Danger in the jungle

The rainforest around Rio Maria is not pristine. The area was logged 50 years or more ago. Large birds that once flew above the trees, such as the Scarlet Macaw, are gone, most likely captured by locals. No howler or spider monkeys are left in this jungle, and the collared peccary (javelina) is not found as it once was. These mammals were probably taken for food or the pet trade by people. This region is not protected and is too close to human habitation for most large animals to survive collection or hunting. Still, the small plants and animals are very diverse and the jungle here has much to offer to biophilic (biology loving) visitors.

The ability of the jungle to rebound from logging is a direct consequence of the millennia that these trees and associated plants have interacted with humans. Panama has been inhabited for at least 11,000 years. The indigenous people have a sophisticated culture, that among other things, developed unique and ornate styles of pottery. In this region, called Coclé, the indigenous culture required rotating agriculture which would have been slash and burn. The jungle in the flat parts around Rio Maria has very likely, over thousands of years, been repeatedly been cut (slashed), burned, cropped and after a few years left to return to jungle to recover its fertility.

While the jungle around Rio Maria was missing some components of an extensive, old-growth, tropical rain forest, it still had incredible diversity and beauty. Only in recent history have humans developed the machines and population densities to completely remove jungle from tremendously large areas. There is little hope the diversity will return to the areas of massive deforestation as it does to the small patches that are cleared for a few years by native agriculturists under slash and burn cultivation. We know that very plant and animal diversity could coexist with the traditional native practices, but those days are now gone.

Working in the forest requires caution. Those who work in the jungle say that falling trees and limbs are the greatest danger. If you are unlucky, one will fall and hit you in the head. If you spend much time in the jungle you will hear limbs falling, and the trees in even this re-grown rain forest can be a couple of hundred feet high, so the branches can gain considerable momentum before they strike an unlucky researcher below. Each tree limb plays host to numerous epiphytes. These epiphytes include the orchids and a number of what we commonly see as houseplants in homes in developed countries of temperate climates (for example ferns, spider plants). These plants take advantage of the limbs of the trees to grow higher in the canopy where they can get far more light than they could on the forest floor. The mass of plants on each branch grows to a greater and greater mass. Eventually the weight is too much for some branches to bear and they come crashing down.

The large trees tend to have shallow root systems that are spread across the jungle floor to intercept nutrients that reach the soil there. Tropical jungles generally have very poor soil and organic materials containing nutrients are rapidly degraded and the nutrients they contain scavenged quickly. This is part of the reason for slash and burn agriculture; the vegetation that is cut down and burned provides nutrients for a few years, but the soil is not productive so the fields are abandoned after a few years. Unfortunately, if cropping continues the soil becomes so
unproductive that not even the jungle can return.

The shallow roots are not good at holding up the trees, and this is made up for by the buttresses (broad supportive ribs) that extend away from the base of the trunks. Even with the buttresses, a large tree will fall occasionally. Because it is connected to others by dense vines, not only will it smash the trees directly where it falls, but also the falling trunk will take many smaller trees down with it.

Tarzan movies are not very realistic, but there really are vines that could support a large primate that crisscross the jungle canopy. We tested this as college students in the jungle finding vines on hills that would allow us to swing high into the air.

When a large tree falls and takes others down with it, the light gap that enters the forest will allow new rapidly growing trees to grow up into the canopy. This process is part of what leads to the tremendous tree diversity in the tropics; the light gaps promote species that would not be able to compete in the dense closed canopy of the jungle.

A newly fallen tree also attracts local people scouring the forest for exotic orchids that might have been growing high in the canopy before the tree fell. These plants can bring a hefty price. The orchids are for sale in the local markets and collectors around the world support a legal and illegal orchid trade.

There are other dangers; toxins are common. Some palm trees commonly found near the ground on of the jungle have large poisonous spikes that will cause a nasty allergic response in the impaled hand unlucky enough to grab a trunk to avoid a fall. Large garishly colored caterpillars have poisonous spines. While these caterpillars are not aggressive, inadvertently brushing against one is not advised.

Paraponera ants that crawl on tree trunks are also called bullet ants because a bite from this inch-long ant feels like a bullet and causes pain for 24 hours. Their large mandibles cause what is said to be the most painful insect sting of all; the pain results from a potent neurotoxin. Initiation rights of some indigenous South American people entail repeated bites from these ants. It is difficult to imagine being stung 20 times without screaming, but this is what is reportedly what it takes to be a man in some cultures.

Poisonous snakes are also a concern, but are less common at higher elevations. It is possible that the bushmaster, Lachesis sp., the largest (up to 14 feet long) of the pit vipers, could be encountered up to 4000 feet elevation. The Fer-de-Lance, Bothrops asper, can be found on the ground or juveniles can be found in trees. Tree vipers also known as eyelash vipers, (two species at high elevations), hang from trees. Hog nosed vipers, tropical rattle snakes, and coral snakes all can be found in Panama. All these species are poisonous and bites from some can be fatal. It is always best to watch where you are stepping and move with care when walking in the jungle. This is not sandal country (but the next day we would see the exception) and boots, not flip flops, are advised. The dry season we were in, is also the time when the bushmasters are most likely to bask near Rio Maria, so we were particularly careful to watch for these vipers.

