藓类-兴安落叶松林木质物残体贮量及组成

摘要

以大兴安岭藓类-兴安落叶松林为研究对象，估算木质物残体（WD）的贮量及组成，分析WD随着龄组的动态变化趋势。WD 又可分为粗木质残体(CWD)和细木质残体（FWD），随着对 CWD 研究的不断深入，CWD 的直径划分标准有了改进，美国学者把直径大于10 cm的WD定为CWD，但我国大多学者的研究仍然沿用以往的直径大于2.5 cm的标准，致使研究结果与国际研究无法进行比较。鉴于此，采用新的 CWD划分标准，分析CWD的物种组成、径级结构、腐烂等级及树种组成等特征，揭示CWD密度、体积和生物量贮量及特征随着龄组的变化趋势。结果表明，（1）WD体积和生物量为2.09~151.03 m3·hm-2和1.57~55.11 t·hm-2。从组成上来看，中龄林以倒木和小枝为主（占73.00%），近熟林以枯立木和倒木为主（占96.04%），过熟林以枯立木为主（93.18%）。从类型上来看，中龄林均为FWD，近熟林和过熟林中CWD生物量达75%以上。（2）龄组显著影响着藓类-兴安落叶松林WD和CWD的生物量和组成。随着龄组的增加，WD生物量和枯立木比例逐渐增加，倒木和大枝比例减小。CWD 生物量和体积随着龄组的增大而逐渐增加。（3）近熟林中 CWD密度、体积和生物量（217株·hm-2、40.51 m3·hm-2、20.61 t·hm-2）均小于过熟林（258株·hm-2、138.82 m3·hm-2、48.88 t·hm-2）。（4）近熟林CWD体积和生物量均以Ⅱ-Ⅲ级腐烂为主（两者之和分别占90.81%和89.01%），过熟林以Ⅲ级腐烂为主（占36.15%和41.23%）。（5）过熟林CWD密度、体积和生物量均以10~20 cm为主，且以枯立木居多。%The storage of woody debris (WD) and the dynamic of WD with age groups were analyzed in SPhagnum-Bryum-Larix gmelinii forest of Daxing’ an mountains. WD may be divided into the coarse woody debris (CWD) and fine wood residues (FWD). The diameter larger than 10 cm for WD was defined by American scholars, but the most of scholars in our country still use the previous standard that diameter is larger than 2.5 cm. Due to the different classification standard of CWD, the research results in our country are not comparable with international results. In this study, the new standard of division for CWD (2.5 cm) was adopted. We analyzed the species composition, diameter class structure and the decay class of CWD, and change trend of density, volume and biomass storage of CWD with age groups. The results are as follow. The volume and biomass of WD were 2.09-151.03 m3·hm-2 and 1.57-55.11 t·hm-2 in SPhagnum-Bryum-Larix gmelinii forest respectively. The middle-age forests is mainly composed by the fallen wood and the branchlet (account for 73%), while the near-mature forest is mainly composed by the dead standing tree and the fallen wood (account for 96%), the over-mature forest is mainly composed by the dead standing tree primarily (93%). For the composition of WD, the middle-age forest is composed by CWD completely, the biomass of CWD is more than 75%in near-mature forest and over-mature forest. The biomass of WD and CWD in SPhagnum-Bryum-Larix gmelinii forest all increased with age groups. At the same time, the proportion of dead standing tree increased, while the fallen wood and bough decreased with age groups. The density, volume and biomass were 217 plant·hm-2, 40.51 m3·hm-2, 20.61 t·hm-2 and 258 plant·hm-2, 138.82 m3·hm-2, 48.88 t·hm-2, respectively in the near-mature forest and the over-mature forest. The volume and biomass of CWD are mainly composed byⅡ-Ⅲlevel decay (the sum accounted for 90.81%and 89.01%respectively ) in the nearly mature forest, and the mature forest is mainly composed by Ⅲ level decay (accounted for 36.15% and 41.23%). The density, volume and biomass of CWD were mainly composed by the component which have 10-20 cm diameter in the mature forest, and the majority were the dead standing trees.