Stipa Purpurea Research Articles

Litter chemical structure is more important than species richness in affecting soil carbon and nitrogen dynamics including gas emissions from an alpine soil

Plant litter can influence many fundamental ecosystem functions during decomposition. However, the mechanism of litter diversity effects on belowground ecological processes remains unclear, especially with regard to soil C and the N cycle in alpine ecosystems. In this study, we incubated the litter of four alpine steppe species (SP: Stipa purpurea, CM: Carex moorcroftii, LP: Leontopodium pusillum, AN: Artemisia nanschanica) alone or in mixture with soil. The litter-mixing experiment was conducted to determine the effects of litter diversity on soil C and N dynamics in an alpine steppe in Northern Tibet. Litter treatments significantly enhanced CO2 and N2O emissions and decreased CH4 immobilization in general; soil organic C, total N, water soluble organic C, water soluble organic N, microbial biomass C, microbial biomass N, and urease activity were also enhanced, while soil total inorganic N was decreased by litter treatments. Plant species richness poorly affected soil C and N dynamics, while litter chemical structure, such as C, N, lingin:N, phenol:N, cellulose, and cellulose:N, significantly affected soil C and N dynamics. Non-additive effects of litter mixture were predominant on soil C and N dynamics, while antagonistic effects were more frequent than synergistic effects. These results indicated that litter addition can significantly impact soil C and N dynamics through non-additive effects of litter mixture, and litter chemical structure is more important than species richness in affecting soil C and N dynamics of the alpine steppe in Northern Tibet.

Spectral characteristics of alpine grassland and their changes responding to grassland degradation on the Tibetan Plateau

Remote sensing is used as the indispensable technology in alpine grassland degradation assessment especially at regional scale on the Tibetan Plateau. However, the lack of field spectral data, as the foundation of remote sensing, due to the formidable natural and climate conditions hinders the understanding of spectral characteristics of alpine grassland and their degradation assessment. In this study, spectral characteristics of alpine grasslands and their changes responding to degradation were explored. The results showed that the main spectral characteristics for discriminating the dominant species of alpine meadow (Kobresia littledalei and Kobresia pygmaea), alpine steppe (Stipa purpurea) and desert (Potentilla fruticosa) are spectral features of chlorophyll, cellulose and water which are related to their growth form, plant inclination and residue of withered leaf sheaths. The spectral curves of alpine meadow have a much smaller variety over the whole spectral region compared to those of alpine steppe and desert which generally have weaker chlorophyll and water absorption features and more noticeable non-vegetation features. Different grassland degradation processes exhibit different patterns of spectral characteristics change due to the species composition, vegetation succession, vegetation coverage and soil background. Grassland degradation can happen without obvious vegetation coverage reduction or even with an increment of NDVI (normalized difference vegetation index). Therefore, the assessment of grassland degradation cannot be fulfilled well using single vegetation index or spectral feature. The combination of several vegetation indices or hyperspectral remote sensing along with the priori knowledge is needed in order to perform the assessment more accurately in further studies.

Effects of soil fertility on the N:P stoichiometry of herbaceous plants on a nutrient-limited alpine steppe on the northern Tibetan Plateau

Plant nutrient concentrations and their correlations with soil nutrient conditions are regarded as effective tools for exploring plant adaptation and resource utilisation strategies in a severe environment. However, few comparative studies have addressed the nutrient traits of different organs along natural fertility gradients. We quantified the nitrogen (N) and phosphorus (P) concentrations and N:P ratios in roots and leaves of 139 plant samples from 14 species on a nutrient-limited alpine steppe on the Tibetan Plateau. Next, we explored the correlation between root and leaf nutrient traits of different plant functional groups as well as soil fertility. Soil P had a significant impact on plant N:P stoichiometry, whereas soil N had little effect on plant nutrient traits. Leaf P and the N:P ratio of legumes exhibited more sensitive responses to soil P than roots. Among non-legume species, however, root N and P concentrations of Stipa purpurea and Orinus thoroldii (grasses) were more sensitive than N and P concentrations of leaves to variations in soil P availability. In contrast, leaf P and the N:P ratio of Leontopodium nanum, Potentilla bifurca and ect. (forbs) exhibited more sensitive responses to soil P than roots. Both root and leaf nutrient traits of Carex moorcroftii (sedges) were uncorrelated with soil fertility. The N:P stoichiometry of different functional groups showed disparate responses to soil P, and even the roots and leaves of the same functional group exhibited inconsistent correlations with soil nutrients. The distinct response patterns to soil nutrient conditions across functional groups helped elucidate the diversification of alpine plant adaptations to nutrient-poor environments and offered insights into quantifying the trade-off of different organs in co-existing species between resource use/conservation “strategies” and soil fertility.

