West of the Fields

A tropical ecologist reporting from the field. Musings on life and art, botfly extractions, tropical plant identification, beer, parrots, machetes. Etc.

Sunday, September 24, 2006

The Silver Bullet to the rescue

In the next few weeks, I’m attempting to finish one big chunk of my fieldwork for my thesis. I’m doing the last four (out of 30) vegetation inventory transects. The technique I use is called a Gentry transect, after its inventor, the eccentric and brilliant botanist Al Gentry. He knew the Amazonian flora better than anyone, and before his untimely death in 1996 (a plane crash in the coastal mountains of Ecuador) he pioneered methods for rapid vegetation surveys. A Gentry transect is 0.1 hectares of forest (about a quarter acre), in five narrow strips of 2x100 meters, each set 10 meters apart. Within each strip, you record the species that you find, and the size of each plant above your chosen diameter cutoff. You also take a sample to make a voucher specimen. The genius of a Gentry transect is that you don’t need to set up a plot—you just run a hundred meter tape measure out in the forest, and cut yourself a stick one meter long to check whether things on either side of the tape fall inside or outside the area . Anybody who’s spent time setting up plots in forests of any sort can immediately see the advantage. Instead of wasting your field time making sure your corners are square (which they never are, in this hilly terrain), you can just set out a tape along a compass line and start working. Hence the “rapid” in rapid vegetation surveys. With my field assistant Marisol, I’ve been able to get transects done very rapidly indeed. It used to take me 2-3 days to finish, and now we can consistently do it in one day. It’s a long, long day, though.

Last Tuesday I took a trip around the back-country of Tirimbina, on marginal 4-wheel-drive roads, with a man named Edwin Pereira. He works at CATIE, a Costa Rican institute for forestry and conservation research. He and his collaborators Diego Delgado and Bryan Finnegan had offered to let me work in their plots—young secondary forest sites where all the trees above 10 cm diameter are labeled and identified to species—and I jumped at the chance. Not only do they know the land use history of these sites really well, they also have the trees identified. In nearly every transect, I find some tree so large, so tangled in vines, or with its leaves so high up that it’s nearly impossible to identify. It always bugs me to have to put INDET in my data book. So to work in a site where the all the trees are marked and identified is a huge help.

Edwin took me to five sites, all of them ideal for the sort of work I want to do. The last place we visited was a patch of young forest right beside the Tirimbina-Magsasay road.

“How can I recognize the place?” I asked Edwin as we bumped and careened down the rutted red mud and gravel. Other sites had certain landmarks: the rusted-out tractor, the pejibaye grove, the two-log bridge with most of its cross-slats washed away that I’ve always called “the sketchy bridge.”

“El Hueco,” he replied.

I’d pored over the maps of Tirimbina and Magsasay in preparation for the trip, but I couldn’t remember seeing any town or intersection labeled “El Hueco.” But when we came around the turn in the road and saw it, there was no doubt in my mind. “El Hueco” (which my mind belatedly translated: The Pothole) was an expanse of churned-up red mud perhaps five meters wide and equally long, subsuming the road.

“Hace dos semanas, un chapulín se metió alla,” he said, pointing to one quivering side of the mudflat. “Es muy profundo.” Two weeks ago, a chapulín buried itself there. It’s very deep. Chapulín is one of those Costa Rican words with a delightful smorgasbord of meanings: grasshopper, punk kid, tractor. Judging by the shape and size of El Hueco, I guessed it was probably the lattermost.

On the weekends I have access to the car that my advisor’s field assistants use during the week. It’s a little gray Suzuki Samurai, tiny and none too quick, that my friend Marcía dubbed “The Silver Bullet.” For ordinary highway driving, it’s kind of a pain; so low-geared that I shift on the KPH dial just about where I’d shift an ordinary car in MPH. But once you get off the blacktop, lock the wheel hubs, and set it in 4L, the Silver Bullet is worth its weight in gold.

Yesterday being Saturday, Marisol and I returned to the patch of forest beside El Hueco. It’s a young, dense, viny stand of forest, full of the usual biting, stinging, and stabbing things that abound in such a place. We came very close to stepping on a pit viper as we negotiated one tangle of vines. Around mid-day, we heard the sound of splashing, spinning wheels and a few shouts from the direction of El Hueco.

“Somebody actually tried to cross that thing! Do you think we should check it out?” I asked. Marisol was obviously as ready for a break as I was, because she set down the Hefty bag of plant samples without another word and started for the plot entrance.

At the road, we found a pickup truck sunk past its hubcaps in the hole left by the chapulín. Three generations stood around the edge of the mud pit: grandfather, mother and father, and two small girls, the youngest with an adorable missing-tooth grin. The truck had made it surprisingly far into El Hueco before it foundered.

“Puedo ayudar?” I asked. It seemed kind of hopeless: the truck was sunk so far that its engine was probably taking on water. It was probably several times more massive than the Silver Bullet (parked high and dry on the Tirimbina side of El Hueco, the direction where the family was headed). But I didn’t want to leave them there.

The grandfather grinned, revealing fewer teeth than his grandchild. “Doble tracción?” Four wheel drive?

“En este camino? Claro que si.” On this road? Of course.

He nodded. “Vamos.”

I backed up to the very edge of El Hueco. We connected the vehicles with a complex jury-rig of webbing straps, chain, and nylon rope. When the hook on their chain proved too large for the hitch coupling on the back of the Silver Bullet, we improvised a connection with some pieces of scrap metal they found in the back of the truck. The car radio was blaring reggaetón, lo que pasó, pasó... and I vaguely wondered what would happen if the truck was too much for the Silver Bullet and both vehicles ended up in the mud.

I was briefly reminded of a trip last year to Volcan Barva, where the roads are even worse. At one point (I wasn’t driving, thankfully), the truck floundered with one rear wheel hanging over a giant rut. Four of us balanced on the hood on the diagonally opposite corner, bringing just enough weight down to give it traction. Throughout this whole episode, the radio was playing Eternal Flame. Few moments in Latin America are without a soundtrack.

I checked the improvised tow straps one last time and got in the driver’s seat. Here goes nothing. I eased the Silver Bullet forward (dale mambo, dale mambo... lo que pasó, pasó...) The tires held on the dry road, and the straps held together, and, mirabile dictu, the truck rolled right up out of the mud behind me. The engine wasn’t even straining. The children cheered. Never again will a snide word about the Silver Bullet pass my lips.

It was nearly dark by the time Marisol and I finished the transect, and well past dark by the time I finally dragged my stinking self into the dining hall at La Selva, just in time to catch dinner. Twenty-six down, four to go.


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