On Saturday, February 7, my intro biology and intro botany students along with other bio students from UH West O’ahu, met at the Cultural Learning Center at Ka’ala Farm for the first of our three service learning projects this semester. This kipuka (area of older land surrounded by younger lava flows) now serves as a traditional kalo farm, and ecological restoration site. The UH West O’ahu students contributed to the ecological restoration of native Hawaiian dry forest under the supervision of Bruce Koebele, the native plant project coordinator at Ka’ala Farm.
The restoration of native dry forest is important for a number of reasons:
1) Over 95% of the native dry forest is already gone. In the past, native forest was cut out for grazing and agriculture, and today invasive plants quickly take over regions where native dry forest plants might otherwise thrive.
2) Many of the native dry forest species are endangered or threatened. Restoration projects are important form of in situ conservation for these species.
3) Many of the plants that make up the native dry forest are also important cultural resources. Restoration projects keep these plants viable for the cultural value they provide, in addition to their ecological roles.
4) Lastly, what little native dry forest remains is often inaccessible, and therefore ‘invisible’ to local people. Restoration projects help raise awareness of the threats the native dry forest species face, and build a commitment to protecting the remnants of this habitat.
The Ka’ala site has been overrun with invasive plants, namely kiawe and koa haole trees, as well as guinea grass. These species were introduced to the dry forests of Hawai’i as part of cattle ranching efforts in the 1800s. Kiawe is an excellent shade tree, while koa haole protects against soil erosion and guinea grass is good for cattle fodder. Unfortunately, all of these species are also rather effective invaders and have overtaken the dry forest from native Hawaiian species. Our first step was to remove these invasive plants and prepare the ground for planting of native species.
As with our sites last semester, we watered the empty hole in order to provide an underground water source for our plants. Supplying water under the plant not only encourages the roots to grow down (where they are more likely to intersect future water supplies), but also keeps the water we just added from evaporating. While we waited for the water to soak in, we helped Bruce clear out a pile of tree trunks that had been removed from a nearby restoration site.
As we walked to the log pile, Bruce stopped to point out a couple ‘ilima (Sida fallax) individuals. Though ma’o hau hele (aka yellow hibiscus) is the state flower, each island also has its own representative flower. ‘Ilima, which is also a member of the hibiscus family, is the island flower of O’ahu. What was exciting about the individuals Bruce pointed out was that they were ‘volunteers’ – plants that were not explicitly planted, but which grew up on their own. This indicates that the restoration efforts at Ka’ala are proving successful for propagating new individuals and becoming a self-perpetuating healthy native dry forest.
Once the logs were removed, we returned to our cleared site to plant our native plants. Bruce supplied us with five different species of native plants:
Lonomea, loh-noh-may-uh, (Sapindus oahuensis): This endemic (found only in Hawai’i) tree is a member of the soapberry family and is found only on the islands of O’ahu and Kaua’i. Lonomea seeds are also commonly used in lei and its hard wood was used to make ‘o’o (the Hawaiian digging tool) prior to the use of metal. Despite its rarity, lonomea is not endangered.
Keahi, key-ah-hee, (Sideroxylon polynesicum): This indigenous (found in Hawai’i and elsewhere) tree is listed as ‘at risk’. The fruits of keahi produce a sticky sap which was once spread on tree branches to capture birds in order to obtain their feathers for ceremonial Hawaiian clothing.
Hala pepe, hah-lah peh-pay, (Pleomele hawaiiensis): This tree is endemic to Hawai’i and is federally listed as endangered. The large flowers of the hala pepe are often used for making lei, and the leaves are an important component of the hula as the hala pepe tree represents the hula goddess Kapo.
Kulu’i, coo-loo-ee, (Nototrichium humile): This endemic tree is also federally listed as endangered and is found only on the islands of O’ahu and Maui (and its continued survival on Maui is questionable). Within O’ahu, kulu’i is only found within the remnants of the dry forest zone in the Wai’anae Mountains.
Abutilon sandwicense,This endemic shrub is found only on the island of O’ahu, and is federally listed as critically endangered, and, like kulu’i, is found only in the Wai’anae Mountains. Its Hawaiian name has been lost, so we know little of its use or importance historically. Like several indigenous and endemic organisms, A. sandwicense takes its Latin name from the name Captain Cook gave to the Hawaiian islands: the Sandwich Islands.
After planting, we surrounded each plant with weed cloth, to help give our baby plants some room to grow without competition from nearby weeds.
In addition to all the plants we learned about, we also happened upon some unintended wildlife! We saw some invasive giant African snails (Lissachatina fulica), which were introduced to Hawai’i in the 1930s (probably via the pet trade) and can wreak herbivoral havoc on plants. One of the ones we found had been crunched underfoot, which allowed us to see it was carrying eggs. It was hard to feel bad that we had prevented it from fully raising its young, considering the problems they could cause for our newly restored system. We also found a small blindsnake (Ramphotyphlops braminus) which is the only terrestrial snake in Hawai’i (although the yellow-bellied sea snake is sometimes found here, too). Their small size and worm-like underground burrowing make them a rare find. It is not clear when blindsnakes were introduced, but it is likely they arrived as castaways on nursery plants. Lastly, we also saw a couple of the lesser brown scorpions (Isometrus maculates), which are also introduced.