关键词: 北京西山, 枯落物, 持水特性

Abstract:

This paper mainly studied water-holding characteristics of forest litter of six tree species (Robinia pseudoacacia, Platycladus orientalis, Acer truncatum, Cotinus coggygria, Pinus tabulaeformis, Quercus variabilis) in Beijing Xihan forest health demonstration areas. The results showed that: 1) The total litter storages in the 6 different forests were: 26.01 t·hm^-2 for A. truncatum, 10.82 t·hm^-2 for Q. variabilis, 8.96 t·hm^-2 for C. coggygria and 4.52 t·hm^-2 P. orientalis. The order was P.tabulaeformis＞A. truncatum＞Q. variabilis＞R. pseudoacacia＞C. coggygria＞P. orientalis. 2) The dynamic changes in water-holding capacity, water-absorbent rate and time of forest litters under different forests were basically similar. Water-holding capacity of the non-decomposed litter was greater than that of the half-decomposed litter. The water holding capacity of litter had a positive correlation with the duration of water immersion. Being immersed in water for 8 h, the forest litter usually reached its maximum water-holding capacity. That is to say, after 8 h, the water holding capacity had no longer significant changes with further increase in soaking time; in the initial 2 h, the water-absorbent rate of non-decomposed and half-decomposed litter was fastest; in 4-6 h afterimmersion, the rate rapidly decreased; 6 h later, the rate of decline slowed down significantly, and the water-absorbent rates of the two kinds of litters converged. 3) The largest water holding ratio ranged from 75.44 percent to 278.65 percent among different forest litters. The biggest water holding ratio of conifer species was smaller than that of the broad-leaved species except Pinus tabulaeformis forest litter which had significantly higher ratio than other broad-leaved species. The order of the greatest water-holding capacity in different forest litters was: P.tabulaeformis＞Q. variabilis＞A. truncatum＞R. pseudoacacia＞C. coggygria＞P. orientalis. 4) The effective retain of different f forest litters was: Q. variabilis 2.33 mm, P. tabulaeformis 2.12 mm, A. truncatum 2.00 mm, R. pseudoacacia 1.19 mm, C. coggygria 0.89 mm, P. orientalis 0.23 mm, and the order was: Q. variabilis＞P. tabulaeformis＞A. truncatum＞R. pseudoacacia＞C. coggygria＞P.orientalis.

Key words: Beijing Xishan, litter, water-holding characteristics