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

9411785巴扎兹本论文的研究将评估林下植物在新英格兰中部森林苗木库形成特征中的作用。林下植被可能会影响树木的发育和组成，因为它是所有树木种子和幼苗必须经过的过滤器。该项目将探索林下植物是否起到了影响所有物种苗木丰富度的一般过滤器的作用，或者林下过滤器的选择性是否可预测地影响树种组成和苗木银行的相对大小结构。树苗和林下植物的空间相关性将在已绘制覆盖树地图的林分中描述，以便可以独立于种子雨模式建立苗木-林下植物关系。对自然更新树苗在不同林下类型下的生长和成活进行为期两年的监测。通过林下操作的田间试验，将测试两种优势蕨类植物的存在和身份对橡树、红枫和黄桦种子和幼苗的传播、萌发、生长和存活的影响。森林更新的研究主要集中在树苗的生长与树冠位置和条件的关系上，而对林下草本植物和灌木层如何影响林分演替的研究很少。这项研究的结果将通过将注意力集中在形成覆盖层移除释放的先进再生剂的起始阵列的过程上，来增加对干扰后森林更新的理解。

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.