A framework for ecosystem services valuation.

In the recent article, “Managing Invasive Aquatic Plants in a Changing System: Strategic Consideration of Ecosystem Services,” Hershner and Havens (2008) reject the need to manage certain aquatic plant invaders. The authors claim that Phragmites australis invasion is acceptable because it provides three ecosystem services: habitat, soil stabilization, and nutrient uptake and retention. We strongly disagree with this conclusion. Without a comprehensive valuation framework, the concept of ecosystem services is of little use to decision makers. The services referenced by Hersher and Havens may be of lesser value than the services lost as a result of P. australis invasion. Using P. australis invasion as an example, we suggest a framework for ecosystem services valuation that incorporates three important considerations: quality of service, weighting of services, and time frame.