Of all the earth's environments, alpine regions are arguably the most vulnerable to climate change. This is especially true for alpine areas on islands. In both Hawai'i and New Zealand, about 11 percent of the land area is above the tree line, the definition of an alpine environment. In addition to climate change, these island ecosystems are particularly vulnerable to damage from human activity and the invasion of alien species. Of all the earth's environments, alpine regions are arguably the most vulnerable to climate change. This is especially true for alpine areas on islands. In both Hawai'i and New Zealand, about 11 percent of the land area is above the tree line, the definition of an alpine environment. In addition to climate change, these island ecosystems are particularly vulnerable to damage from human activity and the invasion of alien species.