Balancing Native Wetland Types and Ecosystem Function Conservation in the Face of an Aggressive Plant Invader

Wetlands provide a multitude of ecosystem services that are important to people including water filtration, flood attenuation, carbon sequestration, and recreational opportunities such as birding and hunting. Wetland plants support these services by performing important underlying ecological processes called ecosystem functions which include removing heavy metals from water and providing habitat for migratory birds. The provisioning of these functions varies through space and time, by vegetation type, and via impacts from other factors like climate and management actions. Wetland managers are responsible for maintaining these functions and services within their management complexes to align with their agency’s mandates. Unfortunately, managers have limited budgets and must make prudent decisions regarding where to allocate their resources to meet management goals and objectives. In this study, we modeled seven ecosystem functions (aboveground and belowground carbon storage, aboveground and belowground nitrogen storage, aboveground biomass, seed nutrient content, and bird diversity) and mapped eight of the dominant wetland types including an invasive, non-native grass Phragmites australis (Phragmites) that support the seven modeled functions in Great Salt Lake wetlands, USA. We also modeled the risk of invasion by Phragmites and generated optimized conservation planning scenarios that inform managers where to focus their efforts to maintain both the ecosystem functions and the desired dominant wetland types found within two heavily managed wetland complexes at the Great Salt Lake. Due in large part to the tightly coupled relationship between these functions and the wetland types we assessed, we found that it is possible for wetland managers to achieve their conservation objectives of managing for both specific wetland types and important ecosystem functions at any conservation target level that aligns with their management goals. Thus, the level to which these functions and wetland types are conserved is dictated by management objectives and the available resources (e.g., water, finances, personnel) rather than by an inability to meet management goals based on spatially conflicting ecosystem functions and wetland types.