Long-Term Elevation Plots (LTEP) (Altitudinal transects vegetation data along three rivers in the Luquillo Experimental Forest)

The composition of plant communities changes with elevation in the Luquillo Experimental Forest (LEF). The goal of this project is to document the patterns of these changes, and in particular, to determine whether the distributions of individual species are independent of one another, or whether they are related, in either a congruent or a hierarchical manner. Thirty-two permanent vegetation plots, each 50m by 20m are being established in the LEF, with 5 plots along the Icacos river, 11 along the Mamayes river and 16 along the Sonadora stream. The plots were established at every 100m in elevation, starting at 200m above sea level. All woody, free-standing stems greater than 1cm dbh were marked, identified and mapped into 5x5 subquadrats. We anticipated that gradient analysis will show whether the distributions of species are coincident or independent, enabling us to evaluate whether separate, genuine plant communities exist in the LEF. Because the plots are permanent, we also expected that they allow us to better evaluate how different vegetation types, at different elevations, respond to large scale disturbances, especially hurricanes. Support for this work was provided by grants BSR-8811902, DEB-9411973, DEB-9705814 , DEB-0080538, DEB-0218039 , DEB-0620910 , DEB-1239764, DEB-1546686, and DEB-1831952 from the National Science Foundation to the University of Puerto Rico as part of the Luquillo Long-Term Ecological Research Program. Additional support provided by the University of Puerto Rico and the International Institute of Tropical Forestry, USDA Forest Service.卢基洛实验森林（Luquillo Experimental Forest, LEF）内的植物群落组成随海拔梯度发生变化。本项目的目标是记录这类变化的模式，尤其旨在明确单个物种的分布是彼此独立，还是以协同或层级的方式相互关联。本研究于LEF内设立了32个永久性植被样地，每个样地规格为50米×20米：其中沿伊卡科斯河（Icacos River）设置5个、沿马马耶斯河（Mamayes River）设置11个、沿索纳多拉溪（Sonadora Stream）设置16个。样地以每100米海拔为间隔设立，起始海拔为海平面以上200米。研究人员对所有胸径（diameter at breast height, dbh）大于1厘米的直立木本茎干进行标记、物种鉴定，并在5×5的小样方中完成定位与绘图。我们预计通过梯度分析可揭示物种分布是重合还是独立的，以此评估LEF内是否存在独立且真实的植物群落。由于该样地为永久性样地，本研究还期望借助其更好地评估不同海拔的植被类型如何响应大规模扰动，尤其是飓风灾害。本研究的资助资金来自美国国家科学基金会（National Science Foundation）授予波多黎各大学的多项拨款，具体包括BSR-8811902、DEB-9411973、DEB-9705814、DEB-0080538、DEB-0218039、DEB-0620910、DEB-1239764、DEB-1546686以及DEB-1831952，属于卢基洛长期生态研究计划（Luquillo Long-Term Ecological Research Program）的一部分。本研究还获得了波多黎各大学以及美国农业部林业局国际热带森林研究所的额外资助。