Alpine shrublands, as a zonal vegetation, are widely distributed on the Qingzang Plateau, and play ecological functions such as soil and water conservation, conservation of water resources, and biodiversity protection in the regional ecosystem. This study used a unified and standardized method to set up 58 quadrats to investigate the species composition, quantitative characteristics and habitat information of the main alpine shrublands of the Haizi Mountain in Batang, China. Based on “Vegegraphy of China” compilation and research standards, the alpine shrublands in this area can be divided into three vegetation types, 11 alliances, and 21 associations. This paper presents descriptions on the characteristics for each association and provides the original data from all survey plots.

Aims Subalpine dark coniferous forests are an important representative of the cold-temperate coniferous forests in China. Dark coniferous forests dominated by spruce (Piceaspp.) and fir (Abies spp.) are the main body of subalpine forests on the eastern edge of the Qingzang Plateau and an important ecological defense in the upper reaches of the Yangtze River in China. In this study, we examined the community composition and structure of such a dark coniferous forest based on the first census data of the 25.2 hm² Wanglang forest dynamics plot in western Sichuan.

Methods The plot was established following the standard protocol of Forest Global Earth Observation Network (ForestGEO) and all free-standing stems with diameter at breast height (DBH) ≥ 1 cm were tagged, mapped, measured and identified to species.

Important findings A total of 56 574 individuals belonging to 46 species, 27 genera and 15 families are tagged, including 4 coniferous species, 6 evergreen broad-leaved species and 36 deciduous broad-leaved species. There are 13 rare species (≤1 individuals per hm²), accounting for 28.26% of the total number of species and 0.16% of the total number of individuals in the plot. Abies fargesiivar. faxoniana(9 440 individuals) and P. purpurea (1 645 individuals) are the dominant and constructive species in canopy, accounting for 26.03% and 10.69% of the total importance value, and 55.22% and 24.84% of the total basal area (37.87 m²·hm^-2), respectively. The number of individuals of deciduous broad-leaved species accounted for 78.48% of the total individuals. Among them, Philadelphus purpurascens, Lonicera nervosaand Euonymus frigidusare the dominant species in shrub layer. The number of individuals of evergreen broad-leaved species is 268, and all these species belong to genus Rhododendron. The composition of the size distribution shows typical characteristics of old-growth forests. Picea purpurea is the largest tree species (max DBH = 127.07 cm) and the mean basal area (0.14 ± 0.18) m² is much higher than that of A. fargesiivar. faxoniana(0.056 ± 0.11) m². The size class distribution of all woody species shows an inverse J-shaped distribution, indicating that the community is in a stable and healthy recruitment state. Results of the point pattern analysis reveal that the five dominant tree species (important values ≥5) all show aggregated distribution patterns. However, as the spatial scale increases, all five species tend to be randomly distributed. The results of this study provide basic information for future studies on the diversity maintenance and regeneration mechanisms of subalpine dark coniferous forests in western Sichuan, and the conservation and management of this unique forest ecosystem.

Plot-based data are an important foundation for studying plant community characteristics and compiling vegetation monographs, vegetation map, and vegegraphy. It is the key data source of studies in vegetation ecology. To understand the species composition, community characteristics, and distribution pattern of special plateau vegetation on the Qingzang Plateau (QZP), this study uses the data of 338 sites including 758 plots in different regions of the QZP from 2018 to 2021 to analyze the species composition, floristic characteristics, and vegetation classification of plateau plant communities. A plot-based dataset of plant community on the QZP is then established. The 758 plots have 837 plant species belonging to 279 genera from 65 families in the alpine and temperate vegetation communities. The largest number of species are found in five families: Asteraceae (134 species), Poaceae (88 species), Fabaceae (75 species), Rosaceae (43 species), and Cyperaceae (40 species), as well as five genera: Artemisia (29 species), Pedicularis (27 species), Saussurea (25 species), Astragalus (23 species), and Poa (23 species). The floristic composition is mainly temperate (145 genera) and cosmopolitan (36 genera). The growth forms of the species are mainly herbs (83.51%) and shrubs (10.87%), and the life forms of herbs and woody plants are mainly perennial herbs (88.23%) and deciduous shrubs (83.67%), respectively. A total of 338 sites can be divided into four vegetation formation groups, 10 vegetation formations, 20 vegetation subformations, 78 alliance groups, and 117 alliances, in which 34 are steppe alliances, 33 are meadow alliances, 33 are desert alliances, 14 are shrubland alliances, and 3 are coniferous forest alliances. This dataset covers most of the alpine shrubland, meadow, steppe, desert, and temperate steppe, desert vegetation regions of the QZP. This work provides a solid foundation for exploring the vegetation characteristics and regularity of vegetation zonal differentiation and determining the impacts of climate change and human disturbances on alpine vegetation and their ecological restoration. The dataset also provides a reference for the updating of the next generation of China's vegetation map.

