So, you are probably expecting me to give a scientific definition of invasive species. Well, I could do that, but first I want to tell you a story…
My story begins several years ago when I was in southern Brazil in the state of Santa Catarina. I went to Brazil with the focused mission in mind of working with the Nature Conservancy to combat invasive species in the beautiful land of samba and the Amazon. Unfortunately, I was not able to work with the Nature Conservancy because of visa restrictions, but what I managed to get a job teaching English with a private English school.
One weekend, I decided to take a trip with my fabulous friend, Tania, from Botswana to a magical log cabin in a city about 45 minutes south of where I was living at the time. We arrived at the log cabin and feasted on home grown veggies and meats and then spent some time around the fire playing music. The next day, the owners of the cabin left to go on a surfing trip and Tania and I were left in charge of the ranch.
We cooked a wonderful meal of pizza for lunch on the wood-burning stove and then proceeded to ingest some of nature’s finest fungi. This was a unique experience for me and I did not know what to expect. After a few hours I began to realize that things were quite different. Colors were more vivid and everything had a certain clarity about it, including my thoughts and perceptions of reality. I began to wander into the forest when a large hardwood tree called guarapuvu, known as the city tree of beautiful Florianopolis, caught my eye. The guarapuvu tree is amazing, filled with beautiful yellow buds on it branches when it is in bloom. Its lushness is symbolic of the incredibly rich biodiversity of the Atlantic Forest which it inhabits. Less than 17 percent of the Atlantic Forest remains in Brazil. I once heard that you can find 700 species of plants in one square mile in the Atlantic Forest!!!
Around the base of the tree was a series of vines gripping the life out of some smaller trees nearby. Remember, I was toting some potent fungi in my belly during this walk. I could see how the vines were actually at war with the trees, reaching upward and struggling to steal vital nutrients and water from the trees. It all played out vividly in front of my eyes for the first time. I could almost see the tree trying to reach away from the vines toward the sun, but having little luck escaping their grasp.
Well, this imagery may seem a bit silly to some, but I saw it. The reason I give this description is to illustrate how invasive species work. They grow faster, they can handle harsh conditions such as little water and sunlight, and they often have defenses such as thorns and toxins that keep predators away from them. They literally choke the life out of the native species. This is why invasive species are invasive. They can dominate native species. They produce more seeds or reproduce faster. Invasive species are usually brought in by humans for certain benefits such as ornamental value, to feed livestock or to sell and they spread to natural areas where they begin to reproduce quickly and displace native species.
A very common example of an invasive species here in the U.S. is kudzu. The U.S. brought kudzu in to prevent erosion in 1876, but it quickly grew out of control and now blankets many forests in the southern part of the U.S. So what? Why do we care if invasive species spread? Invasive species can cause massive economic damage to crops, they change entire ecosystems and they are the second leading cause of decreases in biodiversity on planet Earth. The fire cycles of California were completely disrupted by many of the grasses brought in by the Spanish. Just imagine how much we spend in dollars and lives trying to control and prevent California wildfires and you will have a small piece of the picture of what invasive species can do. So the next time you go hiking, check the bottom of your boots first. You might be carrying the seed of an invasive plant along with you to somewhere that it does not belong.