Physiological and proteomic adaptation of the alpine grass Stipa purpurea to a drought gradient.

Stipa purpurea, an endemic forage species on the Tibetan Plateau, is highly resistant to cold and drought, but the mechanisms underlying its responses to drought stress remain elusive. An understanding of such mechanisms may be useful for developing cultivars that are adaptable to water deficit. In this study, we analyzed the physiological and proteomic responses of S. purpurea under increasing drought stress. Seedlings of S. purpurea were subjected to a drought gradient in a controlled experiment, and proteins showing changes in abundance under these conditions were identified by two-dimensional electrophoresis followed by mass spectrometry analysis. A western blotting analysis was conducted to confirm the increased abundance of a heat-shock protein, NCED2, and a dehydrin in S. purpurea seedlings under drought conditions. We detected carbonylated proteins to identify oxidation-sensitive proteins in S. purpurea seedlings, and found that ribulose-1, 5-bisphosphate carboxylase oxygenase (RuBisCO) was one of the oxidation-sensitive proteins under drought. Together, these results indicated drought stress might inhibit photosynthesis in S. purpurea by oxidizing RuBisCO, but the plants were able to maintain photosynthetic efficiency by a compensatory upregulation of unoxidized RuBisCO and other photosynthesis-related proteins. Further analyses confirmed that increased abundance of antioxidant enzymes could balance the redox status of the plants to mitigate drought-induced oxidative damage.

Response ofKobresia pygmaeaandStipa purpureaGrassland Communities in Northern Tibet to Nitrogen and Phosphate Addition

The Tibetan Plateau is of fundamental ecological significance to China, Asia, and the world. In recent years, Tibetan grasslands have suffered from severe degradation due to climate change and anthropogenic disturbance. In this study, nitrogen (N) and phosphate were applied to a moderately degraded Kobresia pygmaea meadow and Stipa purpurea steppe in the arid alpine northern Tibetan Plateau. The results showed that with increasing nitrogenous fertilizer, the height, coverage, biomass, and importance value of the K. pygmaea population decreased whereas the population of S. purpurea exhibited the opposite trend. Application of a mixed fertilizer with the same amount of N and phosphorus (P) (5 g each per m2) doubled the biomass of the K. pygmaea meadow and increased the aboveground biomass of the S. purpurea steppe by 72.3%. The nitrogenous fertilizer increased the total biomass and belowground biomass of the S. purpurea steppe, whereas the mixed fertilizer was beneficial to aboveground grass recovery. Application of 10 g N 5 g P m−2 fertilizer increased aboveground biomass by 164.8%, whereas the belowground biomass was less than the control by 4.7%. The N and P fertilizer did not affect soil pH, except for some changes in soil N and P contents.

Isolation and Functional Analysis of SpWOX13 from Stipa purpurea

Members of the WUSCHEL-related homeobox (WOX) gene family encode plant-specific transcription factors that play key roles in controlling gene expression at all stages of plant development. In the present study, we isolated and characterized SpWOX13 (GenBank accession no. KJ713172), a member of the WOX gene family, from Stipa purpurea. Sequence and phylogenetic analyses showed that SpWOX13 belongs to an ancient clade of WOX genes. A subcellular localization analysis indicated that SpWOX13 localizes in the nucleus. The transcript levels of SpWOX13 were higher in young leaves and the vegetative apex than in other tissues of S. purpurea. Ectopic expression of SpWOX13 in Arabidopsis resulted in late flowering plants as these showed more rosette leaves. Histological analyses of the transgenic plants showed aberrant arrangements in the tunica cell layers of the shoot apical meristem. Scanning electron microscopy analyses revealed that the leaf pavement cells were larger in SpWOX13-overexpressing transgenic plants than in wild type. Our results suggest that SpWOX13 is involved in delaying and/or inhibiting cell differentiation.