Climate diagram can be used to reflect visually observation data of temperature and precipitation as well as information of weather stations. It is an effective tool for studying the relationship between vegetation and climate. This paper aims to provide the atlas of climate diagrams of the Qingzang Plateau, based on the 30-year averaged observational records of national surface weather stations during 1951-1980 and 1981-2010, respectively, in order to understand the plateau climate feature of every vegetation region and to further explore the vegetation- climate relationships on the plateau. The atlas of climate diagrams of 205 weather stations on the Qingzang Plateau for both the two 30-year periods were produced according to the standard of climate diagrams in Vegetation of China. Results showed that the temperature and precipitation of the Qingzang Plateau were overall low in the whole year but relatively higher in summer, and differed obviously among different vegetation regions. The mean annual temperature and annual precipitation showed an increasing trend from the first 30-year period of 1951-1980 to the later one of 1981-2010. Although the number of weather stations in the western plateau is very sparse, this climate diagram dataset covers every vegetation regions of the plateau surface. This atlas can be used effectively to study the relationships between vegetation and climate, and conveniently to display the climate environment of the plateau.

Aims Juniperus community is an important component of natural forest resources in the Three-River-Source Region, which is significant in maintaining biodiversity and ecological security on the Qingzang Plateau. Yet, the information on the characteristics of the Juniperus community is lacking due to their special geographical location and varied topography. In this study, the main vegetation types of Juniperus community were investigated, and the main characteristics of each community type were described quantitatively by analyzing data from 53 plots. Methods Based on the analysis of forest resources inventory data in the Three-River-Source Region, the representative distribution area of Juniperus was selected to set up 7 sites, a total of 53 plots. Through the investigation of field communities and plot properties, the importance of each species was quantified and calculated. The principle of life form and dominance methods in Vegetation of China were used to determine community types. Important findings (1) The Juniperus plant community in the Three-River-Source Region was divided into 6 alliances, and then further divided into 15 associations. (2) In total, 142 species of seed plants were recorded, which was belonged to 34 families and 90 genera. Among them, Compositae was the major family, accounting for 16.20% of the total species. (3) The vertical structure of the community was obvious, in which the dominant species in the tree layer was single. The dominant species in the shrub layer were Berberis diaphana, Potentilla glabra and shrubby Juniperus tibetica. The herb layer were dominated by Carex and Pedicularis. (4) Among the geographical elements of seed plant species, the Temperate distribution accounted for 52.59% of the total species, while the rest was Chinese endemic species accounting for 47.41%. Temperate Asian, East Asian and Central Asian were the dominated areal-types in the Temperate distribution. Furthermore, the floristic elements of Hengduanshan flora and Tanggut flora were mixed formed the unique characteristic areal-type in the region.

Pollen record is an essential data for reconstructing paleovegetation and paleoclimate. It is important for the studies of paleoenvironmental evolution, characteristics of paleoclimate change and simulation of paleobiogeochemical cycles from site to regional and global scales. In this paper, we collected and sorted out the pollen data records from published and unpublished Chinese literature between 1960 to 2020. The records included sample numbers, sampling locations (latitude, longitude and altitude of sampling sites), sample types, data sources, data types, surrounding vegetation, references, and pollen taxa, their compositions as well. They were filtered and standardized to integrate a pollen dataset of China. This dataset consists of 4 497 modern pollen sampling sites, including 660 published data from the Chinese Quaternary Pollen Database, 1 763 from early published data and 2 074 from recently collected data, belonging to 772 pollen taxa. The samples were mainly from surface soils (3 332 sites), and the rest were from moss plosters, surface sediments from lakes and the ocean. The sampling sites are widely scattered around China representing different geographical regions and vegetation types: 24.91%. in the temperate desert region, 24.02% in the subtropical evergreen broad-leaved forest region, followed by the temperate grassland region (16.14%) and alpine vegetation region of Qingzang Plateau (15.83%). The data can be divided into the raw data (58%) and numerical data (42%) according to their sources, and grain count (59%) and calculated pollen percentage (41%) by data type as well. The database constructed from the samples over China during the past half-century+ period is, though by far from complete, good representation of most of the areas in China, which can be effective in the reconstruction of past vegetation and climates as modern verification.

