Meet Your Neighbors
It might be surprising to learn that many of the plants and animals you see when you walk around your neighborhood are not meant to be here. That is because these plants are not native - they come from somewhere other than Hawaii. Usually, they are from similar tropical zones, such as South America, Africa, Asia, or other Pacific Islands. They are often brought and planted because they look pretty and they grow well.
Golden eldorado, origin: Solomon Islands; photo by Hartono Subagio (ignartonosbg)
Bougainvillea, origin: South America; photo by Florencia Rosenfeld (@floristeady)
Plumeria, origin: Mexico, South America, Caribbean; photo by pisauikan (@pisauikan)
In fact, nearly all of the most popular landscaping plants are nonnative. Some of these include Golden eldorado (Pseuderanthemum reticulatum), Bougainvillea (genus Bougainvillea), and Plumeria (genus Plumeria). These plants can often be seen decorating yards and along roadways. How many of them have you seen? Do they tend to be more common in certain areas or around certain types of buildings? Do any of these surprise you?
Thankfully, these species are not currently thought to be invasive. As garden plants, they are often kept in check by landscapers or land owners. However, that’s not true of all ornamental plants brought into Hawaii. Miconia (Miconia calvescens), Christmas berry (Schinus terebinthifolia), and pampas grass (Cortaderia spp.) were all common ornamental plants used in Hawaii. Now, all of them are considered invasive.
What does this mean for Oahu? It means these plants are fighting local native plants for space, food, and water - and they’re winning. Many of the nonnative species that become invasive do so because they root or grow quicker, have more seeds, or can survive unique conditions such as wildfires. Sometimes, they bring along a disease or ailment which native plants struggle to fight against - such as Rapid Ohia Death. These plants are dangerous not only to other plants, but also to the wildlife, often taking the place of needed homes or food. This includes the food of our native honeycreepers (subfamily Carduelinae; a very picky type of seed and nectar-eating bird) and endemic yellow-faced bee (Hylaeus assimulans), both of which are very important native pollinators. If these invasive plants take over, Oahu may no longer look like the home we all know.
What does this mean for us? It means that we are likely to see fewer native plants and fewer native birds. It means that microclimates and ecosystems will change - which means hotter weather, more fires, and more landslides. Hotter weather from the loss of native shade trees; more fires due to higher amounts of dead brush and fire-starting plants; and more landslides as we lose our dune and mountain-stabilizing adaptive plants. It may even affect our water supply; as we lose plants adapted to the salinity and our soil layers are removed through rain or landslides, we additionally lose the ability to fully filter the water that makes it into our aquafers. We may also see less water make it into our aquafers, as run-off into the ocean increases.
Thankfully, there are some things that can be done. For one, plant native plants whenever possible. There are many examples of native plants that are beautiful for landscaping. Second, learn to identify invasive plants, and report them! For tips on how to identify species, look at our handy guide. Reporting invasive plants (or animals) can be done at 643pest.org or by calling 643-PEST.
Activity Guide:
Meet Your Neighbors Activity Guide (Google Doc)
Further Reading:
Non-invasive Landscape Plants with Fragrant Flowers, by Patti Clifford and Kent Koyashi: https://www.ctahr.hawaii.edu/oc/freepubs/pdf/OF-46.pdf
Identifying & Introducing Alternative Ornamental Landscape Plants…, by Dr. Andy Kaufman et al.: https://dlnr.hawaii.gov/hisc/files/2013/03/HISC_Green_and_Healthy_Hawaii_Final_Report_Dr_Kaufman.pdf
