Effects of Prescribed Brazing and Burning Treatments on Fire Regimes in Alien Grass-Dominated Wildland-Urban Interface Areas, Leeward Hawaii

摘要

The forests and shrublands of Hawaii's leeward regions once formed continuous vegetative cover across the landscape, broken only by geologically young lava flows. However, today they occur only in small remnant patches imbedded within expansive non-native grasslands. This drastic reduction in forest cover has resulted from the direct and indirect effects of the following factors: wildfire, grazing (cattle, goats, and sheep), alien and invasive species, other land-uses, and related climatic and ecological changes. Many endemic Hawaiian plant and animal species have disappeared from this landscape as a result of these changes and today, 31 dry forest plants, 3 species of birds and one bat known from this region are federally recognized as being in danger of extinction. Lowland areas have suffered the greatest losses and highland areas still support the largest and most intact native plant communities. Introduced as an ornamental to Hawaii island in 1917, fountain grass (Pennisetum setaceum) now covers approximately 208 square miles (132,965 acres). Native to northern Africa and Mediterranean coastal areas, the aggressive invasive continues its spread on all fronts where it overtakes native ecosystems and threatens residential areas. Land ownership within this leeward region locally referred to as West Hawaii is divided approximately evenly among State Management Areas, U.S. Army training lands, and private lands. Under dry and windy conditions typical in West Hawaii, fountain grass ignites easily from roadside sources and spreads across the landscape swiftly.