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1.
Understanding of treeline ecotone ecophysiological adaptation to climate warming is still very limited. Furthermore, it is difficult to predict which plant species could dominate in the future. For this reason, a study was conducted in the treeline ecotone, East Tibetan Plateau to detect the adaptation of the dwarf willow(Salix eriostachya) to experimental warming. Compared to ambient conditions, the experimental warming advanced the bud break by 12 days, delayed the leaf abscission by20 days, and prolonged the growing period by 28 days.It also increased photosynthesis(47%), number of leaves(333%), leaf area(310%), and carbon sequestration of the dwarf willow. Experimental warming did not affect carbon use efficiency, but decreased water use efficiency significantly.Experimental warming enhanced the clonal ramets of Salix eriostachya(+ 3.7 shrubs m-2). The frequent air temperature fluctuations had minor effect on Salix eriostachya. Based on these findings, we highlighted that Salix eriostachya could dominate in the community treeline ecotone of east Tibetan Plateau in the future climate warming scenario.  相似文献   

2.
Climate warming is expected to advance treelines to higher elevations. However, empirical studies in diverse mountain ranges give evidence of both advancing alpine treelines as well as rather insignificant responses. In this context, we aim at investigating the sensitivity and responsiveness of the near-natural treeline ecotone in Rolwaling Himal, Nepal, to climate warming. We analysed population densities of tree species along the treeline ecotone from closed forest stands via the krummholz belt to alpine dwarf shrub heaths (3700-4200 m) at 50 plots in 2013 and 2014. We quantified species - environment relationships, i.e. the change of environmental conditions (e.g., nutrient and thermal deficits, plant interactions) across the ecotone by means of redundancy analyses, variation partitioning and distance-based Moran's eigenvector maps. In particular, we focus on explaining the high competitiveness of Rhododendron campanulatum forming a dense krummholz belt and on the implications for the responsiveness of Himalayan krummholz treelines to climate change. Results indicate that treeline trees in the ecotone show species-specific responses to the influence of environmental parameters, and that juvenile and adult tree responses are modulated by environmental constraints in differing intensity. Moreover, the species - environment relationships suggest that the investigated krummholz belt will largely prevent the upward migration of other tree species and thus constrain the future response of Himalayan krummholz treelines to climate warming.  相似文献   

3.
The alpine treeline ecotone is an important component of mountain ecosystems of the Nepal Himalaya; it plays a vital role in the livelihood of indigenous people, and provides ecosystem services. However, the region faces a problem of paucity of data on treeline characteristics at the regional and landscape scales. Therefore, we used Remote Sensing (RS), and Geographic Information Science (GIS) approaches to investigate cross-scale interactions in the treeline ecotone. Additionally, European Space Agency land cover map, International Center for Integrated Mountain Development (ICIMOD) land cover map, ecological map of Nepal, and United States Geological Survey Shuttle Radar Topography Mission-Digital Elevation Model were used to analyze treeline pattern at the regional scale. Digital Globe high-resolution satellite imagery of Barun (eastern Nepal) and Manang (central Nepal) were used to study treeline patterns at the landscape scale. Treeline elevation ranges from 3300-4300 m above sea level. Abies spectabilis, Betula utilis, and Pinus wallichiana are the main treeline-forming species in the Nepal Himalaya. There is an east to west treeline elevation gradient at the regional scale. No slope exposure is observed at the regional scale; however, at the landscape scale, slope exposure is present only in a disturbed area (Manang). Topography and human disturbance are the main treeline controlling factor in Barun and Manang respectively.  相似文献   

4.
Variations in leaf functional traits of Abies georgei var. smithii at 3700, 3900, 4100, 4300, and 4390 m altitude were investigated in 15 typical plots in the Southeastern Tibetan Plateau. In each plot, three seedlings were selected, of which functional leaves in current-year sunny branches were chosen for the measurement of morphological, photosynthetic, and physiological and biochemical characteristics, and their variations were analyzed. Results showed that significant variations existed among the leaf functional traits of A. georgei var. smithii along the altitudinal gradient, as well as their physiological adaption indicators. Leaf area decreased, while the mass per area and thickness of leaf increased at an altitude above 4,100 m. The maxima of pigment, total nitrogen concentration, net photosynthesis rate during light-saturated, and when water use efficiency appeared at 4100 m altitude. In addition, A. georgei var. smithii seedlings regulated the activities of superoxide dismutase and ascorbate peroxidase to resist abiotic stress under 4100 m altitude. Meanwhile, malondialdehyde concentration and the dark respiration rate rapidly increased, which indicates that A. georgei var. smithii seedlings suffered from heavy abiotic stress from 4100 m to 4390 m altitude. Basing on variations in leaf functional traits along the altitude gradient, we inferred that 4100 m altitude was the suitable region for A. georgei var. smithii growth in the Sygera Mountain. Moreover, the harsh environment was the main limiting factor for A. georgei var. smithii population expansion to high altitude.  相似文献   

