Soil-Borne Pathogens and Tree Recruitment in Temperate Forests

0090056。ClayJanzen和Connell描述了寄主特有的天敌通过促进寄主物种附近异种生物的繁殖来促进群落多样性的生态机制。这一“负反馈”理论构成了这项调查的概念框架，测试植物和土壤-微生物的相互作用多年来一直被生态学家忽视。土壤微生物对植物适合度有许多消极和积极的影响，它们对植物种群和群落结构的基本重要性现在被广泛接受，但人们对其了解很少。该项目是对土传真菌病原体对黑樱桃招募和种群动态的负反馈的继续研究。将进行实地调查，以确定黑樱桃幼苗在演替早、中、晚三个地点的存活率。为了评估真菌病原菌(腐霉)的寄主专一性程度，黑樱桃和其他植物的种子将在实验室无菌和接种腐霉的琼脂中萌发。同样，10种植物的种子将在温室条件下无菌和接种的土壤中萌发。来自田间、实验室和温室研究的结果将与收集的田间自然植物分布数据进行比较。最终目标是确定土传病原体在苗木建立、空间分布和演替变化中所起的作用。这项研究可以极大地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.