以生態模式探討植物性狀與土壤微生物組成對 植物土壤回饋之種間差異的影響

Plant Trait and Microbial Composition Interactively Determine Species Variation in Plant Soil Feedback —a Modeling Approach

柯柏如(Po-Ju Ke)

指導教授 ： 丁宗蘇

共同指導教授 ： 三木健(Takeshi Miki)

國立臺灣大學/生物資源暨農學院/森林環境暨資源學研究所/碩士(2013年)

https://doi.org/10.6342/NTU.2013.00237

摘要

植物與土壤間交互作用所產生的回饋現象(植物土壤回饋)會改變植群發展。因此，了解植物功能性狀如何調控植物土壤回饋強度之種間變異為植群研究的重要議題。過去研究只探討枯落物養分循環或土壤微生物之單一因子所造成之回饋現象。然而這兩項因子並非獨立，分開討論會忽略枯落物與微生物間的間接交互作用。此外，過去研究忽略了不同的微生物會透過不同的機制影響枯落物動態。本研究建立一個生態模式，同時納入枯落物循環與土壤微生物對植物土壤回饋的影響，以了解植物功能性狀如何調控植物土壤回饋強度，並探討土壤微生物群聚組成如何影響不同功能性狀的相對重要性。結果顯示當把土壤微生物的影響納入枯落物回饋的模式時，影響力較強的功能性狀差異相當大。此外，土壤微生物群聚組成會影響功能性狀的相對重要性，其中枯落物分解速率的重要性會隨著菌根菌的豐度增加而顯著上升。此模式預測在沒有土媒病害的土壤中，易分解及會與菌根菌形成高效益互利共生的植物佔有生長優勢；而當土媒病害豐度高時，具有較佳防禦策略的植物會佔優勢。本研究結果可應用於了解功能性狀如何在不同土壤環境中影響外來種的入侵。

關鍵字

功能性狀生態學 ； 枯落物分解 ； 菌根菌 ； 土媒病害 ； 間接交互作用 ； 族群層級結構 ； 外來植物入侵

並列摘要

Interaction of plants with the nearby soil environment, a process termed plant-soil feedback (PSF), is a structuring force for vegetation development. Understanding how plant functional traits control PSF strength variation among species is thus critical for plant community ecology. Studies have highlighted either nutrient cycling (litter-mediated PSF) or soil biota (microbial-mediated PSF) separately as two main drivers of PSF and thus focus on different sets of plant traits. However, the two PSF drivers are not independent and their way of interaction depends on the functional type of microbes (i.e. pathogens and mycorrhizas). An ecosystem model coupling indirect interaction between litter and microbial feedback is presented to identify which traits have strongest effect on PSF strength and, its dependence on soil microbial community composition. This model shows that the identity of the most influential plant functional traits alters when microbial-mediated PSF is considered along with litter-mediated PSF. The relative importance of traits depends on microbial composition. In particular, the importance of litter decomposability increases with the relative abundance of mycorrhizas due to its indirect positive effects on litter production. Plants with more easily-decomposable litter and with more beneficial plant-mycorrhiza associations are more advantageous than other plants species in pathogen-free soils. On the other hand, plants with better defense traits are expected to be dominant in pathogen-rich soils. The results can provide useful insights into understanding the key determinants of successful plant invasion in different soil environments.

並列關鍵字

functional trait-based ecology ； litter decomposition ； mycorrhiza ； soil pathogen ； indirect interaction ； population stage structure ； exotic plant invasion

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