There are many benefits to restoring a watershed and its ecosystems and the services that these places provide are priceless to our culture and way of life.
Learn about each of the ways that the land sustains us.
WATERSHEDS & ECOSYSTEMS
Hahai no ka ua i ka ulula’au
The rain follows the forest
A watershed is an area of land, such as a mountain or valley, which collects rainwater. We all live in a watershed. In Hawai‘i, a watershed is called an ahupua‘a. Communities of humans, plants, and animals all depend on the ahupua‘a for hydrological functions and the ecological functions it can influence.
Wai, or fresh water, is an extremely important resource. The importance of it was well understood by ka po‘e kahiko (the people of old) in that the term for rich or wealthy is waiwai. In this context, a person's wealth is determined by how much water he has access too. The wai provided the people with the ability to grow crops and in essence provided life. In tradition, Hawaiians established ways in which wai would be used for the benefit of all the people and not just one person.
wai | water
wai wai | wealth
THE WATER CYCLE IN AN AHUPUA‘A
Rain water slowly seeps into the ground, slowed by a stratified forest of trees, ferns, mosses, and under-story species, then is filtered by the soil and rocks, and collects in an underground layer called an aquifer. This collected water along with surface waters in streams and springs supply communities with fresh water.
Rain is also absorbed through the roots of plants and contributes to oxygen release via photosynthesis. We now know that native Hawaiian plants absorb 30% more water than non-native plants.*
Remaining water flows down-slope into streams and rivers as surface runoff and travels into the ocean or creates important wetlands providing habitat for many unique aquatic and terrestrial species.
WHY DO WE WORK TO PROTECT THE AHUPUA'A?
IMPROVE WATERSHED FUNCTION
Increase water quality and quantity
The native Hawaiian forest plays a critical role managing clouds, wind, humidity, air quality and rainfall patterns. The tree canopy and understory consisting of shrubs, ferns and mosses play critical components of a watershed’s ability to collect rainwater. Fog condensing on trees high up in watershed areas, can increase rainfall collection and absorption by as much as 30% annually. Restoring the once great koa and ohia forests will increase fog interception and hydraulic lift (transfer of deep soil water to near surface soil regions via tall (>10m) tree root systems), which will enhance nutrient cycling, moderate water runoff, and increase soil moisture, leaf litter, and soil nitrogen.
During their 35 million year history the biota that first arrived to the Hawaiian Islands came via the waves, wings or by wind (ocean currents, birds or air currents). These new arrivals encountered numerous niches due to the elevation changes from sea level to 13,000 feet and a variety of micro climates from desert to rain forest to exploit. The geographical advantages combined with the lack of competitors, allowed an explosion of successive ecological shifts known as adaptive radiation. For example, two genera of violets—Viola and Isodendrion - evolved from two separate introductions, each of which was followed by a moderate degree of adaptive radiation*.
PROTECT NATIVE BIODIVERISTY
Conservation of unique, endemic plants
Due to their relative isolation, the biota in the Hawaiian islands is said to have been naturally introduced by one of three means, wind borne, ocean borne or transported by birds before humans arrived. Successful colonization was rare, however those plants and animals that did survive found numerous niches to develop into highly specialized flora and fauna. Some examples of adaptive radiation include honeycreepers, land snails, lobeliads, silver sword plants and a variety of insects. In all, approximately 1,700 species of native Hawaiian plants evolved from about 300 separate species and 10,000 species of native Hawaiian insects may be descended from only 350 to 400 separate founders*.
Restoration of leeward Haleakalā forests is consistent with Federal and State programs to protect Federally designated critical habitat for Maui’s threatened and endangered plants and animals.
*Source: National Academy of Sciences: https://www.nap.edu/read/10865/chapter/8
MITIGATE CLIMATE CHANGE
Act as Natural Air Filters and Reduce the Impacts of Climate Change
Forests are the “lungs of the earth”, absorbing carbon dioxide and releasing oxygen that we need to survive. An additional benefit of the forest is its ability to capture greenhouse gases. These types of gases that when added to the atmosphere, tend to trap heat from the sun resulting in a gradual increase in temperatures that may eventually result in climate changes. By planting trees such as Koa, the carbon dioxide and other greenhouse gases can be sequestered.
PREVENTING THE LOSS OF WATERSHED FUNCTION
Many of the existing watershed partnerships today, such as LHWRP, are located in the high elevations where the majority of intact native forests remain or have the potential to be restored.
As native plants and animals evolved in the islands, the normal defenses that had developed on the main continents no longer applied and were replaced by more necessary adaptations.
Then as humans began to arrive, they brought with them a variety of creatures from ungulates to alien insects that would over time decimate the natural diversity that had evolved to the point that many of the endemic flora and fauna could not survive.
The upland rainforests were semi protected due to their harsher terrain however the leeward dryland forests were virtually destroyed, with only 5-10% of that habitat remaining.
Visit our "HOW" section to learn more about how we are working to prevent the additional loss of this ecosystem and restore it to its original glory.