I haven't written anything for the past few days because my fiancee and I were vacationing in Puerto Rico. If you haven't been to the island, I highly recommend that you visit. The people are generally nice and the natural scenery is incredible.
The highlight of our trip was our visit to El Yunque National Forest, the only tropical rainforest in the United States. We spent two days there; the first hiking the Rio Sabana trail on the closed and remote south side of the forest, and the second following the sites along Highway 191, the main drag through the forest to the north. Both sides offered distinct and interesting vegetation.
The most interesting thing I learned about (thanks in part to my fiancee, who has some training in rainforest ecology) is one process by which rainforests manage their species numbers. Some species of trees, such as the yagrumo, which feature large, mitten-shaped leaves, serve as pioneer species, which quickly grow and establish themselves in an area where the forest canopy has broken or the local soil content is unfavorable to other species. These trees live for a short amount of time (~40 years for the yagrumo!), and then are followed by more permanent trees in a process known as secondary succession. In the tabonuco forest, these are the tabonuco trees. Pioneer species tend to be hardy, fix nutrients into the soil, and provide more nutrients once they die and are decomposed.
As I hiked through the forest, I was also in awe of the natural energy balance involved with the rainforest. One particular process in this balance occurs with all plants: the conversion of sunlight into glucose and eventually ATP. Since the yagrumo trees grow very quickly in a short amount of time in poor nutrient-conditioned soils, I imagine that they are relatively efficient converters of light energy into chemical energy. Should we ever wish to harness photosynthesis as a controllable energy source, I believe we should look to the pioneer species and their biochemistry as a first step.