Amazon Adventures in Science - Two

Project background: In the Biosphere 2 rainforest, there remain 25% of the original number of planted species. Why did these species survive and not the others? What factors drove this local extinction? Under the glass in Biosphere 2, it is HOT! As you climb up to the upper levels, it gets even hotter. At times during B2's life, the cooling systems were run at a minimum of energy. After this period (before U of Arizona), many of the trees got cooked! I think that heat was one of the strong pressures that formed the plant community which exists today.

How do plants deal with heat? One of the most important factors seems to be the ability to produce large amounts of anti-oxidants, which volatilize (or are emitted in gaseous form) from the leaf and are measured as volatile organic compounds (VOC). In high heat, an organism's physiology and chemistry runs faster and makes more mistakes. These mistakes can be in the form of "free radicals", which are powerful oxidants that can destroy cells. This is why the plant needs good antioxidants.

Importance: Some of these VOCs drive very important atmospheric interactions. Some of them act as nuclei for cloud water, and actually make it rain over the forest. Isoprene, the most commonly studied VOC from plants, can either reduce or increase ozone in the atmosphere, depending on local conditions.

My question: Are plant communities at forest edges dominated by species that emit high amounts of VOCs? As the Amazon (and other forests) becomes increasingly fragmented, or chopped into pieces, these interactions between forest edges and atmosphere become increasingly important.

My methods: To standardize the leaf environment, I'll use a device that clamps onto the leaf and controls light, temperature, and CO2 concentrations. (The device is normally used to measure photosynthesis.) To measure VOCs, I'll use a new advance in air monitoring technology, a hand-held detector that can measure VOCs at the parts-per-billion (ppb) level! This instrument will measure gases from the exhaust line from the leaf chamber.

Ty