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Accueil du site → Doctorat → Chine → 2007 → Co-variation of Vegetation and Soil Quality during Ecosystem Restoration in the Hilly Region of the Semiarid Loess Plateau

Lanzhou University (2007)

Co-variation of Vegetation and Soil Quality during Ecosystem Restoration in the Hilly Region of the Semiarid Loess Plateau

蒋金平;Jiang Jin Ping

Titre : Co-variation of Vegetation and Soil Quality during Ecosystem Restoration in the Hilly Region of the Semiarid Loess Plateau

Auteur : 蒋金平;Jiang Jin Ping

Grade : Doctoral Dissertation 2007

Université : Lanzhou University

Résumé
The hilly region of the semiarid Loess Plateau locates the ecosystem fragile zone innorthwest china, and is one of the most severe ecosystem degraded areas. Serious soil erosionand water loss, vegetation destruction, and frequent arid and sand blown by wind in recentyears which led to ecosystem instability. It was not only a threat to the sustainabledevelopment for the region, but also maybe impact other nearby areas and east regions. Soilquality restoration and soil management is the key for vegetation construction andeco-environment sustainable development in the semiarid Loess Plateau. Aimed at therequirement of eco-environment construction and the hotspot in soil and environment sciences inthe Loess Plateau, taking on the soil and vegetation by three vegetation restoration measurements(abandoned land, establishing seeded grassland and shrub) in typical hilly region of the semiaridLoess Plateau (Lanzhou region) as research object, through field experiment and lab test,combining with historical data collection and field investigation, soil quality evolvementmechanism in the process of ecosystem restoration was studied in this project. The vegetationtraits and soil quality indicators changes were identified in different vegetation restoration ways,and using some statistical analysis tools (Duncan’s multiple range comparison, simplecorrelation and principal components analysis) to analyses quantificational soil quality factorsfor opening out the relationship between vegetation development and soil quality factors.Finally recommendation for vegetation restoration and soil quality improvement was proposed.The goal was to provide scientific reference for vegetation rehabilitation and soil quality care inthe semiarid Loess Plateau, and enrich the theory and method for soil quality management. Themain results were as follows:1. Co-variation of vegetation and soil quality in different age alfalfa fields :(1) The vegetation traits of different old alfalfa fields : the yields of alfalfa increased withthe prolong of planted ages from 3- to 9-year-old, but the speed of alfalfal yield increasing wasfaster during the period of time from 3- to 5-year-old, and the yield was relatively stability in9-year-old alfalfa field, the largest yield was 406 g hay/m-2, alfalfal yield would decrease after9-year-old with the degradation of alfalfal. The evegetation coverage and plant height trends weresimilar with the yield, with the largest values 85.5% and 52.8cm, respectively. Alfalfa severedecay and lots of them dead after 20 year, the yield observably decreased, the coverage and plantheight were very low. The richness of plant species increased with the growing years. There weremore species richness in 25-year-old alfalfal field, it was 22.(2) The soil quality of alfalfa field indicated distinct different during long-termdevelopment. Soil organic carbon (SOC), total N and available P notable decline from 3- to9-year-old alfalfa fields at 0-60cm depth, the lowest values were 7.95g kg-1, 1.20g kg(-1) and7.12 mg kg-1, respectively. The three properties values durative increased after 15-year-old.The pH values gradually decreased with the alfalfa older, it was 7.78 in 25-year-old alfalfafield. Microbial activity indexes (microbial biomass carbon (MBC), microbial biomassnitrogen (MBN), and basal respiration (BR)) continuously declined from 3- to 9-year-old after planted, and the lowest values were found in 9-year-old alfalfa field, they were 88.5.0μg Cg-1, 16.3μg N g-1, 0.356 CO2-Cμg g-1 h-1 at 0-20cm depth (spring). They increased after9-year-old, and these values in 25-year-old alfalfa field were 254.6.0μg C g-1, 52.2μg N g-1and 0.55 CO2-Cμg g-1 h-1, respectively, at 0-20cm depth (autumn). Soil qCO2 has reversechange trend with microbial biomass in different old alfalfa fields, the lowest value wasindicated in 25-year-old alfalfa field, and it was 2.25μg CO2-C kg-1 MBC h-1 at 0-20cm depth(autumn), the largest value was 4.02μg CO2-C kg-1 MBC h-1 at 0-20cm depth (spring) in9-year-old alfalfa field.Soil hydrolytic enzyme activities (urease, invertase, neutral phosphatase and cellulolyticenzyme activity) gradually decreased from 3- to 9-year-old alfalfa field with the year gradient,and the change trend was reverse after 9-year-old

Mots clés : Semiarid Loess Plateau; ecosystem restoration; vegetation traits; soil quality evolvement; soil physical and chemical property; soil microbial activity; soil enzyme activity;

Présentation (CNKI)

Page publiée le 6 mai 2013, mise à jour le 5 octobre 2017