Revising traditional theory on the link between plant body size and fitness under competition: evidence from old-field vegetation

The selection consequences of competition in plants have been traditionally interpreted based on a “size-advantage” hypothesis – that is, under intense crowding/competition from neighbors, natural selection generally favors capacity for a relatively large plant body size. However, this conflicts with abundant data, showing that resident species body size distributions are usually strongly right-skewed at virtually all scales within vegetation. Using surveys within sample plots and a neighbor-removal experiment, we tested: (1) whether resident species that have a larger maximum potential body size (MAX) generally have more successful local individual recruitment, and thus greater local abundance/density (as predicted by the traditional size-advantage hypothesis); and (2) whether there is a general between-species trade-off relationship between MAX and capacity to produce offspring when body size is severely suppressed by crowding/competition – that is, whether resident species with a lar...

传统上，学界基于「体型优势（size-advantage）」假说解释植物竞争的选择效应：即在邻株带来的强烈拥挤/竞争压力下，自然选择通常更青睐体型相对较大的植物个体。然而，这一假说与大量观测数据相悖——植被群落中几乎所有尺度下的常驻物种体型分布通常均呈现显著的右偏态特征。本研究通过样地调查与邻株移除实验，验证了两个研究假说：（1）具有更大最大潜在体型（maximum potential body size，MAX）的常驻物种，是否通常拥有更高的本地个体定植成功率，进而具备更高的本地种群丰度/密度（即传统体型优势假说的预测结果）；（2）当体型因拥挤/竞争受到严重抑制时，MAX与物种繁殖产出能力之间是否普遍存在种间权衡关系——即拥有体型更大的常驻物种是否