Litter Yield,storage And Decomposition Dynamics In Guanshan Forest Monitoring Plot

Litterfall is an important part of forest ecosystem and must be paid attention to in the study of forest ecosystem function.The establishment of large-scale forest plots for location monitoring is an effective way to reveal the function and role of litter in material storage and nutrient cycling.From 2017 to 2018,based on the 12 hm² forest dynamic monitoring sample plot in Guanshan,Jiangxi Province,we carried out monitoring of litter yield dynamics and investigation of litter reserves in different forest layers?July 2017?.At the same time,decomposition experiments of leaf litter on different forest layers,mixed decomposition of leaf litter of different phenological species were carried out.The results are as follows:?1?Litter yield of the whole plot was 5703.30 kg·hm^-2·a^-1.Litter dynamics were bimodal,with the main peak occurred in November-December,accounted for 19.97%of the total,and the secondary peak occurred in March-April?5.73%?.The litter rhythm of the three dominant species was quite different.The leaf litter of Cunninghamia lanceolata and Alniphyllum fortunei were unimodal,with the concentrated litter period from November to December,and the leaf litter of Castanopsis eyrei was bimodal,with little difference between the two peaks?November-December and March-April?.?2?The ground litter storage was 4098.13 kg·hm^-2,the aerial litter storage?height was0.3-5.0 m?was 99.62 kg hm^-2,and the aerial litter storage accounted for 2.43%of the total,and the forest type and plant canopy density had great influence on the aerial litter storage.?3?Litter yield rank of three stands in this plot was:Cunninghamia lanceolata forest(6518.11 kg·hm^-2·a^-1)>broad-leaved forest(5745.34 kg·hm^-2·a^-1)>Phyllostachys edulis forest(4476.75 kg·hm^-2·a^-1);Litter storage was:Cunninghamia lanceolata forest(4791.37kg·hm^-2·)>Phyllostachys edulis forest(4297.17 kg hm^-2)>broad-leaved forest(3762.27kg hm^-2).?4?The decomposition rate of leaf litter in the aerial(H₅,H_0.5)was slower than that on the ground?H₀?,while the decomposition stage of different species were quiet different.The aerial and ground decomposition rates of Cunninghamia lanceolata and Castanopsis eyrei leaf litter were not significantly different at the early stage of decomposition,but the aerial decomposition rates were slower than the ground at the middle and the late stages,and the aerial decomposition mass remaining percengtages of Cunninghamia lanceolata?79.61%?and Castanopsis eyrei?67.30%?leaf litter were significantly higher than the ground?70.09%,52.40%?at the 55th week.The decomposition rate of leaf litter of Alniphyllum fortunei in H₅ was significantly slower than that of H_0.5.5 and H₀ at the early stage of decomposition,but there was no significant difference at the late stage of decomposition.?5?During mixed decomposition,the leaf litter of Castanopsis eyrei(undecomposed Castanopsis eyrei-UC_EE,semi-decomposed Castanopsis eyrei-SC_EE)with different decomposition degrees had a great influence on the decomposition rate and nutrient release of the leaf litter of Alniphyllum fortunei.After 45 weeks,the mass remaining percentages of A_FT+UC_EEE mixed decomposition of Alniphyllum fortunei?70.36%?was significantly higher than A_FT+SC_EE?55.64%?,while the residual rates of C,N,P?51.84%,89.57%,83.85%?of A_FT+UC_EEE mixed decomposition of Alniphyllum fortunei were higher than A_FT+SC_EE?38.33%,77.91%,73.65%?.There was no significant difference of decomposition rate and nutrient release of SA_FT+C_EEE and C_EEE mixed decomposition in the earliy decomposition stage.The above results showed that the stand type of Guanshan forest plot had great influence on the yield and storage of litter,and aerial litter was also one of the storage forms of litter,but aerial litter decomposition slowed down the decomposition rate of litter.Castanopsis eyrei,an evergreen tree species,had a certain inhibitory effect on the decomposition of the fallen leaves of Alniphyllum fortunei,a deciduous tree species,and the effects of the fallen leaves of different decomposition degrees on mixed decomposition were different.This paper provides a new perspective for litter quantity and decomposition research,provides a theoretical reference for in-depth understanding and reasonable assessment of material circulation and element flow in forest ecosystem,and also lays a foundation for long-term forest monitoring in the region.