Mycorrhizal Ecology of Plant Colonization of Glacier Forefronts

植物对根共生(菌根)真菌的相对依赖性对植物在新土壤上的演替可能是至关重要的，但这一生态学领域几乎没有受到关注。华盛顿州北喀斯喀特山脉的冰川就适合这一目的。在消退过程中，它们堆积的碎石最初没有共生真菌，随着距离冰川末端的距离增加，共生真菌的暴露时间会增加。随着时间的推移，在这些冰川前缘定居的植物将与邻近的未受干扰的群落中的同一物种进行菌根形成的比较。这三个主要类群是：(1)在没有共生真菌的情况下生存；(2)依靠空气中散布的菌根真菌；(3)依靠流动土壤中散布的菌根真菌。第一组的植物被预测为第一个定殖者，其次是第二组和第三组。田间取样、温室和生长室接种实验将验证这一假设。如果是真的，这将解释为什么冰川附近的许多种子生产植物中只有几个是最初的殖民者。这一对生态学理论的贡献在解释演替现象和恢复受干扰或退化的生态系统方面有许多应用。

The importance of relative dependency of plants on root- symbiotic (mycorrhizal) fungi may be critical to plant succession on new soils, but this area of ecology has received little attention. Glaciers of the North Cascade Mountains of Washington suit this purpose. In receding, they deposit rubble initially devoid of symbiotic fungi, which increase in time of exposure with distance from the glacier terminus. Plants that colonize these glacier forefronts over time will be compared with the same species in adjacent, undisturbed communities for mycorrhiza formation. The three major groups are plants that (1) survive without the symbiotic fungi, (2) depend on mycorrhizal fungi dispersed by air, and (3) depend on mycorrhizal fungi dispersed with moving soil. Plants in group 1 are predicted to be first colonizers, followed in turn by groups 2 and 3. Field sampling and greenhouse and growth chamber inoculation experiments will test the hypothesis. If true, it will explain why only a few of the many seed-producing plants adjacent to glaciers are initial colonizers. This contribution to ecological theory has many applications in interpreting successional phenomena and in rehabilitating disturbed or degraded ecosystems.