Effects Of Simulated Precipitation Changes On Leaf Litter Decomposition And Nutrient Release In Natural Evergreen Broad-Leaved Forest In Rainy Area Of Western China

In recent years,problems such as the variations of precipitation pattern caused by global climate change have become more and more serious,which has aroused widespread concern in the world.Precipitation changes will have an impact on the carbon cycle of regional ecosystems,change the soil moisture and directly affect the use of water by vegetation and soil microbes and will affect the function and process of terrestrial ecosystems indirectly.Forests are an important part of terrestrial ecosystems and forest litter plays an important role in nutrient cycling and energy flow.At the same time,it is an important part of the plant carbon pool and a key link in global carbon balance.To investigate the effect of precipitation changes on the decomposition of forest litter,the study used natural evergreen broad-leaved forests in the Rainy Area of Western China as the research object.From November 2013 to November 2015,Control(CK: Comparison),water reduction 5%(W1: Water reduction 1),Water reduction 10%(W2: Water reduction2),Water addition 5%(W3: Water addition 3)and Water addition 10%(W4: Water addition 4)5 treatments were set,in-situ decomposition tests were conducted to study the effect of precipitation changes on leaf litter decomposition and nutrient release.The main findings are as follows:(1)The treatment with 5% water reduction and 5% water increase had no significant effect on the soil moisture content of the natural evergreen broad-leaved forest in the Rainy Area of West China.The treatment with 10% water reduction significantly reduced the soil moisture content.The treatment with 10% water addition significantly increased soil moisture content.Each treatment had no significant effect on the soil temperature of natural evergreen broad-leaved forest in the Rainy Area of Western China.(2)During the decomposition experiment of 2 a,the leaf litter of the natural evergreen broad-leaved forest in Rainy Area of Western China decomposed rapidly in the early stage and mainly concentrated in the summer of 2014,and the decomposition was slow in the later period;there was no significant effect on the decomposition of leaf litter by increasing and reducing 5% water.The treatment with 10% water reduction caused a significant increase of 2.32 a in 95% of the litter decomposition time and inhibited the decomposition of leaf litter.The treatment with 10% water addition reduced the leaf litter decomposition by 0.29 a in 95% of the time,and promoted the decomposition of leaf litter.(3)The water-reducing treatment increased the contents of C,N,and P in the litter decomposing process of natural evergreen broad-leaved forest in Rainy Area of Western China,but the water-reducing 5% treatment had no significant effect on the P content in the decomposition process;The content of C,N and P in the leaf decomposition process is significantly reduced.The 5% water-reducing treatment had no significant effect on the residual ratio of C,N and P in the litter decomposition.The treatment with 10% water reduction significantly increased the residual rates of C,N and P in the decomposition process,and inhibited the release of C,N and P.Increased water treatment significantly reduced the residual rate of C,N,and P in the decomposition process,and promoted the release of C,N,and P.(4)The 5% water reduction treatment had no significant effect on the lignin content in the litter decomposition process of natural evergreen broad-leaved forest in Rainy Area of Western China.The 10% water reduction treatment significantly increased the lignin content during the decomposition of leaf litter and inhibited the degradation of lignin during the decomposition of leaf litter;the water-increasing treatment significantly reduced the lignin content during the decomposition process and promoted the degradation of lignin during the decomposition of leaf litter.The water-reducting treatment significantly increased the cellulose content during the decomposition process and inhibited the cellulose degradation.The water increasing treatment significantly reduced the cellulose content in the decomposition process and promoted the degradation of cellulose.(5)Water-reducing treatment had no significant effect on C/N and C/P in the litter decomposition process of natural evergreen broad-leaved forest in Rainy Area of Western China.The enhanced water treatment significantly increased C/N and C/P in the decomposition process.(6)There was a significant positive correlation between the residual ratio of the leaf litter of each precipitation and C,N,cellulose residual rate and C/P,and a significant negative correlation with lignin/N,and lignin and cellulose/ There is no significant correlation between N.Compared with P residual rate,lignin residual rate,C/N,and cellulose/N,C,N residual rate,cellulose residual rate,C/P,and lignin/N can better reflect natural conditions in Huaping area of western China.The rate of leaf litter decomposition in green broad-leaved forests is a good indicator of litter decomposition.In summary,the increase or reduction of 5% precipitation has no significant effect on leaf litter decomposition and soil moisture content.A 10% reduction in precipitation significantly inhibits litter decomposition and reduces soil moisture content,while a 10%increase in precipitation significantly promotes litter decomposition and increases soil moisture content.This shows that the change in precipitation does affect the decomposition of forest litter,which in turn affects the material circulation and energy flow in forest ecosystems.At the same time,the response of leaf litter decomposition to changes in precipitation is related to the intensity of precipitation changes.