Soil Quality Evolvement Mechanism In The Process Of Ecosystem Restoration And Its Management In Loess Hilly-gully Region

Soil quality restoration and soil management is the key for vegetation construction andeco-environment sustainable development in the Loess Plateau. Aimed at the requirement ofeco-environment construction and the hotspot in soil and environment sciences in the LoessPlateau, taking on the soil in the erosion environment on the hilly Loess Plateau as researchobject, through field experiment and lab test, combining with historical data collection andfield investigation, soil quality evolvement mechanism in the process of ecosystem restorationwas studied in this project. Soil quality indicators in the erosion environment were identified.Regression models for soil quality assessment were also established, and limiting soil qualityfactors were identified. Finally recommendation for vegetation restoration and soil qualityimprovement was proposed. The goal was to provide scientific reference for vegetationrehabilitation and soil quality care in the hilly Loess Plateau, and enrich the theory andmethod for soil quality management. The main results were as follows: 1. Soil quality assessment indicators and corresponding assessment model for theerosion environment in the hilly gully region of Loess Plateau were established, thecriterion for soil quality assessment in the region were also set up. Through factor analysisand discriminant analysis, combining with sensitivity analysis, 8 soil quality indicatorsincluding organic matter, K10,anti-scrubility,CEC,invertase,MWD,available phosphorousand MICMWD, were identified from 29 soil chemical , physical and biological indicators of208 soil sampling sites in 10 landuse types. Integrated soil quality evaluation model wasestablished by applying weighted integrating method in fuzzy mathematics. The integratedevaluation results to the topsoil in 10 landuse types on the hilly-gully region of Loess Plateaushowed that there were significant differences in soil quality among landuse types. Soilquality in natural forestland belonged to grade 1 with the best soil quality; soil quality innatural shrub land and vegetable land was in the next place and belonged to grade 2; soilquality in natural grassland belong to grade 3 and in planted woodland and shrub land wasnear to grade 3; soil quality in planted grassland, revegetated grassland, cropland and orchardiv 黄土丘陵区生态恢复过程中土壤质量演变及调控belonged to grade 4. As a whole, soil quality in the research area was in lower level. 2. The evolvement rule of soil chemical, physical, biological indicators and soilquality index was clarified with landuse years in different landuse types. The regressionmodels for soil quality evolvement were also established. There were significant positivecorrelations between landuse years and soil total nitrogen, organic matter, labile carbon,available nitrogen, available potassium, C/N, situation of micro-aggregate, structurecoefficient, MICMWD, MWD, aggregate stability, SMBC, SMBN, phosphatase, invertaseand urease, in revegetated grassland and planted woodland. Significant positive correlationswere also found between landuse years and soil total nitrogen and organic matter in orchardand planted shrub land. Significant positive correlation was showed between landuse yearsand K10 in revegetated grassland. Linear function or power function was suitable for fittingthe correlations mentioned above and was used to establish the regression models for soilchemical, physical and biological quality evolvement with landuse years. Based on the soilquality evolvement models established, we estimated that the time needed for soil quality toreach to middle level was 66, 42, 25 and 21 years respectively in revegetated grassland,orchard, planted shrub land and planted woodland. It's only 10 years for soil quality invegetable land to reach to high level. 3. In the hilly-gully region of Loess Plateau, land use change was the driving forcefor soil quality change. Effected by land use change, th...