Reaserches On Decompositon Of Three Fern Leaf Litters In Jinyun Mountain

Succession of the forest ecosystem is often limited by nutrient. Litter quality and decomposition is the key factors effecting the nutrient cycling of the ecosystem, The former determines the potential contribution of the litter and the later control the nutrients cycling ratio in ecosystem. Plant litter traits is the most important factor effected the decompositon, but different plant litter have different traits including different initial chemical content and different chemical compositon. So different plants composition of the ecosystem wil infulence the nutrient cycling and the succession of the forest.Fern is a common plant groups distributed throughout tropical and subtropical regions of the world,some often forms a mat-like understory, especially in open areas. As a important forest floor, ferns plays an important role in ecosystem dynamics, but is often overlooked in ecological research.To understand the short-term decomposition process of the ferns litter, nutrient release dynamics and the factors effect the process, and its performance in different succession stages of decomposition, explore its role in forest nutrient cycle and its potential impact on the forest succession.We chosen leaf litter of three ferns(Woodardia japonica, Dicranopteris dichotoma, Hicriopteris chinense)as the experimental material, and use litterbag method in three contrasting vegetation types(COF short for coniferous forest, CEF short for coniferous and evergreen broad-leaved mixed forest, EVB short for evergreen broad-leaved fores)in Jinyun Mountain, Chongqing. We analysis dynamics of the mass, nutrient release loss and mircoarthropod community during the decomposition for 1 year (12 month). Our results show as follow:1. Dynamics of the mass loss of the pinna and petiole had a similar pattern, that was fast-slow-fast, during one year decomposition. After one year, The moss loss of pinna (61.77%) is nearly three times as peitole (21.62%). Thought the yearly decay rate coefficients(K) is no significant differentce among forest types during the decompositon, but the mass loss of the pinna has a consistent ruleis, that is COF<CEF<EVB. The K of Woodardia japonica pinna and petiole were faster than Dicranopteris dichotoma and Hicriopteris chinense.2. Nutrient concentration showed significant difference among different species litters and various leaf parts.Litter nutrient concentration from hight to low arranged in order of C, K, N, P. We find that N concentration of pinna is 4.3 times as petiole,and P concentration is nearly three times as petiole. Litter mass loss was significant positively correlated with initial N, P, and K, Howerver, it was significant negative correlated with initial C concentration and C/N. During the decomposition, N of litter was released-accmulated pattern, P of litter was accmulated. K of litter was Sustained released. Nutrient released of pinna was higher than petiole, and vary in different species and different forest types.3. We collected 13016 specimens meso-microarthropods, which belong to 18 orders, Acarina and Collembola were the dominant groups, accounting for 95.64% of the total. The change of the soil meso-microarthropods community was not obvious in the early stage of litter decomposition, however, with the Synphyla, Araneae, and other groups gradually into the litter bags, the soil meso-microarthropods community composition changed significantly in the mid-to-late stage of decomposition.With the litter decomposition, the number of soil meso-microarthropods, falling rapidly at the early stage and slowly in the later. The dynamics of groups of soil meso-microarthropods exterted a "W" shape, and the maximum peak of the groups quantity was observed in May and July. In addition, the biodiversity index increased significantly with the litter decomposition. In the process of the litter decomposition, change of the the soil meso-microarthropods community groups, individual number, number of groups, change of and biodiversity index is the same tendconsistent in three different forest types.The results of this short-term decompositon experiment suggested that, initial element concentration is the most important factor effect the moss loss, nutrient release of the fern leaf litter,and because high C, C/N, low N, P,the K of the petiole is lower than pinna. The soil meso-microarthropods conmunity structure were change follow the decay of the fern litter, because of the moss loss and nutrient loss. The decompositon of the fern litter were a slight respond for the forest succession although it is not significant.