World Rainforest Day

The Philippines has several forest types and one of them is the tropical lowland evergreen rainforest, also known as the Dipterocarp forest. But sadly they are the most affected by the many anthropogenic factors such as logging, kaingin (slash and burn farm), encroachment of settlers, conversion to palm oil plantations, and many others. Much of our remaining large tracts of Dipterocarp forest are found in the Sierra Madre Mountain Range, Samar Island Natural Park, Palawan, and Mindanao.

The tropical lowland evergreen rainforest is so diverse compared to other forest types because of the vertical layering of a habitat called forest stratification. These different layers are emergent, canopy, understory, and the forest floor. Each layer has its own ecological niche that supports unique sets of flora and fauna. 

Emergent layers are large dominant trees sticking out of the canopy layers, usually large dipterocarp species. These trees are the most preferred nesting sites of the Philippine Eagle which provide protection to its young from predators but sadly there is also the large-bole trees preferred by loggers cut.

The canopy layer forms at the mat of the crown of trees around 60-90 feet above the ground which receives 90% of the sunlight. The canopy layer is home to many epiphytes (orchids, ferns, moss, etc.) and arboreal animals (monkeys, tree frogs, flying lizards, etc.). Many species are yet to be discovered in this area especially the invertebrates (insects, arachnids, etc.) that never go down to the ground.

The understory receives only around 2-15% of the sunlight that breaks through the spaces of the canopy layer. This is dominated by some shade-loving trees, palms, and herbs. Some trees develop flowers directly on their trunk which is called cauliflorous which will more accessible to their pollinators. 

While the forest floor is the darkest zone in the tropical lowland evergreen rainforest but nonetheless it is home to so many unique flora and fauna. It is covered with thick layers of forest litter where many detritivores and heterotrophic are found such as arthropods, fungi, and some plants. This is where we can find the giant flowers of many Rafflesia species found nowhere else.

Our remaining tropical lowland evergreen rainforest is still full of mysteries and surprises. We still have time to do more fieldworks and research to uncover new species and new understanding that is useful to us. Let us protect this forest not only for today but for our future generations to come.

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