As we dived off of the main highway and onto a deeply channeled clay track cut narrowly through the glistening and vibrantly green mess of foliage so peculiar to tropical rainforests I felt immediately relieved of my fatigue. I enjoyed the site of familiar faces—the Melastomataceae family with its conspicuously ladder-like secondary venation, as diverse and dominant as ever on roadside edges; the creeping Dilleniaceae with its dark, sandpaper leaves; the ringed trunks of Cecropia with leaves shaped like giant human hands more than two feet across.
Cecropia leaf: conspicuous early colonizer of high-sun areas
Josema, our lively chauffer who dubbed himself appropriately with two of the five English words he knew, “Professional Driver”, nimbly negotiated some 25 km of a road some would consider unwalkable!
A treefall bars the way on the entrance road to BDFF. Experienced hands with a couple of machetes make quick work of it!
Cook and “mateiro” (forest guide) Antonio and I spent the next two nights at the Colosso field station—simply a few tin roofs with tarp walls and a simple kitchen, and ample places for hanging hammocks. This is one of several sites belonging to the Biodiversity Dynamics of Forest Fragments Project (BDFFP), which for about twenty years has been monitoring the evolution of plant communities in different-sized fragments, regenerating pastures with different histories of land clearings, animal dispersal across gaps and different forest regeneration stages, and anything else that could be conjured up under the project’s title. The prominent forest edge I had been envisioning for my study did actually not exist anymore at these sites as the pastures have now been regenerating for 15 years. However, we identified a nice edge along a road within regenerating pasture, which would perhaps be an even more appropriate representation of a plant community evolved in a high-heat environment. The ‘original’ shaded primary forest understory community for comparison to the edge would be the central hectare of a ~9-ha square fragment.
Colosso field station... that's pretty much it! The instruments wait out the rain under the tin roof.
These three days were a perfect example of the clash between high hopes and the reality of the field! The first step was to make measurements of photosynthesis on ‘shade’ (forest interior) and ‘sun’ (regenerating pasture) plants to make sure they could both handle the standard light level I wanted to throw at them for measuring VOC emissions (plants can shut down photosynthesis if exposed to much higher light than they are accustomed). While waiting for CO2 cartridges to arrive by boat from Santarem, I planned to simply use ambiental air for measurements. With a leaf clamped in a chamber with light shining on it, the LiCor 6400 compares CO2 coming into the chamber to CO2 going out and thereby calculates photosynthetic uptake of carbon. (More details on photosynthesis and instrument function in later blog entry devoted to this subject.) It turns out that ambiental CO2 concentrations, particularly near the ground, are way too erratic for these measurements! After several cumbersome iterations of method alteration to overcome this problem, I finally figured out that if I just fill a trash bag with ambient air and tie it around the machine’s air intake I get nice, stable CO2 concentrations due to the evenly mixed air! On the last day, after being rained-out for half of day 2, we set out to complete our measurements with this excellent method and the last pair of batteries imminently died (note to self, why not bring the charger?). We made good use of our time by identifying every plant species in the regenerating pasture.
Chamber head of LiCor-6400 clamped to leaf for photosynthesis measurements.
Flower from the Melastomataceae family, I love these flowers!
A hawk spreads its wings to be cleansed by the afternoon rain.
Antonio reviewing one of our plant guides in the ‘dining room’.
An evening walk finds an excellent Cane Toad enjoying a puddle! Those large sacks behind its head exude poison from the open pores, explaining its completely unconcerned demeanor.
