Studies On The Fall-litter Of DaShu Mountain Forest Park In Hefei City

Litter is an important part of carbon pool,and its decomposition is a major process of nutrient friendly-cycling in forest ecosystem.Furthermore litter is also related to the global change caused by the increasing of CO₂ concentration in the air.Da Shu Mountain forest park is a important ecological public-welfare forest in He Fei city.Through studying the litter-fall of its four important forest types,the standing stock and nutrient content of the litter,the decomposing rate,and the changing of C concentration,N concentration,P concentration,C:N ratio and C:P ratio in four forest types' litter-fall,the progresses of nutrient cycling and carbon cycling of forest ecosystem can be understood more clearly,By investigating four different typical forests in the park,we found that there were significant differences in litter standing stock in different types,the largest is 14000kg/hm², the smallest is 8500kg,/hm²,and the former is 1.6 times bigger than the latter,and the standing stock was following a order of Quercus acutissima forest＞broad-leaved mixed forest＞broad-leaved and coniferous mixed forest＞Liquidambar formosana Hance forest. The percentage of litter amounts of every component in the total litter was in the same descending order:leaf(over 50%)＞branch(18%nearly)＞fruit(less than 10%)＞impurities(less than 10%)in every forest type.The total standing stock of the forest park was 4314620kg,and the amounts of organic C,N,P and K content were 2027871.4kg,54920.8kg,2398.9kgå’Œ18889.4kg,respectively.Through studying the monthly and annual fall-litter of four forests,Great differences of the annual litter amounts between different typical forests was detected.Leaf and branch litter accounted for over 85%-92%of the total amounts of litter-fall.There were two litter peaks in a year,occurred from May to July,from October to November,respectively.The annual litter amounts of Liquidambar formosana Hance forest,Quercus acutissima forest, the mixed broad-leaved forest and the mixed broad-leaved and coniferous forest were 10796 kg·hm^-2·a^-1,9623kg.hm^-2·a^-1,9757kg·hm^-2·a^-1,为7588kg·hm^-2·a^-1,respectively.Variance analysis of fall-rules between different forest-types told that the influence of type and time on the fall-rule was notable greatly.The study on the variance analysis of the decomposition of 4 types of forests reflected litter decomposition was controlled greatly by time.Forest types also had notable influence on the decomposition.The litter decomposing 50%and 95%needed 337-372d,1.3-8.6a.The results showed that C concentration decreased finally in 4 types of forests,and the changing of N concentration was in a same order:increasing slowly—decreasing slowly—decreasing sharply,after one year,N concentration decreased.But,the percentage of C concentration in litter in different time was different.The changing of P concentration in Liquidambar formosana Hance forest and the mixed broad-leaved forest litter was stable; that of the other two types of forests was dynamical.But,after one year,the P concentration increased a little.The K concentration in Liquidambar formosana Hance forest and Quercus acutissima forest showed the same order:decreasing slowly—increasing slowly;that in the mixed broad-leaved forest showed decreasing slowly all the same;But the K concentration in the mixed broad-leaved and coniferous forest was waving.Finally,the K concentration all decreased significantly.The changing of C:N in 4 types of forests was in a same order: decreasing slowly—increasing—decreasing sharply.And the C:N decreased at last.But,the changing of C:P in Liquidambar formosana Hance forest and the mixed broad-leaved forest litter was stable quietly,and showed decreasing slowly.While the other two types of forests showed the changing of C:P was increasing—decreasing,and after one year,the C:P all decreased slowly.Totally,the result didn't the mixed dominance of the mixed forest.The nutrient of N,P and K of the litter that yearly returned to the soil were 13920.08kg, 988.69,10914.94kg,respectively.And the litter released 893667.70kg C to the sky.So,the litter took an important role in carbon and nutrient cycling of forest ecosystem.Finally,.through analysis of the correlation between soil respiration and soil C:N,soil and sky temperature,soil C,soil humidity,we found there was a good correlation between soil respiration and soil C:N,soil and sky temperature,soil C.but,the correlation between soil respiration and soil humidity didn't exist.So,the soil respiration was influenced by many environment factors.The result told that the yearly amounts of CO₂ released to the sky from the soil and litter was 8562x10⁵kg,and the amounts of CO₂ released by Liquidambar formosana Hance forest,Quercus acutissima forest,the mixed broad-leaved forest and the mixed broad-leaved and coniferous forest were 2460x10³kg·hm^-2·a^-1,1579x10³kg·hm^-2·a^-1, 2237x10³kg·hm^-2·a^-1,1661x10³kg·hm^-2·a^-1,respectively.