Study Of Soil Respiration Characteristic And Its Influence Factors Under Typical Revegetation Lands In Loess Hilly-gully Region

Since the full implementation of Green for Grain Project in loess hilly-gully region,vegetation types have been great changed and the area of vegetative cover has been substantial increased.In order to understand the influence of Green for Grain Project on the global carbon balance,incidentally to provide basic date for evaluation that the effects of vegetation restoration in loess hilly-gully region on global climate change,this paper has done an in-depth study about soil respiration rate in 5 typical revegetation lands,and the main impact factors on soil respiration in loess hilly-gully region.5 typical revegetation lands,include Robinia pseudoacacia(RP),Caragana korshinskii(CK),Platycladus orientalis(PO),mixed arbor(Robinia pseudoacacia and Platycladus orientalis,MA)and abandoned land(AB),were selected as study objects,and slop cropland was selected as the comparison.Characteristics of total soil respiration(Rt)and soil respiration components,include microbial respiration(Rs)and root respiration(Rr),in selected lands were discussed,and the main impact factors such as soil physical and chemical properties,root characteristics and microbial characteristics were studied,the relations between total soil respiration,soil respiration components and the main impact factors were analyzed at last.The main conclusions showed as follows:(1)Rt of selected lands in loess hilly-gully region ranged from 0.45 to 3.81?mol·m-2·s-1,and Rs ranged from 0.34 to 2.56?mol·m-2·s-1,Rr ranged from 0.26 to 1.40?mol·m-2·s-1.Rt,Rs,and Rr of the the selected lands were significantly changed during the growth period(from April to October),and the dynamics of them showed a monopeak curve during the growth period,all of them increased firstly and then decreased,reached their maximums in August.Rt,Rs,and Rr of RP increased with the increasing length of vegetation restoration.Percent of Rs to Rt among the selected lands ranged from 59.90 to 67.98,which was greater than that of Rr to Rt.(2)Among Rt,Rs,and Rr,Rs had the best correlation with soil temperature(Ts),and the correlation was extremely significant,then was the Rt(r=0.307),Rr has the minimal correlation with Ts(r=0.223);soil water content(SW)has less effect on soil respiration and soil respiration components,and the correlations were not significant;soil respiration and soil respiration components had significant negative correlation with soil pH;Rt was highly correlative with SOC and TN content,but the correlations were not significant,while the correlations between SOC,TN content and Rs,Rr were relatively not high.(3)Correlations between soil respiration,soil respiration components and FR were negative,and not significant;the correlations between Rt,Rs,Rr and fine root organic carbon content(RC)were extremely significant;Rt had extremely significant correlation with fine root nitrogen content(RN),and the correlations between Rs,Rr and RN were significant.(4)Rt and Rs had extremely significant correlations with soil microbial biomass carbon content(MC)in 0~10 cm and 10~20 cm soil layer,and the correlation between Rr and MC content in 0~10 cm soil layer was also positive significant;the correlation between Rt and soil microbial biomass nitrogen content(MN)in 0~10 cm and 10~20 cm soil layer was positive significant,while correlations between Rs,Rr and MN content in 0~30 cm soil layer were not significant.