estimated at 322.4 μg/（m2.h）, 16.7 μg/（m2.h） and 76.7 mg/（m2.h）, respectively; and the values for the alpine grassland were -88.2 μg/（m2.h）, 12.7 μg/（m2.h）, 57.3 mg/（m2.h）, respectively. The gas fluxes showed large seasonal and annual variations, suggesting weak fluxes in the non-growing season. The relationships between these gas fluxes and environmental factors were analyzed for the two alpine ecosystems. The results showed that air temperature, precipitation, soil temperature and soil moisture can greatly influence the fluxes of CH4, N2O and CO2, but the alpine grassland and alpine wetland showed different feedback mechanisms under the same climate and environmental conditions.
基金supported by the CAS/SAFEA International Partnership Program for Creative Research Teams (KZZD-EW-TZ-06)
文摘Understanding the vertical distribution patterns of soil microbial community and its driving factors in alpine grasslands in the humid regions of the Tibet Plateau might be of great significance for predicting the soil microbial community of this type of vegetation in response to environmental change. Using phospholipid fatty acids （PLFA）, we investigated soil microbial community composition along an elevational gradient （3094-4131 m above sea level） on Mount Yajiageng, and we explored the impact of plant functional groups and soil chemistry on the soil microbial community. Except for Arbuscular Mycorrhizal fungi （AM fungi） biomarker 18：2ω6,9 increasing significantly, other biomarkers did not show a consistent trend with the elevational gradient. Microbial biomass quantified by total PLFAs did not show the elevational trend and had mean values ranging from 1.64 to 4.09 ktmol per g organic carbon （OC）, which had the maximum value at the highest site. Bacterial PLFAs exhibited a similar trend with total PLFAs, and its mean values ranged from 0.82 to 1.81 μmol （g OC）-1. The bacterial to fungal biomass ratios had the minimum value at the highest site, which might be related to temperature and soil total nitrogen （TN）. The ratios of Gram-negative to Gram-positive bacteria had a significantly negative correlation with soil TN and had the maximum value at the highest site. Leguminous plant coverage and soil TN explained 58% of the total variation in the soil microbial community and could achieve the same interpretation as the whole model. Other factors may influence the soil microbial community through interaction with leguminous plant coverage and soil TN. Soil chemistry and plant functional group composition in substantial amounts explained different parts of the variation within the soil microbial community, and the interaction between them had no impact on the soil microbial community maybe beeause long-term grazing greatly reduces litter. In sum, although there were obvious differences in soil microbial communities along the elevation gradient, there were no clear elevational trends found in general. Plant functional groups and soil chemistry respectively affect the different aspects of soil microbial community. Leguminous plant coverage and soil TN had important effects in shaping soil microbial community.
基金financially supported by the Natural Science Foundation of China (U1303201, No. 31400440 and No. 31370512)China Agriculture Research System (CARS-34)+2 种基金Natural Science Foundation of Yunnan Province (2016FB059)funding for Airong Li from The Youth Innovation Promotion Association of Chinese Academy of Sciencesthe Young Academic and Technical Leader Raising Foundation of Yunnan Province (2014HB047)
文摘Fertilization has been shown to have suppressive effects on arbuscular mycorrhizal fungi(AMF) and root hemiparasites separately in numerous investigations, but its effects on AMF in the presence of root hemiparasites remain untested. In view of the contrasting nutritional effects of AMF and root hemiparasites on host plants, we tested the hypothesis that fertilization may not show strong suppressive effects on AMF when a plant community was infested by abundant hemiparasitic plants. Plants and soil samples were collected from experimental field plots in Bayanbulak Grassland, where N and P fertilizers had been applied for three continuous years for control against a spreading root hemiparasite, Pedicularis kansuensis. Shoot and root biomass of each plant functional group were determined. Root AMF colonization levels, soil spore abundance, and extraradical hyphae length density were measured for three soil depths(0 e10 cm, 10 e20 cm, 20 e30 cm). Partial 18 S r RNA gene sequencing was used to detect AMF diversity and community composition. In addition, we analyzed the relationship between relative abundance of different AMF genera and environmental factors using Spearman's correlation method. In contrast to suppressive effects reported by many previous studies, fertilization showed no significant effects on AMF root colonization or AMF species diversity in the soil. Instead, a marked increase in soil spore abundance and extraradical hyphae length density were observed. However, fertilization altered relative abundance and AMF composition in the soil. Our results support the hypothesis that fertilization does not significantly influence the abundance and diversity of AMF in a plant community infested by P. kansuensis.
