Leaf Level Physiology, Chemistry and Structural Traits, Far North Queensland Rainforest SuperSite, Daintree Rainforest Observatory, Cape Tribulation, 2012

Objectives: (1). Quantify rates of leaf respiration (both in darkness and in the light) and associated leaf traits in a wide range of tropical tree species (2) Establish the extent to which rates of leaf respiration and associated traits change in response to changes in light availability within the canopy. (3). Quantify the temperature dependence of leaf respiration of tropical tree species, using leaves sampled from the top and lower positions of the canopy. Experimental design and methods: In September 2010, we surveyed rates of light-saturated photosynthesis (measured at ambient and elevated atmospheric CO2 concentrations), leaf respiratory CO2 release (both in darkness and in the light) and related leaf traits (area:mass ratios, and concentrations of nitrogen, phosphorus and soluble/insoluble carbohydrates) in 16 tropical species growing at the Cape Tribulation Canopy Crane site. Leaves were sampled at two positions in the canopy (sun-exposed/top-canopy and shade-leaves/lower canopy). Light response curves of leaf CO2 exchange were used to calculate rates of leaf respiration in the light (using the ‘Kok’ method). We will also quantified short-term temperature dependences of leaf respiration in the upper and lower canopy leaves.

研究目标：(1) 量化多种热带树种的叶片呼吸速率（涵盖黑暗与光照条件）及相关叶片性状；(2) 明确冠层内光照可利用性变化对叶片呼吸速率及相关性状的影响程度；(3) 利用冠层顶部与下层采集的叶片样本，量化热带树种叶片呼吸的温度依赖性。实验设计与方法：2010年9月，我们于开普特里布勒申（Cape Tribulation）冠层塔吊观测样地，对16种生长于此的热带树种开展测定，内容包括光饱和光合速率（分别在大气CO₂浓度与升高CO₂浓度条件下测定）、叶片呼吸CO₂释放速率（黑暗与光照条件下）及相关叶片性状（叶面积与干质量比、氮、磷及可溶性/不溶性碳水化合物浓度）。叶片采集自冠层两个位置：向阳冠层顶部叶片与遮阴冠层下层叶片。通过叶片CO₂交换的光响应曲线，采用Kok法（Kok method）计算光照条件下的叶片呼吸速率。此外，我们还测定了冠层上下层叶片的短期呼吸温度响应特性。