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.