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Now showing items 1 - 7 of 7

  • Land Use and Land Cover Change in the Kailash Sacred Landscape of China

    Duan, Cheng   Shi, Peili   Song, Minghua   Zhang, Xianzhou   Zong, Ning   Zhou, Caiping  

    Land use and land cover change (LUCC) is an important driver of ecosystem function and services. Thus, LUCC analysis may lay foundation for landscape planning, conservation and management. It is especially true for alpine landscapes, which are more susceptible to climate changes and human activities. However, the information on LUCC in sacred landscape is limited, which will hinder the landscape conservation and development. We chose Kailash Sacred Landscape in China (KSL-China) to investigate the patterns and dynamics of LUCC and the driving forces using remote sensing data and meteorological data from 1990 to 2008. A supervised classification of land use and land cover was established based on field survey. Rangelands presented marked fluctuations due to climatic warming and its induced drought, for example, dramatic decreases were found in high- and medium-cover rangelands over the period 2000-2008. And recession of most glaciers was also observed in the study period. Instead, an increase of anthropogenic activities accelerated intensive alteration of land use, such as conversion of cropland to built-up land. We found that the change of vegetation cover was positively correlated with growing season precipitation (GSP). In addition, vegetation cover was substantially reduced along the pilgrimage routes particularly within 5 km of the routes. The findings of the study suggest that climatic warming and human disturbance are interacted to cause remarkable LUCC. Tourism development was responsible land use change in urban and pilgrimage routes. This study has important implications for landscape conservation and ecosystem management. The reduction of rangeland cover may decrease the rangeland quality and pose pressure for the carrying capacity of rangelands in the KSL-China. With the increasing risk of climate warming, rangeland conservation is imperative. The future development should shift from livestock-focus animal husbandry to service-based ecotourism in the sacred landscape.
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  • Nutrient limitation of alpine plants: Implications from leaf N : P stoichiometry and leaf delta N-15

    Wanek, Wolfgang   Zhou, Caiping   Richter, Andreas   Song, Minghua   Cao, Guangmin   Ouyang, Hua   Kuzyakov, Yakov  

    Nitrogen (N) deposition can affect grassland ecosystems by altering biomass production, plant species composition and abundance. Therefore, a better understanding of the response of dominant plant species to N input is a prerequisite for accurate prediction of future changes and interactions within plant communities. We evaluated the response of seven dominant plant species on the Tibetan Plateau to N input at two levels: individual species and plant functional group. This was achieved by assessing leaf N : P stoichiometry, leaf delta N-15 and biomass production for the plant functional groups. Seven dominant plant species-three legumes, two forbs, one grass, one sedge-were analyzed for N, P, and delta N-15 2 years after fertilization with one of the three N forms: NO3-, NH4+, or NH4NO3 at four application rates (0, 7.5, 30, and 150 kg N ha(-1) y(-1)). On the basis of biomass production and leaf N : P ratios, we concluded that grasses were limited by available N or co-limited by available P. Unlike for grasses, leaf N : P and biomass production were not suitable indicators of N limitation for legumes and forbs in alpine meadows. The poor performance of legumes under high N fertilization was mainly due to strong competition with grasses. The total above-ground biomass was not increased by N fertilization. However, species composition shifted to more productive grasses. A significant negative correlation between leaf N : P and leaf delta N-15 indicated that the two forbs Gentiana straminea and Saussurea superba switched from N deficiency to P limitation (e. g., N excess) due to N fertilization. These findings imply that alpine meadows will be more dominated by grasses under increased atmospheric N deposition.
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  • Simulated distribution of vegetation types in response to climate change on the Tibetan Plateau

