As reconstructed by Christopher Potter, scientist investigating the secrets of the rainforest
(This is not an actual day, but a composite view of what could be a typical research day for a team of researchers)
The Sun seems to rise quickly at 6 a.m. sharp as I view the canopy of trees from my large cotton hammock. It is attached to the side of a field cabin capped with a tin roof. Under my light blanket and the mosquito net I use to deter the occasional insect, I wake up to slightly cool air. Quickly, the warmth of the tropical Sun will erase this coolness.
Near the equator in the Amazon rainforest of Brazil the Sun always rises during the same quarter hour year round and sets twelve hours later. The days are not that long when you have to gather scientific information, especially when you consider that it can rain for hours at a time. Among the many goals of our research team, we are working together to find out how much carbon is being captured or lost by the wide variety of lush vegetation here.
The air is moist and smells pungent with the slight odor of flowers and undefined scents of rainforest vegetation. Because the sunshine quickly penetrates openings in the natural canopy of leaves above our field station, the light is clear, and the colors are brilliant and saturated.
I swing out of the hammock in my gym shorts and a tee shirt, and I start to dress. I will wear a light, long-sleeved cotton shirt. The day will soon be hot, and I need to protect my arms from the sun, thorns and prickly vegetation.
I also put on my lightweight khaki pants. I usually wear tennis shoes, but sometimes, I’ll wear my light hiking boots if I might have to trudge through muddy terrain. Also, essential for me in this climate are sunglasses, a wide-brimmed cotton hat and insect repellant that I apply mainly around my ankles. There are millions of almost microscopic chiggers that would drive me crazy, if I didn’t take proper precautions. I’d spend days scratching without the repellant that we can buy from the local pharmacy.
Next, I reach under my hammock and grab my daypack from the cabin’s wooden porch floor. I carry a first-aid kit in the waterproof pack, as well as my laptop computer, a helmet and a safety harness for climbing into the trees and down into pits where we have scientific instruments. The helmet looks like a bicycle helmet. When I say we, I refer to several colleagues with whom I work in study of the rainforest.
It takes a lot of teamwork to accomplish our mission. Scientists, technicians and others from both Brazil and the United States must work closely together. We share all our ideas, tools and data collected from experiments. Just as importantly, we watch out for each other's safety in this rather dangerous place to work.
We’re not camping here. We have full facilities – including indoor plumbing. A local cook makes the delicious meals. For breakfast we usually have fresh, tropical fruit – and eggs anyway we want them. The fruit comes from the local rainforest. I recognize some of the fruit I eat such as guaraná, and açaí. Occasionally, I sample a fruit I have not eaten before. The drink is usually coffee for which Brazilians are famous.
By 6:30 a.m. we are ready to get into a four-wheel drive pickup truck to travel a few miles to the tower research site in the forest. Some of the greatest challenges in this work are going to the field location and getting out again with all of our belongs intact. Also, keeping the sensitive equipment running properly in this climate is a major effort. The overall excitement of our work also must include such essential, but routine tasks as maintenance and other such tasks.
We drive along bumpy, winding red-clay roads just wide enough for two vehicles to pass by each other. There are mud puddles that stretch across the road. They are the result of yesterday’s rain. There is torrential rain nearly every day. A dark cloud can pop up at any time. The vehicle is on the verge of getting stuck in the mud on practically every trip. We never actually were stuck in the mire, but some of the puddles are deep enough to ruin an engine.
After about a 20-minutes drive, we park in what had been a logging ‘deck.’ Private companies formerly used this area to stack logs cut from the forest, and that’s why locals call it a deck even though it now looks like a fairly innocent clearing in the forest.
A half-mile hike on a narrow, muddy trail through the trees takes us to the tower research site. On the way we hear what seems like thousands of birds making the loudest, wildest cries you can imagine. Someone in our group heard a rumor that a jaguar resides in the area, and perhaps the birds are sounding an alarm. Because of the densely leaved canopy, we rarely get clears views of birds. We are particularly on the outlook for Macaws. These birds are very beautiful and endangered. They can be brilliant scarlet, or blue and yellow.
