The Effects Of The Controlled Plants Structure In Sub-alpine Region Of Western Sichuan On Litter, The Decomposition Of Litter And Bryophyte

Forest litter is the main material base of organic matter and the basis for the maintenance of soil fertility, and the main approach of material cycling and energy flowing in forest ecosystem, and the litter nutrient return in the maintenance of forest has a significant affect to the maintenance of soil fertility .Sub-alpine is an important "ecological barrier" of upper reaches of the Yangtze River. Through the research to plant diversity sub-alpine can provide important reference to sub-alpine afforestation can and ecological restoration. Test from July 2007 onwards, Li County, Aba Prefecture in Sichuan,and selected the artificial mixed forest and pure forest which was created in 1986.After the different treatment of the mixed forest, we went to research the number of litter, litter nutrient return, weight loss rate of decomposition bags, decomposition bags of nutrient dynamics, and the water holding ability of moss and litter for two years, and the results showed that:(1)By the experimental observations, the annual litter amount of mixed forest and the coniferous forest were 7905.04kg/hm2 and 6287.41 kg/hm2; Between the different treatments, thatⅠ-1,Ⅰ-2,Ⅰ-3, the respective annual litter amount were 7905.04 kg/hm2,7009.26 kg/hm2 and 6540.44 kg/hm2.We can find than after we compare the mixed forest and coniferous forest,and the stands which was deal by different treatment, no matter what kind of forest,litter peak occurred in April and October of each year ,the litter was typical for dynamic "bimodal" type. Mixed forest is higher than coniferous; comparison is higher than others.(2)Mixed forest and coniferous forest, the size of return amount is K> P> N. From the nutrient point of view the total return, mixed forest> coniferous forest; Among different treatments, the size of return amount is K> P> N. From the total amount of nutrient, comparison is higher than others. At the same time, the peak of the amount of litter nutrients return(N, P, K) is main in April and October. The rest of other months,the nutrient return amount is relatively low.(3) Mixed forest and coniferous forest litter on the dynamic changes of the organic carbon content is volatile, less regularly and taking on circulating-fall changes. C/N changes in volatility is also higher, at April and October, C/N is relatively higher than other months, and the C/N of coniferous forest is bigger than mixed forest.After different treatments of litter, regardless of its broad-leaved composition or coniferous composition, organic carbon concentrations were maintained at a high level. Coniferous litter organic carbon content is higher than broad-leaved litter. Two types of litter, litter C/N ratio was relatively high in the annual March to April, and October to November. In litters, coniferous C/N is relatively bigger than broad-leaved.(4) After 24 months of decomposition, the large aperture litter bag weight loss rate was 56.032%, coniferous litter bag weight loss rate was 45.832%. While, the weight loss rate of small aperture litter bag was 51.608% in mixed forest, coniferous forest was 41.076. The weight loss of large aperture litter bag is bigger than small aperture bag, and the weight loss rate of mixed forest litter is bigger than coniferous forest.After two years decomposition, in addition to N concentration increased, both P and K were decreased. The coniferous forest N concentration was higher than mixed forest. The coniferous forest P concentration was higher than mixed forest. The coniferous forest K concentration was higher than mixed forest. The coniferous forest C/N was higher than mixed forest. This show that the litter in litter bag which is under coniferous forest decomposed slowly than the litter bag which is under mixed forest.Stands of three different treatments, in addition to N concentration increased, both P and K were decreased. The size of N concentrations was I-2> I-3> I-1; P concentration in size: I-3> I-2>Ⅰ-1; K concentration in size:I-3> I-2> 1-1; C/N in size:Ⅰ-3> I-2>Ⅰ-1. By different treatment and two years decomposition, the N,P,K concentration of large aperture and small aperture of control group were the lowest. This showed that the litter bag of the control group decomposed faster than others, and even easier than others.(5) In the mixed forest, the storage amount bryophyte and litter layer was 10.02 t/hm2,the maximal water holding capacity was 54.96 t/hm2, the average mean maximal water holding rate was 839.70%; Bryophyte storage amount was 2.43 t/hm2, the maximal water holding capacity was 11.47 t/hm2, the maximal water holding rate was 472.23%,and the water absorption rate decreased from 7683.2g-kg-h-1 to 256.5 g·kg·h-1after 24h; litter storage amount was 7.59 t/hm2, the maximal water holding capacity was24.07 t/hm2, the maximal water holding rate was 317.22%, the water absorption rate decreased from 8530.1g-kg-h"1 to 321.4 g·kg·h-1 after 24h.2)In the coniferous forest,bryophyte and litter layer storage amount was 9.37 t/hm2, the maximal water holding capacity was 45.07 t/hm2,the maximal water holding rate was 766.05%;Bryophyte storage amount was 2.13 t/hm2, the maximal water holding capacity was 9.68 t/hm2, the maximal water holding rate was 454.85%, and after 24h,the water absorption rate decreased from 6444.4 g·kg·h-1 to 231.4 g·kg·h-1; while, litter storage amount was7.24 t/hm2, the maximal water holding capacity was21.20 t/hm2, the maximal water holding rate was 292.68%,and after 24h,the water absorption rate decreased from 7004.9 g·kg·h-1 to 251.4 g·kg·h-1.Therefore, on the aspects of water holding capacity,water holding rate, or water absorption rate, the mixed forest was always higher than coniferous forest.