Stipa sareptana var. krylovii alliance is one of the typical steppes endemic to Central Asia. The eastern border of its distribution is adjacent to the meadow steppes on the Hulunbeir Plateau, the western border extends to the desert steppes on the Ulanqabu Plateau and Tianshan Mountains, and the southern border lies among the warm temperate steppes on the Loess Plateau. The distribution of this alliance also spreads into the alpine steppes on the eastern margin of the Qinghai-Xizang Plateau. The broad its distribution suggests that S. sareptana var. krylovii alliance has wide ecological adaptability. In this study, we described and analyzed the eco-geographical distribution, community characteristics and classification of S. sareptana var. krylovii alliance based on data from 117 plots. The results showed that there are 336 seed plants belonging to 36 families and 131 genera in these plots. The families with more than 15 species are Gramineae, Compositae, Leguminosae, Rosaceae, Chenopodiaceae and Liliaceae. Among all species in these plots, 91.67% are rare species with occurrence frequency smaller than 20%. Besides S. sareptana var. krylovii, the most common species in this alliance include Cleistogenes squarrosa, Heteropappus altaicus, Agropyron cristatum, Koeleria cristata, Potentilla bifurca, Salsola collina, Allium tenuissimum and Leymus chinensis. In addition, hemicryptophytes are the most common life form within the surveyed plots, accounting for 66.37% of all species. Xerophytes are the most common water ecological type, accounting for 61.19% of all species. East Palearctic element was the major floristic geographical element, accounting for 33.33% of all species. Based on the China Vegetation Classification System, S. sareptana var. krylovii alliance could be classified into 6 association groups and further into 45 associations.

Aims Fagus L. has a disjunct distribution in the northern temperate zone, and there is a rich collection of Tertiary fossils from East Asia, Europe and North America. A panbiogeographical analysis of Fagus was undertaken to analyze the distribution pattern and evolution of the genus.
Methods Distribution data of 581 records of 10 species were obtained from herbaria and monographs. Track analysis of panbiogeography and software MartiTrack were used for data analysis.
Important findings Results indicated that there was no generalized track linking the distributions among China, Japan, Europe and North America or even between China and Japan, two adjacent areas in East Asia. Two regional generalized tracks were only found within China and Japan. These facts imply that the Fagus distribution cannot be explained by dispersal. Dispersal probably only occurred in limited and/or local regions and not as dispersal across the northern temperate zone in the Tertiary. The disjunction most likely resulted from (1) geological historical events such as Tethys westward movement, Qinghai-Tibet Plateau uplift, and Asian monsoon action, (2) climate change since the Tertiary, especially climate fluctuation during Quaternary glaciation, and (3) Fagus biological characteristics with regard to humid and temperate climate and annual rainfall.

Pollen data are the foundation of reconstructing past vegetation patterns and of studying past climate changes and interactions among atmosphere, biosphere and human activities. We searched for pollen-related literature published and reported from the 1960s to 2008 and collected late Quaternary pollen sampling information for China. We focused on the past 20 000 years before present (aBP), especially the Holocene. Information includes site name, detailed location in text and in latitude, longitude and elevation, sample type, sediment depth, number of pollen samples, radiocarbon dating, time period, and reference. There are 2 324 surface pollen samples from soils and lakes and 987 cores/profiles of sediment fossil records. Among them there are 714 fossil pollen sampling sites with high quality data of pollen and radiocarbon dating. Despite research has been performed by domestic and international paleo-scientists in collecting pollen samples and in Quaternary studies in China, geographical gaps exist due to the limitation of financial support and poor topographical conditions. These include the northern and northwestern desert areas, non-settlement area of the Tibetan Plateau, mountainous areas of middle-southern China and highly disturbed areas of eastern China. More pollen sampling records are needed to update and complete the information database. Such information will greatly benefit the Quaternary Chinese Pollen Database. Furthermore, scientific questions can be addressed based on the databases, such as what the geographical patterns of paleovegetation in China were during the late Quaternary, what were the key times of vegetation shifts (abrupt changes), what were the driving factors of vegetation changes, climate change or human disturbances, and how have vegetation changes influenced local and regional climates?

Estimating carbon storage in terrestrial ecosystems has been a central focus of research over the past two decades because of its importance to terrestrial carbon cycles and ecosystem processes. As one of the most widespread ecosystem types, China’s grasslands play an important role in global change research. The grasslands in China, which are distributed primarily throughout the temperate regions and on the Tibetan Plateau, were classified into 17 community types. In the present study, a statistical model was established to estimate grassland biomass and its geographical distribution in China based on a grassland inventory data set and remote sensing data (Normalized Difference Vegetation Index) using GIS and RS techniques. We found that there was a significant correlation between aboveground biomass density and the maximum annual NDVI when expressed as a power function (R2=0.71, p<0.001). The aboveground biomass was estimated to be 146.16 TgC (1Tg=1012 g) and belowground biomass was estimated as 898.60 TgC (6.15 times of the above biomass) for a total biomass of 1 044.76 TgC. This value accounts for about 2.1%-3.7% of the world’s grassland biomass. The grassland biomass is distributed primarily in the arid and semiarid regions of Northern China and the Qinghai-Xizang Plateau. The average biomass density of China’s grasslands was 315.24 gC·m-2, smaller than the world average. The aboveground biomass density decreases from southeastern China toward the northwest corresponding with changes in precipitation and temperature. Furthermore, aboveground biomass density reached the lowest levels at 1 350 m elevation and peak levels at 3 750 m above sea level which most likely is related to China’s three-step topographical background. The ratio of total biomass of grassland to forest biomass in China is 1/4, much higher than that of the world, suggesting a greater contribution of grasslands to China’s carbon pool.

