CRB: Endemic Tree Loss from Fragmentation of Disperser Assemblages

0090056. ClayJanzen和Connell描述了寄主特异性天敌通过促进异种在焦点寄主物种附近的扩散来促进群落多样性的生态机制。这个“负反馈”理论形成了这个调查测试植物和土壤-微生物相互作用的概念框架，多年来一直被生态学家忽视。土壤微生物对植物适应性有许多负面和积极的影响，它们对植物种群和群落结构的根本重要性目前已被广泛接受，但知之甚少。本项目是土传真菌病原菌对黑樱桃供种和种群动态负反馈研究的延续。将进行实地调查，以确定黑樱桃幼苗在早期，中期和后期演替地点的存活率。为了评估真菌病原体（Pythium）的宿主特异性程度，将黑樱桃和其他植物物种的种子在实验室中无菌和接种了Pythium的琼脂中发芽。同样，十种植物的种子将在温室条件下无菌接种的土壤中发芽。田间、实验室和温室研究的结果将与田间自然植物分布收集的数据进行比较。最终目的是确定土传病原体在幼苗建立、空间分布和演替变化中的作用。这项研究可以大大提高我们对这些复杂和长期被忽视的相互作用如何影响群落多样性和演替的有限认识。

0090056. ClayJanzen and Connell described ecological mechanisms by which host-specific natural enemies promote community diversity by facilitating the proliferation of heterospecifics in the vicinity of the focal host species. This "negative feedback" theory forms the conceptual framework of this investigation testing plant and soil-microbe interactions, which have been overlooked for years by ecologists. Soil microbes have numerous negative and positive effects on plant fitness, and their fundamental importance to plant populations and community structure is now widely accepted but poorly understood. This project is a continuation of research into the negative feedbacks of soil-borne fungal pathogens on black cherry recruitment and population dynamics. Field surveys will be conducted to determine the survival of black cherry seedlings in early, mid, and late successional sites. To assess the degree of host-specificity of the fungal pathogen (Pythium), seeds from black cherry and other plant species will be germinated in the laboratory in sterile and Pythium-inoculated agar. Similarly, seeds from ten plant species will be germinated in sterile and inoculated soils under greenhouse conditions. Results from the field, laboratory and greenhouse studies will be compared with data collected on natural plant distributions in the field. The ultimate objective is to determine the role played by soil-borne pathogens in seedling establishment, spatial distributions, and successional change. This research can substantially advance our limited knowledge about how these complex and long-overlooked interactions influence community diversity and succession.