黑河天涝池五种植被类型土壤呼吸速率动态特征及其影响因子

PDF HTML阅读 XML下载 导出引用 引用提醒 黑河天涝池五种植被类型土壤呼吸速率动态特征及其影响因子 DOI: 10.5846/stxb201311102706 作者: 作者单位: 兰州大学生命科学学院干旱农业生态研究所草地农业生态系统国家重点实验室,兰州大学生命科学学院干旱农业生态研究所草地农业生态系统国家重点实验室,兰州大学生命科学学院干旱农业生态研究所草地农业生态系统国家重点实验室,兰州大学生命科学学院干旱农业生态研究所草地农业生态系统国家重点实验室,兰州大学生命科学学院干旱农业生态研究所草地农业生态系统国家重点实验室,兰州大学生命科学学院干旱农业生态研究所草地农业生态系统国家重点实验室 作者简介: 通讯作者: 中图分类号: S154.4 基金项目: 国家自然科学基金项目(91025015) Variation in soil respiration rate and factors affecting it in five vegetation types in Tianlaochi catchment in Heihe River Author: Affiliation: State Key Laboratory of Grassland AgroEcosystem,Institute of Arid AgroEcology,School of Life Sciences,Lanzhou University,甘肃,甘肃,甘肃,甘肃,甘肃 Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:对黑河天涝池流域的5种典型植被类型(干草原、亚高山草原、亚高山灌丛、祁连圆柏林和青海云杉林)的土壤呼吸速率及其影响因子进行测定分析。结果表明:5种植被类型土壤呼吸速率具有典型的日变化和月变化模式;5种植被类型土壤呼吸速率大小表现为亚高山草原 > 干草原 > 亚高山灌丛 > 祁连圆柏林 > 青海云杉林,土壤呼吸速率的变化范围因植被类型的不同而有所差异;5种植被类型土壤呼吸速率与土壤温度、地表温度和大气温度呈显著的指数关系,且与地表温度和大气温度的相关性强于土壤温度;5种植被类型的土壤呼吸速率与湿度呈显著的线性负相关,R2为 0.55-0.93,与风速呈显著的线性正相关关系;通过主成分分析表明影响5种植被类型土壤呼吸速率的主要因素各不相同,整体表现为在整个生长季 0-60 cm土壤的水热状况是主要的影响因素,其次是土壤表层的环境因子,最后为太阳辐射。 Abstract:Soil respiration (Rs) is an important component of an ecosystem's carbon cycle and the main pathway for carbon release from the ecosystem into the atmosphere. The transfer of carbon between the ecosystem and atmosphere is of interest in the study of greenhouse gas emission. In order to understand characteristics of the Rs dynamics and the factors controlling it, this study was conducted in five typical vegetation types in Tianlaochi catchment area of the Heihe River, located in Qilian Mountains, Northwestern China. Rs, soil temperature, and soil moisture were measured by an automated soil CO2 flux system (LI-8100) from May to September in 2013, and weather data for the corresponding study period were obtained from the weather station located in the experimental plot. The results showed that Rs in the five vegetation types displayed clear diurnal dynamic pattern. The Rs rate differed in different vegetation types, from the highest in subalpine steppe (2.01 to 12.10 μmol m-2 s-1), followed by Stipa purpurea steppe (1.40 to 8.45 μmol m-2 s-1), subalpine shrub (0.85 to 9.24 μmol m-2 s-1), Sabina przewalskii forest (1.09 to 4.14 μmol m-2 s-1), to the lowest in Picea crassifolia forest (1.25 to 3.19 μmol m-2 s-1). The daily change of Rs followed the fluctuations in surface air temperature, and there was a hysteresis between Rs and soil temperature. Rs rate had obvious seasonal variation, increasing from May and reaching the maximum in July, and then decreasing until the final measurements in September. The statistical analysis indicates that Rs rate was significantly positively correlated with soil temperature, surface air temperature, and air temperature, which relationship can be expressed with an exponential function. In relation to the temperature, Rs rate was more correlated to surface air temperature and air temperature than to soil temperature. For example, surface air temperature explained 79%-95% of the variation of Rs rate during the observation period, and air temperature explained 50%-77%, whereas soil temperature in the top 10 cm layer explained only 23%-47%; Rs rate had a significantly negative correlation with soil moisture in five vegetation types with R2 ranging from 0.55 to 0.93. Further analysis indicated the positive linear correlation between Rs rate and wind speed. Principal component analysis showed that soil temperature and moisture in the top 0-60 cm layer of the soil are the first-line impact factors for Rs rate in five vegetation types. The temperature and moisture in surface soil are the second main impact factor, and solar radiation is the third main factor to affect Rs rate. The results indicate that Rs was significantly different in different vegetation types, and changes in vegetation alter the pattern of the Rs rate. This study has important implications as it helps to understand the role that different vegetation types play in reduction of carbon emission. Such information will lay a foundation for assessing carbon source or carbon sequestration of different vegetation types in Qilian mountainous area. 参考文献 相似文献 引证文献