    Zhou, Caiping   Ouyang, Hua  

    Questions: What is the relationship between alpine vegetation patterns and climate? And how do alpine vegetation patterns respond to climate changes?Location: Tibetan Plateau, southwestern China. The total area is 2 500 000 km(2) with an average altitude over 4000 m.Methods: The geographic distribution of vegetation types on the Tibetan Plateau was simulated based on climatology using a small set of plant functional types (PFTs) embedded in the biogeochemistry-biography model BIOME4. The paleoclimate for the early Holocene was used to explore the possibility of simulating past vegetation patterns. Changes in vegetation patterns were simulated assuming continuous exponential increase in atmospheric CO2 concentration, based on a transient ocean-atmosphere simulation including sulfate aerosol effects during the 21st century.Results: Forest, shrub steppe, alpine steppe and alpine meadow extended while no desert vegetation developed under the warmer and humid climate of the early Holocene. In the future climate scenario, the simulated tree line is farther north in most sectors than at present. There are also major northward shifts of alpine meadows and a reduction in shrub-dominated montane steppe. The boundary between montane desert and alpine desert will be farther to the south than today. The area of alpine desert would decrease, that of montane desert would increase.Conclusions: The outline of changes in vegetation distribution was captured with the simulation. Increased CO2 concentration would potentially lead to big changes in alpine ecosystems.
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  • Interactions of plant species mediated plant competition for inorganic nitrogen with soil microorganisms in an alpine meadow

    Song, Minghua   Xu, Xingliang   Hu, Qiwu   Tian, Yuqiang   Hua, Ouyang   Zhou, Caiping  

    Sources of competition for limited soil resources, such as nitrogen, include competitive interactions among different plant species and between plants and soil microbes. We hypothesized that plant interactions intensified plant competition for inorganic nitrogen with soil microorganisms. To test these competitive interactions, one dominant species (Kobresia humilis Serg) and one less abundant gramineous herb (Elymus nutans Griseb) in an alpine ecosystem were selected as target species to grow under interactions with their neighboring plants and without interaction treatments in field plots. N-15-labeled ammonium and nitrate were used to quantify their partition between plants and soil microorganisms for 48 h after tracer additions. Responses of K. humilis to interactions from their surrounding plants were negative, while those of E. nutans were positive. Species identity, inorganic nitrogen forms, and plant interactions significantly affected the total amount of nitrogen utilization by soil microorganisms and plants. Although plant interactions have negative effects on nitrogen uptake of K. humilis, there is an increase in microbial immobilization of nitrogen under presence of its neighbors. For E. nutans, facilitation from surrounding plants is in favor of their nitrogen uptake. Compared with K. humilis, competition for N-15 - NO3- and 15N - NH4+ was less intensive between E. nutans and microorganisms. N-15 - NH4+ recovery by soil microorganisms and plants were not more than or much lower than their utilization of N-15 - NO3- under different interaction treatments. These results suggested that the partitioning of inorganic nitrogen between plants and soil microorganisms is mediated by plant - plant interactions and interactions between plants and soil microorganisms.
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  • Determination of 27 amino acids' levels in seminal plasma of asthenospermia and oligospermia patients and diagnostic value analysis

    Deng, Mingjie   Lin, Feiyan   Zhou, Caiping   Chen, Yuyan   Xuan, Leijie   Wang, Hongzhe   Feng, Tiantian   Hu, Lufeng  

    Amino acids (AAs) are abundant in seminal fluid and play an important role in the reproduction process. However, the functional significance of AAs in seminal is not clear. This study was designed to profile the AAs in seminal fluid of asthenozoospermia (AS) and oligospermia (OL) patients and evaluate its potential diagnostic value. To determine the true function of AAs in seminal fluid, an ultra high performance liquid chromatography-mass spectrometry (UPLC-MS/MS) was developed and validated. The seminal fluid samples collected from 76 AS patients, 58 OL patients, and 76 healthy subjects were determined by UPLC-MS/MS and analyzed by fisher discriminant and receiver operating characteristic (ROC). The results showed that, the AAs levels were dramatically decreased in AS and OL patients compared with healthy subjects. What's more there were significant variation in the AAs profile of AS and OL patients. Specifically, some polar AAs decreased, while nonpolar AAs increased in OL patients. Based on the level of AAs, 93.4 % of original and 90.9 % of cross -validated grouped cases were correctly classified between AS patients, OL patients, and healthy subjects. The further ROC analysis shows that glutamic acid, tyrosine, aspartic acid, proline, and tryptophan have the diagnostic value (P < 0.01) in the three groups. Moreover, aspartic acid and glutamic acid exhibit a high correlation (Correlation Coefficient >0.9) in AS, OL, and healthy subjects. In conclusion, there are significant variation in AAs profile in seminal plasma of AS and OL patients with high accuracy in fisher classification. The associations between the levels of AAs in seminal fluid of AS, OL, and healthy subjects may have clinical applications in providing valuable diagnostic indicator. (C) 2020 Published by Elsevier B.V.
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  • Spatial variability of soil moisture at typical alpine meadow and steppe sites in the Qinghai-Tibetan Plateau permafrost region

