When is a Tree not so Nice?
Whistling pines are tall and majestic trees. The sound of the wind whistling through the branches is soothing and the shade underneath is a welcome relief on a hot, sunny day. A forest of these pines produces a thick, soft carpet of needles that is a perfect place for a blanket and picnic. With all these nice features, why all the fuss? Why are scientists so worried about what these lovely trees will do? Why are they telling us these trees will harm wildlife, deny our native birds food and shelter and even prevent our beloved sea turtles from nesting on their primordial beaches?
The unfortunate reality is, the scientists are right. The whistling pine is more properly known as the Australian pine, Casuarina equisetifolia, and is native to Australasia and islands in the South Pacific. In the Caribbean it is a non-native plant and is invasive. Invasive means that it invades a habitat, with human help, and then proceeds to displace the rightful owners, both plants and animals. Where there was once a diverse ecosystem of many different plants along with their associated insects, butterflies, frogs and lizards, and colourful birds, you now have only Australian Pines with possibly a tiny fraction of the original wildlife. Our native flora and fauna are ill-equipped to deal with such aggressive and successful trees. So, why is the Australian pine so successful and why can’t our native species get along in this new world order? More importantly, what will likely happen if we just let nature take its course? Should we worry and should we intervene and do something? If so, what exactly? These are tough questions, especially for those of us who are not scientists and who just like to enjoy the natural world as we see it. Let’s dig deeper.
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First, we need to recognize that we humans have a very short lifespan when compared to the ecosystems around us. We have a hard time comprehending even a century, while a million years is but a blink of an eye to Mother Nature. As humans, we view the world from our own life experiences. Other than the trained ecologists, most of us think of the natural world as we first encountered it and think that is the way it is supposed to be and always has been. It is hard for us to understand what the natural world looked like before we arrived. Can you imagine that just a few centuries ago monk seals frolicked in the beach surf throughout the BVI, and manatee lounged in the calm waters of Road Harbour and the Bight of Norman Island? That was a natural sight in these islands for thousands of years until man appeared and changed everything. Yet, today, we consider it perfectly natural that none of these creatures exist. Scientists refer to this phenomenon as “shifting baselines;”we accept the environment as we first find it and consider it natural. That’s exactly why we can go to Anegada and see forests of Australian pines and think it is perfectly natural and beautiful. That is how it has always been. Those pines are part of our heritage, a part of our environment that we should cherish and protect. Sounds good, doesn’t it? The truth is, it is simply not true.
Well, let’s consider a few basic facts. First, Australian pines are not really pines at all. They are angiosperms, flowering plants, not gymnosperms, as the true pines. It’s actually a deciduous tree, a member of the Casuarinaceae. The details are best left to the botanists and those with a scientific bent. They look like pines and they can grow over 100 feet tall. They are very salt tolerant and can survive in harsh conditions and outcompete nearly every plant in our area for living space. Most interesting is the characteristic of allelopathy, the ability to produce chemicals toxic to other plants. Once Australian pines get a foothold in a habitat they can literally poison the competition. On our beaches, they poison or crowd out the native seashore plants. The native plants have deep roots that hold dunes and sand in place during storms. Australian pines have shallow surface roots so storms will erode the dunes and wash away the sand leaving a tangle of forlorn looking trees.
So, how does this affect our wildlife? If you visit a native coastal plant community, there are many kinds of trees, shrubs, vines and flowers. Think of all our native orchids. How about the seagrape, that magnificent coastal tree that provides shelter and shade, food for birds, and people, too? Australian pines will poison or crowd out nearly all those plants. What about our beloved sea turtles? Few animals have figured so prominently in the history of Caribbean life or are more emblematic of the islands. Sea turtles must come ashore to lay their eggs. They crawl up high on the beach searching for just the right shady spot where they can dig a deep hole to deposit their treasure for the next generation. So what do you think will happen to their eggs when that shady spot is a forest of Australian pines? The thick impenetrable roots will not allow the turtles to dig and lay their eggs in a safe, moist environment. The turtle may lay her eggs on the surface, vulnerable to the elements and predators. Instead, she may search for another location. What if there is no other location? Do you still prefer those whistling pines over the turtles and other wildlife, and are you willing to let man-made nature take its course as the pines expand and cover more and more of our islands? Consider this.
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Parts of Florida and the Bahamas were invaded many decades ago. In places, Australian pine forests stretch to the horizon and have virtually eliminated entire coastal ecosystems, turtles included. Want a closer example? Visit Anegada. The first documented Australian pine introductions occurred about 1968 in the vicinity of the Anegada Reef Hotel and Neptune's Treasure. In a few decades, the Australian pine has spread throughout the island. Faster and faster they consume the seashore. They are displacing plants and animals that really were there from the beginning. Right now, many people love them. Whistling pines are so lovely to see. But, do we really want to think of a future where Anegada is totally covered with Australian pines and there are practically no turtles or other native wildlife? The solution is simple to explain, but much less simple to implement.
Controlling invasives relies on scientific recommendations and community support. Sure, having a few in your yard, or a small grove here and there is probably okay. But, be careful that they do not “escape” and overwhelm the real natural environments. As humans we have learned to live with change. We have altered the planet and in some places completely homogenized the ecosystems. Fortunately, in the Virgin Islands we still have some areas that are mostly natural and similar to the original condition. Future generations of wildlife, and people too, will be happy if we control the spread of Australian pines and keep them from conquering our coastlines. Wouldn’t it be nice to try and preserve some of that primordial landscape for our grandchildren to enjoy?
