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

这项研究将集中在树冠结构对4种具有不同建筑格局的速生新热带树种苗木的光截获和生长的意义。这四个物种，Cecropia obtusifolia，Helicarpus appendulatus，Piper auritum，和Trema micrantha，呈现了一种树冠结构的光谱，从单一树枝上生出的几片大叶子到分枝树冠上生出的许多小叶。生长在田间的苗木的光截获能力将通过计算机模拟来估计，计算机模拟结合了树叶显示的测量和树冠光环境的半球照片。光拦截能力将与18个月内的增长相关。这一分析将得到受控环境中苗木生长的研究的补充，在该研究中，相对生长速率被分解为三个因素，即环境光水平、截获的光量和光的利用效率。最后，每个物种的个体将被生长在空间不同的环境中，以评估树叶展示的建筑和形态成分的可塑性。这项研究将对树冠结构在光截获和碳增益方面的功能意义进行定量分析。

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.