Native, exotic

When Typhoon “Glenda” roared through the Philippines last month, it left a trail of uprooted trees. We counted 138 of those uprooted trees at the University of the Philippines Diliman campus.

The mildest adverse effect of the uprooted trees was road obstruction. Other forms of damage were more serious, the trees falling on houses and vehicles. A number fell on electric posts, complicating the efforts of the Manila Electric Co. to restore electricity. Fortunately, there was no human casualty from the falling trees.

Topping the list of uprooted trees were the acacias, those much-beloved trees planted by the pioneer batches of UP students who first came to the new Diliman campus in 1948. You find them all over the campus, especially around the academic oval, providing shade for hundreds of joggers who come to Diliman every day.

Also among the uprooted trees were a number of star apple or kaimito trees, again much-loved by UP students, especially those who lived in dorms.  There are so many of these trees on UP property that informal settlers in the area have been able to harvest (without UP permission) the fruits every summer, and to sell them on the roadside.

So common are the acacia and star apple trees that we tend to think of them as “Filipino” trees. Turns out they’re not. Biologists call them “exotic,” meaning they were introduced into the Philippines.

I have to clarify that “native” trees do not necessarily mean the plants are found only in the Philippines. Such plant and animal species would be called “endemic.” When we say “native,” we mean native to the geographical region where we are.  What we call “native” are plants that may be distributed through Southeast Asia, and sometimes even further into New Guinea and the South Pacific islands.

Plants introduced from Central America, the other side of the world, are no longer called “native” but exotic. These exotic species may thrive well after they’re introduced into the Philippines because some of the conditions in their original habitat might be found here as well. Plants native to Central America found a hospitable semitropical climate here, so the plants can survive… until they meet our climactic extremes, like Glenda and its strong, sustained winds.

The acacia trees had relatively shallow roots, which made them easy to uproot. I haven’t quite figured out why star apple trees are so vulnerable, but I do remember many of them surrounding the houses I lived in and being damaged by typhoons.

Amok trees

Back at UP Diliman, several gmelina trees also came crashing down….  much to the relief of several building administrators. The gmelina, together with mahogany, have been favorites for tree-planting projects because they grow rapidly.

Too rapidly, unfortunately. The gmelina trees grow quickly because their roots spread out quickly. They’re voracious in sucking up water, depriving nearby plants of their fair share and causing them to stunt.  The roots, meanwhile, snake their way to incredible distances, sometimes destroying other plants or, in urban areas, the pavements.

Sounds like a horror movie, right? Plants gone amok, on a rampage.

I don’t want to demonize these exotic species. What’s important is planning our tree-planting more carefully.  Sixty years ago, even UP’s biology professors were not aware of the implications of planting acacia trees. They probably knew these would become grand, towering trees, and that was what was important for a university campus.

What we’re seeing is evolution, and natural selection, at work. Native tree species adapted, across thousands of years, to local conditions, from the types of soil to the climate. Biology professor Perry Ong recently showed me a computerized analysis of aerial surveys of forest areas in various parts of the country. What is most striking is the way trees of the same species tend to cluster together.

The trees flourish together in a particular area because each species has its own optimum amount of sunlight, water, and other environmental conditions. In a way, they “search” for those conditions, thriving when these are found. Seeds that unfortunately get dispersed to a less optimum environment might germinate and develop into seedlings, but are less likely to survive.

Growing environmental awareness means a better appreciation of studies concerning plant interactions with their environment. The findings of the scientists are slowly finding applications. Sometime last year, I ran into some environmentalist-friends in a restaurant. They were meeting with officials of an upper-class subdivision, who were interested in learning about native trees for their residential area.

Learning and planning

There are books now on native trees. In 2012, Green Convergence for Safe Food, Healthy Environment and Sustainable Economy published “Philippine Native Trees 101,” featuring that number of species. That same year, Aboitiz Foundation came out with “Shades of Majesty: 88 Philippine

Native Trees.”

According to “Philippine Native Trees 101,” we have some 3,600 native trees, two-thirds of them endemic. To name some of the native trees, we have agoho, tindalo, almaciga, lumbang, batino, dita, bignai, antipolo, marang, yakal, and, of course, our national tree, narra.  “Plant-smart” readers will recognize many of the plants as having many uses, from edible fruits to resins to lumber.

In UP Diliman, Washington SyCip and friends put up a garden of native trees, and commissioned a manual to describe the plants. All these books have lavish photographs to show the trees in their natural conditions.

Learn more about native trees, and plan your own backyard, or community. Recently a friend texted me about his plans to plant mahogany in a newly acquired property. My friend’s text came in just as I was meeting with Emil Sotalbo, the retired former head of our Campus Maintenance Office who continues to advise Diliman on landscaping and plants.  He shook his head and said: “Introduced,” pausing almost ominously, “and invasive.”

It makes sense going native, not just for sentimental or even nationalistic reasons, but also for very practical considerations of reducing the risks of losing life, and property.

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