Spatial analysis of Phragmites australis at Long Point Peninsula

Session: 32. - Long-Term Monitoring: Achievements, Challenges, and Solutions

Jennifer Jung, Canadian Wildlife Service, [email protected]
Jon Midwood, Department of Fisheries and Oceans, [email protected]
Daniel Rokitnicki-Wojcik, Environment and Climate Change Canada, [email protected]

Abstract

Spread of non-native Phragmites australis ssp. australis (hereafter Phragmites) in the lower Great Lakes threatens biodiversity, making it a high priority for management.  Control is expensive and time intensive, and often a multi-year process.  An assessment of the temporal and spatial spread of Phragmites as well as identification of factors contributing to its spread is needed for better informed management efforts.  In this study, spatial characteristics of Phragmites in Big Creek and Long Point National Wildlife Areas were quantified using airphoto delineations from 1945 to 2013, and 2010 LiDAR. Three management units differing in size, habitat, and anthropogenic disturbance were compared. Boosted regression tree models were employed to predict future distributions to 2022. Dramatic increases in Phragmites cover (14–37% annually) were measured starting in the mid-1990s. Dispersal was an important factor (14–66%). Expansion was highly variable and increased with longer perimeters. Major predicting factors were proximity to existing stands, vegetation class, and elevation. Vulnerable habitats were characterized as low lying, low sloped, marsh and shallow aquatic vegetation, and areas near water and development. Under static water-levels, Phragmites is predicted to continue spreading at near current rates to 2022 and may begin to encroach into drier habitats.

1. Keyword
Spatial analysis

2. Keyword
coastal wetlands

3. Keyword
Phragmites australis

4. Additional Keyword
National Wildlife Area

5. Additional Keyword
Boosted regression tree