Cope Olivia L, Lindroth Richard L, Helm Andrew, Keefover-Ring Ken, Kruger Eric L
Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI, 53706, USA.
Department of Entomology, University of Wisconsin-Madison, Madison, WI, 53706, USA.
New Phytol. 2021 Apr;230(2):710-719. doi: 10.1111/nph.17166. Epub 2021 Feb 1.
The ability to tolerate neighboring plants (i.e. degree of competitive response) is a key determinant of plant success in high-competition environments. Plant genotypes adjust their functional trait expression under high levels of competition, which may help explain intra-specific variation in competitive response. However, the relationships between traits and competitive response are not well understood, especially in trees. In this study, we investigated among-genotype associations between tree trait plasticity and competitive response. We manipulated competition intensity in experimental stands of trembling aspen (Populus tremuloides) to address the covariance between competition-induced changes in functional trait expression and aspects of competitive ability at the genotype level. Genotypic variation in the direction and magnitude of functional trait responses, especially those of crown foliar mass, phytochemistry, and leaf physiology, was associated with genotypic variation in competitive response. Traits exhibited distinct plastic responses to competition, with varying degrees of genotypic variation and covariance with other trait responses. The combination of genotypic diversity and covariance among functional traits led to tree responses to competition that were coordinated among traits yet variable among genotypes. Such relationships between tree traits and competitive success have the potential to shape stand-level trait distributions over space and time.
耐受相邻植物的能力（即竞争响应程度）是植物在高竞争环境中成功的关键决定因素。植物基因型在高水平竞争下会调整其功能性状表达，这可能有助于解释种内竞争响应的差异。然而，性状与竞争响应之间的关系尚未得到充分理解，尤其是在树木中。在本研究中，我们调查了树木性状可塑性与竞争响应之间的基因型间关联。我们在颤杨（Populus tremuloides）实验林中操纵竞争强度，以研究基因型水平上竞争诱导的功能性状表达变化与竞争能力各方面之间的协方差。功能性状响应的方向和幅度的基因型变异，尤其是树冠叶质量、植物化学和叶片生理学方面的变异，与竞争响应的基因型变异相关。性状对竞争表现出不同的可塑性响应，具有不同程度的基因型变异以及与其他性状响应的协方差。功能性状之间的基因型多样性和协方差的组合导致树木对竞争的响应在性状间相互协调，但在基因型间存在差异。树木性状与竞争成功之间的这种关系有可能在空间和时间上塑造林分水平的性状分布。
