Dissertation Research: The Understory as Ecological Filter: Its Influence on the Abundance, Composition, and Size Structure of Seedling Bank in New England Deciduous Forests

本文的研究将评价林下植物在新英格兰中部森林幼苗库形成特征中的作用。林下植被作为所有树木种子和幼苗必须通过的过滤器，有可能影响树木的发育和组成。该项目将探讨林下植被是否作为一个普遍的过滤器，对所有物种的幼苗丰度产生类似的影响，或者林下植被过滤器的选择性是否可预测地影响物种组成和幼苗库的相对大小结构。树苗和林下植物的空间相关性将在已绘制林下树图的林分中进行描述，以便幼苗-林下植物的关系可以独立于种子雨模式建立。在不同林下类型下，对自然招募的树苗进行为期两年的生长和存活监测。涉及林下操纵的田间实验将测试两种优势蕨类植物的存在和特性对rd栎、红枫和黄桦种子和幼苗的扩散、发芽、生长和存活的影响。森林更新的研究主要集中在树冠乔木的位置和条件下树苗的生长，但对林下草本和灌木层如何影响林分演替知之甚少。这项研究的结果将增加对扰动后森林再生的理解，将注意力集中在形成由砍伐林冠层释放的高级再生物的起始阵列的过程上。

9411785 Bazzaz This dissertation research will evaluate the role of understory plants in shaping characteristics of the seedling bank in central New England forests. The understory has the potential to influence development and composition by acting as a filter through which all tree seeds and seedlings must pass. This project will explore whether the understory acts as a general filter that influences seedling abundance of all species similarly or whether selectivity of an understory filter predictably influences species composition and relative size structure of the seedling bank. Spatial correlations of tree seedlings and understory plants will be described in stands where overstory trees have been mapped so that seedlings-understory relationships can be established independently of seed rain patterns. Growth and survival of naturally recruiting tree seedlings will be monitored under different understory types for two years. Field experiments involving understory manipulation will test the effects of the presence and identity of two dominant ferns on dispersal, germination, growth, and survival of rd oak, red maple, and yellow birch seeds and seedlings. %%% Studies of forest regeneration have focused on the growth of tree seedlings with respect to the location and condition of canopy trees, yet little is known about how the understory herb and shrub strata influence stand succession. Results of this study will add to an understanding of forest regeneration following disturbance by focusing attention on processes which shape the starting array of advanced regenerants released by overstory removal.