Effects Of Pinus Massoniana-dicranopteris Dichotoma Community Restoration On Soil Respiration In Eroded Red Soil Areas

Soil carbon pool plays an important role in the process of global change.In eroded red soil,restoration of vegetation may enhance soil carbon sequestration,which is of great significance to retardation of global change.But how it does still remains unclear.Soil respiration is an important link between the soil and the atmosphere in CO2 exchange.To a certain extent,the flux of soil carbon emission determines whether the soil is a sink or a source of carbon in the ecosystem.It is,therefore,essential to study impacts of vegetation restoration on soil respiration for better understanding of the mechanism of soil carbon sequestration in severely eroded red soil.In this study,two Pinus massoniana plantations,13 years old(Y13)and 31 years old(Y31),in Hedian Town,Fujian Province,were selected for comparison with a tract of virgin land(YO)nearby,in soil respiration.We also set up different treatments,including No dicranopteris dichotoma removal(NDR),No dicranopteris dichotoma removal(DR),bare land without dicranopteris dichotoma(BL).The results are as follows:(1)The soil respiration in Y13 and Y31 were significantly higher than that in YO(P<0.05),the soil respiration flux of Y0,Y13,Y31 was 459 g·m-2·a-1,1150 g·m-2·a-1,1234 g·m-2·a-1,respectively.The result show that he vegetation restoration exert an important impacts on soil respiration.(2)Compared with the bare land without dicranopteris dichotoma,NDR of Y0,Y13,Y31 increased by 14.24%,31.30%and 26.78%,respectively,while the dicranopteris dichotoma removal,Y13 and Y31 was decreased by 22.09%,5.95%,respectively,In Y0,dicranopteris dichotoma removal,increased in temperature result to soil respiration increased by 8.8%.We hold that dicranopteris dichotoma has important effects on soil respiration in the process of restoration of vegetation.(3)The litter biomass of Pinus massoniana was 71.41 g·m-2·a-1 in Y0,Y13 and Y31 was 270.28 g·m-2·a-1,379.52 g.m-2m·a-1,The litter biomass of dicranopteris dichotoma in Y0,Y13 and Y31 was 39.2 g·m-2m·a-1?219.41 g·m-2·a-1?210.94 g·m-2·a-1,respectively.After that,the soil organic carbon and total nitrogen were higher in NDR than in BL,indicating that the soil respiration was promoted by the return of a large number of litter and the increase of the substrate quantity.On the other hand,the C/N of the litterfall foliage of the Pinus massoniana was lower than that of the foliage of the Pinus massoniana,it is the litterfall of dicranopteris dichotoma is easier to decompose.The microbial biomass,bacterial PLFAs,and fungi PLFAs and F/B were higher in NDR than in DR.After the removal of the fern,it showed a downward trend.It showed that the microbial activity was promoted after the cover of the fern.In addition,the ammonium nitrogen and acid phosphatase were higher in NDR than in DR,but the lower pH in in NDR than in BL,It was shown that the coverage of dicranopteris dichotoma is beneficial to alleviate the N restriction and soil microbes can utilize organic P via the production of extracellular phosphatase enzymes which promote the increase of soil respiration.