The Kunluns, the Karakorums and the Himalayas converge and form a great group of mountains to the north-west of the Tibetan Plateau. The Sino-Pakistan Highway crosses these mountains. The vegetation along the highway shows remarkable variation. Shrub dese

A multivariate analysis of woody plant communities with a 76 × 53 (sites x species) species matrix, 76 × 8 environment matrix and 76×2 spatial coordinates surveyed in the mid-section of northern slopes of Qilian mountain is presented. The results show: 1)nine communities (9 formations consisting of 17 associations) are identified from the 76 plots ( Kalidium foliatum shrubland, Reaumuria soongorica shrub, Nitraria tangutorum shrubland, Caryopteris mongolica shrubland, Caragana stenophylla shrubland, Caragana jubata shrubland, Potentilla fruticosa shrubland, Sabina przewalskii forest, and Picea crassifolia forest; 2) fifty-three woody plant species are classified into 5 ecotypes: hyper-desert, montane dry, montane intermediate, montane wet, and montane cold types; 3) the species abundance of woody plant communities explained by environmental and spatial variations reaches 23.98%;among these the species matrix explained by non-spatial environmental variation accounts for up to 17.66 % of variation, spatial variation that is not shared by environmental variation explains up to 1.40%, spatial structured environmental variation up to 4.92% and 76.02 % of undetermined variation remains due to biological and random factors.

The area of the Karakorum-Kunlun Mountains is not so rich in flora. 827 species, subspecies and varieties of higher plants were recorded in the area of ca. 400, 000km2. Those plants belong to 272 genera of 60 families. Among them there are only 5 fern species of 3 genera of 3 families and 14 gymnosperms of 3 genera of 3 families. There are 136 grass species (Gramineae). The families each of which have more than 50 species observed there were Compositae, Leguminosae, Cruciferae, Cyperaceae and Chenopodiaceae. Of the taxa in the area, 44.5% belongs to the Central Asian geographic elements and 21.7% to Qingzang Plateau elements in terms of genera. But the Qingzang Plateau elements dominated in the sections of the Kumkol Basin of the Middle Kunlun (see Fig. 1 Ⅰ 5), the southern flank of east part of the West Kunlun (Ⅱ 2) and the southern flank of the Middle Kunlun (Ⅱ 3). The higher the altitude of the belts is, the greater the proportion of Qingzang Plateau geographic elements is . The proportion of Centra Asian elements decreases while the proportion of the Qingzang Plateau elements increases as the altitude raises. These two elements are similar in proportion at ca. 4250 m above sea level. The floristic differentiation between the southern and the northern flanks of the Kunlun is much more apparent than that between the West and Middle Kunlun. The results of this study show that the demarcation line between the Central Asian sub-region and the Qingzang Plateau sub-region runs along the Karakorum-Kunlun Mountains.

Littledalea racemosa is one of the endemic grass species distributed only in the Qinghai-Xizang Plateau, and mainly within the alpine belt between 4400—4900m above sea level. The distribution area of the alpine steppe dominated or co-dominated by L. racemosa is delineated by the Kunlun Mountains in the north, the Tuotuohe river in the south, and the Hoh xil Mountains in the west. The steppe community is relatively poor in species, only 34 species being recorded in the 8 investigated plots. The 61.8% of the species are of Qinghai-Xizang Plateau geographic elements, and more than half (also 61.8%) of species belongs to the hemicryptophytes. Most of species are perennial with exceptions of 2 prostrate shrubs and I annual. Based on the species composition and structure of the investigated communities, at least 4 community-types of the alpine steppe were distinguished. they were the L. racemosa dominated steppe, the L. racemosa and Carex moorcroftii co-dominated steppe, the L. racemosa and Astragalus confertus (A. polycladus) co-dominated steppe, and the L. racemosa and Stipa purpurea co-dominated steppe. The difference of soil texture and structure were the principal reason for formation of these community-types.

This paper deals with some ecophysiological characteristies of plant growth, parameters of physiology, material accumulation and community composition in apline bushland. The results are as follows:

1 Leaf area index and average rate of growth of some species of Gramineae, Cyperaceae m Dasiphora fruticosa alpine shrub are increased with decreaded grazing intensity. The height and coverage of the community were negatively correlated with grazing intensity (P<0.001).