基金funded by the Youth Projects of National Natural Science Foundation of China(Grants No.41701100)the Science and technology project of Sichuan Provincial Department of Education(Grants No.15ZB0023)。
文摘Alpine grassland is the typical vegetation in the eastern Qinghai–Tibetan Plateau,which has important ecological service functions,and also supports the development of alpine stock farming.In recent years,under both the natural and human disturbance,alpine grasslands in this area have appeared to different degrees of desertification.A diagnosis of the desertification degree serves as the basis for grassland ecological restoration.This study constructs a comprehensive index based on remote sensing called alpine grassland desertification index(AGDI)to monitor the areas and degree of desertification.The most relevant indicators of desertification,namely,vegetation fraction,aboveground biomass,soil moisture,and land surface temperature,were selected to establish AGDI.The geographical detector is used to reselect and assess these indicators.The results show that the overall verification accuracy of AGDI is 82.05%.In particular,the accuracy of identifying severe desertification is the highest.Our study confirms that the desertification of alpine grasslands in the eastern Qinghai–Tibetan Plateau is characterized by fragmentation.Thus,Landsat-8 OLI data with a spatial resolution of 30 m is more suitable than MODIS data for alpine grasslands desertification monitoring.The research results can provide a methodological reference for monitoring desertification of alpine grasslands and other grassland regions in the world.
文摘In this study, two different methods including Digital Camera and Reference Panel （DCRP） and traditional in situ fPAR observation for measuring the in situ point fPAR of very short alpine grass vegetation were compared, and the Moderate Resolution Imaging Spectroradiometer （MODIS） fPAR products were evaluated and validated by in situ point data on the alpine grassland over the Northern Tibetan Plateau, which is sensitive to climate change and vulnerable to anthropogenic activities. Results showed that the MODIS alpine grassland fPAR product, examined by using DCRP, and traditional in situ fPAR observation had a significant relationship at the spatial and temporal scales. The decadal MODIS fPAR trend analysis showed that, average growing season fPAR increased by 1.2 × 10^-4 per year and in total increased 0.86% from 2002 to 2011 in alpine grassland, when most of the fPAR increments occurred in southeast and center of the Northern Tibetan Plateau, the alpine grassland tended to recover from degradation slightly. However, climatic factors have influenced the various alpine grassland vegetation fPAR over a period of 10 years; precipitation significantly affected the alpine meadow fPAR in the eastern region, whereas temperature considerably influenced the alpine desert steppe fPAR in the west region. These findings suggest that the regional heterogeneity in alpine grassland fPAR results from various environmental factors, except for vegetation characteristics, such as canopy structure and leaf area.
文摘Knowledge of nitrous oxide(N_(2)O)exchanges through soils and atmosphere in various ecosystems has been of great importance in global climate change studies.However,the relative magnitude of surface and subsurface N_(2)O production sources from the alpine grassland ecosystem is unclear.In the present study,the N_(2)O concentration profile from 1.5 m in depth in soil to 32 m in height in air was measured from July 2000 to July 2001 in alpine grassland located in the permafrost area of the Qinghai-Xizang Plateau,which revealed that N_(2)O concentrations had a distinct variation pattern both in air and in soil during the study period.Mean N_(2)O concentrations in the atmosphere were significantly lower than those in the soil,which induced the N_(2)O emission from the alpine steppe soil into the atmosphere.Mean flux of N_(2)O in this alpine grassland experiment site was 0.05×10^(-4)μmol·m^(-2)·s^(-1).But the variation in N_(2)O emissions did not show any clear trends over the whole-year experiment in our study site.The highest N_(2)O concentration was found at the depth of 1.5 m in the soil while the lowest N_(2)O concentration occurred at the height of 8 m in the atmosphere.Mean N_(2)O concentrations in the soil increased significantly with depth.This was the influence of increasing soil moistures,which induced the increasing denitrification potential with depth.The mean N_(2)O concentrations at different heights in the air remained a more steady state because of the atmospheric negotiability.Seasonal variations of N_(2)O concentrations showed significant correlations between the neighbor layers both in the soil and in the atmosphere.The seasonal variations of N_(2)O concentrations at all horizons in the soil showed very clear patterns,with the highest concentrations occurring from the onset of frost to the freeze-thaw period and lowest concentrations occurring during the spring and the summer.Further analyses showed that the seasonal variations of N_(2)O concentrations in the soil were hardly explained by soil temperatures at any depth.Temporally,atmospheric N_(2)O concentrations at all heights exhibited almost the same seasonal pattern with the soil N_(2)O variations,while soil is believed to be the predominant natural source of atmospheric N_(2)O near the earth surface in this alpine grassland area.Also,a significant correlation was found between N_(2)O emissions and soil N_(2)O concentrations at 0.2 m in depth during the study period.This implied the variation of N_(2)O concentrations in the soil surface horizon was the most direct driving force of N_(2)O exchanges between the soil and the atmosphere.Soil atmospheric N_(2)O at surface layers is the main source of N_(2)O emissions from the soil surface to the atmosphere.Soil N_(2)O concentrations at deeper layers were all significantly higher than those at surface layers,which indicated that N_(2)O was diffused from the deeper layers to the surface layers in the soil,and finally was emitted to the atmosphere.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program(Grant Nos.2019QZKK0301 and 2019QZKK0307)。
