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Effect Of Warming In Different Depth Of Soil Carbon Emissions On The Natural Forest Of Castanopsiskawakamii

Posted on:2019-05-29Degree:MasterType:Thesis
Country:ChinaCandidate:C LiFull Text:PDF
GTID:2370330575461463Subject:Ecology
Abstract/Summary:PDF Full Text Request
As the second largest carbon?C?flux between terrestrial ecosystems and the atmosphere,soil CO2 emissions play a crucial role in regulating the global C cycling.However,previous studies focused on CO2 emission from soil surface,only a handful of studies have systematically explored CO2 emissions from deep soil and their response to soil solutions.As an significant component of soil C pool,deep soil?depth?20 cm)accounts for more than 50%of the soil with a thickness of lm.Therefore,the study of deep soil CO2 emissions and their response to climate change are urgent need to be performed,which will provide an accurate assessment to the impact of climate change on the global ecosystem C cycle.From February 2017 to December 2017,this study conducted continuous monitoring of soil C emission at different depths in warming plots of natural forests of Castanopsis kawakamii from the Sanming Forest Ecosystem and the Global Research Station in Fujian Province.Simultaneously,soil temperature,soil water content,soil nutrient content and the quantity and quality of soil dissolved organic matter?DOM??mainly spectral characteristics,etc.?at different depths were measured in order to provide a preliminary understanding of the effects and mechanisms of warming on soil carbon emissions in different soil layers.The results showed that the warming treatment?W?significantly increased soil CO2 emission in 0-10 cm and 10-20 cm soil layers,but significantly decreased in soil CO2 emission in 20-40 cm soil layers.In this study,the soil CO2 emission of 0-10 cm and 10-20 cm layers in W were 5.80 ?pmol · m-2·s-1 and 2.62?mol · m-2·s-1,respectively.In relative to control treatment?CT?,W specifically increased soil CO2 emissions by 20.45%and 23.69%,respectively.While soil CO2 emission was 1.10?mol · m-2·s-1 of 20-40 cm layer in W,which was 59.73%lower than CT.After W treatment,the change of soil temperature in each soil layer may be the root cause of soil respiration in different soil layers.In this study,soil temperature in each soil layer treated with W was 25.64 ?,24.67 ? and 23.52 ?,which were 18.37%,14.27%,and 10.89%higher than the CT,respectively?p<0.05?.Changes in temperature lead to shift in DOM properties of soil solutions in different soil layers,directly causing changes in soil CO2 emissions in different soil layers.In this study,W had no significant effects on the FI in the DOM?characteristic of DOM?and Fn?355??fluorescent dissolved organic matter?in soil solutions in 0-10 cm and 10-20 cm soil layers.In 20-40 cm layer,the FI value of W?3.09?was significantly higher than CT?2.24?and Fn?355?value of W?223.97?was significantly lower than CT?419.17?,indicating that the decomposition of organic carbon process by the underlying microorganisms is more DOM than CO2,which may be the reason for the decrease of CO2 emission in 20-40 cm layer.In 0-10 cm and 10-20 cm layer,W significantly decreased E2/E3,stearic acid,phytosphingosine,scopolamine,etc.,indicating that DOM is more easily used by microbes in the soil after warming.This may be the main cause of the increase in soil carbon emissions from W treatment of 0-10 cm and 10-20 cm.
Keywords/Search Tags:Warming, Deep soil, Soil CO2 emission, DOM, Uv-visible spectrum, Fluorescence spectrum
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