2. Changes of the aralytical growth parameters: LAR, SLA, LWR and LAI were negatively correlated with grazing intensity. Leaf area index was positively correlated with biomass (P>0.005); Aboveground biomass was negatively correlated with grazing intensity (P<0.001).

3. The species numbers of Gramineae, Cyperaceae in Dasiphora fruticosa shrub community were decreased in heavily grazed area and increased in lightly grazed area. But the proportion of Forb was increased with heavy grazing and decreased with light grazing. Thus light grzaing in alpine scrub showed profitable for plant growth and regeneration.

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Qinghai Lake is the largest inland one in China. It is situated in the northeastern part of Qinghai-Xizant (Tibetan) Plateau. The area of Qinghai Lake region is 29661km2. The lake area is 4304.5km2 measured in 1986.

The vegetation types distributed in Qinghai Lake region mainly include desert vegetation, temperate steppe, alpine shrub, alpine meadow, alpine steppe and alpine subnival vegetation. In this region, the dominant vegetation types are of alpine ones, and the temperate types are only distributed in the area near the lake.

Based on our investigation and analysis, some characteristics of vegetation succession in this area are showed as follows:

(1) The forest is a stage of regression. Only two tree species(Sabina przewalskii and Picea crassifolia)are distributed as relic species in this area.

(2) The alpine vegetation types are relatively developing, but the temperate vegetation are not.

(3) The vegetation around Qinghai Lake has its individual characteristics and special successional trend, In general, vegetational landscape in Qinghai Lake region has been tending to become one which has a strong adaptation to extremely high and harsh habitats.

According to the study on succession of aquatic environment and palaeoclimatology and ancient sporopollen analysis. The climate of this area tended to become colder and drier although the fluctuation did exist during the process of change. Under the increasing pressure caused by this climatic change, the plant species which adapted the change got developed, and the development of individual species which did not adapt to this change was suppressed and inhibited, This is the reason why vegetation around Qinghai Lake tended to success towards the type adapting extremely high and harsh habitats.

Qinghai Hoh Xil region is situated in the central part of the Qinghai-Xizang (Tibetan) Platean, the western side of the Qinghai-Xizang Highway between the Kunlun Mountains in north and the Tangkulashan Mountains in south (about 33˚52′—36˚16′ N lat.; 89˚24′—94˚04′ E long.). It is more than 80000km in size and the average altitude is as high as 4600—5000m while some peaks over 6000m. Most of this region is depopulateted because of its extreme elevation harsh climate, short growth period of forage grasses and difficulty for traffic. The mean temperature is lower than -5℃ in the whole year and lower than 6℃ in the hottest month, lower than -16—20℃ in the coldest month in most of areas of this region. The growing season of forage grasses is shorter than 100 days. The mean annual precipitation is relatively abundant with about 240--300mm in the eastern part and gradually reduced towards the northwest. About 69% of the total precipition falls in the three wormest months (June—Auguest) when plants grow. Soil is usually rough for its strong physicla effects and also week in biological effects. About 200 seed-plant species of 73 genera of 29 families have been noted in this region. Daisy family(Compositae), grass family (Gramineae),cabbage family (Cruciferae), and pea family. (Leguminosae) are the four richest species families. Families of grass, sedge (Cyperaceae), pea and daisy are the four most important ones in regetation composition. Stipa, Littledalea, Kobresia, Carex, Astragalus, Oxytropis, and Saussurea etc. are the most important genera. Almost 79% species are of Qinghai-Xizang Plateau geographic elements. About 69% species are hemicryptophytes the most adaptable lifeform to this kind of climate.Alpine steppe, Alpine meadow and alpine sparse vegetation are the main vegetation types. They occupy 51%, 14% and 26% of the total area respectively. Other types such as cushion vegetation, alpine desert, prostrate scrub etc. are also found. Generally the alpine steppe is distributed in the central part of the region, while the alpine meadow in the southeast and the alpine sparse vegetation in the northwest. This pattern of vegetation distribution is determined by the climatic factors. But vegetation distribution in some places is strongly affected by the following factors: landform, soil physical structure, soil moisture and soil salinity etc.

