Dissertation Research: Light Interception and Growth in Four Pioneer Tree Species with Contrasting Canopy Architecture

本文将重点研究树冠结构对四种不同树型的快速生长的新热带树种幼苗截光和生长的意义。四种植物Cecropia obtusifolia、Heliocarpus appendiculatus、Piper auritum和Trema micrantha在树冠结构上呈现出不同的特征，从很少的大叶片在单枝上生长到许多小叶片在分枝树冠上生长。在田间生长的幼苗的光拦截将通过计算机模拟来估计，该模拟将叶片显示的测量结果与冠层光环境的半球形照片相结合。光拦截能力将与18个月期间的增长相关。在此基础上，还将对受控环境下的幼苗生长进行研究，将相对生长速率分解为三个因素：环境光照水平、光截获量和光利用效率。最后，将每个物种的个体生长在空间异质性环境中，以评估叶片展示的建筑和形态成分的可塑性。本研究将定量分析树冠结构在光拦截和碳增益方面的功能意义。

The research will focus on the significance of canopy structure for light interception and growth in seedlings of four fast- growing neotropical tree species with contrasting architectural patterns. The four species, Cecropia obtusifolia, Heliocarpus appendiculatus, Piper auritum, and Trema micrantha, present a spectrum of canopy architectures, from few large leaves born on a single shoot to many small leaves born in a branched crown. Light interception of seedlings growing in the field will be estimated with computer simulations which combine measurements of leaf display with hemispherical photographs of the canopy light environment. The light interception capacity will be correlated with growth over an 18 month period. This analysis will be complemented by a study of seedling growth in a controlled environment, in which relative growth rate is decomposed into three factors, the ambient light level, the amount of light intercepted, and the efficiency of light utilization. Finally, individuals of each species will be grown in spatially heterogeneous environments to evaluate the plasticity of architectural and morphological components of leaf display. This research will provide a quantitative analysis of the functional significance of canopy architecture in relation to light interception and carbon gain.