| The Qilian Mountains are an important ecological function area in northwestern my country.Under the background of global warming,their vulnerability and sensitivity have become more prominent.Accurately understanding the physical and chemical properties of soil under different land use patterns in the Qilian Mountains and clarifying the factors affecting grassland productivity can provide scientific advice for the rational use and ecological protection of different land types in arid and semi-arid regions.In this study,five different land use patterns of shrub meadow,alpine steppe,mountain desert grassland,woodland and farmland in the Kangle grassland area in the central Qilian Mountains were used as the research objects.In 2020 and 2021,some soil physical and chemical properties and grassland were determined Productivity status,study the dynamic change law of soil moisture and water storage capacity under different land use modes,further analyze the differences in soil physicochemical properties and ecological stoichiometry values under different land use modes,and explore the key factors affecting the productivity of grassland ecosystems.The specific research results are as follows:(1)The soil moisture content of shrubs meadows and forest gradually decreased with the increase of soil profile depth,while the soil moisture content of alpine steppe,mountain desert grasslands and farmland showed an ―S‖ that first increased and then decreased.The distribution of soil mass and water content in the 0-100 cm soil layer varies sharply with time,while the variation in the 100-200 cm soil layer is significantly weakened.The 0-100 cm soil water storage and evapotranspiration in 2021 are in descending order: shrub and meadow > alpine steppe > farmland > mountain desert grassland > forest.There are soil water deficits in different land use methods in this area.(2)Based on the two-year research results,the soil profiles of five different land use patterns have obvious vertical changes in organic carbon,total nitrogen,nitrate nitrogen,ammonium nitrogen,available phosphorus,and saturated hydraulic conductivity.The phenomenon of "aggregation",that is,decreases with the increase of soil depth,but soil bulk density,p H,and electrical conductivity show an increasing trend with the increase of soil depth.In addition,soil C: P and N: P showed a decreasing trend with the increase of soil depth under different land use patterns.Correlation analysis showed that soil C,N,P and physical properties were significantly related to soil ecological stoichiometry.or extremely significant correlation,among which the soil quality water content and soil bulk density under the five land use modes of Qilian Mountain Nature Reserve are the main factors affecting the soil ecological stoichiometry in this area.(3)The above-ground and below-ground productivity(dry weight)of the three different grassland types were consistent,which were: shrub-meadow > alpine steppe >mountain desert grassland.Among them,the underground biomass is distributed in a "T" shape,and the proportion of the underground biomass in each layer to the total underground biomass gradually decreases with the increase of soil depth.The correlation analysis showed that the aboveground productivity of different grassland types had extremely significant positive correlations with the 10-20 cm soil mass water content and chemical properties with the 0-10 cm soil organic carbon content,respectively,and the respective correlation coefficients were the largest.,with extremely significant negative correlation with soil bulk density,p H value,total phosphorus and electrical conductivity of each layer of 0-30 cm;underground productivity of each layer of 0-30 cm and soil clay,silt,mass water content of the corresponding soil layer,organic carbon,total nitrogen and ammonium nitrogen had a very significant positive correlation,and had a very significant negative correlation with soil bulk density,total phosphorus and pH. |
PDF Full Text Request