Responses Of Soil Respiration And Its Components To Soil Warming In Natural Forests Of Subtropical Castanopsis Kawakamii And In Cunninghamia Lanceolata Plantations

Climate change is a global issue of universal concern to the international community.Soil respiration is one of the main ways to release carbon stocks from the soil to the atmosphere.Increased temperature will affect soil respiration resulting in increased soil respiration and thus change the global carbon balance and thus change the global carbon balance.The IPCC(2013)pointed out that the average global temperature in the last 100 years has increased by about 0.65-1.06?,and it is expected that by the end of the 21st century(2090-2099),the average global temperature will increase by approximately 1.5-3.7?.The effect of simulated warming test on soil respiration under natural field conditions is one of the hot spots in global change research.China's central and subtropical evergreen broad-leaved forests are extremely important global forest carbon sinks,and studies on climate change have implications for subtropical forest ecosystem carbon.The impact of the cycle is significant.This sample site relies on Fujian Sanming Forest Ecosystem and Global Change Research Station.The natural forests of broadleaf forests,including natural forests of Castanopsis kawakamii and Cunninghamia lanceolata plantations dominated by coniferous forests,were studied.(W)and control(CT)treatment plots,5 replicates per treatment.To investigate the effects of warming on soil respiration and its components in different vegetation types.It aims to better cope-with the impact of global warming on subtropical forests.Through the collection of soil moisture data at 4 different depth soil layers at 2 years and the collection and analysis of surface soil respiration data for nearly 1 year,we have obtained the following results:(1)The soil moisture content of natural forests of Castanopsis kawakamii was decreased by 2.07%.0.09%,2.28%,and 1.51%in the 0-10cm,10-20cm,20-40cm,and 40-60cm soil moisture contents after heating.The soil moisture content of Cunninghamia lanceolata plantation increased by-5.68%,0.12%,-1.61%and 4.47%,respectively,in the four soil layers.After warming,the soil moisture content of natural forest and Cunninghamia lanceolata plantation decreased.(2)After the warming,the average total soil respiration rate of natural forests of Castanopsis kawakamii increased by 34.5%,soil heterotrophic respiration rate increased by 13.3%,and soil autotrophic respiration rate increased by 2.53 times.After the Chinese fir plantation was warmed,the total soil respiration rate increased by 187%,the heterotrophic respiration rate increased by 141%,and the autotrophic respiration rate increased by 2.88 times.Regression analysis showed that the soil temperature had a significant exponential relationship with soil respiration,and the moisture content had a significant quadratic equation relationship with soil temperature.According to the soil temperature,the Q10 values of soil total respiration in control and warming plots of natural forests of Chinese oak and Chinese fir plantations were 1.60,2.18,1.48,and 2.53,respectively;the Qio values of soil heterotrophic respiration and temperature were 1.82 and 2.59,respectively,1.97 and 1.90;Q10 values for autotrophic respiration were 2.75,2.77,3.53 and 3.03,respectively.(3)After warming,the total annual respiratory annual flux,heterotrophic annual respiratory flux,and annual autotrophic respiratory flux increased by 404.14 gC·m-2·a-1,183.13 gC·m-2·a-1 and 221.01 gC·m-2·a-1,the annual total annual flux of soil respiration,annual heterotrophic respiration and annual flux of autotrophic respiration increased by 330.70 gC·m-2·a-1,156.39 gC.m-2·a-1 and 174.32 gC·m-2·a-1.