Transcriptome analysis reveals diversified adaptation of Stipa purpurea along a drought gradient on the Tibetan Plateau.

Natural selection drives species adaptations to biotic and abiotic stresses. Species distributed along a moisture gradient, such as Stipa purpurea, a dominant grass in alpine arid and semi-arid meadows on the Tibetan Plateau, provide an opportunity to evaluate the effects of long-term adaptation to differing degrees of drought stress on gene expression. However, the genetic basis of this divergence remains largely unknown. Next-generation sequencing technologies have provided important genome-wide insights on the evolution of organisms for which genomic information is lacking. To understand how S. purpurea responds to drought stress, we selected five populations distributed along the degressive rainfall line on the northwestern Tibetan Plateau that currently present evolutionary acclimation to localized drought pressure at the physiological and biochemical levels and compared their transcriptome responses. In addition, we performed de novo assembly of the S. purpurea transcriptome using short read sequencing technology and successfully assembled 84,298 unigenes from approximately 51 million sequencing reads. We quantified gene expression level to compare their transcriptome responses using mRNA-Seq and identified differentially expressed transcripts that are involved in primary and secondary plant metabolism, plant hormone synthesis, defense responses, and cell wall synthesis. Furthermore, physiological and biochemical evidence supports that abscisic acid (ABA) accumulation and cell wall strengthening derived from the differential transcripts contribute to the tolerance of S. purpurea to drought stress. The mechanisms by which S. purpurea adapts to drought stress provide new insight into how plants ecologically adapt and evolve.

Grassland Degradation Decrease the Diversity of Arbuscular Mycorrhizal Fungi Species in Tibet Plateau

Arbuscular mycorrhizal (AM) fungi play a vital role in restoration of an ecosystem. Grassland degradation in alpine steppe is severe, but the influence of grassland degradation on AM fungi composition in Tibetan Plateau is still not well understood. This research studied the diversity of arbuscular mycorrhizal fungi in degraded alpine steppe, dominated by Stipa purpurea . The results showed that the species richness and abundance of AM fungi in degraded grasslands significantly decreased. In different typical grasslands species, diversity of AM fungi genus Glomus was much higher than other genera ( Acaulospora and Scutellospora ). Compared with normal grassland, the AM fungal species diversity in moderately degraded grassland decreased by 30%, but in lightly degraded and severely degraded grassland, it highly increased with 15.3% and 13.3%, respectively. The species diversity of genus Glomus in moderately degraded grassland and lightly degraded grassland were higher than for normal grassland. Significant differences were observed in a relative abundance of common dominant species among different degraded grasslands. The proportion of dominant species highly increased with the aggravation of grassland degradation. The results suggest that the grassland mild degradation increased the adaptability and stress resistance of species.

