Effects of long-term nitrogen addition and precipitation decreasing on the litterfall production of broadleaved Korean pine forest in Changbai Mountains of northeastern China.

In order to understand the composition and seasonal dynamics of forest litter under the condition of long-term nitrogen deposition and precipitation decreasing at community level in broadleaved Korean pine forest in Changbai Mountains of northeastern China, we collected the litterfall in three different control experiment platform: N addition(NA), reduced precipitation and N addition(RN)and control(CK)with direct collection method at the runoff experimental field in 2015 growing season(June to October). We separated the litter into twig(TW), Pinus koraiensis(PK), Quercus mongolica(QM), other broadleaves(OT) and the reproductive organics and bark(ROB). This paper takes litterfall coefficient as the measure of capacity of forest litter production in comparing the "net" differences among litter groups.The results showed that leaf litter had the largest proportion, quantified 79%-81% of the total, and the Tw and ROB proportion was relatively small, but they can also accounted for 19%-21%;The litter dynamic rhythm was unimodal type and the peak of litterfall concentrated in September and October, and declining precipitation can take the litterfall period of others in advance; Different litterfall components had varied responses to the nitrogen addition and rainfall reduction, nitrogen addition significantly reduced the amount of PK leaf litter, and rainfall reduction significantly increased the amount of other broadleaves and total leaf litter, but QM, TW and ROB litter had no significant response to nitrogen and rainfall controlling; nitrogen addition can restrain the litter of conifer and promote the litter of broadleaved tree species, rainfall will promote the litter amount of all components.