Study On Litter Decomposition Dynamics And Production Of Ten Major Community Types In Xiaoxing’an Mountain,China

As one of important forest areas,Xiaoxing’an mountain play an important role in the global carbon balance.The study of forest litter focused on the broadleaved Korean pine forest,and it’s less about the nutrient dynamics and forest litter production in other communities.Taking ten major forest communities in Xiaoxing’an mountain as test objects,this Paper studied their nutrient dynamics,the quantity and composition, annual decomposition process and decomposition rate in May2009-October2010by using decomposition bag method.The results showed that the annual litter production of primary Korean pine forest is greater than natural secondary forest communities,and litter production had no significant differences, needles accounted for more than60%of the total litter,branches accounted for only5.7%-9.4%.There are two seasonal dynamics,the annual dynamics of the forest litter in Betulacostata,Quercusmongolica-Pinuskoraiensis,Tilia-Pinuskoraiensis,Betulacostata-Pinusko raiensis,Populus davidiana,Betula platyphylla,miscellaneous wood forest appeared to be single climax curve, in which the highest point occurred in August to October. Picea,sp.-Abiesnephlolepis-Pinus koraiensis and Picea sp.-Abies nephlolepis was double peak and the highest point occurred in April and September.Betula platyphylla-Larix gmelinii also was double peak and the highest point occurred in August and October.Litter decomposition rate in ten major communities was in a descending order:Betula costata,Tilia-Pinuskoraiensis,Betulacostata-Pinus koraiensis,Abies nephlolepis-Pinuskoraiensis,Picea sp.-Abies nephlolepis, miscellaneous wood forest, Betula-platyphylla, Betula platyphylla-Larix gmelinii, Populus davidiana,Quercusmongolica-Pinus koraiensis. Ten different forest communities had a fast decomposing stage(0-150d) and a slow decomposing stage(150-540d).The time was required that litter decomposition proposion of95%3.16a-6.84a, it is4times of decomposition half of litter production. Initial N content and C/N ratio were litter chemistry parameters used to predict the rate of decomposition,high initial nitrogen concentration and low C/N will increase the rate of decomposition, C/N ratio and C/P ratio in ten major communities was declines with decomposition time. During the decomposition process, the dynamics of nitrogen, phosphorus,potassium, calcium and magnesium showed different patterns.The trends of ten kinds of forest communities in N concentration was increase-down-up, N concentration will be enrichment,migration patterns of the elements was enrichment-release at the end of the experiment, but migration patterns of the elements was leaching-enrichment-release in miscellaneous wood forest. The concentration of phosphorus in Picea sp.-Abies nephlolepis-Pinus koraiensis, Picea sp.-Abies nephlolepis and miscellaneous wood forest decreased in the early stage, then it will be increased but rapidly decreased at the end of experiment. The enrichment of phosphorus appear in Tilia-Pinuskoraiensis, but others communities was release. The potassium content decreased all the year being washed off in the decomposition process without any enrichment. The trends of magnesium concentration was increase-decrease-increase, the enrichment of magnesium appear in three broadleaf Pinus and Picea sp.-Abies nephlolepis,magnesium concentration in others forest,migration patterns of the elements was enrichment-release.Ca concentration of Tilia-Pinuskoraiensis and miscellaneous wood forest was decreased in the first and then increased, others communities was increase first and then decrease. The calcium concentration of Betula platyphylla-Larix gmelinii and Betula platyphylla was release, in the other stands was enrichment after decomposition experi-. ment.