Study on the Soil Thermal Conditions of Coniferous and Broad-Leaved Mixed Forest in Dinghushan Reserve

Based on the soil thermal measurements from Jan.1stto Dec.31th,2003,the soil temperatures,soil thermal fluxes,the relationship between soil temperatures and net radiation,soil thermal fluxes and net radiation of coniferous and broad-leaved mixed forest in Dinghushan Reserve were discussed in this paper.The following results were gotten:(1) The diurnal changes of soil temperature decreased with the depth of soil layers,and no obvious diurnal changes of soil temperature was detected at the depth of 40 cm.(2) The monthly soil temperature varied acutely at the soil surface layers.(3) There existed significant linear relationship(P<0.000 1) between soil temperature and net radiation at different temporal scales.(4) The changes of thermal fluxes swings at 5 cm soil layer were much milder than that of the surface soil layer,and the diurnal changes of thermal fluxes at 5 cm soil layer lagged behind the surface soil about 0.5-1.0 h.(5) The feedback of the surface soil heat fluxes lagged 2.5 h behind the net radiation,while the soil heat fluxes at 5 cm depth lagged 3.5 h.The soil heat fluxes of the surface soil were more closely related to the net radiation.