Causes and Consequences of Succession in Mycorrhizal Fungus Communities

菌根真菌是大多数陆地植物中普遍存在且有影响力的共生体，它们的群落已被观察到随着时间的推移以可预测的演替顺序相互取代。生态学家不了解菌根真菌的演替组合在功能上有何不同，也不知道功能性状的变化如何与菌根对植物的影响有关。如此重要的共生条件的变化必然会对植物群落和生态系统层面的动态产生广泛的影响。因此，建立一个实验和理论基础，以了解不同的、演替的菌根群落中特征变异的后果和原因，是提出的工作的中心主题。沿海的加州松林是世界上研究最好的菌根演替的例子。在它们中，与成熟的森林环境相比，一套非常不同的菌根物种在烧毁地区和开阔的沙丘上定居幼苗，在成熟的森林环境中，幼苗与普通菌根网络(CMN)中的成年树木相连。实验表明，在森林中招募幼苗对这两种菌根真菌的反应非常不同；然而，生态学家不明白为什么这些外生菌根真菌群落会随着时间的推移而变化，或者连续真菌的连续功能特征如何与它们对植物的影响有关。生长室实验，以及在沿海的加州蒙特利松林(Pinus Radiata)进行的为期三年的田间实验的结果，将建立早期和晚期真菌影响森林下层树苗表现的不同机制。拟议的工作将对保护和营林具有广泛的意义。在其原生的加利福尼亚州和墨西哥的范围内，蒙特利松树只有五个小种群，其中一些濒临灭绝。在这一范围之外，它是世界上种植最广泛的木材树种之一，覆盖多个大陆数百万英亩的土地。作为一种异国情调，它既是一种宝贵的商品，可以抢占采伐当地木材的需要，也是一种侵略性的入侵者，通常会归化到生态系统中。作为这项研究的一部分，三名本科生、一名研究生和一名博士后将接受研究培训。

Mycorrhizal fungi are ubiquitous and influential symbionts of most terrestrial plants, and their communities have been observed to replace each other over time in predictable successional order. Ecologists have no understanding how successional suites of mycorrhizal fungi differ functionally or how changes in functional traits relate to effects of mycorrhizae on plants. Changes in the conditions of such an important symbiosis must have broad consequences for plant community and ecosystem-level dynamics. Thus, establishing an experimental and theoretical basis for understanding consequences and causes of trait variation in distinct, successional mycorrhizal communities is the central theme of the work proposed.Coastal California pine forests harbor the best-studied examples of mycorrhizal succession in the world. In them a very different suite of mycorrhizal species colonize seedlings in burned areas and open dunes compared to mature forest settings, where seedlings are linked to adult trees in common mycorrhizal networks (CMNs). Experiments have shown that recruiting seedlings in forests respond very differently to these two guilds of mycorrhizal fungi; however, ecologists do not understand why these ectomycorrhizal fungal communities change over time, or how successive functional traits of successive fungi relate to their effects on plants. Growth chamber experiments, along with the results of a three-year field experiment in a coastal California Monterey pine (Pinus radiata) forest, wil establish differences in the mechanisms by which early- and late-stage fungi influence seedling performance in the forest understorey.The proposed work will have broad implications for conservation and silviculture. In its native range of California and Mexico, Monterey pine is limited to five small populations, some of which are at risk of extinction. Outside this range, it is one of the most widely planted timber species in the world, covering millions of acres on multiple continents. As an exotic, it is both a valuable commodity that preempts the need to harvest native timber and an aggressive invader, often naturalizing in ecosystems. Three undergraduate students, a graduate student and a postdoctoral research will receive research training as part of this research.