Water, water, everywhere, but not a drop to drink?
Here we are on Kohala Mountain, 2,000 miles from any other land mass, surrounded by salt water. And yet our island is not a desert of sand and palm trees. We have abundant fresh water, and rain forests cover our mountain slopes. And it is because of these mountains and forests that we have so much water. As the prevalent trade winds sweep moisture laden air from the tropical Pacific up and over our mountains, the moist air cools, the humidity condenses into clouds, and rain falls. The forests actually intercept cloud droplets and even more water comes to the earth. The floor of the forest is like a sponge, covered in moss, ferns and leaf litter. The rain soaks into the ground, and filters down through the bedrock, recharging our underground water supply.
What makes native Hawaiian ecosystems so unique and endangered?
￼The Hawaiian archipelago is the most isolated landmass on Earth, and as a result, has the highest percentage of endemic (unique) species of plants and animals on the globe. A few birds that were blown off-course or seeds that were carried more than 2,000 miles from the nearest land source arrived on bare Hawaiian lava rock and have since diverged over the millennia into globally unique and highly endangered living systems on both land and in the water.
More than 90% of terrestrial and freshwater species and 24% of marine species in Hawaiʻi are found nowhere else in the world. This uniqueness, however, means that once a species is lost in Hawaiʻi, it is probably gone forever from the planet. With just 0.2% of the U.S. land area, Hawaiʻi has about 25% of U.S. endangered species.
Unfortunately, the native vegetation of Hawaii evolved without any impact from terrestrial mammals. The trees in the formerly dominant tropical forests are not adapted to grazing or browsing, are uniformly shallow-rooted; their roots are immediately destroyed by the trampling action of hoofed animals or any soil compaction. Similarly, the understory ferns and shrubs evolved with animal impacts limited to use by native birds and a very narrow band of insects. Humans brought farm animals to Hawaiʻi that have since gone wild. These feral pigs, cattle, and goats wreak havoc on our native systems by destroying vegetation, and spreading disease and invasive weeds.