Effect Of Fire On The Soil Organic Carbon Of Three Forests In North Subtropical Areas

In order to understand the effectsof fire to three different forest soil organic carbon and soil active organic carbon of north subtropical areas of China forest,taking Pinus massoniana,Cunninghamia Lanceolata and secondary forest(Quercus fabri Hanceand Lithocarpus glabermainly mixed with a small amount ofCyclobalanpsis glauca)after fire are selectedas the research object,and adjacent forest without forest fire are chosen as a control.Based onthe field sample plot survey and indoor analysis method,soil organic carbon in the depth of 0-50 cmsoil layerand the change of soil liable organic carbon of Pinus massoniana,Cunninghamia Lanceolata forest and secondary forest after one year forest fireare analyzed.The results provide basic data for forest fire effects on carbon cycle of north subtropical forest ecosystem,at the same time the results provide a scientific basis for vegetation restoration and ecological system.The results of the study are as follows:1?The forest fire effects on the soil organic carbon of natural Pinus massoniana forest(1)Compare to the control land,the soil organic carbonof natural Pinus massoniana in the depth of 0~50cm after burning in one year later increasedby 17.38t·hm-2,with an increase of23.78%,with significant differences(P?0.01).Among them,the soil organic carbonof natural Pinus massoniana after burning in one year laterin the depth of 0~10cm?10~20cm respectively increase24.8%?50.9%,with an significantdifferences.(2)The contents of soil total organic carbon(TOC),easily-oxidized carbon(EOC)and light fraction organic carbon(LFOM)in the natural Pinus massoniana land after fire were higher than that of contrast sample area,which were increased by 4.5%~47.6%,6.64%~43.04% and 8.95%~49.10%,respectively with significant differences in the depth of 0~10cm and 10~20cm(P?0.01).The largest increasing of soil organic carbon were appeared in the depth of 0~10cm,increased by 8.62 g·kg-1compared to the sample area.(3)TOC,EOC and LFOM were all significantly related to soil nutrients(total N,hydrolysis N and available K)after the fire.The main reason for the increasing of soil organic carbon could be due to the organic residues which from vegetation layer mixed in the soil.2?The fire effects on the soil organic carbon of natural Cunninghamia Lanceolata forest.(1)Compared withcontrast sample area,the soil carbon storage in the depth of 0~50cm were increased by19.1% and increased by 13.28 t·hm-2after the forestfire in one year later,respectively with significant differences in the depth of 0~10cm and 10~20cm(P?0.01),increased by 8.6 t·hm-2and 3.65 t·hm-2respectively.(2)The contents of soil total organic carbon(TOC),easily-oxidized carbon(EOC)and light fraction organic carbon(LFOM)were higher than those of contrast sample area,which were increased by 1.7%~38.0%?6.6%~33.2% and 3.1%~45.7%,respectively with significant differences in the depth of 0~10cm and 10~20cm(P?0.01).After the forest fires,the increase of TOC,EOC and LFOM were mainly concentrated on the surface of soil land the organic carbon content was increased by 9.22 g·kg-1 in 0~10cm layer.(3)TOC,EOC and LFOM were all significantly related(P?0.01)to soil nutrients(total N,hydrolysis N and available K).3?The fire effects on the soil organic carbonof secondary forest(1)Compared withcontrast sample area the soil carbon storage in the depth of 0~50cm were increased by18.8% and increased 14.34 t·hm-2afterthe forest fire in one year later,with significant differences(P?0.01).The soil carbon storage in the depth of 0~10cm and 10~20cm layer increased by 7.72 t·hm-2 and 5.08 t·hm-2respectively.(2)The contents of soil total organic carbon(TOC),easily-oxidized carbon(EOC)and light fraction organic carbon(LFOM)were higher than those of contrast sample area,which were increased by 3.9% ~ 35.1% ? 9.6% ~ 47.3% and 1.2% ~ 61.4%,respectively with significant differences in the depth of 0~10cm(P?0.01).After the forest fires,the increase of TOC,EOC and LFOM were mainly concentrated on the surface of soil and the organic carbon content was increased by 8.00 g·kg-1 in 0~10cm layer.(3)TOC,EOC and LFOM were all significantly related(P?0.01)to soil nutrients(total N,hydrolysis N and available K)after forest fire.The main reason for the increasing of soil organic carbon could be due to the organic residues which from vegetation layer mixed in the soil.4?The comparisonof three different forest soil organic carbon change by forest fire(1)There is not very significant differences of soil organic carbon about increment in same layer of Pinus massoniana,Cunninghamia Lanceolata and secondary forest type,with No obvious change rule.In the depth of 0~10cm layer,The increment of soil organic carbon followed the orderCunninghamia Lanceolata>Secondary forest >Pinus massoniana.(2)The soil organic carbon storage increased not very significant differences in the depth of 0~50cm,no obvious change rule.In the depth of 0~10cm layer,The increment of soil organic carbon followed the orderCunninghamia Lanceolata>Pinus assoniana>Secondary forest.(3)There is a very significant differences of the easily-oxidized carbon about increment in the depth of 0~10cm layer of Pinus massoniana,Cunninghamia Lanceolata and secondary forest type by moderate fire.The increment of easily-oxidized carbonfollowed the orderPinus massoniana>Secondary forest>Cunninghamia Lanceolata.There is not very significant differences and no obvious change rules in the depth of 10~50cm layer.(4)The light fraction organic carbon increased not very significant differences,in the depth of 0~10cm layer,the increase of light fraction organic carbonfollowed the orderPinus massoniana>Secondary forest>Cunninghamia Lanceolata.In the depth of 10~50cm layer,the increase of light fraction organic carbonfollowed the order:Pinus massoniana>Cunninghamia Lanceolata>Secondary forest.