5.
Plant biomarkers, such as hydrocarbon waxes, are frequently found in various sediments and could be adopted as paleovegetation and paleoclimate indicators. Nevertheless, scarce researches have focused on leaf waxes in higher plants of alpine region. Herein, hydrocarbon leaf wax components of Salix oritrepha, which flourish in Nianbaoyeze Mountains in eastern Tibetan Plateau were fully discussed. The n-alkane distribution in leaves ranges from n-C21 to n-C29 with maxima at n-C25, which were entirely different with Salix taxa displayed in previous surveys in non-alpine regions. The unusual even carbon nalkenes from n-C22:1 to n-C30:1, which were thought to appear only in aquatic organisms, were firstly reported in an alpine plant. Additionally, iso-(2-methyl) alkanes, ranging from i-C23 to i-C29 with maxima at i-C25, which have been commonly reported in microorganisms, were also identified in an alpine plant for the first time. Unusual hydrocarbon distribution detected in Salix oritrepha leaf from Nianbaoyeze Mountains is most likely due to the extreme environment in such alpine region.  相似文献   

6.
In the Garhwal of Uttarakhand, India, the Bhotiya, an ethnically and culturally distinct tribal group, were historically engaged in seasonal migration (i.e. transhumance) to take advantage of scarce mountain resources and trade relations with Tibet. This livelihood practice has all but disappeared. Households are adapting to these changing circumstances by engaging in the collection and sale of the valuable alpine medicinal fungus Ophiocordyceps sinensis, widely known as Cordyceps. The collection of this fungus has exploded, emerging as a lucrative yet high-risk livelihood strategy for many Bhotiya communities. The Bhotiyas’ historic herding and trade-based interactions and knowledge of these alpine environments where Cordyceps are found uniquely positions them to access this valuable biological resource. Elsewhere in the Himalayan region, some households are earning as much as two-thirds of their income from the collection of Cordyceps; in China Cordyceps is now listed as an endangered species due to intense over-exploitation in the Tibetan Plateau. This paper seeks to fill the void in the scientific literature on the social, ecological and economic aspects of the emerging Cordyceps trade in the Garhwal. Our study investigates the socio-spatial dimensions of Cordyceps collection in the high alpine meadows. We document how a fusion of local knowledge and practice with alpine mountain systems has served to reinvigorate the economic integrity of mountain communities at a time of rapid socio-economic change and to reimagine a new relationship between alpine resources and community well-being. The article offers suggestions to address the sustainability of both Cordyceps collection and livelihood activities which hinge on this fungus population. We find a need for (1) community-based conservation measures that are rooted in (2) secure resource access rights for local communities to continue sustainable collection and sale of Cordyceps and (3) participatory-and science-based processes for determining appropriate local collection numbers.  相似文献   

7.
The effects of different phosphorus (P) concentrations (0.36, 3.6, and 36 μmol/L corresponding to low-, middle-, and high-P concentration groups, respectively) and nitrogen (N)/P ratios on the growth and photosynthetic characteristics of Skeletonema costatum and Prorocentrum donghaiense were studied. For both species, the high-P (HP) concentration group showed the greatest algal density and highest specific growth rate. Changes in the maximum efficiency of photosystem II (F v /F m ) were monitored under the various P and N/P conditions. The largest decrease in F v /F m was in the low-P (LP) group in S. costatum and in the HP group in P. donghaiense. There were high rapid light curves and photochemical quantum yields (Φ PSII) for S. costatum in the HP group, while the actual photosynthetic capacity was higher in P. donghaiense than in S. costatum in the MP group. Under eutrophic but relatively P-restricted conditions, P. donghaiense had higher photosynthetic activity and potential, which could cause this dinoflagellate to increasingly dominate the phytoplankton community in these conditions. Under the same P concentration and N/P ratio, P. donghaiense had a larger relative maximum rate of electron transport and higher Φ PS II values than those of S. costatum. These differences between P. donghaiense and S. costatum may explain the interaction and succession patterns of these two species in the Changjiang (Yangtze) River estuary from a photosynthesis perspective.  相似文献   