    Yang, Zhaoping   Hua Ouyang   Zhang, Xianzhou   Xu, Xingliang   Zhou, Caiping   Yang, Wenbin  

    Permafrost degradation has the potential to significantly change soil moisture. The objective of this study was to assess the variability of soil moisture in a permafrost region using geostatistical techniques. The experiment was conducted in August 2008 in alpine steppe and meadow located in the Qinghai-Tibetan Plateau permafrost region. Four soil depths (0-10, 10-20, 20-30 and 30-40 cm) were analyzed using frequency domain reflectometry, and sampling made of 80 points in a 10 m x 10 m grid were sampled. Soil moisture was analyzed using classical statistics to appropriately describe central tendency and dispersion, and then using geostatistics to describe spatial variability. Classical statistical method indicated that soil moisture in the permafrost region had a normal distribution pattern. Mean surface soil moisture in alpine meadow was higher than that in alpine steppe. The semivariograms showed that soil moisture variability in alpine cold steppe was larger than that in alpine meadow, which decreased with depths. Nugget values in alpine steppe were low (0.1-4.5), in contrast to alpine cold meadow. Soil moisture in alpine steppe had highly structured spatial variability with more than 93.4% spatial heterogeneity, and the range decreased with depth. Soil moisture content in alpine cold meadow had a moderate spatial dependence with a range of 51.3-169.2 m, increasing with depth.
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  • Litter species traits, but not richness, contribute to carbon and nitrogen dynamics in an alpine meadow on the Tibetan Plateau

    Jiang, Jing   Li, Yikang   Wang, Mozhu   Zhou, Caiping   Cao, Guangmin   Shi, Peili   Song, Minghua  

    Litter, as afterlife of plants, plays an important role in driving belowground decomposition processes. Here we tested effects of litter species identity and diversity on carbon (C) and nitrogen (N) dynamics during litter decomposition in N-limited alpine meadow soil from the Qinghai-Tibet Plateau. We incubated litters of four meadow species, a sedge ("S", Kobresia humilis), a grass ("G", Elymus nutans), a herb ("H", Saussurea superba), and a legume ("L", Oxytropis falcata), in monoculture and in mixture with meadow soil. CO2 release was measured 21 times during the incubation, and soil available N and microbial biomass C and N were measured before and after the experiment. The organic C decay rate did not differ much among soils amended with monocultures or mixtures of litter, except in the H, S, L, and S+H treatments, which had much higher decay rates. Potential decomposable C pools were lowest in the control, highest in the L treatment, and intermediate in the S treatment. Mineralized N was completely immobilized by soil microbes in all treatments except the control, S+L, and S+G+L treatments. Litter mixtures had both additive and non-additive effects on CO2-C emission (mainly antagonistic effects), net N mineralization (mainly synergistic), and microbial biomass C and N (both). Overall, these parameters were not significantly correlated with litter species richness. Similarly, microbial C or N was not significantly correlated with litter N content or C/N. However, cumulative CO2-C emission and net N mineralization were positively correlated with litter N content and negatively correlated with litter C/N. Litter N content and C/N rather than litter species richness drove the release of CO2-C and net available N in this ecosystem. The antagonistic effects of litter mixtures contributed to a modest release of CO2-C, but their synergistic effects enhanced net available N. We suggest that in alpine meadow communities, balancing species with high and low N contents will benefit soil carbon sequestration and plant competition for available N with soil microbes.
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