The Qinghai Lake region is located in the northeastern of Qinghai-Xizang Plateau, about 36˚15′—38˚20′N,97˚50′—101˚20′E. The elevation of this region is about 3200--5000m about sea level. The vegetation and its distribution in this region was influenced by the existence of Qinghai Lake and the complicated landscape characteristics. Plant species growing in the area is poor. According to preliminary statistics, there are 52 families, 174 genera, 445 species of spermatophytes. The main vegetation types are. needleleaf forest in cold temperate, shrubs in plateau valley, alpine shrubs, sandy shrubs, steppe in temperate, alpine steppe, alpine meadow, swamp meadow, subnival vegetation, and so on. The characteristics of the communities above are described in this paper. The distributional law of vegetation in this region is evident. The horizontal variation of vegetation shows a trend of adapting high-cold habitats from east to west. The temperate steppe, which is distributed in a ring-shaped belt around the lake, is related to the lake basin landscape and the existence of Qinghai Lake. The alpine steppe is found within high-cold habitats. The vertical spectrum in this area from down to up shows steppe-alpine shrubs and alpine meadow-subnival vegetation.As a whole, the region belongs to one part of Qilian Mountains area, and is between the eastern region in Qinghai Province and Qaidam Basin. Based on analysis, vegetation and distribution in Qinghai Lake region has a special pattern and coincides with the climate trends to colder and droughter with the uplift of Qinghai-Xizang Plateau. With all these in mind, we suggest that the Qinghai Lake region, is a relatively independent part of Qilian Mountains area.

Quantitative classification and ordination were applied to the plant communities in the region of Haibei Alpine Meadow Ecosystem open experimental Station. The results have shown that: when correlation coefficient R= 0.85, sixty-four plots were divided into twenty-three types of plant communities every type of which has distinctive characteristics in structure, species composition, ecological conditions and geographical distribution. The results of ordination showed that coordinates of plant communities have close relation with altitude, soil temperature and soil potential.

The characteristics and sucession pattern of alpine shrub lands under different grazing intensities are studied with methods of diversity analysis, clustering and principal component analysis in this paper.The results of diversity analysis show that plant diversity reaches the maximum in the C-group of pasture. The clustering analysis results show that when the correlation coefficient R≥0.90, the plant species taking importance value as characteristic are grouped into 10 types, belonging to constructive plants, dominant plants, and associated plants of different successive phases of plant communities respectively. Principal component analysis has shown that 5 communities of alpine shrub lands under different grazing intensities are grouped into 3 types. The A and B groups of pastures belong to plant communities of 2-layer structures taking shrub and forbes as dominant plants and, the C group of pastures belongs to plant communities taking shrubs as constructive plants and taking forbes and grazing-resistant sedges as polydominant plants and, D and E groups of pastures belong to plant communities of 3-layer structures taking shrubs as polydominant plants.

The Qaidam basin is situated in the north-east Qinghai-Xizang plateau, its distribution pattern of vegetation is very camplicated. The eastern part of it belongs to the semiarid desert steppe zone with the zonal vegetation desert steppe. The middle part belongs to the arid desert zone with shrubby and dwalf semi-shrubby gravelly desert. The western part is an extremely arid bare-desert without vegetation in the gravelly gobi and low mountains. At the bottom of the basin, a ring-shaped belts of the vegetation from the edge toward the centre shows the following sequence: flood plain--the shrubby and dwarf semi-shrubby gravelly desert belt, alluvial plain–the shrubby and semi-arboreou sandy desert belt, alluviallacustrine plain--the shrubby saline desert belt, lacustrine plain–the holophytic grass and forb meadow belt, and finally, bare salt crust and salt lakes.In the mountains of the Qaidam region there is great difference in the vertical belt spectrum of the vegetation between east and west, the vertical spectrum in the desert steppe zone is: mountainous steppe-mountainous evergreen needleaf forest-subalpine shrubland-alpine meadow-alpine sparse vegetation; in the arid desert zone. dwarf semi-shrub mountain rocky desert-alpine steppe-alpine meadow-alpine sparse vegetation;and in the bare desert zone:bare low mountain rocky desert-dwarf shrubby mountain rocky desert-alpine steppe-alpin sparse vegetation.

The eastern part of Qinghai province is located in the confluent zone of Qinghai-Xizang plateau and Loess plateau. The natural vegetation in this region is not only connected with alpine vegetation on the Qinghai-Xizang plateau, but also with vegetation types on the Loess plateau; and formed complex vegetation types. They are: desert-steppe, steppe, forest, scrub, high-cold scrub and high-cold meadow. There is an evident vertical zonal distribution of the vegetation. Because of its special geographical position, the distribution of vegetation shows special pattern and landscape. The vegetation types which is connected with Loess plateau, distributes in the river valley and hills, and the alpine vegetation, which is connected with Qinghai-Xizang plateau, on the mountains. Finally, we suggest that vegetation regionizationally, the eastern region of Qinghai province is the transition zone between Qinghai-Xizang plateau and Loess plateau.

