Dissertation Research: Competition Between Herbaceous and Woody Plants: The Importance of Herbs in Forest Dynamics

虽然草本植物通常只占森林总生物量或产量的一小部分，但通过与树苗的竞争，它们在调节森林组成和动态方面可能至关重要。然而，由于森林中草本植物的丰度变化很大，草本植物对树木形成的影响并不一致。资源竞争理论预测，在土壤养分和水分充足但光照不足的条件下，草本植物将在与木本植物的竞争中胜出，而光照较高或土壤资源水平较低则会使竞争相互作用向有利于木本植物的方向转移。光照和土壤资源的实验操作将采用假设，即高资源地点的草本植物通过降低生长速度和增加树苗死亡率来影响树木组成。沿着草本覆盖梯度进行的观测将用于检验光与土壤资源供应比决定林下木本植物与草本植物竞争结果的一般假设。如果这一假设是正确的，那么树冠间隙、草本植物移除区和其他低资源微点可能通过改变竞争平衡而发挥关键作用，使其更有利于树苗。

Although herbs typically contribute only a minor fraction of the total biomass or production of a forest, they may be critically important in regulating forest composition and dynamics through competition with tree seedlings. However, because forests are extremely variable in herb abundance, the impact of herbs on tree establishment is not consistent. Resource competition theory leads to the prediction that under conditions of abundant soil nutrients and moisture but low light, herbaceous plants will win in competition with woody plants, while higher light or lower soil resource levels should shift the competitive interaction to favor woody plants. Experimental manipulations of light and soil resources will be used the hypothesis that herbs on high-resource sites influence tree composition by reducing growth rates, and increasing mortality rates of tree seedlings. Observation made along herb-cover gradients will be used to test the general hypothesis that the light:soil resource supply ratio determines the outcome of competition between woody and herbaceous plants in understories. If this hypothesis is true, then canopy gaps, herb removal areas, and other low resource microsites could play a critical role by shifting the competitive balance to be more favorable for tree seedlings.