Germination in three R/FR light environments (El Verde)

Experiments were conducted in the Tabonuco forest at Luquillo Experimental Forest to determine the germination success of a number of species in different light environments. Species tested included: Byrsonima spicata, Calophyllum brasiliense, Carapa sp., Choven venosa, Guarea guidonia, Manilkara bidentata, Ochroma pyramidale and an unidentified species known locally as Jobo. Seeds were collected as they fell and placed on moist towling in horticulture trays at four sites. Seeds were kept moist and germination was recorded daily for 81 days and three times weekly for an additional 75 days. Light environments included a site exposed to full sun (FS) and sites with 55%, 75% and 80% cover. Instantaneous light measurements were made with a Licor 1800 spectroradiometer to determine the Red (660 nm) to Far-red (730 nm) ratio (R/FR) (Lee, 1987). Analysis of light data indicated that the four sites chosen provided three significantly different R/FR ratio environments, and that germination of some species was affected by the light environment (Smith, H. & Whitelam, G.C. 1990). Three species failed to germinate in any of the four light environments. 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.

本实验于卢奎略实验森林（Luquillo Experimental Forest）的塔博努科林（Tabonuco forest）中开展，旨在探究多个受试树种在不同光照环境下的萌发成功率。受试物种涵盖：Byrsonima spicata、Calophyllum brasiliense、Carapa sp.、Choven venosa、Guarea guidonia、Manilkara bidentata、轻木（Ochroma pyramidale），以及当地俗称Jobo的未鉴定物种。所有种子均采自自然脱落的个体，随后被放置于园艺托盘内的湿润吸水纸中，共设置4个试验位点。所有受试种子始终保持湿润，实验周期的前81天每日记录萌发情况，后续75天则每周记录3次。本次实验设置的光照环境涵盖全光照位点（full sun, FS）以及遮光率分别为55%、75%和80%的3个遮光位点。采用Licor 1800分光辐射度计（Licor 1800 spectroradiometer）开展瞬时光照测量，以计算红光（660 nm）与远红光（730 nm）的比值（R/FR）（Lee, 1987）。光照数据分析结果显示，所选的4个试验位点共形成3种具有显著差异的R/FR比值环境，且部分树种的萌发过程会受到光照环境的显著影响（Smith, H. & Whitelam, G.C. 1990）。另有3个受试树种在全部4种光照环境下均未萌发。本研究得到美国国家科学基金会（National Science Foundation）的多项拨款支持，包括BSR-8811902、DEB-9411973、DEB-9705814、DEB-0080538、DEB-0218039、DEB-0620910、DEB-1239764、DEB-1546686以及DEB-1831952，相关拨款拨付至波多黎各大学，作为卢奎略长期生态研究项目（Luquillo Long-Term Ecological Research Program）的组成部分。此外，本研究还得到波多黎各大学以及美国农业部林务局国际热带林业研究所的经费支持。