Temporal Changes in Resource Heterogeneity and Vegetation Response in Tree-Fall Gaps

树木倒塌间隙中资源异质性和植被响应的时间变化

• 批准号: 9527701
• 负责人: Andrew Gray
• 金额: $ 7.5万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-09-15 至 1999-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9527701&HistoricalAwards=false
• 关键词: Temporal; Changes; Resource; Heterogeneity; Vegetation

In the coniferous forests of the Pacific Northwest, canopy gaps created by the death of large trees within mature forests are hypothesized to determine the species composition and future development of those forests. In 1990, the investigators established experimental canopy gaps of different sizes within two conifer forests of different age. The main objectives have been to determine the influence of the composition and abundance of vegetation and the availability of resources (e.g. light and moisture) prior to and immediately after gap formation on the pattern of development in old growth forests. The investigators will continue their long-term measurements of plant diversity and abundance, and of light and soil moisture levels, in the experimental gaps. Recent plans for management of federal lands in the Pacific Northwest emphasize managing young forests to encourage a greater diversity of species and structure that is characteristic of old-growth forests. Allowing stands to age naturally may accomplish this goal, but selective tree harvest has also been proposed as a way to achieve structural complexity more rapidly while allowing some commodity extraction. This study will aid in understanding how canopy gaps influence development of old-growth forests, how long it might take for old-growth structure to develop naturally, and whether selective harvest of different sizes of openings can mimic this process. This study will also provide new information on the most appropriate gap size for the establishment and growth of different tree and understory plant species, and the effect of existing vegetation on tree survival and growth.

在太平洋西北部的针叶林中，成熟森林中的大树死亡所产生的林冠空隙被假设为确定这些森林的物种组成和未来发展。 1990年，研究人员在两个不同年龄的针叶林中建立了不同大小的实验林隙。 主要目的是确定林隙形成之前和之后植被的组成和丰富程度以及资源（例如光和水分）的供应情况对原始森林发展格局的影响。 研究人员将继续在实验间隙对植物多样性和丰富度以及光照和土壤湿度水平进行长期测量。 最近的太平洋西北部联邦土地管理计划强调管理幼林，以鼓励增加古老森林特有的物种和结构多样性。 允许林分自然老化可以实现这一目标，但选择性树木收获也被提议作为一种更快实现结构复杂性的方式，同时允许一些商品提取。 这项研究将有助于了解冠层间隙如何影响古老森林的发展，需要多长时间的古老结构自然发展，以及是否有选择地收获不同大小的开口可以模仿这一过程。 这项研究也将提供新的信息，最合适的差距大小为建立和生长的不同树木和林下植物物种，和现有的植被对树木的生存和生长的影响。