Grassland Degradation Decrease the Diversity of Arbuscular Mycorrhizal Fungi Species in Tibet Plateau

Arbuscular mycorrhizal (AM) fungi play a vital role in restoration of an ecosystem. Grassland degradation in alpine steppe is severe, but the influence of grassland degradation on AM fungi composition in Tibetan Plateau is still not well understood. This research studied the diversity of arbuscular mycorrhizal fungi in degraded alpine steppe, dominated by Stipa purpurea. The results showed that the species richness and abundance of AM fungi in degraded grasslands significantly decreased. In different typical grasslands species, diversity of AM fungi genus Glomus was much higher than other genera (Acaulospora and Scutellospora). Compared with normal grassland, the AM fungal species diversity in moderately degraded grassland decreased by 30%, but in lightly degraded and severely degraded grassland, it highly increased with 15.3% and 13.3%, respectively. The species diversity of genus Glomus in moderately degraded grassland and lightly degraded grassland were higher than for normal grassland. Significant differences were observed in a relative abundance of common dominant species among different degraded grasslands. The proportion of dominant species highly increased with the aggravation of grassland degradation. The results suggest that the grassland mild degradation increased the adaptability and stress resistance of species.

Comparing the relationship between seed germination and temperature forStipaspecies on the Tibetan Plateau

Alpine steppe grasslands dominated by Stipa species (Poaceae) on the Tibetan Plateau are important model ecosystems. Here, we present data on seed germination of three typical Stipa species (Stipa purpurea Griseb., Stipa glareosa P.A.Smirn., and Stipa capillacea Keng) from the northern core region of the Tibetan Plateau. We carried out laboratory investigations of germination behavior under both constant and alternating temperatures. Germination varied significantly with temperature. Under constant temperature, we found that temperature and species, but not their interaction, had significant effects on seed germination. Under alternating temperatures, species had a significant effect on seed germination, whereas the effects of alternating temperature and the interaction between species and alternating temperature were not significant. In addition, light and the interaction of light and species had no significant effect on seed germination; however, species had a significant effect, implying that Stipa species on the Tibetan Plateau are not inhibited by light. Base temperatures of S. glareosa, S. purpurea, and S. capillacea were 1.0 °C, 0.1 °C, and –1.4 °C, respectively, with corresponding thermal times at suboptimal temperatures of 233 °C-day, 154 °C-day, and 263.2 °C-day. Our results suggest that Stipa seed germination characteristics are adaptions to a harsh environment and are species-specific.

Stoichiometry of root and leaf nitrogen and phosphorus in a dry alpine steppe on the Northern Tibetan Plateau.

Leaf nitrogen (N) and phosphorus (P) have been used widely in the ecological stoichiometry to understand nutrient limitation in plant. However,few studies have focused on the relationship between root nutrients and environmental factors. The main objective of this study was to clarify the pattern of root and leaf N and P concentrations and the relationships between plant nitrogen (N) and phosphorus (P) concentrations with climatic factors under low temperature conditions in the northern Tibetan Plateau of China. We conducted a systematic census of N and P concentrations, and the N∶P ratio in leaf and root for 139 plant samples, from 14 species and 7 families in a dry Stipa purpurea alpine steppe on the northern Tibetan Plateau of China. The results showed that the mean root N and P concentrations and the N∶P ratios across all species were 13.05 mg g−1, 0.60 mg g−1 and 23.40, respectively. The mean leaf N and P concentrations and the N∶P ratio were 23.20 mg g−1, 1.38 mg g−1, and 17.87, respectively. Compared to global plant nutrients concentrations, plants distributing in high altitude area have higher N concentrations and N∶P, but lower P concentrations, which could be used to explain normally-observed low growth rate of plant in the cold region. Plant N concentrations were unrelated to the mean annual temperature (MAT). The root and leaf P concentrations were negatively correlated with the MAT, but the N∶P ratios were positively correlated with the MAT. It is highly possible this region is not N limited, it is P limited, thus the temperature-biogeochemical hypothesis (TBH) can not be used to explain the relationship between plant N concentrations and MAT in alpine steppe. The results were valuable to understand the bio-geographic patterns of root and leaf nutrients traits and modeling ecosystem nutrient cycling in cold and dry environments.

