Relationship Between Soil Heterotrophic Respiration And Soil Environmental Factors Under Different Cutting Intensities

Forest harvesting could affect soil respiration by changing the hydrothermal conditions,soil properties,and organic matter tulmover rate of forest land.This study was conducted to observe the soil heterotrophic respiration rate,soil chemical properties,soil temperature and moisture at 5 cm of three plots with different cutting intensities and a control plot of broad-leaved Korean pine forest in Jiaohe,Jilin Province,during the growing season of 2018.The effects of harvesting on soil factors as well as the relationship between soil factors and soil heterotrophic respiration under different cutting intensities were analyzed.The main results were as follows:(1)Cutting had a remarkable effect on soil chemical properties(P<0.05).Cutting at various intensities decreased soil pH,soil organic carbon and soil total nitrogen contents,and increased soil C/N ratio significantly(P<0.05).Under all treatments,soil organic carbon,soil total nitrogen and soil C/N ratio of 0-10 cm were significantly higher than those of 10-20 cm soil layer(P<0.05).(2)Soil temperature and moisture differed significantly under different cutting intensities(P<0.05).Soil moisture increased significantly(P<0.05)with increasing cutting intensities.Different intensities of cutting influenced soil temperature differently:medium and heavy cutting increased soil temperature while there was no significant difference between light cutting and control plots.The exponential relationship equation was used to fit the relationship between soil heterotrophic respiration rate and soil temperature.Under four treatments,the exponential regression model explained 40.2 to 72.6%of the change of soil heterotrophic respiration rate.(3)There was no significant correlation between heterotrophic respiration and soil moisture under control,light and medium cutting treatments(P>0.05).However,a negative correlation between heterotrophic respiration and soil moisture was observed under heavy cutting treatment(P<0.05).Surface fitting of soil heterotrophie respiration with soil temperature suggested that they had a positive relationship.However,the response of soil heterotrophic respiration to soil moisture was quite inconsistent.(4)The results of stepwise linear regression analysis showed that the main influencing factors of soil heterotrophic respiration under different cutting treatments was soil temperature.Besides soil temperature,soil moisture and soil surface pH value also affected soil heterotrophic respiration to a certain extent.The four stepwise regression models explained 54.4-66.1%of the variation of soil heterotrophic respiration rate.Compared with the exponential model which used soil temperature as a single factor,the degree of interpretation was lower under control and medium cutting treatments for stepwise regression model,but higher under light and heavy cutting treatments.