Of course, insect-borne diseases are also a concern, as they are in much of the tropics. Diseases found in Panama include malaria, chagas disease, dengue fever, yellow fever, and leishmaniesis. We killed an Assassin Bug in our hotel room, known to be a vector of chagas disease that can be fatal if left untreated. The usual precautions against insect bites and appropriate vaccinations at least decrease the worry. If you see an Assassin Bug in your room in Central America, kill it. These issues are not enough to keep many scientists and ecotourists away. The fabulous diversity and unique area are so attractive, and appropriate precautions minimize the chances of danger .

The First Experience with the Jungle Stream

After each of us had walked up and down the stream, the lead researchers met up and settled on the experimental reach. This was a 300-yard long stretch of stream surrounded by jungle with no major side channels and a variety of pools and shallow areas (riffles) characteristic of the stream. Most streams naturally sort themselves into a series of pools and riffles through the natural processes of erosion. These processes also lead to the typical meanders or “S” shaped bends that characterize flowing waters.

We picked out sampling sites from the top down, each one a bit farther apart from the next, so we could sample correctly. Once the experimental area was set, we worked with Edgardo and the other Panamanian helpers and found the best way to get from each sampling site along the stream to the next. They then used their machetes (a standard item of hiking and work equipment for most rural Panamanians) to clear a rough path. We marked each of the sampling sites along the stream with fluorescent tape, and set up our equipment for the initial measurements.

The trail had its hazards. We could not step in the stream while the experiment was going on, so needed to have minimal crossings and placed logs and rocks to get across where we did need to go. The trail wound its way through a bit of sparse jungle, but the animal trials made false leads and it was easy to wander off the wrong part and we had to pay careful attention. I hoped we would not be caught on the trail after dark. After the sparse jungle the trail went across a marsh, which we filled with logs, but they kept sinking as we would walk across them and the crossing was precarious at best. Right on the edge was a palm tree, and it was natural to grab the tree if you slipped into the mud off the logs. Unfortunately the tree had huge spines and the spines had an irritating substance on them. More than one of us grabbed the tree by mistake and was impaled. It is the kind of mistake you only make once; unfortunately I made that mistake several times.

The trail went next to the stream in parts and up and down steep-slippery sections, and included some logs. At the top of the trial was a large rock bar where we were setting up our system to add the chemicals to the stream. Just above this part there was a branch in the stream and the jungle was a bit more open, so large shafts of sunlight played through the branches onto the stream. This was a beautiful spot where we could see a slope too steep to climb rising between the two stream branches and huge trees towering hundreds of feet above our heads up the slope. Boulders the size of shuttle busses had fallen off the sides of the steep slope and lodged in the stream channel, and massive tree trunks had recently fallen across the stream above taking out many others on their way down. Above our top location, the stream was a jumbled mass, and it was very difficult to get through to the stream above, but the effect was wonderful.

Since we were going to use an inert chemical tracer to follow how nitrogen moved into the animals in the stream, samples needed to be collected to establish a baseline, and also to establish our basic protocols of measurement. Our group split into smaller groups.

One group collected the leaves and algae in the stream that form the base food source for all the animals in the stream. These samples were collected from a known area so we could estimate the relative amount of each that were present in the stream. At previous streams where the frogs had gone extinct the algae had exploded, so we wanted to catch that with detailed measurement. Even in these shaded streams there was enough light to allow some algae to grow.

Other groups collected the tadpoles, insect larvae, crabs, fishes and shrimps that populate the stream. These collections required careful netting and counting of individuals. We needed to be absolutely certain to quantify the existing conditions, because we knew of the changes that were coming and there was no going back. All these collections also needed to be made with much caution to minimize the disturbance of the stream channel so as not to interfere with our measurements in the following days.

Simultaneously, Bob, Alex, Matt and I set about making additional basic preliminary measurements required to start the experiments. Measurements were made with chemical sensors (measuring oxygen gas dissolved in the stream water, temperature, and other important water quality parameters). We started electrodes that would record the chemical conditions and temperature in the stream for the entire duration of the experiment. We took chemical samples required to calculate how to start the experiment the next day.

We started other measurements to determine how the stream responded to pulses of nitrogen and how pulses of tracers we released at the top moved down the stream. The results from these releases allowed us to account for how quickly the water moved through the system, and how much water was flowing. We took background samples of water to measure nitrogen so we could calculate how much nitrogen tracer to add and for how long. All these water samples would be analyzed later that same evening. Bob had a very nice approach where we could add the chemicals streamside and the samples would incubate and be ready to analyze that evening. Length, width and depth of every few feet of stream over the 300 yards or more of the experimental reach needed to be recorded.

