The project I have planned for the summer 2005 program with OTS is an ecophysiological project measuring the temperature responses of photosynthesis of tropical trees and understory plants. Although we have considerable data on the light, humidity, and and CO2 responses of tropical trees, as part of the TOWERS project measuring temperature responses is more challenging and time consuming. The problem is that when you change the temperature at a given water vapor content in the air, the evaporation gradient from the leaf to the air increases at the same time, so that has to be compensated for, something that takes time. We know that mature tropical trees in Costa Rica are responding to warm years with lower growth, and we want to find out if this response is a result of the air temperature exceeding the temperature optimum of photosynthesis.

We will have a computerized photosynthesis system LI-COR LI-6400 that we will use to do this. We will work with plants in the understory and canopy leaves of trees off our two canopy towers.

We are looking for someone who is not afraid of heights, is careful, and has some familiarity with computers and preferablly other instrumentation.

Steve Oberbauer