文摘The Qinghai-Tibet Plateau(QTP)has the largest and highest alpine grassland ecosystem in the world,which is considered to be the most sensitive and vulnerable ecosystem to climate change.Its dynamic changes and driving mechanism have always been widely researched.The Qomolangma National Nature Preserve(QNNP),with the largest altitude difference in the world,was selected as the study area to analyse the spatial-temporal dynamics of grassland coverage and the different characteristics of elevation gradients at the southern slope(SS)and northern slope(NS)with MODIS MOD13Q1 NDVI and MOD11A2 land surface temperature data from 2000to 2019 using the Mann-Kendall trend test and Theil-Sen slope methods.Further,the response mechanism of grassland coverage to climate warming is discussed.The results revealed that from 2000 to 2019,the grassland coverage change in the study area is mainly stable.The increased area proportion of grassland coverage on the southern slope is significantly higher than that on the northern slope,and the decreased area proportion of grassland coverage on the northern slope is significantly greater than that on the southern slope.The change characteristics of grassland coverage in the QNNP exhibit an obvious elevation gradient;the higher the elevation,the greater the increased area proportion of grassland coverage,particularly on the SS.The land surface temperature can be used as a proxy for analysing the temporal and spatial variation trends of air temperature in the QNNP.With the increase of the altitude,the land surface temperature rise rate on both the southern slope and northern slope exhibited an increasing trend,and the sensitivity of grassland coverage to temperature rise was higher on the northern slope.The water condition was the decisive factor for the horizontal and vertical spatial heterogeneity of the dynamic change of grassland coverage,and the melting of glaciers and thawing of permafrost were important sources of water for grassland growth in the QNNP.Climate warming promotes the growth of grassland in areas with a sufficient water supply,but adversely affects the growth of grassland in areas with insufficient water supplies,which will be further intensified by human activities.
文摘Characteristics of plant species diversity of two types of grassland communities (alpine meadow and alpine grassland) was examined and the relationship between species diversity and community dynamics was determined using GPS positioning and in situscrutinization of community of alpine grassland in Nakchu prefecture of Tibet Autonomous Region. The result indicated that: ① there was an unobvious difference between grassland communities in terms of richness index of plant, evenness index, dominant index and diversity index. The species diversity index followed the order Kobresia humilis meadow >Stipa purpurea steppe>K. littledalei meadow; ② the original community created high diversity, while the degenerative community suffering from serious disturbance was of low diversity; ③ the diversity of community plants was closely related to changes of species biomass, and the growth and decline of species in the community; ④ grazing disturbance is a key factor of community dynamics, leading to coexistence of various secondary successions of communities, diversified suitable habitats and species diversity. improvements
基金funded by the National Natural Science Foundation of China (31100337)the Scientific Research Foundation of Nanjing University of Information Science & Technology (2243141301132)
文摘The change of freeze-thaw pattern of the Tibetan Plateau under climate warming is bound to have a profound impact on the soil process of alpine grassland ecosystem;however,the research on the impact of the freeze-thaw action on nitrogen processes of the alpine grassland ecosystem on the Tibetan Plateau has not yet attracted much attention.In this study,the impact of the freezing strength on the soil nitrogen components of alpine grassland on the Tibetan Plateau was studied through laboratory freeze-thaw simulation experiments.The 0–10 cm topsoil was collected from the alpine marsh meadow and alpine meadow in the permafrost region of Beilu River.In the experiment,the soil samples were cultivated at –10℃,–7℃,–5℃,–3℃ and –1℃,respectively for three days and then thawed at 2℃ for one day.The results showed that after the freeze-thaw process,the soil microbial biomass nitrogen significantly decreased while the dissolved organic nitrogen and inorganic nitrogen significantly increased.When the freezing temperature was below –7℃,there was no significant difference between the content of nitrogen components,which implied a change of each nitrogen component might have a response threshold toward the freezing temperature.As the freeze-thaw process can lead to the risk of nitrogen loss in the alpine grassland ecosystem,more attention should be paid to the response of the soil nitrogen cycle of alpine grasslands on the Tibetan Plateau to the freeze-thaw process.
