Maximum stem diameter predicts liana population demography

Determining population demographic rates is fundamental to understanding differences in species life-history strategies and their capacity to coexist. Calculating demographic rates, however, is challenging and requires long-term, large-scale censuses. Body size may serve as a simple predictor of demographic rate; can it act as a proxy for demographic rate when those data are unavailable? We tested the hypothesis that maximum body size predicts species’ demographic rate using repeated censuses of the 77 most common liana species on the Barro Colorado Island, Panama (BCI) 50-ha plot. We found that maximum stem diameter does predict species’ population turnover and demography. We also found that lianas on BCI can grow to the enormous diameter of 635 mm, indicating that they can store large amounts of carbon and compete intensely with tropical canopy trees. This study is the first to show that maximum stem diameter can predict plant species’ demographic rates and that lianas can attain extr..., We measured the diameter of all lianas ³ 10 mm diameter in the BCI plot in 2007 and again in 2017 using liana-specific census methods developed by Gerwing et al. (2006) and Schnitzer et al. (2008). Diameter measurements were taken 1.3 m along the stem from the roots using calipers for stems < 50 mm diameter, and diameter tape for stems ³ 50 mm. If the stem was deformed by bulges, nodes, damage, or other defects at the 1.3 m measurement point, we measured 50 mm below the deformity. In total, there were 175 liana species in the BCI 50-ha plot (Schnitzer et al. 2021); we selected the 77 species that had 100 more individuals in the 50- ha plot (Appendix S1: Table S1) to calculate species population dynamics (measured as turnover). We defined species-specific turnover rate as the geometric mean of individual liana recruitment (Lr) and mortality (Lm) between the two censuses (Phillips & Gentry 1994):  (ln Lr + ln Lm)/2.  Both recruitment and mortality were highly correlated with turnov...,

探明种群统计率（demographic rates）是理解物种生活史策略差异及其共存能力的核心基础。然而，计算种群统计率颇具挑战，需要开展长期、大规模的野外普查。体型或可作为种群统计率的简易预测因子，但在相关数据缺失时，体型能否替代种群统计率发挥作用？本研究依托巴拿马巴罗科罗拉多岛（Barro Colorado Island, BCI）50公顷样地内77种最常见藤本植物（liana）的重复普查数据，检验了“最大体型可预测物种种群统计率”这一假说。研究结果显示，最大茎干直径确实可以预测物种种群更替率与种群统计特征。此外，本研究发现BCI样地内的藤本植物最大茎干直径可达635毫米，表明其可储存大量碳，并与热带冠层树木展开激烈竞争。本研究首次证实，最大茎干直径可预测植物物种种群统计率，且藤本植物可达到极高的……本研究采用Gerwing等人（2006）与Schnitzer等人（2008）开发的藤本专属普查方法，分别于2007年和2017年对BCI样地内所有茎干直径≥10毫米的藤本植物进行了直径测量。测量点位设置在距茎干基部1.3米处：茎干直径小于50毫米者使用游标卡尺测量，直径≥50毫米者则使用直径卷尺测量。若1.3米测量点处的茎干存在凸起、结节、损伤或其他畸形，则在畸形点下方50毫米处开展测量。BCI 50公顷样地内共计记录有175种藤本植物（Schnitzer等人，2021）；本研究选取了其中样地内个体数不少于100株的77个物种（附录S1表S1），用于计算物种种群动态（以更替率表征）。本研究将物种种群专属更替率定义为两次普查期间藤本个体补充率（Lr）与死亡率（Lm）的几何平均值（Phillips & Gentry，1994），计算公式为：(ln Lr + ln Lm)/2。补充率与死亡率均与更替率呈高度相关……