8.
Treeline ecotone dynamics of Abies spectabilis (D. Don) Mirb. in the Barun valley, Makalu Barun National Park, eastern Nepal Himalaya were studied by establishing seven plots (20 m × variable length) from the forestline to the tree species limit: three plots on the south- and north-facing slopes each (S1–S3, N1–N3), and one plot on the east-facing slope (E) in the relatively undisturbed forests. A dendroecological method was used to study treeline advance rate and recruitment pattern. In all the plots, most trees established in the early 20th century, and establishment in the second half of the 20th century was confined to the forestline area. Treeline position has not advanced substantially in the Barun valley, with only 22 m average elevational shift in the last 130 years, and with average current shifting rate of 14 cm/yr. Moreover, no significant relationship was found between tree age and elevation on the south-, north-, and east-facing slopes. The number of seedlings and saplings in near the treeline area was negligible compared to that near the forestline area. Therefore, A. spectabilis treeline response to the temperature change was slow, despite the increasing temperature trend in the region. Beside the temperature change, factors such as high inter-annual variability in temperature, dense shrub cover, and local topography also play an important role in treeline advance and controlling recruitment pattern above the treeline.  相似文献   

9.
Allometric equations of select tree species of the Tibetan Plateau,China   总被引:1,自引:0,他引:1  
The Tibetan forest is one of the most important national forest zones in China. Despite the potentially important role that Tibetan forest will play in the Earth?s future carbon balance and climate regulation, few allometric equations exist for accurately estimating biomass and carbon budgets of this forest. In the present study, allometric equations,both species-specific and generic, were developed relating component biomass(DW) to diameter at breast height(DBH) and tree height(H) for six most common tree species in Tibetan forest. The 6 species were Abies georgei Orr., Picea spinulosa(Griff.)Henry, Pinus densata Mast., Pinus yunnanensis Franch., Cypresses funebris Endl. and Quercus semecarpifilia Smith.. The results showed that, both DBH-only and DBH2 H based species-specific equations showed a significant fit(P0.05) for all tree species and biomass components. The DBH-only equations explained more than 80% variability of the component biomass and total biomass, adding H as a second independent variable increased the goodness of fit, while incorporating H into the term DBH2 H decreased the goodness of fit. However, not all DBH-H combined equations showed a significant fit(P0.05) for all tree species and biomass components. Hence, the suggested species-specific allometric equations for the six most common tree species are of the form ln(DW) = c + αln(DBH). The generalized equations of mixed coniferous component biomass against DBH, DBH2 H and DBH-H also showed a significant fit(P0.05) for all biomass components. However, due to significant species effect, the relative errors of the estimates were very high. Hence, generalized equations should only be used when there are too many different tree species, or there is no species-specific model of the same species or similar growth form in adjacent area.  相似文献   

10.
Biomass is an important component of global carbon cycling and is vulnerable to climate change. Previous studies have mainly focused on the responses of aboveground biomass and phenology to warming, while studies of root architecture and of root biomass allocation between coarse and fine roots have been scarcely reported in grassland ecosystems. We conducted an open-top-chamber warming experiment to investigate the effect of potential warming on root biomass and root allocation in alpine steppe on the north Tibetan Plateau. The results showed that Stipa purpurea had significantly higher total root length, root surface area and tips than Carex moocroftii. However,there were no differences in total root volume, mean diameter and forks for the two species. Warming significantly increased total root biomass(27.60%), root biomass at 0–10 cm depth(27.84%) and coarse root biomass(diameter 0.20 mm, 57.68%) in the growing season(August). However, warming had no significant influence on root biomass in the non-growing season(April). Root biomass showed clear seasonalvariations: total root biomass, root biomass at 0–10 cm depth and coarse root biomass significantly increased in the growing season. The increase in total root biomass was due to the enhancement of root biomass at 0–10 cm depth, to which the increase of coarse root biomass made a great contribution. This research is of significance for understanding biomass allocation, carbon cycling and biological adaptability in alpine grassland ecosystems under future climate change.  相似文献   

