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

9624656卡斯珀这项研究将检查地上和地下竞争对植物性能的综合影响，在一个老田植物群落。 目前的文献假设，它们的综合效应只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。 它们的组合效应是否大于、等于或小于每个单独效应的总和可能取决于地上与地下相互作用的相对强度。 这些想法将在田间试验中进行测试，在两个土壤肥力水平的全因子设计中，地上和地下竞争强度的梯度将被交叉。 将一年生植物- 地下的竞争梯度将通过使用不同程度的邻近根系的可达性的土壤分区创建。 通过拉回邻近枝条的部分，可以改变地上竞争。 这项研究将是第一个直接测试竞争形式的加和性在田间试验。 它还将能够测试地下竞争的重要性是否随着土壤资源的增加而降低。

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.