| Litter decomposition is an important link in the energy flow and material cycle of forest ecosystems,and plays an important role in maintaining the stability of forest ecosystems.Maolan Karst Forest,as the only highly original karst forest in the same latitude,is significantly different from the forest ecosystem under normal landform in terms of habitat conditions,plant community structure,species composition,etc.These differences together determine the uniqueness of the litter characteristics and ecological functions of Maolan Karst Forest.Therefore,the study of karst forest litter has high scientific value.Based on this,the research selected common tree species in the Maolan Nature Reserve,Acer coriaceifolium,Liquidambar formosana,Carpinus pubescens,Cinnamomum camphora,as the research objects,to study the decomposition characteristics of leaves and branches in decomposition bags with different light treatments and apertures,as well as the decomposition characteristics of logs under different light treatments,The results show that:(1)Shading treatment,tree species,and the pore size of the decomposition bag have a significant impact on the leaf decomposition rate.In the early stage of decomposition(0-61 days),the leaf decomposition rate of the four tree species shows a rapid upward trend,and then the increase gradually slows down.After 457 days of decomposition,the leaf decomposition rate in the 1.0mm aperture decomposition bag was higher than that in the 0.05 mm aperture decomposition bag.Under shading treatment,the leaf decomposition rates of Liquidambar formosana,Cinnamomum camphora and Carpinus pubescens in the 1.0mm aperture decomposition bag were all higher than those without shading treatment.The organic carbon content in the leaves of four tree species showed a fluctuating trend throughout the entire decomposition period,while the total phosphorus content in the leaves showed an increasing trend in the early stage of decomposition(0-61 days),and then showed a fluctuating trend.After 457 days of decomposition,the total phosphorus content in the leaves of Cinnamomum camphora and Carpinus pubescens was significantly lower than the initial content(P<0.05),while the total nitrogen content in the leaves of Liquidambar formosana,Cinnamomum camphora,and Carpinus pubescens was significantly higher than the initial content(P<0.05).(2)The tree species and the pore size of the decomposition bag have a significant impact on the decomposition rate of tree branches,while shading treatment has no effect.The quality loss of branch decomposition mainly occurs within 0-61 days.Within 61-457 days of decomposition,the branch decomposition rate showed a slow upward trend.After 457 days of decomposition,the branch decomposition rate of the four tree species reached over 55%,and the branch decomposition rate in the 1.0mm aperture decomposition bag was higher than that in the 0.05 mm aperture decomposition bag.During the process of branch decomposition,the nutrient content of the branches showed fluctuating changes.In the early stage of decomposition(0-61days),the organic carbon and cellulose content of the four tree species branches significantly decreased(P<0.05).After 457 days of decomposition,the organic carbon,total phosphorus,and cellulose content of the four tree species branches were significantly lower than the initial content(P<0.05).(3)As the decomposition of logs proceeded,the density of log of the four tree species gradually decreased,and shading treatment did not have a significant impact on the density of logs.The decomposition constants of Acer coriaceifolium and Cinnamomum camphora log under unshaded treatment were higher than those under shaded treatment.During the decomposition process of logs,the organic carbon and total phosphorus content of logs of Acer coriaceifolium,Liquidambar formosana and Cinnamomum camphora continued to decrease.The total nitrogen content of the four tree species showed a trend of increasing and then decreasing,while the lignin content showed a trend of decreasing and then increasing,while the cellulose content continued to decrease.The interaction between shading treatment and tree species did not significantly affect the organic carbon,total nitrogen,total phosphorus,and total potassium content of logs.(4)The decomposition constants of leaves,branches,and logs of the four tree species are as follows: leaves>branches>logs The decomposition constants of leaves and log of Acer coriaceifolium are higher than those of other tree species.In terms of nutrient content,the organic carbon content of Acer coriaceifolium and Liquidambar formosana log was significantly higher than that of leaves and branches.The total nitrogen and total phosphorus content of the leaves of the four tree species was significantly higher than that of branches and logs(P<0.05),manifested as leaves>branches>log. |
