Thursday, October 29, 2015

Mapping Invasive Plant Distributions

Invasive plants (Introduced plants that have negative effects on the environment) can pose serious problems to ecosystems by extirpating native plants and causing changes in plant-animal dynamics. In aquatics systems, invasive plants often alter water chemistry or displace native populations of aquatic animals. It is, therefore, crucial for ecosystem stability to monitor and control the spread of invasion. 

Scientists in Germany (in 2013) developed software that allows the identification of two submerged invasive plants in German lakes (Elodea nuttalli and Najas marina) from an aerial photo. The software uses reflectance of incident light to detect these plants since each plant species reflects light in a specific way based on both physical structure and pigmentation. These particular plants can also be used as indicators of changing ecosystem conditions because they commonly colonize lakes with rising water temperatures. I think this is cool because it not only allows for easier monitoring of invasive plants (compared to a physical survey from a boat!) but also presents data on invasive plant spread in a way that is easy for the general public to understand.

 The photo itself is a false color image of a shoreline of Lake Starnberg in Germany. The density of invasive plants in the shallow areas of the lake was measured based on reflectance of incident light and then illustrated using a  rainbow of colors signifying various degrees of invasion (blue=non-vegetated sediment, green/yellow= sparse vegetation, red=dense vegetation). Notice that the areas of dense vegetation occur farther from the shoreline. This is common in submerged aquatic plants since they are outcompeted by emergent plants in shallow waters.

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