Sometimes as I walk through this incredible forest, I think back in time for a moment, and I remember when I was younger, in high school. That was when I first imagined I might want to become a scientist because I enjoyed biology most among all of my subjects. It is every biologist’s dream to study the Amazon rainforest with its endless variety of life. Now, I’m living in that vision I first had so many years ago.
One of the nicest times of our day in the rainforest is when we are walking to work. We can enjoy the rainforest, not having to concentrate on gathering data. However, it is already 80 degrees, and the humidity is rising rapidly because the intense energy of the Sun is rapidly evaporating the water from the frequent rains.
The walk is easy. The land is flat, and the dirt is iron-rust red. This soil is generally hard-packed except where we encounter small streams that cross the path. We see centipedes the size of your index finger and ants as big as your thumbnail. These insects don’t bother us because they busy in their own world, and are moving as fast as a crowd of shoppers in a big city.
Once in a while I glance to the side of the pathway and see large termite mounds. They are red because they are made of the iron-rich soil. Some are waist high. A colleague has reminded us that the termites are important because they enrich the soil with nutrients. The rainfall washes away many of the important life-supporting chemicals in the soil. If it were not for the industrious termites, the soil nutrients would not be recycled efficiently from decaying plant matter within ecosystem.
We now reach the boundary of our study plot, marked by fluorescent, yellow tape, similar to tape that construction crews use. The area of the plot is the size of two football fields side by side. One of our major intentions is to minimize disturbing the forest, and, so, you just see the tape and the bases of two, large wooden towers that we use in our work.
These tall towers have been built using common lumberyard materials. Each structure is about five feet square at its base and about 150 feet high. Because they are anchored with guy wires, these structures are remarkably stable. We climb the ladders inside the tower frame to research platforms built about every 30 feet. The design is the product of local engineers. Skilled technicians did most of the difficult construction work. We have installed sensors and detectors every 50 feet up the structure to monitor the physiology of the rain forest. The physiology of the trees includes the study of the rate of photosynthesis and water uptake.
In addition to the towers, researchers also built platforms about a third of the way up the canopy throughout the study area. Catwalks connect the platforms and help us to reach many kinds of trees for study. There are hundreds of tree species there. Most are evergreens, but not ‘needle-leaf’ trees like pines you might envision. Rather, the trees in the study plot are broadleaf species that maintain leaves year round.
It’s now 7:30 a.m., and we begin our ascent of one of the towers. I carry just my pack. Our field study leader and Brazilian scientist, Joaõ, leads the way.
“I’ll take the carbon dioxide sensor,” Joaõ mentions. Then he picks up the sensor, a box-like device that is less than a foot long on its biggest dimension and weighs a few pounds. The climb to the tower top should take us only five minutes, but we stop about halfway up to listen to the sounds of birds and monkeys. Monkeys screech and howl. Like the birds, the monkeys keep their distance, and we rarely see one.
In many of the crotches of nearby tree limbs and trunks there are plants called ‘epiphytes.’ These are Bromeliads, and they are parasitic organisms, but still they do have green leaves. Although these strange plants have aerial roots, the epiphytes around here collect most of the water they need in their vase-shaped leaf ‘bodies.’ These natural urns each may hold as much as a couple of cups of rainwater.
As we move up, we collect leaf samples. We will return these to a research laboratory in the city of Belém, about an hour east by jet. We will analyze the samples for chlorophyll and protein levels in different kinds of leaves. These chemicals control the growth and subsequent decomposition of the foliage.
Belém is near the mouth of the Amazon River on the Atlantic Ocean. Our base camp is located far west of the city, but is only about a one-hour drive on a two-lane highway from the banks of the huge, lazy Amazon that carries more water to the ocean than the Mississippi, the Nile and Yangtze rivers combined.
Until we climb to the top of the canopy, the light remains as dim as twilight. When we emerge from the top of the trees, intense sunlight momentarily blinds us. After a few moments, our eyes adjust to the brilliant light. The view is spectacular. We see what appears to be an ocean of green. It looks like as dense as a super-big head of broccoli with a few giant trees sticking up. We can see large birds flying around. Macaws and other parrots are some of the most interesting ones. These are brilliantly colored, very big parrots. They have long tails shaped like sabers. Macaws also have curved, strong bills.