11.
The decomposition of plant litter is a key process in the flows of energy and nutrients in ecosystems. However, the response of litter decomposition to global climate warming in plateau wetlands remains largely unknown. In this study, we conducted a one-year litter decomposition experiment along an elevation gradient from 1891 m to 3260 m on the Yunnan Plateau of Southwest China, using different litter types to determine the influences of climate change, litter quality and microenvironment on the decomposition rate. The results showed that the average decomposition rate(K) increased from 0.608 to 1.152, and the temperature sensitivity of litter mass losses was approximately 4.98%/℃ along the declining elevation gradient. Based on a correlation analysis, N concentrations and C︰N ratios in the litter were the best predictors of the decomposition rate, with significantly positive and negative correlations, respectively. Additionally, the cumulative effects of decomposition were clearly observed in the mixtures of Scirpus tabernaemontani and Zizania caduciflora. Moreover, the litter decomposition rate in the water was higher than that in the sediment, especially in high-elevation areas where the microenvironment was significantly affected by temperature. These results suggest that future climate warming will have significant impacts on plateau wetlands, which have important functions in biogeochemical cycling in cold highland ecosystems.  相似文献   

12.
13.
White spot syndrome virus (WSSV) is an important viral pathogen that infects farmed penaeid shrimp, and the threat of Vibrio parahaemolyticus infection to shrimp farming has become increasingly severe. Viral and bacterial cross or superimposed infections may induce higher shrimp mortality. We used a feeding method to infect Litopenaeus vannamei with WSSV and then injected a low dose of V. parahaemolyticus (WSSV+Vp), or we first infected L. vannamei with a low-dose injection of V. parahaemolyticus and then fed the shrimp WSSV to achieve viral infection (Vp+WSSV). The eff ect of V. parahaemolyticus and WSSV co-infection on survival of L. vannamei was evaluated by comparing cumulative mortality rates between experimental and control groups. We also spread L. vannamei hemolymph on thiosulfate citrate bile salt sucrose agar plates to determine the number of Vibrio, and the WSSV copy number in L. vannamei gills was determined using an absolute quantitative polymerase chain reaction (PCR) method. LvMyD88 and Lvakt gene expression levels were detected in gills of L. vannamei by real-time PCR to determine the cause of the diff erent mortality rates. Our results show that (1) the cumulative mortality rate of L. vannamei in the WSSV+Vp group reached 100% on day 10 after WSSV infection, whereas the cumulative mortality rate of L. vannamei in the Vp+WSSV group and the WSSV-alone control group approached 100% on days 11 and 13 of infection; (2) the number of Vibrio in the L. vannamei group infected with V. parahaemolyticus alone declined gradually, whereas the other groups showed significant increases in the numbers of Vibrio (P<0.05); (3) the WSSV copy numbers in the gills of the WSSV+Vp, Vp+WSSV, and the WSSV-alone groups increased from 105 to 107 /mg tissue 72, 96, and 144 h after infection, respectively. These results suggest that V. parahaemolyticus infection accelerated proliferation of WSSV in L. vannamei and vice versa. The combined accelerated proliferation of both V. parahaemolyticus and WSSV led to massive death of L. vannamei.  相似文献   

14.
The age, growth and maturation of Sthenoteuthis oualaniensis were determined with statolith data collected with a light purse seine from the Bashi Channel of central Pacific Ocean. The estimated longevity of the squid was no more than 6 months for females, and no more than 5 months for males. Growth in mantle length (ML) was best described by logistic models for both females and males, while growth in body weight (BW) was best fitted by power curves. The maximum absolute growth rate (AGR) and instantaneous growth rate (IGR) in ML or BW both occurred at 91–105 days for females and 76–90 days for males. Back calculated hatching dates were from October to January, with a peak in December, although the short duration of sampling date might have had an influence on the result. The lower percentage of mature females (37.2%) suggested that the study area during the sampling date was not a spawning ground for the species. Size and age at first maturity were 183 mm ML and 136 days for females, whereas they were 156 mm ML and 85 days for males.  相似文献   

