Growth responses to soil water potential indirectly shape local species distributions of tropical forest seedlings
Growth responses to soil water potential indirectly shape local species distributions of tropical forest seedlings
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DOI：
10.1111/1365-2745.13096
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发表时间：
2018-12
影响因子：
5.5
通讯作者：
Stefan J. Kupers;Bettina M. J. Engelbrecht;Andrés Hernández;S. Joseph Wright;C. Wirth;N. Rüger
中科院分区：
文献类型：
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作者：
Stefan J. Kupers;Bettina M. J. Engelbrecht;Andrés Hernández;S. Joseph Wright;C. Wirth;N. Rüger
热带森林中的当地树种分布与土壤水分有效性密切相关。然而，目前还不清楚物种分布是如何形成的人口对土壤水分供应的反应。具体而言，它仍然是未知的增长如何影响物种分布沿着水资源梯度相对于死亡率。我们量化了巴拿马巴罗科罗拉多岛湿润热带森林中旱季土壤水势（SWP）的空间变异，并使用分层贝叶斯方法评估了62个物种的自然再生幼苗对SWP的人口响应（RGRs和第一年死亡率）与物种分布沿着SWP梯度之间的关系。我们还测试了在梯度的湿端或干端更丰富的物种是否表现更好（a）在梯度的“家端”（“最佳家”假设）和（B）“在家里”与共存物种相比（“家优势”假设）。四个和五个物种响应显着SWP的增长或死亡率分别。生长（但不是死亡率）的反应呈正相关的物种分布沿着SWP梯度，更积极（负）的增长反应SWP的物种更丰富，在较高（较低）SWP，也就是说，在潮湿（干燥）的网站。此外，湿分布的物种在SWP梯度的湿端上比在干端上生长得更快（“最佳家庭”），并且在湿端上比干分布的物种生长得更快（“家庭优势”）。死亡率下降，幼苗大小的所有物种。因此，幼苗生长响应SWP间接塑造当地物种分布的影响幼苗大小，从而死亡风险。合成.通过展示生长对土壤水分有效性空间变化的响应如何影响物种分布，我们确定了热带森林水文梯度生态位分化的人口过程。认识到这些生长反应在形成物种分布方面的作用，应能提高对热带森林组成和多样性的认识，沿着降雨梯度和气候变化。
Local tree species distributions in tropical forests correlate strongly with soil water availability. However, it is unclear how species distributions are shaped by demographic responses to soil water availability. Specifically, it remains unknown how growth affects species distributions along water availability gradients relative to mortality. We quantified spatial variation in dry season soil water potential (SWP) in the moist tropical forest on Barro Colorado Island, Panama, and used a hierarchical Bayesian approach to evaluate relationships between demographic responses of naturally regenerating seedlings to SWP (RGRs and first‐year mortality) and species distributions along the SWP gradient for 62 species. We also tested whether species that were more abundant at the wet or dry end of the gradient performed better (a) at their “home end” of the gradient (“best at home” hypothesis) and (b) “at home” compared to co‐occurring species (“home advantage” hypothesis). Four and five species responded significantly to SWP in terms of growth or mortality respectively. Growth (but not mortality) responses were positively related to species distributions along the SWP gradient; species with a more positive (negative) growth response to SWP were more abundant at higher (lower) SWP, that is, at wetter (drier) sites. In addition, wet distributed species grew faster on the wet end of the SWP gradient than on the dry end (“best at home”) and grew faster on the wet end than dry distributed species (“home advantage”). Mortality rates declined with seedling size for all species. Thus, seedling growth responses to SWP indirectly shaped local species distributions by influencing seedling size and thereby mortality risk. Synthesis. By demonstrating how growth responses to spatial variation in soil water availability affect species distributions, we identified a demographic process underlying niche differentiation on hydrological gradients in tropical forests. Recognizing the role of these growth responses in shaping species distributions should improve the understanding of tropical forest composition and diversity along rainfall gradients and with climate change.