|Other Abstract||In this paper, the research object was shrub community in typical areas of the Xinjiang Trtysh River Watershed. According to the quadrat inverstigation and TWINSPAN classification, we characterized the communitie with the species composion, floral feature, ecological niches and species diversity. Calorificvalue of 9 shrub communities was measured. This research has an important scientific guiding significance in understanding the status and role of Shrub vegetation in the ecological construction in the Irtysh River Watershed , and provides scientific basis for ecological restoration and rehabilitation . The main study conclusion are as follows:
(1)A total of 185 species were identified, including 44 shrub species and 141 herb species, belonging to123 genera and 31families. Most of plants belonged to Rosaceae, Compositae and Chenopodiaceae, which are the dominant families in arid regions of northwest China. The flora of shrub species was dominated by the North temperate, the ancient Mediterranean and West Asia to Central Asia components.
(2)Using the TWINSPAN methd, shrub communties in the 55plots could be divided into 9 types of shrub communities or shrub landscape, including plain and valley shrub, montane scrub and plain desert type.
(3) The basic characteristics of the shrub community were studied, with using the niche breadth and niche overlap formula and combining the field survey of the sample plots. The results show that the niche breadth of shrub species varies in different habitats, and environment and resources had high spatial heterogenetity in different shrub communities.
(4)By analysing the shrub community species diversity of species diversity index, evenness index ,dominance index and richness index, the results indicated that the structure of shrub community was simple, the speciesnumber of were few,and the shrub community diversity level was low.
(5)The species diversity of the shrub community is analyzed along altitude gradient.With the increase of the altitude, the Shannon diversity index, Pielou evenness index and species richness index showed a single peak distribution pattern.
(6)The Calorificvalue of species in shrub community were determinted. The Calorificvalue of shrubs was affected not only by their genetic characterstic and life history, which had biological, but aslo subject to environmental constraints and restricted by the community, which had ecological attributes.
(7)Further research on Calorificvalue characteristics of dominant shrub species show that the highest degree of lignification Betula rotundifolia Spach has the highest calorific value; There are differences in calorific value between families. The calorific value of Cupressaceae, Rosaceae and Leguminosae were higher than that of Chenopodiaceae and Polygonaceae;The calorific value of the plant will change with site conditions. The dominant species of shrub in the mountainous region is higher than that of the riparian lowland and desert. By comparing the calorific value of different kinds of shrub organs, there were differences in the Calorificvalue of plant organs. The heat value of the root was the lowest.At last ,we found that calorific value was positively correlated with species diversity index, richness index and evenness index, and negatively correlated with dominance index, but not significantly.|