基金National Key Project for Basic Research on Tibetan Plateau(G1998040800)
文摘In this paper, the CO2 concentrations profile from 1.5 m depth in soil to 32 m height in atmosphere were measured from July 2000 to July 2001 in an alpine grassland ecosystem located in the permafrost area on the Tibetan Plateau, which revealed that CO2 concentrations varied greatly during this study period. Mean concentrations during the whole experiment in the atmosphere were absolutely lower than the CO2 concentrations in soil, which resulted in CO2 emissions from the alpine steppe soil to the atmosphere. The highest CO2 concentration was found at a depth of 1.5 m in soil while the lowest CO2 concentration occurred in the atmosphere. Mean CO2 concentrations in soil generally increased with depth. This was the compositive influence of the increasing soil moistures and decreasing soil pH, which induced the increasing biological activities with depth. Temporally, the CO2 concentrations at different layers in air remained a more steady state because of the atmospheric turbulent milking. During the seasonal variations, CO2 concentrations at surface soil interface showed symmetrical patterns, with the lowest accumulation of CO2 occurring in the late winter and the highest CO2 concentration in the growing seasons.
文摘In this article, we mainly analysis the soil carbon storage of the alpine grassland under different land uses in Qinghai-Tibet Plateau. The samples of this investigation include six experimental fields which are fenced mowing grassland, artificial grassland, winter and spring grazing meadowland, summer and autumn mild grazing land, summer and autumn moderate grazing pasture and summer and autumn severe grazing land and seven soil layers included 0 cm-5 cm, 5 cm-10 cm, 10 cm-20 cm, 20 cm-30 cm, 30 cm-50 cm, 50 cm-70 cm and 70 cm-100 cm. The results show that the soil carbon storage in different soil layers will gradually reduce and the difference was remarkable （P 〈 0.05）. What is more, the soil carbon storage of alpine grassland under different land uses has following sequence： winter and spring grazing grassland 〉 summer and autumn mild grazing land 〉 artificial grassland 〉 summer and autumn moderate grazing meadowland 〉 summer and autumn severe grazing pasture 〉 fenced mowing meadow, and the significant difference between them is remarkable （P 〈 0.05）.
基金jointly supported by grants from the National Natural Science Foundation(42071139)Gansu province Science Fund for Distinguished Young Scholars(21JR7RA066)the independent grants from the State Key Laboratory of Cryosphere Sciences(SKLCS-ZZ-2021)
文摘Soil organic carbon(SOC)and total nitrogen(TN)stocks are usually calculated with samples collected using core samplers.Although the calculation considers the effects of gravel in soil samples,other coarse fragments such as stones or boulders in soil may not be collected due to the restricted diameter of core samplers.This would cause an incorrect estimation of soil bulk density and ultimately SOC and TN stocks.In this study,we compared the relative volume of coarse fragment and bulk density of fine earth determined by large size soil sampler with three core samplers.We also investigated the uncertainties in estimation of SOC and TN stocks caused by this soil sampler procedure in three typical alpine grasslands on the northeast edge of the Qinghai-Tibetan Plateau(QTP),China.Results show that(1)the relative volume and size of coarse fragment collected by large size sampler were significantly(p<0.05)higher and larger than those of core samplers,while bulk density of fine earth,SOC and TN stocks show opposite patterns in all grassland types;(2)SOC and TN stocks determined by core samplers were 17%-45%and 18%-46%higher than larger size sampler for three typical alpine grasslands;and(3)bulk density of fine earth,SOC and TN stocks exponentially decreased with the increasing of coarse fragment content.We concluded that core sampler methods significantly underestimated the volume occupied by coarse fragment but overestimated SOC and TN stocks.Thus,corrections should be made to the results from core samplers using large size samplers on regions with gravel and stone-rich soils in future studies.