Some time was spent just sitting on the stream bank and waiting between measurements, occasionally writing down numbers in the field book. Field research can be a curious mix of rapid, hard, physical work, then intense calculation and concentration, interspersed with waiting and observing.

From El Valle to Rio Maria

Having gotten settled into the hotel with plans made, lists created, and some materials packed and organized, the group piled back into the vehicles and headed into town for dinner. The small restaurant we went to on the main street was also a hotel that catered to young tourists. It was open to the front and to the side overlooking a lush garden. The lone server eventually showed up at our table (it was not exactly clear what took her so long as there was nobody else in the restaurant, but that is Panamanian time) and we ordered some drinks and dinner.

Panamanian food is unique; Americans might assume it is spicy, like Mexican food, but mostly it is not. As with all Central American food, rice and black beans are common. However, fried green plantains (patacones) are often served as a starch instead. Other common starches included potatoes and tortillas. The tortillas are corn patties that are substantially thicker than those common in Mexico. They are fried in oil and are very flavorful. There are a variety of meat dishes and beef is common. Chicken is served in several more diverse dishes. One of my favorites was chicken with garlic (pollo al ajillo). While most Panamanian food is not spicy, this dish is loaded with garlic, about a head of garlic per plate. Those who want chili head in their food can use the habanero pepper sauce that is regularly on the table. The food in the restaurant, while simple, was delicious.

After dinner we returned to the hotel and started going through lists of experimental equipment required for the next day. It took an hour or so to get ready and go over plans with Piet asking questions. We needed to charge up the batteries for field gear and make sure we did not forget anything because the 1.5 hour drive back to the hotel from the field site would preclude getting all our field work done if we had to return for additional equipment. After a rum nightcap, we headed to bed with plans to wake at sunrise.

It was an early start with a quick breakfast of fruit and cereal. Coffee drinkers had theirs, and I had a warm diet coke that I had picked up from the grocery store the day before, yum. We finally loaded the gear into the four wheel drive trucks and hit the road. The trucks are really well set up for the research. They are diesel, and have quite powerful engines, extended cabs, and take a lickin’ and keep on tickin’.

There was actually a road going up along the crater walls through that looked like cliffs from the hotel. The dirt road to the research site wound its way up through the inside of the crater walls and eventually crossed the lip of the crater; the entire road was extremely steep and rough.
As we worked our way up the steep valley leading out of the volcano it became evident that a number of people lived in the valley. A few miles up the road there was a small store and a school. A small soccer field clung to the edge of the hill. A couple times a day, a small bus came along. Most of the small farms up the side of the hill used foot or pack animals to carry materials in and out to the edge of the road, some all the way down to El Valle. As we wound our way up the side of the volcano the jungle became more predominant and the farms farther apart.

Eventually we reached the steepest hill on our trip. At this point the trucks had to be shifted into low 4-wheel drive, and we needed to get a running start at the hill. The trucks are old-style 4-wheel drive and we got out and locked the front hubs before starting. Some of the more nervous (experienced?) passengers got out and started walking up the worst of the hill on foot. This road went straight up the side of the mountain and had deep ruts from winter rains and other 4-wheelers. The vehicles bounced up and down and rocks shot out behind as the wheels spun. One of the drivers did not start fast enough and had to back all the way down and start again. If driving up such a steep hill was difficult, you can imagine the danger of backing down.
We finally got to the top of the hill and wound our way over the rim of the volcanic crater. When gaps in the jungle allowed, we could see all the way down to the coast, and other hills and mountains in the distance. The view was spectacular. The jungle here is very thick and lush. It is a rain forest that catches moisture from the clouds that roll in from the ocean, and the trees are covered with moss, lichens, and epiphytes including orchids. This dense green vegetation occasionally opened up to frame views of a thousand foot high pinnacle created by old cinder cones (Picachao Mountain) on the edges of the volcano. Near the top there were several hundred feet of sheer vertical cliff face of rock, where the volcanic deposits that formed the ancient eroding cone were exposed, otherwise the jungle clung to the cliffs and hills. Flocks of parrots flew across in the distance. A small lake was nestled into the bottom of the pinnacle, this lake had formed when a secondary explosion opened a crater that subsequently filled with water.

After working our way a few miles down the outside flank of the volcano we started to catch glimpses of the valley for the Rio Maria, our research stream. The stream originates high in the steep outer walls of the ancient volcanic crater, as the rivulets combine it forms a large valley that winds its way down the mountain across the coastal plains to the ocean, 20 miles or so away. We parked our trucks near the edge of the bridge and we got out to look at the stream. The sound of calling frogs met us immediately. There were two golden frogs on the stream bank across from where we parked, and we started taking some pictures, but we needed to get our first experiments started so we did not spend too much time looking around.