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Accueil du site → Doctorat → Chine → 2011 → Biodiversity Patterns and Environmental Interpretation of Stipa Breviflora Grassland in Inner Mongolia

Université de Mongolie-Intérieure (2011)

Biodiversity Patterns and Environmental Interpretation of Stipa Breviflora Grassland in Inner Mongolia

张庆;

Titre : Biodiversity Patterns and Environmental Interpretation of Stipa Breviflora Grassland in Inner Mongolia

Auteur : 张庆;

Grade : Doctoral Dissertation 2011

Université : Université de Mongolie-Intérieure

Résumé partiel
Biodiversity is a necessary prerequisite of ecosystem function and ecosystem services. It maintains both the sustainability of natural ecological systems and the well-being of human society. Besides providing material resources for the humanity directly, biodiversity has other important ecological, scientific, and aesthetic values. In recent years, unreasonable exploitation of natural resources by the society has accelerated habitat loss and species extinction. These adverse effects seriously damage ecosystem integrity and pose a threat to human survival and development. Therefore, biodiversity preservation and maintenance is the matter of urgent international concern.In this study we chose Stipa breviflora grassland as the research object and explored biodiversity patterns and their relationships with environmental factors at multiple scales. First, our research contributes to the understanding of ecosystem function and provides additional empirical evidence for theories developed in plant ecology and biodiversity. Second, our findings can provide the needed scientific basis and theoretical support for rational utilization of grasslands and restoration of damaged grassland ecosystems. Main results from the study are outlined below.1. Genetic diversity of S. breviflora grassland in Inner MongoliaGenetic diversity of S. breviflora populations and its relationship with climatic variables were studied using Geographic Information Systems (GIS) and the Random Amplified Polymorphism DNA analysis (RAPD). The RAPD produced a total of 308 bands with twenty-eight arbitrary decamer oligonucleotides. Among those,151 (or 49.03%) were polymorphic to the populations, and 45 (or 14.61%) were unique to specific populations. The genetic diversity of S. breviflora was high, but lower than that of the other two common species in the area-S. grandis and S. krylovii. Eight different geographical populations were analyzed by 3 different methods-the Hierarchical cluster analysis, the Principal Component Analysis (PCA), and the Unweighted Pair-Group Method with Arithmetic mean (UPGMA), which resulted in 2 groups of populations-warm-temperate and temperate. Mantel test showed a significantly positive correlation between genetic distance and geographical distance. Both detrended canonical correspondence analysis (DCCA) and Pearson correlation analysis showed that correlations between genetic differentiation and temperature were strong in the area. In particular, we found significant correlations of genetic differentiation with accumulated temperature≥10°, accumulated temperature≥0°, mean temperature of the coldest and the hottest months, annual mean temperature, and the number of frost-free days. We therefore conclude that temperature variations play an important role in the genetic differentiations of the investigated S. breviflora populations. Genetic flow was found to be and important process in genetic differentiation.2. Species diversity of S. breviflora grassland in Inner MongoliaThe studied populations of S. breviflora contained a total of 161 species belonging to 31 families and 96 genera of Spermatophytes. Species found belong to several families : Compositae (29), Leguminosae (25), Gramineae (23), Liliaceae (10). Hence, the floristic diversity is high. The ratio of genera to species of studied populations was 1/1.68, which is smaller than that of the entire Inner Mongolia (1/3.33) or China (1/8.73). This result suggests that the level of species differentiation is low. We found that vegetation composition is mainly characterized as being representative of the temperate zone, although certain elements of the tropical flora were also found, leading us to the conclusion about the transitional character of the local flora. Statistical analyses of life form occurrences showed that perennial herbs dominated the steppe communities. Besides, shrubs and semi-shrubs were also common life forms. They mainly occupied sandy soils that covered many areas in this region. While xerophytes generally dominated plant communities, non-xerophytes accounted for a larger proportion of species found. We found that different ecological types of water regime controlled the distribution of plant communities.Spatial distribution of S. breviflora grassland communities in Inner Mongolia clearly followed longitudinal and latitudinal gradients:species richness increased significantly with longitude increasing (west-east gradient) and latitude increasing (south-north gradient). We found that species richness increase along the latitudinal south-north gradient is mainly due to the collinearity between environmental factors that change along the latitudinal and longitudinal gradients in the study area

Mots clés : Inner Mongolia; Stipa breviflora; biodiversity; pattern; environmental interpretation;

Présentation (CNKI)

Page publiée le 9 juin 2018