The Forest for the Trees

Forest Food Roughly 80 percent of the food we eat originally came from tropical rainforests. Without rainforests, we wouldn't have the seeds that produce coffee and chocolate. Other rainforest foods include tomatoes, potatoes, rice, bananas, black pepper, pineapples and corn. There are over 3,000 fruits found in rainforests. People in the Western World make use of about 200 of them, but the indigenous tribes of the rainforest make use of over 2,000. Rainforest tribes also have a knowledge of rainforest medicine that far exceeds the Western World's. One major problem with deforestation is the devastating effect it has on these tribes. As these cultures are lost, so is their extensive knowledge of the vast resources of the rainforest, whose wild plants are vital to our well being.

We saw in the last section that the ample sunlight and extremely wet climate of many tropical areas encourages the growth of towering trees with wide canopies. This thick top layer of the rainforest dictates the lives of all other plants in the forest. New tree seedlings rarely survive to make it to the top unless some older trees die, creating a "hole" in the canopy. When this happens, all of the seedlings on the ground level compete intensely to reach the sunlight. Most other plants survive by taking advantage of the trees that form the canopy layer.

Many plant species reach the top of the forest by climbing the tall trees. It is much easier to ascend this way, because the plant doesn't have to form its own supporting structure. Lianas, long, woody plants that can grow more than 8 inches (20 cm) across, will often climb tall trees all the way up to the canopy layer. At the top of the forest, these climbers may spread from tree to tree, making the canopy ceiling even thicker.

Some plant species, called epiphytes, grow directly on the surface of the giant trees. These plants, which include a variety of orchids and ferns, make up much of the understory, the layer of the rainforest right below the canopy. Epiphytes are close enough to the top to receive adequate light, and the runoff from the canopy layer provides all the water and nutrients they need, which is important since they don't have access to the nutrients in the ground.

Photo courtesy Todd Fearer This tree has become covered in epiphytes. Note the vines and thick root balls that have formed in the branches.