秦岭火地塘天然次生油松林倒木储量与分解

Storage and Decomposition of Fallen Wood in a Pinus tabulaeformis Secondary Forest at Huoditang Forest Region in the Qinling Mountains

粗头直径≥10cm,长度通常≥1m,倾斜度超过45°的死木质残体称为倒木（Harmon et al.,1996）。倒木是森林生态系统的重要组成部分,在森林生态系统中倒木与生产者、消费者、分解者之间都有着密切的营养关系,其结构与功能相互制约,相互影响。倒木对森林中生产者的更新有着不容忽视的作用,为各类植物提供了生境,而且还对森林生态系统的演替起着重要的作用（侯平等,2001）;

In this study,storage and composition of fallen wood were investigated by sampling in a fixed area plot in a natural secondary Pinus tabulaeforims forest at Huoditang forest region in the Qinling Mountains.The fallen wood mass in the region was 8.25 t · hm-2,of which P.tabulaeformis and Toxicodendron vernicifluum accounted for 69.58% and 30.42%,respectively.The storage of fallen wood investigated according to an international classification showed that the storage of decay class Ⅱ was dominant,accounted for 42.06% of the total,and the storage of decay class Ⅴ accounted for only 8%.The relationship of density and decomposition was simulated by monomial exponential attenuation model,and the decomposition constant of P.tabulaeformis fallen wood was 0.039 93(R2 = 0.981 78),while that of T.vernicifluum fallen wood was 0.045 33(R2 = 0.982 68).The monomial exponential attenuation model predicted that it would take 17 and 75 years to decompose 50% and 95% of P.tabulaeformis fallen wood,and take 15 and 66 years to decompose 50% and 95% of T.vernicifluum fallen wood.