基金Supported by the Financial Research Foundation of Sichuan Academy of Geological Survey(51000023Y000008287156).
文摘At first,the ecological restoration technology of abandoned mines is summarized,and the paths and models of mine ecological restoration in Zoige grassland area under the background of carbon neutrality are analyzed.Moreover,the problems and deficiencies in the current research on mine ecological restoration in Zoige grassland area are initially identified,and the future research trend is prospected to provide a reference for the path of carbon reduction by mine ecological restoration in Zoige grassland area and other alpine grassland areas in the future.
基金The Xizang Autonomous Region Science and Technology Project(XZ202401JD0029,XZ202501ZY0086,XZ202501ZY0056)The National Natural Science Foundation of China(31600432)+1 种基金The Lhasa Science and Technology Plan Project(LSKJ202422)The Chinese Academy of Sciences Youth Innovation Promotion Association(2020054)。
文摘High-precision models enable the visualization of spatiotemporal patterns of soil microorganisms in the Qinghai-Xizang Plateau,a region highly sensitive to global change.However,large-scale,high-resolution data on soil bacterial and fungal communities,particularly in relation to the ecological impacts of fencing,remains relatively scarce,thereby limiting studies on the spatiotemporal distribution patterns of soil fungi and bacteria.This study constructed models of soil fungal and bacterial abundance andα-diversity(total abundance,major phylum abundance,primary functional group abundance,and species/phylogenetic/functionalα-diversity)in the alpine grasslands of the Qinghai-Xizang Plateau,based on observational data and utilizing the random forest method.Under fencing conditions,the variations in soil fungal and bacterial abundance andα-diversity were collectively explained by temperature,precipitation,and radiation,accounting for 46%-88%of the variation;while under grazing conditions,the inclusion of NDVI allowed these four factors to explain 47%-92%of the variation.The relative biases between simulated and observed values for fungal and bacterial abundance andα-diversity were lower than 10.83%,and the simulated values explained the variation in observed values ranging from 75%to 100%.The slopes of the linear regressions between observed and simulated values ranged between 0.81 and 1.00.Consequently,the random forest models constructed in this study demonstrated high accuracy and they can predicted the total abundance,major phylum abundance,primary functional group abundance,andα-diversity of soil microorganisms in alpine grasslands.These models can serve as a robust foundation for future related research.
基金supported by the Regional Science and Technology Collaborative Innovation Special Project of Ngari in Tibetan Autonomous Region of China(QYXTZX-AL2022-05,QYXTZX-AL2024-05)the Second Tibetan Plateau Scientific Expedition and Research Program(2019QZKK0600)+1 种基金the Tibet Central Government Guides Local Funding Projects(XZ202301YD0012C)the Joint Key Research Fund under cooperative agreement between the National Natural Science Foundation of China(NSFC)and Tibet Autonomous Region(TAR)(U20A2005).
文摘We screened 161 eligible papers of experimental data across the Tibetan Plateau for meta-analysis,in order to systematically assess and validate potential application of plant resource allocation strategies,such as the optimal allocation hypothesis,the isometric allocation hypothesis,and the allometric allocation hypothesis under environmental changes,and to explore the effects of environmental factors(temperature change,grazing intensity)on plant resource allocation strategies in alpine grassland ecosystems on the Tibetan Plateau.Overall,we found that the aboveground and belowground growth relationship in alpine grasslands follows the allometric growth hypothesis,which was unaffected by warming,grazing and their interactions.In addition,the biomass transferred between aboveground and belowground,the former was decreased,while the latter was increased under warming conditions in alpine steppe implies that the resource allocation strategy in alpine steppe grassland may potentially follow the optimal allocation hypothesis.We further found that the effect of soil properties on biomass,not the biomass allocation,was different under warming and grazing conditions in alpine grasslands,which further confirms the above conclusion.In addition,warming helped to mitigate the negative effects of grazing,which indicated that the interaction between warming and grazing is important in alpine grassland ecosystems.Overall,the results of this study are of theoretical significance for understanding how moderate grazing affects the growth of plants in alpine grasslands under changing climate.
