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Université de Shihezi (2015)

Study of Sensitivity of Plant Diversity to Precipitation Change in The Gurbantünggüt Desert

曾勇

Titre : Study of Sensitivity of Plant Diversity to Precipitation Change in The Gurbantünggüt Desert

Auteur : 曾勇

Grade : Master’s Theses 2015

Université : Université de Shihezi

Résumé
At present, plant diversity loss has become the ecological issues of the word. A lot of studies show that the impact of climate change on plant is widely and serious. Desert ecosystems receive little rainfall, have low levels of plant diversity. Plants have evolved unique adaptations. These include drought and heat resistance and tolerance to saline-alkaline soils. The Gurbantünggüt Desert is a resource base for desert adapted plant germplasm. However, plant growth high susceptibility to climate change. So, it is important to protect desert plant resources and the ecological environment by researching the influence of climate change on desert plant diversity.The desert was divided into five sub-regions based on the difference of precipitation and plant diversity characteristics from preliminary survey.We anlysized plant the change of diversity and precipitation for 5 years(2009-2013). This study analyzes how change occurs in different life forms plants and specific species differ in slope position on sand dunes in relation to variations in climate. The specific finding are follows :(1) We analyzed the relationship between species riches and environmental factors using stepwise regression analysis. Variables included total annual precipitation, mean annual temperature, the coefficient of variation(Cv) of both daily precipitation and monthly temperature, 3-6 month precipitation, 3-6 month average temperature. Plant diversity was positively correlated with annual precipitation and3-6 month precipitation.(2) Annual precipitation, the Cv of daily precipitation, mean annual temperature in five sub-regions in desert exhibited an increasing trend from 1977 to 2013 years. Seasonal precipitation has obvious increasing trend from year to year. Seasonal average temperature almost has no change from year to year. Precipitation has significant influence on interannual variability of vegetation coverage. The variability of vegetation coverage and precipitation have the same change trend. The plant diversity(α diversity, evenness, and richness) are high in regions with relatively high precipitation, and plant diversity are low in regions with lower precipitation. Plant diversity was positively correlated with annual precipitation.(3) Species richness of ephemeral plants, annual plants, perennial herbs and shrubs of regions with relatively high precipitation were higher than those of regions with lower precipitation.Ephemeral species richness significantly increased with increasing precipitation, life-histories waswere(greatest to least) : ephemeral plants>annual plants >perennial herbs>shrubs. The dominant species, species number and species composition are different across the 5 sub-regions. The species number in regions with relatively high precipitation was significantly higher than low rainfall regions.(4) The dominant species coverage and density was positively correlated with precipitation in desert.The coverage and density of shrubs Ephedra distachya and Seriphidium terraealbae are likely to increase with increasing precipitation. The coverage and density of Haloxylon persicum and Calligonum leucocladum are likely to decline with increasing precipitation.There was no link between Haloxylon ammodendron and precipitation. The density of fifteen twenty-fourths herb species increased with increasing precipitation. The cover of nineteen twenty-fourths herb species increased with increasing precipitation. The density and coverage of 10 species reached significant level. Only Hypecoum parviflorum did decrease with increasing precipitation. The coverage change of different plant life-forms has increased trend with 3-6 month precipitation increased. The widely distributed Calligonum leucocladum, Horaninowia ulicina, Haloxylon persicum, Salsola praecox, and Tetracme recurvata has declined trend with 3-6 month precipitation increased. The narrow distribution Alyssum linifolium and Orobanche coerulescens also has declined trend with 3-6 month precipitation increased.(5) Species richness of different slope positions on the dunes in regions with relatively high precipitation was significantly larger than regions with relatively lower precipitation. Precipitation effects on plants differed according to their slope positions on the dunes. Increased precipitation resulted in increased species richness in the lower and inter-dune area, and these were higher than the upper dune and top. Species turnover declined with increasing precipitation.We found that if future precipitation continues to increase, distribution advantage of herb plants increases. However, Haloxylon persicum and Haloxylon ammodendron are dominant desert species with important ecological functions, but their frequency distribution are likely to decline with increasing precipitation.This study will be useful analysis features of climate change, the regional plant diversity catalogue, long-term dynamic monitoring of desert vegetation, the estabilishment of protection areas, protection of plant resources of resistance and sustainable management, vegetation restoration and so on in the Gurbantünggüt Desert

Mots clés : precipitation amounts; coefficient of variation of precipitation; mean annual temperature; coefficient of variation of temperature; plant diversity;

Présentation (CNKI)

Page publiée le 1er juillet 2017, mise à jour le 3 avril 2018