The Study Of Some Problems About Effects Of Selective Cutting On Soil Respiration Of Forest Land

Soil respiration is a process of releasing CO₂ from soil.It is composed of three biomass processes(Respiration of soil microbe,respiration of root and respiration of soil animals) and one abiotic process(oxidation of mineral with carbon).It is one source of CO₂.Forest soil respiration is an important component part of soil respiration in land ecological system,and its change will be a long time effect against globle carbon balance.Forest cutting changed the structure of forest ecological system,or changed the using aim,and will change of the value of CO₂ released.So,to study the effect of forest cutting on soil respiration is very significance.By using LI8100 and by meansing of statistic method,this paper studied the response of soil respiration to soil temperation diurnal change in plantation forest,the sensitivity of soil respiration to soil temperature and moisture after select cutting,the effect of stump in gap on soil respiration rate and the seasonal change and yearly change of soil respiration after select cutting.All above in paper were the first study.The main results were follow:(1) The study result of the diurnal change of soil respiration rate in five type plantation of Betula platyphylla Suk,Juglans mandshurica Maxim,Fraxinus mandshurica Rupr,Pinus sylvestris Linn.Var and Larix gmelini Rupr forest showed that,there was heterogeneity evidently of soil respiration.Soil respiration rate of 5 type plantation forest appeared high value in day and low value in night,and the high value only had one time in measuring date.The response of soil respiration rate of 5 type forest to ground temperature and 10cm depth temperature is not one route.It was appeared hysteresis of the response of soil respiration rate to ground temperature and was appeared advancement of the response of soil respiration rate to 10cm depth temperature.The 10cm depth temperature was the main factor of affect the soil respiration rate.There were two time range of the mean happened in measuring date.(2) The result showed by studing response of soil respiration to soil tempruature and moisture in a conifer-broadleave forest after of select cutting in Xiaoxingan Amount,select cutting were not made the soil tempreture evident difference bue changed the sensitivity of soil respiration to soil temperature.Q₁₀ value were higher in cutting land than that in no cutting land.The response of soil respiration to soil temperature were higher in cutting land than that in no cutting land.This phenomenon was the result of the response of three partitioning respiration to soil temperature.Litter layer respiration had less sensitivity.Root respiration and mineral respiration had higher sensitivity.The more select cutting intensity(60%,71%),the more sensitivity.Select cutting not made the moisture evident difference.Soil respiration response to soil moisture was not strong.Soil moisture was not the main factor of influence the change of soil respiration rate.(3) The result showed by studing the Effect of Betula platyphylla Suk.plantation forest in gap of Stump on Soil Respiration rate,the effect of stump on soil respiration in gap will be a long time.It effected the value and distribution of soil respiration in gap.The respiration rate of gap soil with stump more than soil respiration rate without stump.Decay degree was the important factor of affecting soil respiration in the gap.The soil respiration rate of stump gap changed from high to low,and then to high about the centre of stump regularly.The max value of spatial heterogeneous grade of soil respiration rate were decrease according to decay index of stump.The max value of the spatial heterogeneity grade were decrease according to the increase of decay degree of stump in the gap with stump.(4) The result showed by studing the season change of soil respiration in a conifer-broadleave forest after select cutting in Xiaoxingan Amount,soil respiration presenced the well season change after select cutting.The soil surface CO₂ flux has good correlated with soil temperature and soil moisture.This two facts could explain 68.10%～98.90%of the variation.Litter CO₂ flux has bad correlated with soil temperature and soil moisture,this two facts could explain 12.60%～89.80%of the variation.Root CO₂ flux and mineral soil CO₂ flux has better correlated with soil temperature and soil moisture,this two facts could explain 12.60%～89.80%and 40.30%～99.50%of the variation.(5) The result showed by studing the yearly change of soil respiration in a conifer-broadleave forest after select cutting in Xiaoxingan Amount,select cutting increased the annual respiration rate.Select cutting made soil organic matter content change.soil organic matter content was the main factor that effect the annual respiration rate change.this will be a long process.Effect were different in different cutting intensity.There was a significant quadratic correlation between the mean soil respiration and cutting intensity.Select cutting made soil temperature and moisure change.Soil temperature and moisure change were two main factors that effectting the annual respiration rate.The annual respiration rate of litter layer soil was increased yearly.This made litter layer as a source of carbon.There was a significant quadratic correlation between the mean soil respiration of litter layer and cutting intensity.During measure time,the select cutting with moderate density made more mean soil respiration of litter layer,and less and large density made less mean soil respiration of litter layer.The annual respiration rate of roots fluctuated. There was a significant correlation between the mean soil respiration of roots and cutting intensity.During measure time,the select cutting with less density made less mean respiration of roots,moderate and large density made large mean respiration of roots. The response of annual respiration of meniral to cutting intensity was no evident.The effect of meniral respiration to annual soil respiration was no significant.