Effects Of Simulated Warming And Cooling On Soil Nutrients And Soil Enzyme Activities In Evergreen Broad-leaved Forest Of Wuyi Mountains

Currently,global climate change with the main characteristic of global warming is greatly changing the process of land ecosystems.which will undoubtedly cause profound impact on forest ecosystems,the main body of terrestrial ecosystems.Forest soil is an important part of forest ecosystem,which provides the necessary nutrients and environmental conditions for the development and growth of forest.Because the soil nutrient can reflect the fertility condition well and the soil enzyme participates in all the biochemical processes of the soil,the nutrient and enzyme are two important parts of forest soil.However,the effect of simulated temperature change on soil nutrient and soil enzyme activity in subtropical forest has rarely been reported.Therefore,the subtropical evergreen broad-leaved forest soil in the WuyishanNational Nature Reserve is chosen as the research object for the natural environmental gradient experiment.In the experiment,the untact soil columns of the evergreen broad-leaved forest(elevation at 1058 m)were transplanted to the altitude of 162 m to simulate warming and to the altitude of 1980 m to simulate cooling,respectively.The knowledge of effects of increasing and cooling temperature on soil nutrients and the enzyme activities of soil in subtropical evergreen broad-leaved forests areexpected to provide basic data and theoretical basis for understanding the response of subtropical forest ecosystems to global climate change.The main results are as follows:1.Simulated warming significantly increased soil pH and temperature.Simulated cooling significantly increased soil pH but decreased soil temperature.There is significant seasonal differences in soil temperature among treatments of warming,cooling,and in situ control.2.Under different temperature treatments,soil nutrient content showed a clear seasonal trend.Compared with the in-situ control,the increase in temperature and decrease in temperature both significantly changed the soil nutrient content.3.Under simulated warming conditions,,SOM,TN,TP,and TK all appeared to have the highest values in the July,soil DOC,NO3--N,and NH4+-N contents were all in the January.The warming significantly changed the soil nutrient content,and there were significant differences in soil nutrients in different quarters.Warming resulted in a significant increase in soil C/N,C/P,and N/P in the October and a significant decrease in the other three quarters.4.Under simulated cooling conditions,the contents of SOM,TK and DOC in soil all reached the highest value in the July;the contents of TN and TP in soil all appeared the highest value in the April;Both soil NO3--N and NH4+-N contents peaked in the January.Compared with the control,simulated cooling significantly changed soil nutrient content,but there were significant differences in soil nutrient content changes in different quarters.Cooling results in a significant increase in soil C/P and N/P in the October,and a significant decrease in the remaining three quarters;soil C/N in the October and the April increased significantly,and decreased significantly in the other two quarters.5.Under different temperature treatments,soil enzyme activity had obvious seasonal variation characteristics.Compared with the in situ control,the increase in temperature and decrease in temperature both significantly changed the soil enzyme activity.6.The activities of soil ?G,SC,NAG,LAP,UE and AP are significantly affected by warming.The responses of different soil enzyme activities to simulated warming were different.Generally speaking,the warming increased the activities of soil ?G,UE and AP,and increased the activities of NAG,LAP and SC in soil.Compared with the in situ control,there was no significant difference in the activity of soil ?G,NAG and LAP in the April.There was no significant difference in the activity of soil AP,UE and LAP in the July.7.The activities of soi1 ?G,SC,NAG,LAP,UE and AP are significantly affected by cooling.Different soil enzyme activities had different responses to simulated cooling.The cooling significantly decreased soil ?G activity and increased soil NAG,LAP,SC,AP and UE activities.Compared with in situ control,there was no significant difference in soil NAG activity in the October,and no significant difference in soil AP activity in the January,but no significant difference in soil LAP activity in the April and the July.There was no significant difference in soil UE activity in the July.8.Simulated warming and simulated cooling changed the relationship between soil enzyme activity and nutrients.