Research On The Heterogeneity Of Soil Respiration In Different Forest Types In The Dabie Mountains

The Dabie mountainous area has a special location and is an important ecological barrier in central China and the Yangtze River Delta.The forest coverage rate in the area is high and the ecological resources are abundant,but the local ecological environment is fragile and the ecological protection task is arduous.Under the influence of global climate change,maintaining the ecological functions of the Dabie Mountain forest ecosystem is an important task for regional development.Soil respiration,as a key link in the carbon cycle of the forest ecosystem,has an inestimable role in determining the carbon budget of the forest.In this study,four forest types with similar site conditions in the Tianma National Nature Reserve,Dabie Mountains,Anhui Province were selected as the research objects,and their dynamic changes and environmental factors were analyzed.relationship.the result shows:?1?The daily and seasonal changes of soil respiration rate of the four forest types showed a single?peak change trend.The maximum daily change occurs at 14?16 hours.The maximum seasonal variation occurs from July to August.The daily average and monthly average values of respiration rate are:broad-leaved mixed forest>coniferous-broad mixed forest>Huangshan pine forest>Chinese fir forest.?2?The daily and seasonal changes of root respiration rate of all forest stands are single-peak type,and the maximum daily change occurs at 12?14 hours.The peak of seasonal change occurs in August.The daily mean order of root respiration rate is:Huangshan pine forest>coniferous broad-leaved mixed forest>Cunninghamia lanceolata forest>broad-leaved mixed forest.The order of monthly mean value is:coniferous and broad-leaved mixed forest>broad-leaved mixed forest>Chinese fir forest>Huangshan pine forest.?3?The daily changes of the microbial respiration of the four forest stands,the seasonal changes are in a single peak trend,and the maximum daily change occurs at 12?16 o'clock.The peak of seasonal changes occurs from July to August.The daily respiration and seasonal variation average respiration rate are in the order of broad-leaved mixed forest>Huangshan pine forest>coniferous and broad-leaved mixed forest>Chinese fir forest.?4?Soil temperature and soil moisture are the main factors that affect the change of soil respiration rate.The total respiration of the four forest stands has a significant exponential relationship with soil temperature and a significant quadratic relationship with soil moisture,where soil temperature can explain the total soil Respiration of 81.6%?89.8%variation,soil moisture can explain 53.9%?80.1%variation of total soil respiration.The combined effect of the two-factor model of temperature and humidity can explain74.7%to 88.4%of the total soil respiration variation.The order of temperature coefficient Q₁₀ is:coniferous and broad-leaved mixed forest?3.10?>Huangshan pine forest?2.81?>broad-leaved mixed forest?2.76?>Chinese fir forest?2.36?.?5?The contribution rate of autotrophic respiration of four forests fluctuated between5.43%and 34.92%,among which microbial respiration accounted for 80%of total soil respiration and root respiration only accounted for 20%.?6?The order of total soil CO₂ emissions is:broad-leaved mixed forest>coniferous-broad-leaved mixed forest>Huangshan pine forest>Chinese fir forest.During the peak season,the CO₂ emissions from July to August are significantly higher than in other months.?7?The fit between photosynthetically active radiation of four forest stands and soil respiration rate is low.The air temperature,humidity and soil respiration rate have a high degree of fit,and they are all extremely significantly related.There is no obvious correlation between wind speed and soil respiration rate.