Destroy the forest, the rains will cease to fall, and the land will become a desert.
A watershed is an area of land, such as a mountain or valley, which collects rainwater. We all live in a watershed. Communities of humans, plants, and animals all depend on the watershed for hydrological functions and the ecological functions it can influence. Freshwater accumulating during a rain event:
1) infiltrate into the ground slowly filtering down through the soil and rocks collecting into an underground layer called an aquifer. Surface waters and groundwater supply residents and communities with drinking water;
2) are absorbed by plants that contribute to oxygen release and;
3) form streams and rivers (surface runoff) that flow into the ocean or create important wetlands (a distinct ecosystem that is saturated with water seasonally or permanently) providing habitat for many unique aquatic and terrestrial species.
The Hawaiian equivalent of a watershed is the ahupua‘a. Many ahupua‘a land division boundaries run from ridge to reef. Rainwater flows from the top of the mountain known as the wao akua (realm of the gods), to the wao kanaka or the realm of man. Each community within the ahupuaʻa relied on the freshwater the forest supplied.
Loss of the Watershed
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.
In many cases the normal defenses that had developed on the main continents no longer applied and were replaced by more necessary adaptations. 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. Rainforests were semi protected due to their harsher terrain however the leeward dryland forests were virtually destroyed with only 5-10% remaining. Many of the existing watershed partnerships today such as LHWRP, are located in the higher elevations where the majority of intact native forests remain or have the potential to be restored.
Benefits of Restoring the Watershed
Primary benefits can be expected from native forest restoration:
1. 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.
2. Act as Natural Air Filters and Mitigate the Effects 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.
3. Perpetuation of important Hawaiian cultural resources
Early Polynesian settlers utilized mountain areas as a source for their water, both for human use and agriculture. They harvested mountain plants and animals for food; medicinal and ceremonial uses; housing and canoe construction and a variety of other uses. To settling Hawaiians, the high islands of the archipelago must have appeared as the ultimate gift from their ‘akua (Gods). Having a deep connection with nature known as mana and utilizing a set of rules based around conservation known as the kapu system, it was everyone’s responsibility in the Hawaiian community to mälama ‘äina (care for the land). If the people cared for the land, the land would care for the people.
4. Conservation of unique, endemic plants and animals
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. 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.
5. Diversification of Maui’s Rural Economy
Most regional experts in conservation and land management believe that and the existing cattle industry, future silviculture and conservation can be dovetailed into a complementary land management scenario where economic interests and biological conservation can be maximized.
6. Protect our Marine Ecosystems from Erosion
When forests are lost, the root systems of trees and other vegetation are no longer available to hold soils together. This can cause an increase in erosion and sedimentation. Additional particulates from the soil are carried by the water down to near shore marine waters, smothering coral reef ecosystems. Living corals play an essential role in everything from water filtration, fish reproduction and shoreline protection dissipating much of the force of incoming waves and buffering shorelines from currents, waves, and storms.