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Accueil du site → Doctorat → Chine → 2008 → The Structure and Dynamics of Plant Communities and the Dominant Population in Minqin Desert Grassland

Gansu Agricultural University (2008)

The Structure and Dynamics of Plant Communities and the Dominant Population in Minqin Desert Grassland

Liu Xiao Chun

Titre : The Structure and Dynamics of Plant Communities and the Dominant Population in Minqin Desert Grassland

Auteur : Liu Xiao Chun

Grade : Doctoral Dissertation 2008

Université : Gansu Agricultural University

Résumé partiel
Minqin Desert Grassland as our part of the Mongolian plateau grasslands area, located in the arid desert region of Shiyang River downstream, is a long-term adaptation to the natural and social environment, the result of natural succession in a particular environment. Maintain the Minqin regional ecological environment is stable to withstand the hazards of sandstorm, plays an extremely important role in promoting local economic development, an important part of the local ecological environment and the socio-economic development. Therefore, to study the changes in vegetation dynamics and community characteristics of the region, has a very important significance to the local ecological environment and the socio-economic development. Minqin Desert Grassland major plant communities through field survey, combined with \. The main content of the study : the Minqin desert grassland type and its plant community types and distribution : plant community structure characteristics (including the number of the species composition, physical characteristics, diversity, dominant populations and distribution patterns) ; through plotted advantage kinds of age structure diagrams and static life curve analysis of the dynamic changes and trends of the Dominant Plant Populations. The results are as follows : (1) According to REN Ji Zhou Yuanshi grasslands comprehensive and sequential classification Minqin Desert Grassland classified as the Ⅳ A4-tepid extremely dry (temperate desert steppe). Minqin Desert Grassland indicators can be divided into three sub-categories to soil type and terrain features, the gravelly desert grassland, the sandy desert grassland and salinization desert grassland. (2) the gravelly desert grassland distribution denudation low mountains and its surrounding areas in northern Minqin, salinization mainly distributed desert grassland in Minqin Basin, the lowest point of the Western rivers, the ancient lake basins of the East major rivers and rivers Tail Strip Article massive, sandy desert grassland was distributed between the oasis and gravelly desert grassland. Minqin Desert Grassland general characteristics : sparse vegetation, few varieties, poor quality, low yield, the total area of ??934,639.80 hm to 2, which gravelly desert grasslands and sandy desert grassland accounted Minqin Desert Grassland area 39.44% and 37.66%, respectively. (3) the Minqin desert grassland plant communities representative Nitraria communities, community soongorica, Kalidium communities, Phragmites communis, Tamarix Community Oxytropis davidii communities, Wood Overlord communities, of Caragana microphylla microphylla children community, film fruit Ephedra community, Mian davidii communities. The largest communities Nitraria community area of ??approximately 310290.20 hm 2, accounting for 33.20% of the Minqin Desert Grassland ; the smallest communities Cotton davidii communities, with an area of ??approximately 8736.00 hm to 2, accounted for 0.93 of the Minqin Desert Grassland %. (4) the number of the Minqin desert grassland plant communities : the relatively small number of species, the the quadrat survey shows : most plant species the cathead thorn communities, only 17 species, at least the reed community is only five kinds of Minqin Desert 41 grassland species. The number of individuals of the species in various communities rarely less than 1 times 16.67 to 66.67% of the plant species in quadrats average number of occurrences. Other than Phragmites communis communities, other communities mainly dwarf shrubs and subshrubs ; analysis from a number of plants, Ephedra przewalskii community, cotton thorns community, the Kalidium community and of Oxytropis aciphylla community the shrubs, semi-shrubs more than 90% ; soongorica community, although the of Caragana intermedia community and wood Overlord communities shrub layer dominant advantage in numbers, but the majority of the herbaceous layer is smaller annual herb. (5) the Minqin desert grassland plant communities, in addition to of Oxytropis aciphylla community wood Overlord communities, the important values ??of the dominant populations of other communities are very prominent ; Ephedra przewalskii community Ephedra przewalskii important value Shakespeare dominant populations Bubble thorn above 159.78 ; the cotton thorn community in cotton davidii population important value of 204.35, above the Shakespeare dominant populations Nitraria 160 ; soongorica the communities in soongorica populations important value Biya the dominant species Su wolfberry higher 134.5 ; Salt claw claw communities in the populations Kalidium value Shakespeare advantage species Nitraria above 179.84 ; Caragana microphylla populations important values ??Shakespeare the dominant species tanguticum Nitraria Caragana intermedia community Nitraria Oxytropis thorn values ??higher 92.12,121.37 and 112.98 ; the Nitraria community and Phragmites communis the the Nitraria populations and the important values ??of Phragmites communis population accounted for a larger proportion. (6) are the dominant population distribution pattern of Minqin desert grassland plant communities cluster distribution, this distribution pattern and population reproductive strategy, population biology, as well as the harsh habitat conditions. Ephedra przewalskii, white thorn, reed and cotton thorn asexual reproduction, the formation of the mother plant as the center of the cluster distribution pattern ; the Kalidium soongorica Oxytropis thorn korshinskii and wood Overlord in seed germination

Mots clés : Minqin Desert grassland Plant communities Populations Dominant species Distribution pattern Species diversity

Présentation (Dissertationtopic)

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