15.
Water vapor in the earth′s upper atmosphere plays a crucial role in the radiative balance, hydrological process, and climate change. Based on the latest moderate-resolution imaging spectroradiometer(MODIS) data, this study probes the spatio-temporal variations of global water vapor content in the past decade. It is found that overall the global water vapor content declined from 2003 to 2012(slope b = –0.0149, R = 0.893, P = 0.0005). The decreasing trend over the ocean surface(b = –0.0170, R = 0.908, P = 0.0003) is more explicit than that over terrestrial surface(b = –0.0100, R = 0.782, P = 0.0070), more significant over the Northern Hemisphere(b = –0.0175, R = 0.923, P = 0.0001) than that over the Southern Hemisphere(b = –0.0123, R = 0.826, P = 0.0030). In addition, the analytical results indicate that water vapor content are decreasing obviously between latitude of 36°N and 36°S(b = 0.0224, R = 0.892, P = 0.0005), especially between latitude of 0°N and 36°N(b = 0.0263, R = 0.931, P = 0.0001), while the water vapor concentrations are increasing slightly in the Arctic regions(b = 0.0028, R = 0.612, P = 0.0590). The decreasing and spatial variation of water vapor content regulates the effects of carbon dioxide which is the main reason of the trend in global surface temperatures becoming nearly flat since the late 1990 s. The spatio-temporal variations of water vapor content also affect the growth and spatial distribution of global vegetation which also regulates the global surface temperature change, and the climate change is mainly caused by the earth's orbit position in the solar and galaxy system. A big data model based on gravitational-magmatic change with the solar or the galactic system is proposed to be built for analyzing how the earth's orbit position in the solar and galaxy system affects spatio-temporal variations of global water vapor content, vegetation and temperature at large spatio-temporal scale. This comprehensive examination of water vapor changes promises a holistic understanding of the global climate change and potential underlying mechanisms.  相似文献   

16.
The neon flying squid (Ommastrephes bartramii) is a short-lived opportunistic species widely distributed in subtropical and temperate waters in the North Pacific Ocean. The life cycle of O. bartramii from planktonic eggs to nektonic adults is closely linked to oceanographic conditions. The fluctuations in O. bartramii abundance and distribution tend to increase and widen continuously due to the heavy influences of ocean-climate events on various spatio-temporal scales. In this study, we reviewed the interaction between O. bartramii and oceanography variability in the North Pacific with respect to large-scale climatic-oceanic phenomena including El Niño, La Niña, Kuroshio, Oyashio and Pacific Decadal Oscillation (PDO), as well as regional environmental variables such as sea surface temperature (SST), sea surface height (SSH), sea surface salinity (SSS), chlorophyll-a (Chl-a) concentration, and plankton density. The population dynamics of O. bartramii is mediated mainly by meso- and large-scale climatic-oceanic events (e.g., Kuroshio and Oyashio Currents) rather than other local environmental conditions (e.g., SST and Chl-a concentration), because all of the oceanographic influences are imposed on the context of large-scale climate changes (e.g., PDO). An unstructured-grid finite-volume coastal ocean model coupled with an individual-based model is proposed to simulate relevant physical-biological oceanographic processes for identifying ocean-climate influence and predicting O. bartramii distribution and abundance in the North Pacific. Future research needs to be focused on improving the knowledge about early life history of O. bartramii and evaluating the relationship between marine physical environment and two separate passive drifting life stages of O. bartramii including free-floating eggs and planktonic paralarvae.  相似文献   

17.
There is considerable concern that isoflavones, such as genistein in fish feed composed of soybean protein, aff ects somatic growth in fish. Our previous works demonstrated that 30 and 300 μg/g dietary genistein had no significant eff ect on growth performance in Nile tilapia (Oreochromis niloticus), but the higher level of genistein (3 000 μg/g) significantly depressed growth. This study was conducted to further examine the eff ects of dietary genistein on the endocrine disruption on growth hormone/insulin-like growth factor-I (GH/IGF-I) axis in Nile tilapia (O. niloticus). Juvenile fish were fed by hand twice daily to satiation with one of four isonitrogenous and isoenergetic diets, each containing either 0, 30, 300 or 3 000 μg/g genistein. Following an 8-week feeding period, plasma GH and IGF-I levels were investigated by radioimmunoassay and gene expression levels of gh, ghrelin, gnrhs, ghr, npy, npyrs, pacap, ghrs, igf-I, igf-Ir, and igfbp3 were examined by real-time PCR. The results show that no significant change in plasma GH and IGF-I levels in fish fed with diets containing 30 μg/g and 300 μg/g genistein. mRNA expression of genes along the GH/IGF-I axis remained unaff ected, except for igf-Ir, which was stimulated by the 300 μg/g genistein diet. While in fish fed the 3 000 μg/g genistein diet, the plasma GH and IGF-I levels decreased, and mRNA expression of gh, ghr2, npyr1, igf-I, and igf-Ir were also significantly depressed. In contrast, npy and igfbp3 mRNA expression were enhanced. This study provides convincing evidence for growth impediment by genistein by disturbing the GH/IGF-I axis in Nile tilapia O. niloticus.  相似文献   

