Airborne remote sensing of invasive species and their effects on canopy chemistry.
Asner, Gregory*,1, Vitousek, Peter2, 1 Department of Global Ecology, Stanford, CA, USA2 Department of Biological Sciences, Stanford, CA, USA
ABSTRACT- Biological invasions present a challenge to both ecological research and conservation efforts, but few studies have determined the location and ecological effects of invasive species at landscape to regional scales. We used airborne imaging spectroscopy to detect the presence of two chemically-distinct invasive species in montane rain forest of Hawaii Volcanoes National Park. Our approach measured canopy fractional cover, canopy water content, and leaf N concentrations in a 1360 ha area once dominated by Metrosideros polymorpha (ohia) and other native species. Remote measurements showed that the nitrogen-fixing invasive tree Myrica faya doubled canopy nitrogen concentrations and water content as it replaced native forest, while the understory herb Hedychium gardnerianum reduced nitrogen concentrations in the forest overstory and substantially increased forest water content. This novel remote sensing approach indicates the geographic extent, degree of infestation, and biogeochemical impacts of these two distinct invaders; its wider application could enhance the role of remote sensing in ecosystem analysis and management.
Key words: invasive species, Hawaii, canopy chemistry, biogeochemistry
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