In my last column, I wrote about the declining forests in Anne Arundel County. I know we have an ever-increasing population in central Maryland, but the value of trees extends beyond the obvious: it also affects our efforts in growing gardens and crops.
Old growth forests provide the perfect environment for many living organisms, all of which evolved long before us. The first thing we think of our forests providing to humans is oxygen. We cannot live without this. Most of the gain in atmospheric oxygen is the result of photosynthesis by land plants, primarily forests. Two trees provide enough oxygen for one person to breathe over the course of a year. Each tree can remove 4.3 pounds of air pollutants while producing oxygen. In the book Nature’s Temples, the Complete World of Old Growth Forests author Joan Maloof writes that the larger, older and more complex a forest is, the more efficient it is at producing oxygen and removing carbon dioxide.
Forests are also important for a healthy water cycle. Maloof writes that a single tree can intercept 100 gallons of rainwater and more than half the drinking water in the United States originates from forests. Removing old forests and replacing them with young plantings often results in reduced water flow by up to 50 percent and takes as long as 150 years to recover.
Biodiversity of insects is extremely important as our birds need them for food and we need them as pollinators. Just as large predators keep smaller prey in check, we also need insects to keep plants in check.
Instead of thinking of our native insects as injurious to plants, think of them as tiny gardeners trimming here and there. Trees respond by producing anti-insect chemicals and many insects can detoxify these chemicals. So we get insects that feed only on specific trees which helps keep the forest in check and not allow one species to take over.