The Case for and Against Phragmites australis: An Ecosystem Service Cost-Benefit Analysis for Chesapeake Bay Marshes

Invasive species are a global issue, occurring virtually everywhere there is a significant human population. It is typically assumed that these invasive species are less preferential to the uninvaded native habitats that they invade and sometimes replace and should be extirpated. This assumption is often made a priori to scientific investigation. This work tests that assumption by analyzing the grass Phragmites australis , invasive to Chesapeake Bay coastal wetlands, using ecosystem service valuation. We review the literature and analyze published data to estimate the range of carbon sequestration, nitrogen removal, and wildlife habitat that can be expected in a Chesapeake Bay marsh dominated by Phragmites australis and a marsh characterized by typically observed high marsh species. Phragmites dominated marsh was found to differ from native high marsh (characterized by species such as Spartina patens , Scripus oleneyi , and Distichlis spicata) in the quantity of ecosystem services provided, with Phragmites providing greater carbon sequestration and native high marsh having greater nitrogen removal and wildlife habitat quality. The two systems under median conditions were found to provide very similar economic value, with native high marsh providing greater value under optimal conditions for both systems. An analysis considering the net present value of control costs and ecosystem service value indicates that it is not a net economic benefit to control for Phragmites, unless the cost is low to moderate and the benefit is high, i.e. the system is able to maintain or return to optimal wildlife habitat. These results can be used to inform land management decisions in the Chesapeake Bay region.