The Qinghai-Xizang (Tibet) Plateau is Unique area in natural condition, there alpine vegetation is the richest and the widest distribution, the main types are the alpine scrub, the high-cold meadow, the high-cold steppe, the high-cold desert and sparse vegetation on alpine flowstone slope and the alpine cushion vegetation.These plant communities occupy the alpine belts between the upper line of forest and the permanent snow-line, and they distributively have horizontal regional differentiation from the southeast to the northwest of the Plateau. According to the vegetation characteristics of the vertical belts of mountains and climate condition of the various regions of the Plateau, it may be considered that the vertical vegetation belt spectra of the mountains in the southeast part of the Plateau belong to the humid type of the vertical belt in structure, and those in the center and the northwestern parts of the Plateau belong to the arid type. In addition, the diversify of alpine vegetation: arid. the ecologic-geographic distribution of the alpine cushion vegetation are also. discussed in this paper.

The Central kunlun Mountains, starting from the wulus River in the west to the Andi River in the east, stretching more than 600 km, has an average elevation of 6000 m. Wild seed plants growing in the area are classified into 52 families, 211 genera and 398 species, the flora characterized by purity of floral composition and complicated geographical factors. On its northern slope, the precipitation of the mid-mountain zone and the lower-alpine zone ranges from 300–500 mm and the steppe zone is well developed, especially the steppe zone of the Cele Mountain region (middle section of the Central Kunlun Mountains) is best developed. Above the steppe zone there is no alpine desert, but alpine meadow.The vertical zonal distribution of the vegetation type on the northern slope are as follows. 1. Mountain desert, starting from the piedment line (mostly 2200 m or 2500 m) to 3000 m. 2. Mountain desert steppe 3000—3200 m. 3. Mountain typical steppe, 3200–3600 m. 4. Alpine steppe, 3600–3800 m (sunny slope up to over 4200 m). 5. Alpine meadow, 3800 –4200 m. 6. Alpine cushion vegetation found only in the eastern section and where in combination with the distribution of alpine meadow. 7. Sparse vegetation on alpine flowstone slope, 4200–5000 m.The interior of the Central Kunlun Mountains is extremely clod and dry, and mostly covered by deserts of gravels, where alpine deserts and alpine desert steppes appear in tracts dotting the mountain range.

The succession law of the alpine meadow was studied with the method of quantitative analysis under the different grazing intensities in this paper. The results have proved that there are close successive relations among communities under different grazing intensities. Clustering result shows that when correlation coefficient R>0.851), 24 species plants of a community were grouped into 6 types, they respectively belong to dominant, constructive or accompanying species of successive different phases of a community and that when R>0.870, communities under 6 grazing intensities were grouped into 2 types. They respectively belong to community taking grasses as polydominant and of 2 layer structure, and taking Kobresia humilis and forbes as polydominant and of 1 layer structure.

The forest area in the southern part of Gansu Province lies in the valley lands of the Minshan Mountains, including the mountainous area of the upper and middle reaches of the Bailongjiang and the Touhe Rivers between 103°10′—104°40′E and 32°30′—34°50′N, namely the greater part or part of the counties of Diebu, Zhougu, Lintan, Zhuoni and Wenxian. The vegetation in this area should be regarded as a part of the deciduous broadleaf forest and Picea-Abies forest province in the valley of the Minshan Mountains, which belong to the zone of cold-temperate mountain coniferous forest subregion of cold-temperate moutain coniferous forest in the southeastern part of the Qing-Zang plateau.

Baizha forest region located in the southeastern Qinghai-Tibetan Plateau is the border of the high-mountain coniferous forest distribution. The plant species and structures are simple. This region is a transition zone from forest vegetation to high-cold scrub and meadow In a certain sense, this paper represents some of the characteristics of the intermediate state of Qinghai-Tibetan Plateau vegetation between forest and meadow.

The Gongga Mountain is located on the southeast fringe of the Qinghai-Xizang Plateau, i. e. the middle part of the Great Snow Mountain Range of the Hengduan Mountain Ranges. The Gongga Mountainous region is situated in 29˚20′—30˚00′N. and 101˚30′—102˚10′E., with its main peak being 7556m above sea level. There are 2500 species of vascular plants belonging to 869 genera and 185 families in Gongga Mountainous region. The main floral characteristics of the Gongga Mountainous region are shown as the antiquity of the origin of the floristic composition; marked differentiation of species; abundant endemic species; complex composition and obvious geographical replacement phenomenon. The main vegetation types of the Gongga Mountains are: Subalpine conophorium of Abies, Picea; mid-mountain eonophorium of Pinus and Tsuga; low-mountain conophorium of Pinus, Cunninghamia, Cupressus, and Keteleeria; mixed wood of conophorium and broad-leaf forest of Tsuga, Acer and Betula; evergreen forest of Cinnamomum, Phoebe, Machilus, Lithocarpus and Cyclobalanopsis; deciduous broad-leaf forest of Quercus, Betula, Acer, Populus and Alnus; hard-leaf evergreen forest of Alpine-Quercus; alpine bush-wood of Rhododendron, Salix and Sabina; river-valley busy-wood of Acacia, Opuntia and Bunhinia; alpine meadow and “rock stream” sparse vegetation of Kobresia, Festuca, Allium, Saussurea, Soroseris, etc.The horizontal zones of vegetation in the Gongga Mountainous region is the aiphyllium with the characteristics of the east and west parts of subtropics in China.The vertical belts on the eastern slope are: 1. Evergreen broad-leaf forest belt at alt. 1100—2200m. 2. Coniferous and broad-leaf mixed forest belt at alt. 2200–2500m. 3. Subalpine coniferous forest belt at alt. 2500—3600m. 4. Alpine bush and coryphilum belt at alt. 3600–4600m. 5. Open vegetation belt of alpine “rock stream” belt at alt. 4600–4900m.6. Alpine nival belt at alt. 4900m.The vertical belts on the western slope are: 1. Subalpine coniferous forest belt at alt. 2800—4000m 2. Alpine bush and meadow belt at alt. 4000–4800m. 3. Open vegetation belt of alpine "rock stream" belt at alt. 4800—5100m. 4. Alpine nival belt at alt. 5100m.

