Interactions Between Reaumuria Soongorica Comunity Structure And Dynamics Of Soil Microbial Characteristics And Nutrients Properties During The Vegetation Restoration

Soil is an important component of terrestrial ecosysteml,and plays a crucial role in spatial distribution pattern of plant diversity.Soil microorganisms play acentral in decomposing organic matter,in detrmining the release of mineral nutrients,and in nutrient cycling,they affect soil nutrient contents, chemical-physical properties,and consequently,primary productivity.Soil quality restoration and soil management is a key question for vegetation restoration and eco-environment sustainable development for the hilly region of the semiarid Loess Plateau.It has theory and reality significance to study on Vegetation- soil-microorganism change at the semiarid Loess Plateau.In order to provide scientific reference for vegetation restoration and soil care in the Loess Plateau,the change of soil carbon and nitrogen and soil bacterial diversity were studied by designed five gradient levels of plant cover of Reaumuria soongorica at Lanzhou Experiment Base of Environmental Afforestation of South-North Mountains.The results showed:.1.Based on the research of Reaumuria soongorica in study area,using the length of crown diameter and the width of crown diameter as parameters,the fitted equation was set up and tested to estimate the aboveground biomass of Reaumuria soongorica.The fitted equation is given: y=0.7643x-0.0161(R~2=0.8709 P＜0.001),which had a relatively high accuracy and a fine quadratic relationship between the predicted values and measured values.2.Plant cover and aboveground biomass of Reaumuria soongorica increased with plant species diversity nd tended to be the highest with biomass 35.62 g/m2(total cover 48.73%),then species diversity decreased while plant biomass increased,and all plant diversity distribution pattern showed a normal distribution during plant restoration.3.Soil organic carbon(SOC),total nitrogen(TN),soil microbial biomass C (MBC) and microbial biomass N(MBN) gradually increased with vegetation cover.SOC,TN,MBC and MBN increased quickly before the vegetation cover approaching 48.73%.There were similar trend between soil microbial biomass(MBC and MBN) and nutrients(SOC and TN) under the same vegetation cover.4.Aboveground biomass showed a positive relationship with soil microbial biomass C and N(P＜0.05).SOC and N were positively correlated with the vegetation cover,aboveground biomass and soil moisture(P＜0.05).MBC,MBN,TN,MBN/TN showed positive relationship with SOC and TN either(P＜0.05),while MBC was positively associated with MBN(P＜0.05).The positive correlation between MBC and SOC or TN suggested that there were close relationships between soil microbial biomass and nutrients during the vegetation restoration,which also showed that the vegetation restoration improved the soil nutrient status and indirectly affected the soil microbial biomass.5.Soil bacterial diversity increased with vegetation cover,and then gradually remained at a quite constant level,although soil microbial communities structure was different from each other under different vegetation cover.There are no correlation between plant species diversity and soil bacterial diversity.These results imply that in arid and semiarid areas with sparse vegetation and lower plant diversity,the increase of the vegetation cover of Reaumuria soongorica obviously changed the ecological function of the soil.However,the unilateral increase of vegetation cover will have less effect to the soil properties.