18.
Flavobacterium columnare causes columnaris disease in freshwater fish. In the present study, the antigenic regions of five outer membrane proteins (OMPs), including zinc metalloprotease, prolyl oligopeptidase, thermolysin, collagenase and chondroitin AC lyase, were bioinformatically analyzed, fused together, and then expressed as a recombinant fusion protein in Escherichia coli. The expressed protein of 95.6 kDa, as estimated by 10% sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was consistent with the molecular weight deduced from the amino acid sequence. The purified recombinant protein was used to vaccinate the grass carp, Ctenopharyngodon idella. Following vaccination of the fish their IgM antibody levels were examined, as was the expression of IgM, IgD and IgZ immunoglobulin genes and other genes such as MHC Iα and MHC IIβ, which are also involved in adaptive immunity. Interleukin genes (IL), including IL-1β, IL-8 and IL-10, and type I and type II interferon (IFN) genes were also examined. At 3 and 4 weeks post-vaccination (wpv), significant increases in IgM antibody levels were observed in the fish vaccinated with the recombinant fusion protein, and an increase in the expression levels of IgM, IgD and IgZ genes was also detected following the vaccinations, thus indicating that an adaptive immune response was induced by the vaccinations. Early increases in the expression levels of IL and IFN genes were also observed in the vaccinated fish. At four wpv, the fish were challenged with F. columnare, and the vaccinated fish showed a good level of protection against this pathogen, with 39% relative percent survival (RPS) compared with the control group. It can be concluded, therefore, that the five OMPs, in the form of a recombinant fusion protein vaccine, induced an immune response in fish and protection against F. columnare.  相似文献   

19.
In present study, the inbreeding depression (ID) of growth and survival of Manila clam (Ruditapes philippinarum) was investigated at larval and juvenile stages. Nine inbred families (A 2, B 2, C 2, D 2, E 2, F 2, G 2, H 2 and I 2) were established by mating within nine full-sib families with expected inbreeding coefficient of 0.25. Inbred families showed significant differences in shell length and hatching rate of D-larvae (straight-hinged larvae). The larvae of the nine inbred families grew slower than those of control group (CG), and their ID value ranged from 0.81% ± 6.09% to 16.10% ± 1.49%. The ID value of larval survival rate varied between 27.47% ± 9.36% and 70.50% ± 13.66%. The ID was also detected for juvenile growth in A 2, B 2, C 2, and D 2, which ranged from 4.60 ± 2.21 to 17.71 ± 7.73. The A 2 family maintained the highest juvenile survival rate, whereas the other inbred families exhibited ID values varying between 62.79% ± 4.54% and 96.14% ± 0.87%. The linear relationship of estimated ID between growth and survival was negatively correlated (R = ?0.434, P < 0.05). The results of this study suggested that the ID of growth was common at the larval stage but was less prevalent at juvenile stage. In contrast, the ID of survival increased from larval to juvenile stage. A better understanding of the effect of inbreeding may aid to selective breeding of Manila clam.  相似文献   

20.
The ecological concept of Plant Functional Types(PFTs), which refers to the assemblage of plants with certain functional traits, has been introduced for the study of plant responses to the environment change and human disturbance. Taking the alpine meadow community in the Zoigê Plateau as a study case, this paper classified PFTs in terms of plant nutrition traits. The sequential results are as follows.(1) The main herbages in the Zoigê Plateau included 16 species in 5 families. Among the five families, Cyperaceae vegetation accounted for 81.37%of herbage area in total, while the remaining 4families occupied less than 20%. As for the species,Kobresia setchwanensis Hand.-Maizz. was dominant,accounting for 48.74% of the total area; while the remaining 51.26% was comprised of Polygonum viviparum L., Anaphalis fiavescens Hand.-Mazz.,Stipa aliena Keng and other species.(2) By using the Principal Component Analysis(PCA), the assessment of herbages nutrition was carried out based on the comprehensive multi-index evaluation model.Polygonum viviparum L. had the highest nutritional value score(1.43), and Stipa aliena Keng had the lowest(-1.40). Nutritional value of herbage species had a significantly positive correlation with altitude(P0.01) in the Zoigê Plateau.(3) Based on the nutritional values, herbages in the Zoigê Plateau could be grouped into 3 nutrition PFTs(high, medium and low) by using the Natural Breaks(Jenks) method.  相似文献   

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