| 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. |
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