Tree abundance in eight 1-ha tropical forest plots in northeastern Costa Rica from 1997-2017

In 1997, four 1-ha plots were established in secondary forests (12-25 yr since establishment on former pasture) in northeastern Costa Rica, in and around La Selva Research Station. In 2005, four additional plots were established, two in 10-yr old sites and two in old growth sites. The dataset contains information for 155,378 trees. Each year, from 1997-2017 all stems with a diameter of breast height ≥ 5 cm were censused in each site within 100 subplots of 10m x 10m. All but a few individuals were identified to species with confirmed identifications by local experts and vouchers. Life form for each species was also recorded as tree (reaching canopy), midtree (midstory tree), treelet (understory tree), shrub, liana, palm, or understory palm. The specimen-based data set contains data for all trees that were alive (not completely dead) and standing in each annual census, including notes on new recruits or damaged trees. Each tree individual is identified by a unique stem identifiation code and each entry has a unique specimen code. Each tree had a unique numbered tag, nailed into the stem. Locations of diameter measurements were painted on each tree to minimize annual variation and field technians had data from the prior year to confirm information for each tree. These were generally taken at 1.3 m height. In cases where a buttress or stilt root caused a stem irregularity, the measurement point was moved upwards beyond any stem irregularity. The diameter measurement for each specimen reflects each year's measurement point.1997年，研究人员于哥斯达黎加东北部的拉塞尔瓦研究站（La Selva Research Station）及其周边区域，在原本为牧场、恢复时长12至25年的次生林中设立了4块1公顷样地。2005年，研究人员新增设立4块样地，其中2块位于恢复时长10年的样地，另外2块位于原始林样地。 本数据集涵盖155378株树木的相关信息。1997年至2017年的每年，研究人员都会在每个样地内的100块10米×10米的小样地中，对胸径（breast height）≥5厘米的所有茎干开展普查。 除极少数个体外，其余所有植株均经当地专家确认鉴定并留存凭证标本（vouchers），鉴定精度达物种水平。研究人员同时记录了各物种的生活型，具体包括乔木（可到达冠层）、中乔木（林中层乔木）、小乔木（林下乔木）、灌木、藤本、棕榈及林下棕榈。 本基于标本的数据集收录了每年普查中存活（未完全死亡）且仍直立的所有树木数据，包含新定植个体或受损树木的相关记录。每株树木均通过唯一的茎干识别码进行标识，每条记录亦配有唯一的标本编码。所有树木均配有专属编号的金属标牌，钉于茎干表面。为减少年度测量误差，研究人员会在每株树木的胸径测量位置涂刷标记，且野外技术人员可参考上一年度的测量数据以确认每株树木的相关信息。常规测量高度为1.3米，若树木存在板根或支柱根导致茎干形态不规则，则将测量点上移至该不规则结构以上的位置。每份标本的径级测量值均对应当年的测量点位。