Obligate to facultative shift of two epiphytic Lepisorus species during subtropical forest degradation: Insights from functional traits
Obligate to facultative shift of two epiphytic Lepisorus species during subtropical forest degradation: Insights from functional traits
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亚热带森林退化过程中两种附生植物的兼性转变：来自功能性状的见解
DOI：
10.1016/j.foreco.2018.12.037
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发表时间：
2019
影响因子：
3.7
通讯作者：
Li Su
中科院分区：
文献类型：
--
作者：
Chen Quan;Lu Hua-Zheng;Liu Wen-Yao;Wu Yi;Song Liang;Li Su
附生蕨类植物是受森林群落组成和结构突然变化强烈影响的重要植物类群。然而，我们对它们对森林退化的反应的理解仍然存在一个关键差距，特别是在物种分布和功能特征的变化及其潜在机制方面。在这里，我们调查了中国西南地区亚热带原始森林及其两阶段退化森林的两个蛇兔属物种的垂直分布，并测量了生长在陆地（即地面）和0.5-2.5m附生森林生境的个体的18个植物功能性状。我们发现，这两个物种的相对丰度在原始森林的树冠高度约为 8-16 m 处达到峰值，但在两个退化森林的树干高度为 0-4 m。陆生个体仅出现在次生林中，这两个物种在较低的树干和林地上的相对丰度随着退化森林内树冠的开放度而增加。附生植物功能性状和可塑性的主成分分析为与光适应和营养策略相关的两套性状提供了证据。此外，这两个物种的形态和生理特征的变化揭示了针对森林退化的资源利用权衡。原始林附生个体具有较高的光捕获能力，而次生林附生个体具有较高的光合能力和资源利用效率。在同一次生林中，陆生个体倾向于适应低光照的林下环境，并且比附生同种更能有效地利用养分。总之，这些结果表明，两种专性附生蕨类植物在次生林中转变为兼性，并且随着森林退化，它们的微生境占用率下降到较低的树干和林下土壤。他们可以通过在种内水平调整其功能特征来实现这种转变，从而促进根茎延伸以找到持久性的最佳栖息地。
Epiphytic ferns are an important group of plants strongly affected by sudden changes in forest community composition and structure. However, a key gap persists in our understanding of their responses to forest degradation, specifically concerning the changes in species distributions and functional traits and their underlying mechanisms. Here, we investigated the vertical distribution of twoLepisorusspecies of a subtropical primary forest and its two-stage degraded forests in Southwest China, and measured 18 plant functional traits of individuals growing in terrestrial (i.e., on the ground) and 0.5–2.5 m epiphytic forest habitats. We found that the relative abundance of both species peaked at heights of approximately 8–16 m in the canopy of primary forest but at heights of 0–4 m on tree trunks in two degraded forests. Terrestrial individuals occurred only in secondary forests, and the relative abundance of these two species on lower tree trunk and forest ground increased with canopy openness within degraded forests. Principal component analysis of the epiphytes’ functional traits and plasticity provided evidence for two suites of traits related to light acclimation and nutrient strategies. Furthermore, variation in both species’ morphological and physiological traits revealed resource use trade-offs in response to forest degradation. Epiphytic individuals in primary forest had higher capacity for light capture while those in secondary forests had a higher photosynthetic capacity and resource-use efficiency. Within the same secondary forest, terrestrial individuals tended to acclimate to a low-light understory and were more efficient in their nutrient use than epiphytic conspecifics. Together, these results showed a shift of two obligate epiphytic ferns to be facultative in secondary forests, and underwent a downward shift in their microhabitat occupancy to lower tree trunks and understory soils in response to forest degradation. They could achieve this shift by adjusting their functional traits at an intraspecific level, which promoted rhizome extensions to find optimal habitats for persistence.