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Université de Shihezi (2020)

Disturbance Effect of Dominant Rodents on Haloxylon ammodendron in the South Edge of Gurbantunggut Desert


Titre : Disturbance Effect of Dominant Rodents on Haloxylon ammodendron in the South Edge of Gurbantunggut Desert

Auteur : 向雁玲;

Grade : Master’s Theses 2020

Université : Université de Shihezi

In desert ecosystem,the assimilated branch of Haloxylon ammodendron has high nutritional value and is an ideal source of water and nutrition for desert rodens.Rodents often burrow and build burrow systems under the bush of H.ammodendron,and collect assimilated branches and seeds of H.ammodendron near the burrow systems.The activities of herbivores can change the morphological characteristics of plants,the content of nutrients and the physical and chemical properties of soil.After being fed by herbivores,plants will adopt various defense strategies to maintain their normal growth and development.To some extent,changes in plant morphology and nutrient content can be regarded as a low-cost defense mechanism.Age can affects the best defensive strategy of plants.H.ammodendron of different ages stage may show different physiological and ecological responses under the disturbance of rodents.Moreover,in the southern edge of the Gurbantunggut Desert,the physiological and ecological responses of different age groups of H.ammodendron to the disturbances by rodents are not clear.In our study,the physical and chemical properties of soil under shrubs,above-ground morphological characteristics along with physiological and biochemical features of assimilating branches in different height of H.ammodendron(young,30-100cm ;middle-aged,100-200cm ;mature,>200cm)in burrowed areas and non-burrowed areas were compared in he southern edge of the Gurbantunggut Desert.We found that :(1)The disturbance of rodents makes the proportion of young and mature H.ammodendron in the burrowed areas greatly reduced.The decrease of the proportion of mature H.ammodendron showed that the mortality of H.ammodendron was high during the transition period from middle aged H.ammodendron to mature H.ammodendron.But the proportion of middle aged H.ammodendron(0.44)increased.It shows that the mortality of H.ammodendron was low in the process of transition from young H.ammodendron to middle aged H.ammodendron.(2)The disturbance of rodents can strengthen the"Fertile Island"effect of H.ammodendron,and has a certain impact on the"Salt Island"effect of H.ammodendron.This is mainly reflected in the increase of soil SOM,TN,an and AP content under shrub,especially the content of AN,TN and AK in the surface soil(0-20cm).The pH value of soil in the depth of 20-40 cm increased significantly under the H.ammodendron shrub.(3)The disturbance of rodents promoted the basal diameter,branch and crown of H.ammodendron,but slightly inhibited the plant height.The changes of morphological characteristics of young and middle-aged H.ammodendron were more extensive than that of mature H.ammodendron.In the burrowed areas,the increase of basal diameter was only significant in the young H.ammodendron.The crown diameter and total branching rate of H.ammodendron increased significantly in both young and middle aged H.ammodendron.

Mots clés : Haloxylon ammodendron; age groups; population structure; assimilating branches physiological and biochemical features; soil physical and chemical properties;

Présentation (CNKI)

Page publiée le 2 novembre 2020