Comparison of vernal pool characteristics in an old-growth forest and a disturbed urban forest in Southern Ontario

Abstract

There is a large incentive to understand vernal pool ecosystems in Southern Ontario, as they serve essential ecological functions within forests – including providing critical habitat for at-risk amphibians like Jefferson salamanders. Additionally, while deforestation has drastically reduced the quantity of vernal pools in this region, it is unclear how these landscape alterations have affected the quality and characteristics of vernal pools in remaining woodlots. This study addresses this gap in knowledge, by evaluating whether or not vernal pool characteristics vary between an old-growth forest (Backus Woods) and a more disturbed forest (Hamilton) in Southern Ontario. Using fall field surveys, I recorded characteristics of 10 vernal pools in the Hamilton region and 13 vernal pools in the old-growth forests of Backus Woods, and used GIS to evaluate their landscape context. Vernal pools in the Hamilton region had less shaded canopies, shallower depths, and higher water conductivities and total nitrate nitrogen concentrations than those in Backus Woods. Hamilton vernal pools occurred nearer to forest edges and adjacent urban lands, whereas those in Backus Woods were located within larger regions of forest and were surrounded by agricultural land. Land use was not a significant predictor of vernal pool characteristics; instead, forest structure (e.g., disturbed vs old-growth, coniferous vs deciduous) likely played a key role in determining how vernal pool characteristics responded to the surrounding landscape. My results support that human disturbances such as land use alteration can influence vernal pool characteristics, which may influence habitat suitability of at-risk amphibians.