A Study On The Soil Respiration Rate Of Mixed Coniferous Broad Leaved Forest In The Growing Season In Taiyue Mountain, Shanxi Province, China

Forest soil respiration is an important part of the soil respiration in terrestrial ecosystems,the variation of which will bring far-reaching influence on the balance of global carbon.Precise measurement of soil respiration and quantify the relationship between soil respitation and environmental factors is the most basal and exigent problem in global change research.Taiyue Mountain belongs to the Taihang Ranges in East Shanxi,and situated between N36°18′～37°05′,E111°45′～112°33′,The climate is cool and arid in winter,but warm and rainy in summer.This study measured seasonal changes in the soil respiration rate,soil temperature at 10cm depth,air temperature and relative humidity above ground,and soil moisture in mixed coniferous broad leaved forest communities using LI-8100 automated soil CO₂ flux system.The objectives of this study were as the following:1) to analyze the seasonal variation characteristics of soil respiration rate,and compare that among the difference forest types,and slope aspect and position;2) to evaluate the relationships between soil respiration rates and soil temperature,air temperature,RH above ground,and soil moisture.Measurements of soil respiration rates were carded out for one growth season.The result showed that:1) There were remarkable seasonal changes in soil respiration rates in the forest communities with changes in soil temperature at 10cm depth,air temperature above ground.Soil respiration rates of the forest communities were greatest in July(3.25μmolCO₂·m^-2·s^-1),The monthly average soil respiration rate was 2.11μmolCO₂·m^-2.s^-1.2) Soil respiration rates on the south-facing slope were higher than that on the north-facing slope,but there were not significant difference between the two slope aspect (p＞0.05);on the lower,mid,and top-slope,soil respiration rates were similar(p＞0.05). 3) there was a significant(p＜0.05) correlation between soil respiration rate and soil temperature at 10cm depth,and the correlation between soil respiration rate and soil temperature(R²=0.982) was higher than that between soil respiration rate and air temperature above ground(R²=0.954) for the forest communities;There was no significant(p＞0.05) correlation between soil respiration rates and soil moisture.4) The average content of soil organic carbon,total nitrogen,and total phosphorus in the 0～20cm soil layer were respectively 20.39g/kg,1.72 g/kg,0.26 g/kg.There were all significant correlation(p＜0.05) between soil respiration rate and the content of soil organic carbon,total nitrogen, in the 0～10cm and 10～20cm soil layers;there was only significant correlation(p＜0.05) between soil respiration rate and the content of soil total phosphorous in the 0～10cm soil layer.5) The average soil respiration rate were in the order of Quercus liaotungensis(2.58μmolCO₂·m^-2·s^-1)＞Quercus liaotungensis -Larix principis-rupprechtii mixed forest(1.88μmolCO₂·m^-2·s^-1)＞Pinus tabulaeformis (1.64μmolCO₂·m^-2·s^-1).The soil respiration rates in Quercus liaotungensis Koidz.was significantly greater than that in Pinus tabulaeformis Carr.and mixed forest(p＜0.05),but there were not significant difference in soil respiration rates between the Pinus tabulaeformis Carr.and mixed forest(p＞0.05).