Below‐ground competition drives the self‐thinning process of Stipa purpurea populations in northern Tibet

AbstractQuestionsAbove‐ground, below‐ground and individual mass–density relationships for perennial herbs were examined along a natural precipitation gradient in northern Tibet. We asked: (1) how do the self‐thinning exponents respond to variation in precipitation; and (2) what mechanisms drive the observed population self‐thinning?LocationThe alpine grassland of northern Tibet.MethodsForty‐seven fenced sites along a precipitation gradient were established and surveyed in 2011 and 2012. Data (geographic coordinates, elevation, and vegetation information) were collected for Stipa purpurea populations at each site. Population self‐thinning exponents were estimated using reduced major axis regression.ResultsThe self‐thinning exponents for below‐ground (−1.27, −0.47) and individual biomass (−1.26, −0.46) increased with increasing mean annual precipitation, but those for above‐ground biomass decreased with precipitation (0.18, −0.25). Soil resources (moisture and nutrients) are a more important constraining factor for below‐ground components than light is for above‐ground components. Root competition for below‐ground resources dominated in S. purpurea population self‐thinning. The driving force of density regulation changed from above‐ground competition to below‐ground competition with increased drought stress. Our results indicate that an increased root/shoot ratio was linked to enhanced below‐ground competition and weakened above‐ground competition. Our study further confirmed the hypothesis that plant populations in different environments exhibit different biomass allocation patterns, which, in turn, leads to different biomass–density relationships.ConclusionsOur study revealed the mechanisms of population self‐thinning for perennial herbs in the extreme environment of northern Tibet, where below‐ground processes play a critical role in regulating population self‐thinning. Our study also advances understanding of the interactions between above‐ and below‐ground processes, providing baseline knowledge useful for local grassland management.

Molecular cloning and characterization of a novel SK3-type dehydrin gene from Stipa purpurea

Stipa purpurea, an endemic forage of the grass family in the Tibetan Plateau, is highly resistant to drought. Dehydrins (DHNs) are stress proteins involved in plant protective reactions against environmental stress. In this study, the full-length DHN open reading frame (ORF) cloned from S. purpurea, named SpDHN1, was 816 nucleotides length and encoded a protein of 271 amino acids. Phylogenetic and sequence characterization analysis revealed that the DHN gene was an SK3-type DHNs. Subcellular localization analysis indicated that SpDHN1 was localized in the cytoplasm and the plasma membrane. SpDHN1 function analysis provided new evidence to support the antioxidation of SpDHN1 in plant responses drought stress. Ectopic expression of SpDHN1 in Arabidopsis thaliana plants showed more resistance to drought stress than the wild-type, indicating that SpDHN1 may be a potential candidate gene for genetic improvement of crops to improve stress tolerance.

Spatiotemporal Variation in Soil Nutrient of Stipa purpurea Steppe Fenced in the Qinghai Lake Region

Soil restoration is a major aspect of ecological restoration.The study was conducted in Stipa purpurea steppe fenced for years,to detect the spatiotemporal variation of soil nutrient after fencing.The results showed that in the same plot the contents of available N,P and K in surface layer significantly higher than those in the second layer,and there were no significant differences among the lower layers.Fencing had different effects on different available nutrients: It had little effect on available K,however,the content of available P was mostly higher than that of CK,and the content of available N was a bit higher than that of CK.Fencing had little effects on the content of total K and total P,while the content of total N decreased with soil depth,and was higher than that of CK in the surface layer after fencing(increased by 19.9%).The content of soil organic matter(SOM) decreased with soil depth,and long time fencing resulted in the elevation of SOM content.Correlation analysis showed that the contents of available K and total K had no significant correlation,the contents of available P and total P,available N and total N both showed significant correlation,and SOM only showed significant correlation with total nitrogen among total nutrients.And fencing resulted in slightly elevation of pH value;Soil bulk density increased with soil depth,but no significant difference was found between fencing and CK.Fencing resulted in elevation of soil nutrient,but it was a very slow course,so the protection for Stipa purpurea steppe should be preceded.

