RUI: Grass Effects on Tree Seedling Success in the Pairie-Forest Border: Competition and Facilitation along a Multiple Resource Gradient

尽管水在干旱和半干旱环境中很重要，而且围绕竞争和资源梯度做了大量工作，但还没有研究区分根和地上部竞争对土壤水分梯度的影响。如果我们想要了解草原群落林木育苗的生态学，这些信息是至关重要的。这项研究将研究干旱和半干旱环境中木本苗木的建立。Cedar Creek LTER现场将进行一项大型多因素田间试验，在该试验中将操纵水输入、氮输入和来自牧草的竞争。这项实验将允许量化草在水氮梯度上对根、地上部和整个植株的竞争。它还将允许对上述每种组合中的树苗(栎树和椭圆栎树)之间的根和地上部竞争强度进行独立的量化。这项研究将为资源供应对草和树之间竞争相互作用的影响提供重要的新信息。尽管这项研究是在一个单独的地点进行的，但它应该对竞争理论产生广泛的影响，因为它与水和养分有关，并对预测植物对自然和人为干扰的反应具有广泛的意义。这项拟议研究的结果应该有助于理解全球和区域环境变化，包括氮沉积水平的增加、降水的变化以及外来草本植物的取代可能会如何影响草原群落中木本植物的建立。

9873673Davis Despite the importance of water in arid and semi-arid environments and the numerous amount of work centered around competition and resource gradients, no studies have been made to separate out the effects of root and shoot competition along a soil water gradient. This information is critical if we are going to understand the ecology of wood seedlings establishment in grassland communities. This research will examine the establishment of woody seedlings in arid and semi-arid environments. A large multi-factor field experiment will be undertaken at the Cedar Creek LTER site in which water input, nitrogen input and competition from grasses will be manipulated. This experiment will permit the quantification of root, shoot and whole plant competition by grasses along the water-nitrogen gradient. It will also allow an independent quantification of root and shoot competition intensity between the tree seedlings (Quercus macrocarpa and Q. ellipsoidalis) in each of the above combinations. This research should provide important new information on the effect of resource supply on competitive interactions between grasses and trees. Although implemented at a single site, the research should have broad implications for competition theory as it relates to water and nutrients and for predicting plant response to natural and human-caused disturbance. Findings from this proposed research should help in understanding how global and regional changes in the environment involving increased levels of nitrogen deposition, changes in precipitation, and replacement of native by exotic grasses my be affecting woody seedling establishment in grassland communities.