| Grazing is a main way to use the desert steppe in Inner Mongolial.It is of great significance to study the distribution of soil organic carbon under different stocking rates,and to restore the grassland ecological and promote the precision grazing.Based on different stocking rates of long-term grazing plot,including CK?LG?Lightly grazed??MG?Moderately grazed?and HG?Heavily grazed?,the dynamic distribution of soil organic carbon content and spatial heterogeneity and its influence factors were studied by the high density sampling and statistical methods,to understand the process and mechanism of grassland degradation,to contain the further destruction of grassland ecology,and to provide data and theoretical support for the sustainable development of the local animal husbandry.The main results are as follows:1)Grazing reduced soil organic carbon content in Stipa Breviflora desert steppe,soil organic carbon content in CK area was significantly higher than that in LG,MG and HG area?P<0.05?,followed by CK(12.80mg·kg-1)>MG(11.94 mg·kg-1)>HG(11.77 mg·kg-1)>LG(11.73 mg·kg-1).The organic carbon content of each grazing area than control area decreased by 8.43%?LG?,8.43%?MG?,7.33%?HG?respectively,soil organic carbon content in MG area was slightly higher than that in LG and HG areas,and there was no significant difference between different grazing areas.The grazing intensity did not affect the change trend of organic carbon content in the 0-30cm soil layer,and gradually decreased with the depth of the soil layer.The range of change was 13.55-14.99g kg-1?0-10cm?,11.60-12.66 g kg-1?10-20cm?,10.01-10.20 g/kg-1?20-30cm?.Grazing had a certain effect on the content of organic carbon in 0-20cm topsoil.Moderate grazing was conducive to reducing spatial heterogeneity of soil organic carbon and increasing its spatial autocorrelation.,the degree of autocorrelation in turn:MG?77.70%?>LG area?73.10%?>HG area?67.10%?>CK area?66.00%?;The block gold value CK area and HG was significantly higher than that of other grazing areas,there were many uncertainties and randomicity of the variation,which indicates that some ecological processes on the sampling scale less than 2.5m can not be ignored and need further study.2)Grazing reduced the total nitrogen content of soil,the soil organic carbon was positively correlated with the total nitrogen of soil,and the correlation between HG area and CK area was extremely significant;Grazing had no significant influence on total phosphorus in soil,and the total phosphorus in soil was positively correlated with soil organic carbon,and the HG area was extremely significant.3)In the study of regional micro-topography,soil organic carbon content had a significant negative correlation with altitude,and the soil organic carbon content decreased with the elevation of altitude.With the increase of soil layer,the response degree of soil organic carbon to altitude gradually decreased,indicating that surface soil was the main occurrence area of soil organic carbon change. |
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