Tropical Gardening: Plant trees to reduce carbon dioxide and pollutants

  • MCourtesy photo Marine biologist Drew Mcwhirter, the grandson of Tropical Gardening columnist Norma Bezona, and the team he is with clean debris on Kure Atoll. Scientists studying the human impact on the Northwestern Hawaiian Islands are also cleaning up marine debris that is adversely affecting the life and health of endangered species.

Earth Week officially concludes this weekend, but it reminds us that we should now be focusing on Earth Year and even Earth Century! A serious effort to plant trees in the coming decades can mitigate the effects of global warming.

My marine biologist grandson, Drew Mcwhirter, recently reminded me that the coral reefs and oceans are even more important in sequestering carbon and supplying oxygen to the planet. He is in the Northwestern Hawaiian Islands on a marine debris project along with a team of scientists studying the ocean and impact of humans and global warming.


To learn more, you can easily access information with a computer search of “Papahanaumokuakea marine debris project.”

Since what happens in our oceans is not always visible, we tend to focus on what we see on land every day, thus the emphasis on planting trees.

Most visitors to Hawaii are fascinated by the beauty and diversity of our gardens. What they might not recognize is how our gardens express the many cultures and ethnicities of the Aloha State. But Hawaii’s flora is very different from when the first human arrived here. Many of the plants we associate with Hawaii were introduced in the past 200 years.

Plants found by the first people to arrive in the Hawaiian Islands were endemic, that is they evolved here and could not be found anywhere else in the world. Another group of plants were the indigenous species, meaning they were found here before human inhabitants but also found in other regions, such as naupaka, kou and milo that grow all through the coastal tropical Pacific. Indigenous and endemic species are considered native.

There weren’t many food or fiber plants until the Polynesians brought what we call the canoe plants. These were the first exotic, non-native species and include the coconut, kalo, ti, breadfruit, banana, sugar cane, kukui nut, sweet potato, noni, turmeric and may others.

All the flowering trees such as the Royal Poinciana, Rainbow Showers and African Tulip that catch our attention are relatively new. Hibiscus, Bird of Paradise, Bougainvillea, Heliconia, orchids and Anthurium species grow in abundance. Then there are the fragrant plumeria, Angel Trumpets, puakenkene, gingers, jasmines, gardenias and many more.

Plus, let’s not forget the fruits and nuts such as mango, banana, papaya, avocado, litchi, macadamia, rambutan, guanabana, cherimoya, Mountain Apple, guava, coffee, pineapple and citrus species.

And there are literally hundreds of palms species here thanks to the International Palm Society.

It is obvious that humans and the animals and plants they brought with them have had a tremendous impact on the species that evolved on the many isolated islands of Pacifica. Today, erosion also is a big problem on most high islands and the rising ocean is swallowing low atolls that have been the homes of islanders for thousands of years.

But by keeping the lush vegetation an integral part of our communities here, we actually do our part to fight pollution and make life more enjoyable. The vegetation stabilizing our soils also helps minimize the amount of pollutants washing into our coastal waters and damaging the valuable coral reefs.


As individuals, one of the easiest ways to decrease the carbon dioxide levels in the atmosphere is to plant trees. There are a number of trees that can help accomplish this purpose. Among the best are natives such as the loulu palms, ohia, hala, wiliwili, hoawa, alahe‘e and a‘ali‘i. Other plants, such as the beach and mountain naupaka, are attractive to many birds and also make good ornamentals. Flowers of the ohia, koa, hau, milo and mamane can even attract some native nectar feeding birds such as iiwi, amakihi, apapane and elepaio.

For more information about creating and maintaining your tropical gardens, contact the University of Hawaii Master Gardeners. In Kona, call 322-4893. In Hilo the number is 981-5199.

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