How a Rainforest Grows

I flew back to Costa Rica this last Friday. I experienced some of the worst (or best?) turbulence I have ever felt flying over a Honduran thunderstorm. I was stuck with a middle seat, but it turned out not to be too bad. To my left (the aisle) was a 15 year old boy named Chris from Albaquerque. He was traveling with his grandma on summer vacation. To my right (window) was a law student named Greg from Univ of Washington. He was coming to Costa Rica to study international human rights law for the summer. The three of us talked the entire trip. It was the best conversation I have ever had on a plane. By the end of the trip, everyone around me asked for a Finca Project brochure. (Apparently I talk loudly.)

Now I am back down south in Aguabuena. There is a new group of students here and an Earthwatch expedition. I had the chance to listen in on Dr Karen Holl´s lecture to the Earthwatch group about reforestation and rainforest ecology. Taking from some of what she lectured, I wanted to give a little explination of how a rainforest grows and why reforestation is so important...

HOW A RAINFOREST REGENERATES (NATURALLY)

When a forest is cut down (by humans or naturally by storms, avalanches, mudslides, etc..) there are generally two ways it can grow back. One is through seeds and the other is through roots and stems that resprout. Most trees need to start from seed.

Many temperate (non-tropical) forests have seeds that are buried very deep in the soil. They can "hibernate" for up to hundreds of years and then one day resprout. This rarely happens in a tropical rainforest. In the tropics the seeds generally need to be fresh.

Up to 80% of tropical rainforest trees rely on animals of some kind to spread their seeds. Some seeds even require that they pass through the digestive system of certain animals before being able to sprout. Many of the seeds are eaten by birds and then pooped out in a different place later. An average troop of monkeys will disperse 50,000 seeds per week. Other animals will actually plant the seeds, by hording them and burying them, like the dung beetle and some small rodents. Again, some of these trees will only sprout if they are buried by a certain animals.

For this to happen though, there has to be an available resource of trees, seeds, and animals...So what happens when these structures are absent?

WITH A LITTLE HELP FROM SOME FRIENDS

In Aguabuena, over 80% of the original forest has been cut down in the last 50 years. There are only a few stands of forest left, most have no monkies and only a few rodents. A bird has little interest to hang out in an open field long enough to poop some valuable seeds. Therefore there is little infrastructure in place for the forest to regenerate on its own.

That is why it needs a little help from its friends (us). We need to provide some genetics (seeds) and some structure (trees) to jumpstart the natural regeneration. Dr Karen Holl and Rebecca Cole are researching what the minimum structure needed to start this process looks like. There are over 1900 species of trees in Costa Rica. The idea is you dont have to plant every single species. If you have the structure in place, the seeds will come. If you plant them, more will come.