You have been invited to a very special place on our planet, one of the few places where the influence of Homo sapiens is still far lessSouth America travel is not complete without a stop in the Amazon.- Explorama than the dynamic interactions among the millions of other species on the planet. You'll begin in Iquitos, the largest landlocked city in the world, and learn about its history.

The area around the lodges visited by participants in this course is one of the most diverse on Earth; one survey found over 300 species of trees in a single hectare (2.5 acres). Another survey, by an entomologist, found over 1500 species of insects in a single tree. The forest area has a renewal rate of about 80 years (but remember from Week 1, that can only occur if the area is not continually invaded by light.)

To get to the heart of Peru's rainforest, you'll take a plane to landlocked Iquitos. Founded in  1864 and named for the Iquitos tribe, it is the largest city in the world (~500,000) that is totally inaccessible by road. During the rubber boom, Iquitos had better communications with the world than Lima. By boat you'll go down the Amazon and up the Napo River. The ExplorNapo Lodge is located on a tributary, the Sucasari, about 180 km (100 m) from Iquitos. The trip will take about a half hour by bus, and from 3 to 4 hours on the river. Once at the lodge, you'll find the facilities both comfortable and uniquely suited to your surroundings.

At ExplorNapo, the lighting is provided by kerosene lamps and the air conditioning by nature. You'll sleep under mosquito netting, with the water-tight thatch roof of the lodge high above you and open to moths, bats and birds. No one needs an alarm, because the vibrant sounds of the jungle start early each morning. Surrounding the lodge is almost undisturbed rainforest. All access is by river; humans have never created farms or communities in the surrounding area. Look again at the Google Earth image and compare it to the map above.

Tread carefully.You are a valued visitor--but only a guest--in this place.


The Canopy Walkway

It took over two years for Paul Donahue, Teresa Wood and a staff of local workmen to build the canopy walkway. Fourteen platforms were created around trees. (They were accidentally shipped from Malasia to Quito!) Because the soil is so thin, the trees had to be supported by special guide wires to hold the weight of the walkways. The highest walkway is 35 meters (115 feet) above the ground, and the fourteen spans cover about 500 meters. It's primary use is for research, and it's maintained by the Peruvian Foundation CONAPAC.

As you climb the walkway, it's easy to see the strata of the rainforest--from the understory through the canopy, to the giant trees of the cloud forest that emerge from the top of the canopy. Remember the lessons of Weeks 1 and 2; there is a dramatic difference in the light as you climb, from only a few percent at the bottom to brilliant tropical sunlight at the top.

Look carefully, as well, at how plants compete for that light. As you climb the walkway you'll see bromeliads and other epiphytes perching on trees, while lianas stretch from the ground to the canopy catching light as they pump water up for other organisms.

Stop for a few minutes and observe the number of organisms that use a single tree trunk for support. Of course, you may only see  a fraction of them, but it's worth trying to count--vines and epiphytes, algae and fungi, birds, insects and mammals.

It's worthwhile to think back to our Week 1 lessons on Productivity, too. Even when you account for the longer growing season and adjust for the amount of solar radiation, tropical trees in forests like this grow by an order of magnitude faster than their counterparts in temperate forests. That puts both production (of oxygen and food) and evolution into overdrive.

Breathe deeply. Many people call this area "the lungs of our planet."