Research Highlights - Invasive Species

Invasions by plants, animals and insects contribute to global environmental change, but the dynamics and consequences of most invasions are difficult to assess at regional scales. The CAO is mapping the location and impacts of many highly invasive plant species across thousands of acres of Hawaiian rainforest reserves.

From the air, Carnegie scientists, along with partners from the US Forest Service, State of Hawaii, and Stanford University have identified ways that the invaders transform the 3-D structure, chemistry, and biodiversity of native rainforests. Some invaders such as strawberry guava trees from Brazil shade out other plants and are destroying important native Hawaiian forests. Other invaders such as kahili ginger crawl along the forest floor and steal water and nutrients from native trees above. The CAO is demonstrating how a new airborne mapping strategy can identify and track the spread of certain invasive plant species, determine ecological consequences of their proliferation, and provide detailed geographic information to conservation and management efforts.

Images, from top to bottom:

3-D image showing an invasion front (red-pink trees) into a protected forest reserve (blue-green trees) in lowland Hawaiian forests

Cross-sectional views of forest canopies along fronts of biological invasion. The canopies to the left of the vertical dashed lines are comprised of one or more invasive tree species. The forests to the right of the dashed lines were still dominated native trees at the time of CAO overflight.

Detection of the highly invasive Psidium cattleianum (strawberry guava) in lowland Hawaiian forests. The CAO spectral data allow for easy identification of guava trees in red due to their uniquely high growth chemistry. The section view at the top shows CAO LiDAR data indicating the change in forest habitat caused by the invasive tree.