January 26, 2009 --
New technology deployed on airplanes is helping scientists quantify
landscape-scale changes occurring to Big Island tropical forests from
non-native plants and other environmental factors that affect carbon
Forest Service and Carnegie Institution scientists involved in the
research published their findings this month in the journal Ecosystems
and hope it will help other researchers racing to assess threats to
tropical forests around the world.
"Our results clearly show the interactive role that climate and
invasive species play on carbon stocks in tropical forests, and this
may prove useful in projecting future changes in carbon sequestration
in Hawaii and beyond," said Gregory Asner, with the Carnegie
Institution's Department of Global Ecology.
might be the best way to quickly examine rugged ecosystems covered with
dense vegetation that make them difficult to study on the ground or
with satellites, according to the scientists.
showed airborne data correlated with data derived from study plots on
the ground," said Flint Hughes, a Forest Service ecologist at the
agency's Institute of Pacific Islands Forestry and one of the study's
authors. "They also demonstrated what might be the most important
environmental factors affecting forest biomass and carbon
Hughes and his colleagues compared field measurements with data derived from the Carnegie Airborne Observatory (http://cao.stanford.edu/),
a system that uses a combination of lasers capable of measuring
elevation to within six inches, GPS and advanced imaging spectrometers
that can identify plant species from aircraft.
placed the equipment on an airplane that flew over the northeast flank
of the Mauna Kea Volcano and the Hawaii Experimental Tropical Forest,
which the National Science Foundation has designated a National
Ecological Observatory Network candidate site.
compared the information to field observations that included tree
diameter, canopy height and wood density estimates. Their findings not
only demonstrated the effectiveness of airborne observations, but also
offered a landscape-scale view of how alien invasive plants like
strawberry guava might affect biomass levels in the context of carbon
sequestration and climate change mitigation.
Study results suggest fast-growing invaders decrease biomass levels, while slower-growing species increase biomass stocks.
US Forest Service, Pacific Southwest Research Station