Celebrating Hala This Arbor Day

One of the nicest thing about Arbor Day and Earth Day is that they come at the end of the ho’oilo, or the wet season. Which is when we wind down, assess and take stock of what we have accomplished for our seasonal plantings at the Waihe`e Coastal Dunes & Wetlands Refuge.  This ho’oilo, James, Karen and the dedicated volunteers at the Waihe`e Refuge planted 1,200 trees and shrubs, mostly hala, but other species as well, including loulu, ‘ohe makai and kauila.  We are frequently asked how we know what to plant, and, like so many things in life, it is both science and art. 

Of course, we always plant either indigenous or endemic species, but the real trick is to find the right combination of species that allows us to restore both the original native forest composition, and those species that will prove most resilient in a changing climate.  If you have read our past blogs, you will know that we have been able to reconstruct the forest composition of Waihe`e going back at least 3,800 years, and perhaps quite a bit further than that.  As you might expect, Maui before humans arrived was botanically diverse.  However, certain species dominated the landscape, and those species prove their ability to endure changes over time, in other words they have proven to be very resilient. 

However, we can’t pretend that everything is the same.  For example, we are seeing first-hand the result of rat predation on the loulu, the likely cause of their extirpation (local extinction), as the gnawed leaves on many of our loulu demonstrate.  For this reason, we are also planting other species, with hala being the kumu makamae, cherished tree, of our restoration work. 

First hala is indigenous (in the early 1990s an impression of a hala seed, known as a key, was found in lava rock several million years old on the island of Kaua`i), it thrives along the coast, and perhaps most importantly its aerial, or prop roots, are widely known to hold soils against erosion, and, in extreme conditions, slow down the velocity of waves washing ashore.  In this way hala planted along the coast at Waihe`e serve as a type of bioshield, protecting the wetlands behind them from wave and wind erosion, and slowing down the waves that come ashore. As an `ōlelo no`eau from Hawai`i Island says: He iki hala au no Kea‘au, ‘a‘ohe pohaku ‘ala e naha ai. I am a small hala of Kea‘au, but there is no rock hard enough to smash me.

— Dr. Scott Fisher