Collaborative Research: Long-term Studies of Forest Dynamics: Analysis of Seedling and Sapling Populations

合作研究：森林动态的长期研究：幼苗和幼树种群分析

• 批准号: 9108564
• 负责人: Norman Christensen, Jr.
• 金额: $ 3.33万
• 依托单位: Duke University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-08-01 至 1994-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9108564&HistoricalAwards=false
• 关键词: Collaborative; Research; Long; term; Studies

Disturbance is nearly ubiquitous in ecological systems. Consequently, succession, the process of recovery from disturbance, is responsible for much variation in ecosystem structure and function. The primary objective of this research is to understand the process of succession, and the investigators assert that most successional changes in community-level properties and processes can best be understood as resulting from population processes. Although permanent plots are commonly used to examine the dynamics of mature trees, seedling and sapling dynamics remain virtually unstudied, simply because appropriate data have not been available. With the support of the National Science Foundation Long-term Research in Environmental Biology (LTREB) program, the investigators have collected seedling and sapling data from permanent plots in numerous types and ages of forests with observations ranging up to 13 years. Consequently the investigators are uniquely positioned to examine the dynamics of seedlings and saplings as related to succession and site characteristics. The LTREB dataset will be used to address questions related to the dynamics of seedlings and samplings such as the following: (1) How do seedling and sapling establishment, growth, and survival vary with succession and site conditions? (2) Is seedling-seedling competition significant? We suspect that competition with canopy trees controls seedling dynamics, except in canopy gaps, but if seedling interactions are important they will need to be added to forest simulation models. (3) Do canopy trees differentially inhibit conspecific seedlings and saplings? This is a popular hypothesis, largely untested in temperate forest. (4) Can year-to-year climatic variation explain co- existence of similar tree species? Again, this a popular but untested hypothesis. (5) Does seedling vigor change during succession in a fashion consistent with existing models of changing canopy-derived competition (see Peet and Christensen 1987)? This research will provide a unique perspective on successional patterns from a population standpoint.

生态系统中的干扰几乎无处不在。 因此，演替，即从干扰中恢复的过程，是造成生态系统结构和功能发生很大变化的原因。 这项研究的主要目的是了解演替过程，研究人员断言，群落层面的属性和过程的大多数演替变化可以最好地理解为人口过程的结果。 尽管永久样地通常用于检查成熟树木的动态，但幼苗和幼树的动态实际上仍未被研究，仅仅是因为尚未获得适当的数据。 在美国国家科学基金会环境生物学长期研究 (LTREB) 计划的支持下，研究人员从多种类型和年龄的森林的永久地块中收集了幼苗和树苗数据，观测时间长达 13 年。 因此，研究人员具有独特的优势来检查与演替和场地特征相关的幼苗和树苗的动态。 LTREB 数据集将用于解决与幼苗和采样动态相关的问题，例如：（1）幼苗和幼树的建立、生长和存活如何随演替和立地条件而变化？ （2）苗与苗之间的竞争是否显着？ 我们怀疑与树冠树木的竞争控制着幼苗的动态，除了树冠间隙，但如果幼苗的相互作用很重要，则需要将它们添加到森林模拟模型中。 (3)冠层树对同种幼苗和幼树的抑制是否存在差异？ 这是一个流行的假设，基本上没有在温带森林中得到检验。 (4)逐年气候变化能否解释相似树种的共存？ 同样，这是一个流行但未经检验的假设。 (5) 幼苗活力在演替过程中的变化是否与现有的树冠衍生竞争变化模型一致（参见 Peet 和 Christensen 1987）？ 这项研究将从人口的角度提供关于演替模式的独特视角。