Ice Storm Damage in an Ash- and Maple-Dominated Swamp of Southern Ontario: An Investigation of Precipitation Partitioning

English Abstract:

Interactions between vegetation and the hydrologic cycle are important to investigate for determining the effects of climate change, land-use change, and a growing human population on water resources in and around wetlands. Changes in precipitation (P) regimes (frequency and magnitude) or stand characteristics, such as a loss in canopy due to natural or anthropogenic sources, can all have major influences on the amount water received by a wetland. The hydrological input of throughfall (TF) and stemflow (SF) are especially important to quantify for swamps, as small changes in P have the ability to induce shifts and/or losses of species present within wetland communities. This study presents the investigation of the quantity of TF and SF during P events in two swamps of southern Ontario. With the aid of this research, wetland conservation and management authorities can obtain important information regarding the fluxes of water into swamp ecosystems pre- and post- ice storm. This study was designed to determine the quantity of understory P (as TF and SF) in two mixed-deciduous swamps and how these fluxes differ between the two distinct canopy types as well as to how these fluxes differ between years separated by a major ice-storm. Additionally, an analysis of P characteristics (i.e. amount of P, duration and intensity) was performed to determine how they may dictate TF and SF amounts in the two wetland sites.

TF quantities for the ash-dominated swamp averaged 5-10% higher than TF at the maple-dominated swamp over the course of both growing seasons (2013-2014), while SF was only slightly higher in the ash than maple site. The results indicate that even though there was less rainfall in 2014 than 2013, the amount of TF increased at both sites, suggesting that canopy loss after the ice storm significantly increased TF amounts. Additionally, a positive linear relationship was found between amount of P, duration of rain events and P intensity to both TF and SF depths.