Now that we are at the top of the canopy, we can measure the fastest growing leaves and tree parts at the level where the canopy ‘harvests,’ or absorbs, more than half of the sunlight’s energy that strikes the forest. First, I remove my computer from my pack and hook the laptop machine to a ‘data logger.’ It looks like household electrical circuit-breaker box, but the logger has a computer chip that continuously records light levels, humidity levels and air and leaf temperature changes. The logger has a probe that is attached to a leaf. A sensor in the probe collects data that goes to the logger. It has been recording data every 15 minutes for three weeks.
Some people use radio transmitters (telemetry) to send this kind of record data automatically to instruments on the ground. But because we need to get other on-site information as well, it’s easier to for us to gather all the data at one time.
Next, Joaõ switches on the carbon dioxide detector. Carbon dioxide is a gas that is only three parts per 10,000 in the atmosphere (0.03 percent). This gas is the main ‘food’ of green plants. The almost magic process of photosynthesis combines sunlight, water and carbon dioxide to make sugar. Photosynthesis is the engine that drives life at the Earth’s surface.
We will make carbon dioxide measurements over the course of the next couple of hours. The detector has a small, metal chamber in the form of a clamp that fits around a leaf. We keep each leaf sample clamped for about 15 minutes while the device analyzes the leaf for carbon dioxide absorbed and water that evaporates as we wait. We don’t leave the carbon dioxide detector unattended for days at a time as we do with the logger. Besides, you can’t keep the clamp on a leaf for a long time because it would die.
Before we descend, we take more leaf samples. We take a whole leaf for each sample, although we know by experience what each kind of tree is.
Just before climbing down, I look west, and on the horizon I see a large plume of grayish smoke that appears to be as big as my fist from this vantage point.
Our stomachs are growling. It’s now time for lunch.
When we get down a colleague says, “Do you smell the smoke?”
“Yes, definitely, we say.” This smoke comes from slashing and burning that farmers commonly use to clear forestland at the peak of the burning season – usually September in this part of the Amazon.
On some days, the smoke can be thick enough to obscure the Sun, making the light as dim as it appears during a total eclipse. A smoky condition can last for days, and it affects your breathing, making it hard to suck enough oxygen into your lungs. We don’t know how much this smoke may affect plant growth, but some researchers say
that the trees that are cut and burned may very well contribute to global climate change because the smoke contains a potent mixture of ‘greenhouse’ gases that can trap heat near Earth’s surface. The scientific community is still waiting for strong proof regarding the effects of burning on possible climate change.
We hike back to the logging deck area where we parked and to the kitchen shack there. The research team consisting of local and international scientists – men and women – assembles for lunch. We get our food, and we sit at a long picnic table. We feast while listening to local stories and speculation about the Brazilian soccer team strategies in international competition.
Lunch is grilled meat – beef or chicken – rice and black beans washed down with lots of bottled water. This is our usual lunch. We eat well. The food is very filling.
We could use a nap, but a sudden rainstorm interrupts any plans. Big raindrops are warm as they strike my face when I glance up at the sky. We hear thunder and run for cover in the pickup. I look through window, and I see big, black cumulus thunder clouds. I see long, thin trails of lightning etching the sky in white, jagged lines. This storm lasts the better part of an hour. We talk and then doze. Just as suddenly as it came, the storm ends. Sunshine quickly pops into the clearing, like an electric light that someone switched on.
The trail back to the plot is very wet, inundated in certain places. Our first stop in the afternoon is a very deep soil pit that has been covered with a tarp to protect animals and people from falling in. This pit is more than 30 feet deep, six feet long and a yard wide at the surface. Local technicians dug the pit by hand last year. They spent several weeks of hard labor digging the hole and installing sturdy wooden scaffolding to the bottom of the pit.
