Archive for August 26th, 2010

I wake up early to go bird watching. Surprisingly, Ricardo does not, so I go by myself. Unfortunately, this makes it much more difficult to identify birds. Well, this will be a trial by fire. I do see a few birds I know, like the Scarlet-rumped Tanagers, Tropical Kingbirds and a Blue-gray Tanager. My one new bird is a Black-shouldered Seedeater.

Tropical Kingbird

After breakfast, we work on our projects. We put in a few water bars on the trail. The water bars divert the flow of the water off the side of the trail and reduces the speed of the flowing water. The amount of erosion taking place is a function of water volume and speed. We cannot control volume, but with water bars, we can control speed to some extent. The bars must be at a certain angle so that they can be self-cleaning and not accumulate leaves and branches. There is no set formula for this in the tropics, however, and more often than not, we must work around trees and roots to install the water bars. We also move from 300-500 meters, clearing alternate routes, adding water boards, and new switch back trails. The last section of trail by the bean field is somewhat foreboding. The only solution is to bypass the section using switchbacks on a bit of ridge through the tick primary forest. Then we have to reconnect with the bean field trail. While scouting out a trail, I see signs of charcoal. This is odd because there was no terra preta done here and no fires in recent times. Also, I am treated to seeing a red and blue poison dart frog with a tadpole on her back deposit her offspring in a hollow of a tree filled with water. I follow her for about ten minutes as she hops around in the undergrowth, carrying her precious cargo. All the while, I am being eaten alive by the mosquitoes. This is the first time that I notice their size and ferocity. Their tenacity may be caused by their increased numbers following the rains we have been having. They seem to draw a pint of blood before my hand can reach them. I also spot a bird in the underbrush, but despite my crashing through the undergrowth, I am not rewarded with a better view. At least no snake bit me as I rushed in chase.

Red and blue poison dart frog with tadpole

Back at TFI, we eat lunch. After this, we try lighting a fire in a pit to produce charcoal for terra preta. Where Ricardo and Jeff failed, Martin and I succeeded. After inhaling smoke for about fifteen minutes, we light a nice fire. My lungs burn from being inundated by the thick fumes. I find it hard to breath as I am slowly smothered. Fortunately, the fire roars to life and I can get out to see the flames crackling and dancing between the logs.

Starting the fire for Terra Preta

Covering the pit to make charcoal

Terra preta, or biochar, was used by Native Americans in the Amazon region to add to the fertility of the soil. Despite the productivity of the rainforests, soil is very poor. Hydrolysis produces clays here, particularly aluminum and iron suscoxide, which have an expanding lattice structure. This allows them to absorb and hold nutrients and water. However, as they weather through hydration, the clays become amorphous. The lattice breaks down and the clay’s ability to hold nutrients and water is lessened. The only way anything grows here is due to tight and rapid nutrient cycling which can be bolstered with nitrogen fixing legumes and added nutrients from silt. The main limiting factor here is phosphorous, which the mycorrhizae provide to the plants in exchange for sugars. After the clays break down, their cationic exchange capacity, the ability to hold positively charged nutrients like phosphorous, is lessened. They then loose the nutrients, which are leeched out of the soil with rainfall. Indigenous people used charcoal to increase fertility of the soil. Charcoal binds to the nutrients and holds it there for a long time. Add this to slash and burn agriculture at a reasonable scale and a long enough fallow time and the large quantities of organic matter (usually lacking due to rapid decomposition) and extra nutrients and the soil becomes much more fertile.

Once the fire is burning, we add a layer of banana leaves and cover the pit with dirt to make the process anaerobic so wood does not completely burn.

Before dinner, we have a further lecture on biodiversity. Afterward, I work on drawing a mural in the common room. I draw some of the creatures which can be found here, including a red and blue poison dart frog, Common Potoo, trogon, heliconia, Violet Sabrewing, and a Chestnut-mandibled Toucan.

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