Effects Of Selective Cutting On The Spatial And Temporal Distribution Of Fine Root In Mixed Broadleaved-Korean Pine Forest

Spatial and temporal distribution of fine roots biomass was studied using the sequential soil coring method in a virgin broadleaved-Korean pine (Pinus koraiensis) forest and a selection cutting (with was measured40years after commercial selection cutting) forest in Xiaoxing’an Mountains in Northeast China. This research surveyed the fine root biomass, whose size ranging from Omm to2mm, in the two stands through soil core method. And we also surveyed the fine root growth rate (value of G) and fine root death rate (value of M), whose size raging from Omm to lmm, through Minirhizotron technique. Then we came up with the seasonal dynamics according to the data above.(1) The results show that there was no significant difference between the growing season of the original forest and selective cutting forest on dead fine root biomass, living fine root biomass and annual average total fine root biomass (P>0.05); Total fine root Biomass and living biomass of fine roots had significant differences between the two stands in June and September (P<0.05). Dead fine root biomass had significant difference in May, July and August (P<0.05). Biomass of fine roots decreased with increasing soil depth in the two stands,80%of the living fine roots and more than75%of dead fine root biomass distributed in the soil layer from0cm to20cm, The total biomass, living biomass and dead fine root biomass merely had significant difference in the soil layer from30cm to40cm in the two stands (P<0.05).There is no significant difference among the ratio of living fine root biomass, the ratio of dead fine root biomass and the ratio of total fine root biomass in different diameter class (2-5mm and≤2mm) at the same depth of soil in original and selective forest.(2) Values of G of the virgin forest and the selection cutting forest are different from each other in the change of vertical distribution on soil profile from0cm to40cm. Values of G of the two stands have no significant difference in the4soil layers during8sampling intervals (P>0.05). Value of M of the two stands is relatively similar in vertical distribution. During the8sampling intervals, values of M of the two stands have significant difference in the third sampling interval on soil layer from0cm to30cm among the4soil layers(P<0.05). And there is no significant difference in the other soil layers in different sampling intervals (P>0.05). Values of G of both the two stands expressed as a bimodal curve with different peak times. And value of M of the two stands don’t have any significant difference in the4soil layers during the8sampling intervals (P>0.05). The peak value of M in each soil layer appears earlier in the virgin forest than the selection cutting forest. The peak value of M in each soil layer appears earlier in the virgin forest than the selection cutting forest. They have significant difference in the sampling interval, from June14th to June23rd, in three soil layers, from0cm to10cm, from10cm to20cm and from20cm to30cm (P<0.05).