Soil-Borne Pathogens and Tree Recruitment in Temperate Forests

0090056. ClayJanzen和Connell描述了宿主特异性天敌通过促进焦点宿主物种附近的异源物种增殖来促进群落多样性的生态机制。 这种“负反馈”理论形成了这项研究的概念框架，测试植物和土壤-微生物的相互作用，这已经被生态学家忽视了多年。 土壤微生物对植物适合度有许多负面和正面的影响，它们对植物种群和群落结构的根本重要性现在被广泛接受，但了解甚少。 该项目是土传真菌病原体对黑樱桃补充和种群动态的负反馈研究的继续。 将进行实地调查，以确定黑樱桃幼苗的生存在早期，中期和后期的演替网站。 为了评估真菌病原体（腐霉属）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在无菌和腐霉接种的琼脂中发芽。 类似地，来自十种植物物种的种子将在温室条件下在无菌和接种的土壤中发芽。 从现场，实验室和温室研究的结果将与收集的数据在该领域的自然植物分布进行比较。 最终的目标是确定土壤传播的病原体在幼苗建立，空间分布和演替变化中发挥的作用。 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社区多样性和继承的有限知识。

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.