It may be made such ecological analysis for flora formation, the correlation between plant species the distribution patterns in ecological series and 2 and 3 dimensional ordinations of subalpine forest vegetations in western Sichuan as follows:

(1) The flora of subalpine forest in this region has been formed by three process--the convergence of external flora components; the vertical differentiation during the orogenic movement; the internal differentiation within the mountain region accompanying with ecological isolation in south-western China.

(2) As result of a plexus or semi-matrix diagram of species based on correlation analysis for 6 major subalpine forest associations in western Sichuan, the shrub and herb species could be divided clearly into 2 close linkage natural groups-the sciohydrophytic one in higher elevation and the semixerophytic one in lower elevation, and a losse mesophytic group. The mosses could be divided into a close semixerophytic and a close thermophytic group in lower elevation, and a losse scio-hydrophytic group in higher elevation.

(3) Plant species distributing along ecological series are in 4 patterns: 1. narrow in elevation in synusia form on the whole; 2. narrow in elevation in scattered form on the whole; 3. broad in elevation, but narrow distribut in elevation only in synusia form; 4. broad in elevation. The last one has less indicative significance.

( 4) In 2 and 3 dimensional ordination, the samples of 6 major forest associations may be plotted according to the axes related to the elevation, moisture and soil fertility gradients in ordination fields. The positions on each axis and distance values between associations can quantitatively reflect the difference between associations.

The high-cold steppe is extensively distributed in the Qiangtang Plateau, Xizang autonomic region. This paper discusses the floristic composition, geographical elements of flora, life-forms and synusiae as well as ecological groups and growth rhythm of this type of vegetation. Seven groups of the steppe with reference to their ecological distribution principles are described. In comparison with the characteristics of the temperate steppe in the north, this type of steppe is remarkably distinct with the former. Both may be regarded as subtypes of the steppe.

Qinghai Province is situated in northeastern part of Qinghai-Xizang Plateau, where the land utilization varies from place to place because of the different topographic, climatic, and edaphic conditions. From the ecological view-point, the development of agriculture, forestry, animal husbandry and sideline culture are discussed in the following three regions: 1. The Tsaidam Basin. The basin situated in the northwest of the Province is a depression enclosing by high snow-clad mountains in a high plateau, the elevation of its floor varying from 2650-3000 m. The climate is very dry, being from 50 to 150mm. annually. However, during the growing season weather with difference in temperature between the day and night, together with intense radiation and long daytime favours to high yield and best quality of spring wheat, white potatoes, qingke barley, peas, cabbage and sugar beer grown in the areas where irrigated water comes down from the melted moutain snow. The areas also yield newly-introduced apple and cultivated Lyoium. Nevertheless, the extensive area of salty soil is the limiting factor to the agricultural development.2. The Eastern Region. The topography together with its climate of this region is highly variable. Spring wheat, beans, vegetables and deciduous fruits such as apple, apricot, pear and walnut can be well grown it the fertile valleys of the Yellow River and Huangshui River. The valleys are excellent farming areas, being 1600-2300 m. above sea level with rather warm temperature and well developed irrigation In the intermountain basins of about 3000 m. in elevation with moist and cooler climate, rapeseed gives high yield and fine quality. The higher mountains are suitable for raising yaks and goats, while the lower slope should be gradually ceased from farming to grazing. Some coniferous forest must be protected on the northeastern mountains along the river. 3. The Southern Plateau. The Southern province is with rather cold and moist climate mostly at an altitude of 4000-5000 m. The area has extensive grasslands dominated by Kobresia spp. and some grasses suitable for intensive development of animal husbandry. The yak, Tibet’s chief draught animal, is adaptable to the high altitude and cold climate. It serves a means of tranport, and its long hair, its milk, flesh and hide are all utilized.