Effects Of Cutting On Soil Respiration In A Mixed Broadleaved- Korean Pine Forest In Western Foothill Of Changbai Mountain

Respiration was measured by using infrared gas exchange analyzer of Li-Cor 8100 at daytime during the growing seasons (May-October) of 2013-2015 in the mixed broadleaved-Korean pine forest with heavy, medium and light intensity cutting and uncutted control plots in Jiaohe, Jilin Province in northeast China. Soil temperature, moisture, were also measured. The influence of cutting intensity on the soil respiration, soil temperature and soil moisture was analyzed using methods of statistical analysis. And we also evaluated the impact of the change of carbon input on soil respiration under the mixed broadleaved-Korean pine forest in Jiaohe, Jilin Province. Five treatments including a) a control, b) litter exclusion, c) litter addition, d) root exclusion, e) litter and root exclusion were applied to determine the contribution of carbon input to soil respiration. We measured soil respiration from May to December 2014 by using infrared gas exchange analyzer of Li-Cor 8100.The main results were follow:1. We found that with the increase in cutting intensity soil temperature increased, soil moisture reduced. Cutting changed the sensitivity of soil respiration to soil temperate. Qio value were higher in cutting land than that in no cutting land. Cutting significantly affected soil respiration and soil temperature with different cutting intensities, while there were no significant differences in soil moisture among the various cutting intensities. During the growing seasons, The soil respiration was significantly related to the soil temperature at 5 cm depth at all sites. The best fitting model with temperature explained 73% of the variation in soil respiration in the high cutting treatment,65% in the light cutting treatment,58% in the control sites,43% in medium cutting treatment during the measuring periods.2. Cutting increased the CO2 flux, with an average annual increment being from 27.25% to 54.52% compared with the uncutted control plots during both growing seasons. Our findings suggested that in order to reduce the forest soil surface CO2 emission after cutting, a reasonable cutting intensity about 15% should be adopted.3. In the experiment that change of carbon input on soil respiration, The change of carbon input significantly affected soil temperature among different treatments. The soil respiration was significantly related to the soil temperature at 5 cm depth in different treatments sites, But the soil respiration was not related to the soil temperature at 5 cm depth in different treatments sites.4. There was a similar seasonal respiration curve among different treatments. The soil respiration rate with litter exclusion was 1.98% higher than the control, and that with litter addition was 24.81% higher than the control. On the other hand, the soil respiration rate with root exclusion was 36.49% lower than the control, and that with litter and root exclusion was 28.64% lower than the control.5. In order to predict both the soil moisture and soil temperature dependency four two-variable linear /non-linear models were developed and evaluated. By use of those models it was possible to predict the soil respiration in different cutting intensities as a function of both temperature and moisture, with R2 values ranging from 45%-74%. To predict the soil respiration in different carbon input treatment as a function of both temperature and moisture, with R2 values ranging from 62%-95%.