不同海拔梯度柳杉林粗木质残体基础特征

Basic characteristics of coarse woody residues at different altitudinal gradients in a Cryptomeria fortunei forest

探究不同海拔梯度对天宝岩国家级自然保护区天然柳杉林粗木质残体(coarse woody debris,CWD)数量和储量特征的影响,对天然柳杉林的可持续经营管理有着重要意义。通过典型样地与随机取样法,在1400~1700 m(高海拔)、1100~1400 m(中海拔)和900~1100 m(较低海拔)3个海拔梯度对天宝岩天然柳杉林CWD的径阶结构、分解等级和储量特征进行研究。结果表明:除高海拔树桩以大径阶木为主外,其余CWD主要以小径阶木为主,其占比表现为高海拔>中海拔>较低海拔;柳杉林CWD主要分布在1~3 m高度(长度)级,其比重在不同海拔中均处于43%以上;柳杉CWD总体处于分解初期,不同组分CWD分解等级随着海拔的升高表现出不一样的变化趋势;柳杉林CWD储量为32.57 t·hm^(-2),高海拔储量(21.92 t·hm^(-2))显著大于中、较低海拔,以树桩贡献最多(58.7%)。海拔是影响天然柳杉林CWD数量和储量的重要影响因子,同时应控制人为干扰的强度,降低对CWD的清理,维持柳杉天然林正常更新,促进森林可持续发展。

The sustainable management of natural Cryptomeria fortunei forests is of great significance.Thus,this study explored the effects of different altitudinal gradients on the quantity and storage characteristics of coarse woody debris(CWD)in a natural C.fortunei forest in the Tianbaoyan National Nature Reserve.The diameter structure,decay class,and reserve characteristics of the CWD of a natural C.fortunei forest were studied at 1400-1700 m(high altitude),1100-1400 m(middle altitude),and 900-1100 m(low altitude)using typical plots and random sampling methods.The results showed that the CWD mainly consisted of wood with small diameters,and its proportion was in the order of high altitude>middle altitude>low altitude,except for stumps which were dominated by large diameters at high altitudes.The CWD of the C.fortunei forest were mainly distributed from 1-3 m height(length),and its proportion was above 43%at different elevations.The CWD of the C.fortunei were in the early stage of decay,and the decay class of the CWD of different components showed different trends with increasing altitude.The CWD reserve of the C.fortunei forest was 32.57 t·hm^(-2),and the reserve at high altitudes(21.92 t·hm^(-2))was significantly larger than those at middle and lower altitudes,with stump contributing the most(58.7%).The elevation was thus determined to be an important factor that affected the number and reserves of CWD in a natural C.fortunei forest.Additionally,we recommend controlling the intensity of human disturbance,reducing the cleaning of CWD,maintaining the normal regeneration of the natural C.fortunei forest,and promoting the sustainable development of the forest.