LTREB: Competition and Plant Community Structure Along Experimental Gradients of Disturbance and Nitrogen

尽管人们普遍认为营养、干扰 和竞争是控制植物生长的最重要的因素 社区结构，有相当大的争议， 这些因素的相对重要性和作用方式。 这一争论只能通过实验来解决， 同时操纵所有这些变量。 这从未 已经完成了。 这项工作的目标是：1）检查 养分和干扰对植物群落结构的影响 析因实验，将允许他们的互动和 独立的影响进行检查;和2）调查 地上和地下的竞争在塑造 在一定营养和干扰范围内的群落结构 政权。 将进行因子营养和干扰试验， 建在雪松溪自然公园一个经过充分研究的老地方， 明尼苏达州的历史区 限制营养素（氮）和 在这一领域最重要的干扰（地鼠土丘）将 五年后，让社区能够 实验处理下的平衡。 的影响 对土壤、光照和植物群落的处理， 每年测量。 在社区有三年的时间 平衡后，我们将把四个“目标”物种移植到 梯度和使用去除实验来测试是否有竞争力 等级和竞争强度随营养物质而变化， 扰动 这项实验的结果将允许明确的 测试目前，关于相互作用的不同假设， 营养、干扰和竞争 结构

In spite of a general concensus that nutrients, disturbance and competition are the most important factors controlling plant community structure, there is considerable controversy over the relative importance and the modes of action of these factors. This controversy can only be resolved through experiments that simultaneously manipulate all these variables. This has never been done. The objectives of this work are 1) to examine the effects of nutrients and disturbance on plant community structure in a full factorial experiment that will allow both their interactive and independent effects to be examined; and 2) to investigate the role of both above and below ground competition in shaping community structure in a range of nutrient and disturbance regimes. A factorial nutrient and disturbance experiment will be constructed in a well-studied old field at Cedar Creek Natural History Area in Minnesota. The limiting nutrient (nitrogen) and the most important disturbance (gopher mounds) in this field will be applied for five years to allow the communities to approach equilibrium under the experimental treatments. The effects of treatments on soil, light and the plant community will be measured annually. After the communities have had three years to equilibrate, we will transplant four "target" species into the gradients and use removal experiments to test whether competitive hierarchies and competition intensity vary with nutrients and disturbance. The results of this experiment will allow explicit tests of current, divergent hypotheses about the interactions of nutrients, disturbance and competition in shaping community structure.