What is a Dryland Forest?

In 1913 Joseph Rock wrote about the “striking flora” of the dryland regions of Ka`ūpūlehu, neighboring Pu`u Wa`awa`a and other leeward regions throughout the islands. That is where he found “the richest in species as far as tree growth…” during his botanical surveys.

In his book, The Indigenous Trees of the Hawaiian Islands, he went on to write:
    “It is in these peculiar regions that the botanical collector will find more in one day collecting than in a week or two in a wet region... It may be of interest to know that not less than 60 per cent of all the species of indigenous trees growing in these islands can be found and are peculiar to the dry regions or lava fields of the lower forest zone, which in certain localities gradually passes into the middle forest region, carrying a few trees up into the latter zone.”

           
     The difference in the dryland forests of today, compared those of 1913 is staggering. Less than 100 years later,  90% to 95% of dryland forests have disappeared. More than 25% of the species of these ecosystems are on the Federal endangered species list. Instead of expanses of dryland habitat, today there are only scattered remnants. The surviving plants cling to a precarious existence.

    For native people of the region, the plants and land  would not have been considered “peculiar” but rather family or `ohana. The ancient Kumulipo creation chant reveals a complex relationship and dynamic continuum between people, and things of the skies, land and ocean. Within the Kumulipo, plants of the uplands have ocean counterparts, such as the dryland Alahe`e (Walahe`e), Wiliwili, `ūlei, Piko and Kauila (Uwila), Maile seedling (Kuhonua).

    The ancient conservation management system of Kapu or restrictions to protect scarce resources is no longer in place. However the foundation for that thinking is still valued by many today, who believe the highest relationship with these rare grandparent or kupuna trees, has become the spiritual guidance and comfort that is offered by their living presence—and we should mālama or care for them as with any beloved elder. It is believed, “take care of the land and the land will take care of you”.

What is a dryland forest in less poetic terms?
Dry forests annually receive less than 50 inches of rainfall and are most often located on Hawaii’s dry, leeward coasts to mid-level elevation where rainfall is far less.  However, dry forests are uniquely diverse and on the Big Island, also found in Puna and Ka`u as well as at high elevations, as with the palila habitat and māmane forests of Mauna Kea.  Native plants, insects and birds once lived in prolific dryland forests, thriving in a dynamic, rich biodiverse environment that offered balance and bountiful treasures to be cared for and used by Hawaiians.

What grows and lives in the dryland forest?
More than 40 native plant species grow in dryland forests, including the endangered kauila, uhiuhi, koki‘o, ‘aiea and halapepe trees.  In addition, more than 25 percent of Hawaii’s endangered plant species are found in dryland forests. Birds, such as ‘amakihi and the rare palila (an endangered Hawaiian honeycreeper) are also found in dry woodlands.  Other birds, such as the ‘alala, currently exist only in captivity, and researchers eagerly await the opportunity to, once again, release these birds to the wild as soon as conditions in the native forests favor their release, health and proliferation. The rare and endangered `O`kai, or Munduca blackburn-sphinx night moth also makes its home in this habitat.
 

How are dryland forests restored?
Restoration of dryland habitat is a labor-intensive project. 
Once fountain grass has been eliminated, native species are planted and, often, irrigated to supplement natural regeneration.  As the natural system recovers, the work becomes less intensive.  Firebreaks, rodent control and fences that prevent grazing are also critical to protect a recovering forest. While we are seeking and have developed some techniques for efficient means to care for our last dry forests, they presently require a great deal of care.

What happened to Hawaii’s dryland forests?
Land development, deforestation, fires, alien plant species, rodent predation and grazing have degraded and fragmented Hawaii’s dryland forests.  About ninety-five percent of these forests have been destroyed. And many experts estimate less than one percent of the remaining habitat can be considered healthy forest remnants.

What is the common grass I see throughout the lands of leeward Hawaii?
Fountain grass (Pennisetum setaceum) is an introduced ornamental grass common to the drier leeward areas of the Big Island. This highly invasive species suppresses native vegetation and fuels dangerous wildfires that are devastating to native species. Maintaining firebreaks is important to restoration efforts and benefits everyone.

I’ve heard that native rainforests provide important biodiversity balance to watersheds. Do dryland forests play a similar role?
Dryland forests play a crucial role in the creation and maintenance of a healthy “food web.”  Soils, healthy air, waters,  birds, insects, plants, trees and humans all co-depend on healthy dryland forests.  These drylands host a complex living system that varies dramatically from the rainforests of the world.

Where are some dryland restoration projects?
Pu‘u Wa‘awa‘a, Ka`ūpūlehu, Kawaihae Uka, La`i `ōpua, Palama Nui, Kaloko- Honokohau, Volcano National Park, Mauna Kea, Ka`u and Manuka have remnant dry forests.  These public and private lands represent a remarkable diversity of historical, natural, cultural, scientific resources; and a rich history of ancient and contemporary human use. Nähelehele advocates for restoration of these and other dryland ecosystems. Other islands also have dynamic restoration efforts such as the Auwahi project on Maui, and the efforts in the Wai`anae Mountains of O`ahu.

Why should I care?

• Dryland forests play a crucial role in the cultural health and traditions for Hawaiian people.

• Dryland forests are the exclusive home of many endangered native plants and birds.

• When these forests thrive and the plants, birds and soils thrive, a healthy biodiversity abounds, bringing natural harmony and balance between plants, animals and nature.

• By preserving native species, we increase the genetic gene pool and open more possibilities for the evolution of plants and animals to thrive in future environments.

• Dryland forests maintain and promote healthy soils by limiting both water and wind erosion. They also help create cool microclimates.

• More parts of the world are likely to become drylands, given the effects of global warming, and the more we understand about the dynamics and relationships of dryland species, the better we will be able to cope with increasing desertification.

Want to learn more?  See our Resource page or the following links: cultural-ecology or restoration-science.

Want to help?

Mahalo to the Ho`ola Ka Makana`ä (Healing the Place Budding Up Out of the Lava) Outreach Education team at Ka`üpülehu Dryland Forest and HFIA for their contribution to this page from their brochure. [download option here later]