Dynamics of above- and below-ground biomass and C, N, P accumulation in the alpine steppe of Northern Tibet

The temporal dynamics of the biomass, as well as the carbon (C), nitrogen (N), phosphorus (P) concentrations and accumulation contents, in aboveand below-ground vegetation components were determined in the alpine steppe vegetation of Northern Tibet during the growing season of 2010. The highest levels of total biomass (311.68 g m−2), total C (115.95 g m−2), total N (2.60 g m−2), and total P (0.90 g m−2) accumulation contents were obtained in August in 2010. Further, biomass and nutrient stocks in the below-ground components were higher than those of the above-ground components. The dominant species viz., Stipa purpurea and Carex moorcrofti had lower biomass and C, N, P accumulations than the companion species which including Oxytropis. spp., Artemisia capillaris Thunb., Aster tataricus L., and so on.

Biomass estimation of alpine grasslands under different grazing intensities using spectral vegetation indices

We measured and analyzed the spectral reflectance characteristics and biophysical properties such as biomass and vegetation cover of purple feather-grass (Stipa purpurea) alpine steppe grassland under different grazing intensities (no grazing, light, moderate, and heavy grazing) during the growing season. We investigated the effects of grazing intensities on the spectral reflectance and red edge parameters of S. purpurea alpine steppe grassland and established potential models of biomass estimation based on the relationship of spectral vegetation indices and measured alpine grassland biomass in Northern Tibet, China. The results indicated that the spectral reflectance of alpine grassland is similar to the spectral characteristics of typical green vegetation. Reflectance in the near-infrared region of the no grazing treatment was higher than the grazing treatments, while the reflectance of the no grazing treatment in the visible light region was weaker than the grazing treatments. With enhanced grazing intensity, the spectral reflectance of grass canopy followed an increasing trend; the red edge position moved to longer wavelengths, and the amplitude of the red edge decreased in alpine grassland. A significant relationship of measured aboveground biomass and vegetation indices was caculated based on spectral reflectance. Hence, the optimized soil adjusted vegetation index is prefered for the estimation of aboveground biomass of S. purpurea alpine steppe in Northern Tibet, China.

Microsatellite primers in Stipa purpurea (Poaceae), a dominant species of the steppe on the Qinghai–Tibetan Plateau

Microsatellite markers were developed in Stipa purpurea, a dominant species of the steppe and meadow on the Qinghai-Tibetan Plateau. Using the combined biotin capture method, 15 microsatellite primer sets were isolated and characterized. Eleven of these markers showed polymorphism, and the number of alleles per locus ranged from two to seven across 96 individuals from four populations. These markers provide a useful tool to investigate the spatial genetic structure and mating system of Stipa purpurea.

Photosynthetic characteristics of <I>Stipa purpurea</I> under irrigation in northern Tibet and its short-term response to temperature and CO<SUB>2</SUB> concentration

Photosynthetic characteristics of <I>Stipa purpurea</I> under irrigation in northern Tibet and its short-term response to temperature and CO<SUB>2</SUB> concentration

Distribution of Stipa purpurea steppe in the Northeastern Qinghai-Xizang Plateau (China)

The aims of this study were to examine the spatial distribution pattern of Stipa purpurea steppe and to elucidate their possible correlation with environmental factors, by means of multivariate quantitative analysis. Two data sets were subjected to the Two-way Indicator Species Analysis (TWINSPAN), the community similarity analysis and the Detrended Correspondence Analysis (DCA) and Canonical Correspondence Analysis (CCA). The distribution pattern of Stipa purpurea steppe showed obvious geographical heterogeneity in different regions and some homogeneity in the same region. And the altitude, longitude and latitude were the three major environmental factors affecting Stipa purpurea steppe's distribution.