Spatial-temporal Feature Of Soil Carbon And Nitrogen In Horqin Dune-meadow Cascade Ecological Zone

Soil carbon sequestration is a bridge across desertification and climate change.As well as enhancing food security,it can also reduce fossil fuel emissions.And it can be largely impacted by natural factors and human disturbances.In this paper,we studied the spatial-temporal characteristics of soil carbon and nitrogen and their relationships with environmental factors in different landform-vegetation combination units in Horqin dune-meadow cascade ecological zone.The results show that:(1)The soil carbon and nitrogen contents of Caragana microphylla community in the semi-fixed dune had obvious temporal and spatial heterogeneity.The plaque development and hydrological condition were the main factors affecting the heterogeneity.(2)The soil carbon and nitrogen contents of Reed community in the meadow wetland showed distinct spatial and temporal heterogeneity.Vegetation and hydrology were the key factors affecting the heterogeneity.(3)The SOC and TN contents in the Horqin dune-meadow cascade ecological zone were relatively low,being at Grade 3 or below.There were large differences in the profile distributions of soil carbon and nitrogen contents in different landform-vegetation combination units(especially the surface layers).The seasonal variations of soil carbon and nitrogen reserves in each unit were significant and the seasonal dynamicswere different.The soil carbon and nitrogen content/reserve increased along the dune-meadow gradient direction.Soil moisture andsoil texture played an important role in this trend.(4)Different means of recovery(planting shrub and returning farmland)showed different influence characteristics on soil carbon and nitrogen,but both played a role in promoting.Our research is the first toexperimently and comprehensively study the spatial-temporal characteristics of soil carbon and nitrogen in the dune-meadow cascade ecological zone in arid and semi-arid regions.It will provide scientific basis for the assessment of soil ecological function,management of land use,as well as helping in coping with climate change.