Dissertation Research: Interactions Between Above Ground and Below Ground Competition in Old Field Vegetation

9624656卡斯珀这项研究将考察地上和地下竞争对旧地植物群落中植物表现的综合影响。目前的文献认为，它们的综合效应仅仅是每种效应本身的总和。然而，地下竞争可能会影响植物对地上竞争的反应，反之亦然。它们的综合效应是否大于、等于或小于每种单独效应的总和，可能取决于地上和地下相互作用的相对强度。这些想法将在田间试验中得到检验，在田间试验中，地上和地下竞争强度的梯度将在两个土壤肥力水平上以完全析因设计交叉。一年生植物目标个体的生长反应将作为因变量。地下竞争坡度将通过使用相邻根系具有不同可达性程度的土壤隔板来创建。地上的竞争将通过拉回相邻枝条的部分来改变。这项研究将是第一次在田间实验中直接检验竞争形式的可加性。它还将能够测试地下竞争是否随着土壤资源的增加而重要性降低。

9624656 Casper This study will examine the combined effect of aboveground and belowground competition on plant performance in an oldfield plant community. Current literature assumes that their combined effect is simply the sum of each effect by itself. However, belowground competition is likely to affect plant response to aboveground competition and vice versa. Whether their combined effect is greater than, equal to, or less than the sum of each separate effect may depend on the relative strength of the aboveground versus belowground interactions. These ideas will be tested in a field experiment in which gradients in the intensity of aboveground and belowground competition will be crossed in a full factorial design at two levels of soil fertility. The growth response of target individuals of the annual plant, Abutilon theophrasti, will be used as the dependent variable. The belowground competition gradient will be created through the use of soil partitions with different degrees of accessibility by neighboring roots. Aboveground competition will be varied by pulling back portions of neighboring shoots. This research will be the first to test directly the additivity of competitive forms in a field experiment. It will also be able to test whether belowground competition decreases in importance with increased soil resources.