Again, we put on our climbing gear -- our safety harnesses and helmets. We begin to climb down. As we descend we collect samples of water from the soil. We get this water from small tubes that we inserted into the soil cross-section every few yards down when the pit was first dug. The tubes are a little bigger than the diameter of a common soda straw, and they go a couple of feet horizontally into the dirt. At a point farthest into the soil each tube connects to a porous cup that collects the water.
We put each sample a into separate glass flask to transport the samples to our local laboratory for preparation and later analysis in the Belém laboratory. We hope to better understand how the trees and other forest plants ‘harvest’ – or absorb – nutrients from the soil, especially nitrogen, phosphorus and potassium. These also are in commercial fertilizers. Nutrients escape from the soil of the rainforest, traveling in runoff water that quickly finds its way into streams.
It’s now about 3 p.m. of our typical research day and almost time to leave. We have one more task to accomplish, though. Just off the trail that goes back to our vehicle is a stream sampling site. This is a place where the stream narrows, and we can easily access it to take a sample of rapidly moving water.
In narrow places the water runs faster, and in smaller cross-sections of streams we get a better mix of the total chemicals that are leaving the forest. These chemicals eventually will spill into the Amazon River and flow into the Atlantic Ocean, hundreds of miles distant. We use another flask to grab the stream water sample, seal and label it.
Everyone looks tired, but satisfied as we step into the pickup truck passenger compartment. I drive back to the field station. Our trip is not like rush hour in California, but nevertheless, I must still pay close attention to the road, looking for hazards such as fallen tree limbs and the frequent mud puddles. It’s now close to 4 p.m., and the Sun is dropping below the top of the rainforest’s canopy. Twilight-like illumination appears instantly. I switch on the vehicle’s headlights. Shortly, I see the unpainted wooden structures of our station about 100 yards away. The slight smell of dinner cooking makes my mouth water.
We park near the field laboratory building. It is a split plank two-room cabin about 20 by 30 feet. We unload all our samples of leaves and water as well as the equipment including the laptop computer with its store of today’s data. We put all our samples in a wooden crate, and carry it inside.
We still have work to do. First, we put the leaves in labeled paper bags. Then we put them into a special drying oven for a 24-hour stay. As for the water samples, we need to filter it them. We pour the water samples through disposable an analytical paper filters that look much like coffee filters. This filtering removes dirt and other debris, but leaves the dissolved chemicals in the water samples. Finally, we pour the filtered samples into test tubes that we place in the laboratory’s refrigerator. The work in the field laboratory cabin took us about an hour and a half. Every so often, when we have a good quantity of leaf and water samples, one of us will put them into a cooler and travel to the Belém laboratory with them.
Before quitting for the day, we look at the data that we captured in the laptop computer. The charts, graphs and numbers look acceptable except for bad data from a malfunctioning humidity sensor. We make note of this so we will remember to make repairs on the instrument tomorrow when we return to the tower site.
We leave the lab – there are several more of us by now – and I lock it. We stroll to the porch that overlooks a tributary of the Amazon. This river is a great spot to watch the sunset. The water is dark and rich in nutrients. Across the river there is an open area near a docking place for canoes and other watercraft. And looking in that direction we can see the orange and red colors of a magnificent tropical sunset.
After a half hour of talk about the day’s accomplishments, we notice that our surroundings are pitch black. We were hungry before, and now we are even hungrier. We walk to the mess hall-like cabin. After we select the food we want and place it on big metal platters, we sit family-style at long wooden tables. Usually, we have grilled beefsteak or other meat, roasted vegetables and a salad.
We enjoy the meal and then wash up a bit. I hear the music start. It comes from a CD player, and the sound is typical Brazilian music that originated here in the Amazon. This music is fast, with lots of guitar sounds and women singers. Brazilians like to dance, and they like to teach us their favorite steps. The dance is a combination of traditional and more modern movements. I am not sure what we would call it in the United States, but it is fun. We dance about an hour.
Finally, we check out the soccer scores on TV before I go to bed in the hammock. The diesel generator switches off for the night, and all we can hear is the sound of crickets in the dark forest.