Island Shape, Soil Depth, and Plant Biogeography in a Great Lake Archipelago

Keywords: biogeography, Canada, GIS, Great Lakes, islands, plants
Session Type: Virtual Poster Abstract
Day: Sunday
Session Start / End Time: 2/27/2022 05:20 PM (Eastern Time (US & Canada)) - 2/27/2022 06:40 PM (Eastern Time (US & Canada))
Room: Virtual 32

Abstract

Environmental changes have resulted in fluctuating water levels in the world’s bodies of water. Focusing
on a Great Lake archipelago (The Massasauga Provincial Park), this project has three aims: (1) to
determine if island shape and soil characteristics fluctuate based on the water year; (2) to determine if
native and non-native plant species richness varies in response to changing island shape and soil depth
for the islands of interest; and (3) to determine if certain non-native plant species are recurring due to
outcompetition of native species. Soil depth and species richness data were collected in the field during
2001, 2006, 2011, and 2016. Islands were digitized in ArcGIS Pro based on aerial and satellite imagery.
Island shape was calculated as a function of island perimeter to the perimeter of a circle with area equal
to the island. Shoreline shapes did change depending on the water year: shapes were more irregular in
low water years than in high water years. Native and non-native plant species were located on islands
with a more irregular shoreline. Irregular shorelines might better capture water dispersing plants such
as the non-native Sedum acre. Soil depth was positively correlated to native plant species richness. With
soil depth serving as a proxy for habitat diversity, the results show that islands with deeper soils allow
for the presence of both shallow- and deep-rooting plants. The results of the study have implications for
park management, especially as related to non-native plant species presence along island shorelines
with fluctuating water levels.