Abstract:

With Quercus acutissima secondary forest (Ⅳ) and Cunninghamia lanceolata plantation (Ⅴ) as controls, we investigated the litter production patterns, dynamics, turnover time and nutrient returns of three typical returning farmland to bamboo forests, including Bambusa rigida (Ⅰ), Phyllostachys edulis (Ⅱ) and Pleioblastus amarus forest (Ⅲ), in the mountainous region at Changning county, Sichuan Province. The result showed:A bimodal pattern was fitted to litter productions of Ⅰ and Ⅴ, a left-skew monomodal pattern to Ⅱ and Ⅲ, and a right-skew monomodal pattern for Ⅳ. Annual average litter yields of the three bamboo forests were higher than those of Ⅳ and Ⅴ, with a rank of Ⅰ(5.87 t·hm^-2)>Ⅲ(5.47 t·hm^-2)>Ⅱ(4.56 t·hm^-2)>Ⅳ(4.46 t·hm^-2)>Ⅴ(1.93 t·hm^-2). The turnover time of forest litters was in the order of Ⅴ(2.77 a)>Ⅲ(2.19 a)>Ⅰ(2.09 a)>Ⅱ(1.72 a)>Ⅳ(0.43 a). The litter N and P contents in the three bamboo forests were lower than those of Ⅳ and Ⅴ, and the Si content was significantly higher than the controls. The K content was highest in Ⅳ and lowest in Ⅴ. The macro-element returns of N, P, and K was highest in Ⅳ and lowest in Ⅴ, and they were 117.43 and 31.59 kg·hm^-2, respectively. The micro-element returns of Si, Ca, and Mg in the three bamboo forests were all higher than those in Ⅳ and Ⅴ. For different forests, moreover, the total nutrient returns followed the sequence of Ⅰ(382.55 kg·hm^-2)>Ⅲ(295.00 kg·hm^-2)>Ⅳ(179.11 kg·hm^-2)>Ⅱ(142.33 kg·hm^-2)>Ⅴ(53.36 kg·hm^-2). Although there exists relatively self-fertilizing ability in the bamboo forests, they should be mixed with some broadleaf trees, such as Q. acutissima, for supplying N, P and K to promote litter turnover and nutrient return.

Key words: returning farmland to bamboo plantation, litter production, nutrient return, the hilly and mountainous region