【作者】 金毅；

【导师】 于明坚；

【作者基本信息】 浙江大学 ， 生态学， 2015， 博士

【摘要】 亚热带常绿阔叶林是我国亚热带地区的地带性植被,其中最为典型且分布最广泛的类型为中亚热带常绿阔叶林,具有较高的生物多样性。为探讨冰雪灾害对中亚热带常绿阔叶林群落结构的损害,以及冰雪灾害所形成林窗对于森林更新的影响,我们以浙江省古田山自然保护区内24 ha中亚热带常绿阔叶林为例,分析了该森林在2008年初我国南方所发生冰雪灾害前后(即2005-2010年)的群落结构动态,并比较了冰雪灾害所形成林窗内和林内的幼苗更新动态。对于该森林在冰雪灾害前后的群落结构动态,分析了群落径级结构动态、多个粒度上的群落动态以及物种组成动态,发现群落径级结构较稳定,但群落整体补员不足且死亡率较高；多个粒度上的群落动态呈现一致性衰退,但生境间群落动态存在差异；物种多度和胸高截面积多呈减小趋势,但频度和重要值变化不明显。同时,物种多度、胸高截面积、频度和重要值等次序均无明显变化。对于冰雪灾害后林内和林窗内幼苗更新动态,对冰雪灾害所形成林窗、以及与之邻近的林内幼苗进行了对比取样,并进行了为期两年的定点监测。然后,在确认取样充分的基础上,采用谱系和功能群落生态学手段对林窗内和林内幼苗结构以及组成分别进行了比较。发现林窗内幼苗功能和谱系结构(即功能和谱系α发散情况)与林内幼苗无差异；但林窗内幼苗与邻近群落在功能和谱系组成上的相似性(即功能和谱系p发散情况)却小于林内幼苗与邻近群落组成的相似性,提示林窗干扰改变了群落幼苗组成。进一步,采用广义线性混合效应模型研究了林窗对于幼苗更新和物种共存的影响,发现本地种源对群落幼苗组成起着重要影响,但并不妨碍林窗在其基础上促进幼苗更新。同时,林窗对于不同功能群植物幼苗更新的促进效应也有差异。具体地,与林内相反,林窗偏好于促进具有适应高资源环境性状特征(例如较短的叶生活周期)的植物更新；另外,林窗也偏好于促进由风力传播种子的植物更新,可能与该类植物的种子较小,早期定植过程中对高资源环境依赖性较大有关。2008年冰雪灾害对古田山24 ha中亚热带常绿阔叶林群落动态造成了较大的损害；同时古田山中亚热带常绿阔叶林对冰雪灾害干扰具有一定的抵抗力。灾后,扩散限制和生态位等过程对林内和林窗内幼苗更新发挥着重要作用。林窗干扰促进了该森林物种更新,同时也促进了物种间更新生态位分化,对于该森林更新和物种共存具有重要意义。本研究提示冰雪灾害可对中亚热带常绿阔叶林动态产生较为久远的影响。更多还原

【Abstract】 Subtropical evergreen broad-leaved forest (EBLF), which is high in biodiversity, is zonal veg-etation of the subtropical region of China. Among the several subtypes of EBLF, the most typical and widely distributed subtype is the mid-subtropical EBLF. To explore how ice-storm affects the short-term dynamics of mid-subtropical EBLF, as well as how the forest gaps formed during the ice storm affected forest regeneration, we took the 24 ha forest dynamics plot in Gutianshan as an example for studying the community structure pre and post the ice storm (i.e., between 2005 and 2010) which attacked southern China at the start of 2008, and compared the seedling regeneration dynamics in forest gaps formed during the ice storm with nearby forest understory.In exploring the dynamics of forest community structure pre and post the ice storm, by inves-tigating the dynamics of DBH (diameter at breast height) size classed community, multiple grain sized communities and species composition, we found that although the DBH size classed commu-nity structure was highly consistent pre and post the ice storm, community level recruitment was low while mortality was high. Multiple grain sized community dynamics implied general depres-sions, despite the rate of change differed between habitats. Species abundance and ABH (area at breast height) both decreased, but species frequency and IV (importance value) did not change. Besides, the orders of species abundance, ABH, frequency and IV were highly consistent pre and post the ice storm.In exploring regeneration dynamics in forest gap formed during the ice storm and forest un-derstory, we sampled the seedlings (DBH≤ 1 cm) in forest gaps formed during the ice storm and in nearby forest understory, and we monitored the sampled seedlings for a two-year period. Then, after ascertaining sample size adequacy, by adopting the phylogenetic and functional community ecology metrics, we compared community structure and composition of the sampled forest gap seedlings with forest understory seedlings. We found that forest gap seedling functional and phy-logenetic structures (i.e., functional and phylogenetic a dispersions) were not different from forest understory seedlings; but the similarities (i.e., functional and phylogenetic β dispersions) between forest gap seedlings and local trees in functional and phylogenetic compositions were less than that between forest understory seedlings and local trees, implying that forest gap had changed in site seedling compositions. Further, by adopting the generalized linear mixed effects models, we ana-lyzed forest gap influences on seedling regeneration. We found that despite the local seed source heavily influenced seedling composition, it did not prevent forest gap from promoting seedling re-generation and species coexistence. Indeed, in contrast with forest understory, forest gap preferred promoting seedling regeneration of the plants with trait (e.g., short leaf lifespan) that is adapted to high resource environments; besides, forest gap also preferred promoting seedling regeneration of the anemochorous plants, probably due to the small sizes of anemochorous plant seeds, which made them dependent on high resource environments for regeneration.The 2008 ice storm had greatly inpacted the short term dynamics of EBLF in Gutianshan. Nonetheless, this EBLF showed its considerable resistance to ice storm disturbance. After the ice storm, dispersal limitation and niche processes both importantly affected regeneration dynamics in both forest gaps and forest understory. Forest gap disturbance facilitated species regeneration, as well as regeneration niche partitioning, thus playing a critical role in the regeneration and species coexistence of this EBLF. This study suggests that ice storm might pose a long lasting influence on community dynamics of the mid subtropical EBLF.更多还原