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Accueil du site → Doctorat → Chine → 2009 → Reaponse of Soil Quality to Natural Vegetation Restoration Processes in the Ziwuling Area on the Loess Plateau

Northwest University of Science and Technology (2009)

Reaponse of Soil Quality to Natural Vegetation Restoration Processes in the Ziwuling Area on the Loess Plateau

Lv Chun Hua

Titre : Reaponse of Soil Quality to Natural Vegetation Restoration Processes in the Ziwuling Area on the Loess Plateau

Auteur : Lv Chun Hua

Grade : Doctoral Dissertation 2009

Université : Northwest University of Science and Technology

Résumé partiel
Resaerch on interaction between natural vegetation restoration and soil quality may provide important scitifical value for ecological rehabilitation and evaluation of environmental effect. The multiples methods of historical information collection, field investigation, germination experiment of soil seed bank and indoor analysis were used to study soil quality response to natural vegetation succession in the Ziwuling area of Loess Plateau. Characteristics of natural vegetation restoration and the contribution of soil seed bank to aboveground vegetation were investigated ; the the response of soil physical, chemical and microbiological characteristic to vegetation natrural succession were analyzed. Based anlysis of soil properties, the key indices of soil quality were selected. And then, the evaluation index system of soil quality during natural vegetation restoration was built and the effect of environmental factors on vegetation succession had been studied. The main research conclusions are as follows :(1) Characteristic of natural vegetation restoration process : the succession process of natural vegetation restoration in Ziwuling area experienced as Artemisia scoparia community(1-5a)→Lmperata cylindrical community(5-10a)→Leymus scalinus+ Phragmites Trin. Community(10-15a)→Bothriochloa ischaemum+ Carex lanceolata community(15-20a)→Hippophae rhamnnnides- Periploca sepium community(20-30a)+ Sophora viciifolia- Cotoneaster multiflorus community(30-50a)→Acer ginnala community (50-60a). After that, due to influences of landform and soil water moisture, the vegetation succession experienced Betula platyphylla- Populus davidianna community(60-100a) to Quercus liaotungensis climax community(100-150a) on the the slope with good water conditionl, which complated positive succession process on the research area ; but on the sunny slope with poor water condition, the vegetation succession envolved into the landform-soil climax community of Biota orientalis(60-80a). Results showed that the number of species in standing vegetation was 2.4 times than that in soil seed bank and the similarity index between standing vegetation and soil seed bank changed from 0.071 to 0.296. The diversity index change of herbage and shrub during vegetation restoration is expressed as parabola function, and the changing trend of diversity index in soil seed bank was the same as that in standing vegetation. Significant positive correlation was found between diversity index and restoration year.(2) Response of soil physical characteristic to vegetation restoration : soil porosity, field capacity and soil aggregate stability improved with an increase of vegetation restoration year. The fractal dimension (D) of soil aggregate decreased with increasing restoration years, and significant negative correlation between >0.2mm water-stable aggregate content and soil mean weight diameter (MWD) were found. In slow wetting (SW) treatment of the Le Bissonnais (LB) method, parts of big aggregates slaked into small water-stable aggregates through disintegration function,which weakened with an increase of vegetation restoration year. It showed that the stability of soil aggregate was enhanced during vegetation seccession.(3) Response of soil chemical characteristic to vegetation restoration : the content of soil organic matter (SOM), total N, and alkaline N increased as the vegetation restoration year increased, which showed obviously the trend of surface-accumulation (0-5 cm>5-10 cm>10-20 cm). Under the same life form of vegetation, the content of SOM, total N, and alkaline N increased with year. During the vegetation succession, the content of SOM, total N, and alkaline N fluctuated when the community changed from herbage to shrub or from shrub to abor.

Mots clés : natural vegetation restoration vegetation succession soil quality evaluation index Ziwuling area

Présentation (Dissertationtopic)

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