Name
Cumulative Effects of Beaver Ponds and Forest Harvest on Streamwater Chemistry in Boreal Watersheds
Date & Time
Wednesday, May 10, 2023, 2:15 PM - 2:30 PM
Wai Ying Lam
Description
Canada�s boreal forests provide many important ecosystem services and it is crucial that they are managed sustainably. In Ontario, sustainable forest management is largely based on emulating natural disturbances. With respect to stream biogeochemistry, beaver ponds are one of the most common and significant disturbances against which to compare. Thus, there is a need to further our understanding of how beaver ponds and forest management interact and modify the effects of one another. This study examined a suite of surface water chemistry variables, with a focus on the bioaccumulative neurotoxin methylmercury, in 28 headwater streams across 3 years in northwestern Ontario. Some catchments were undisturbed; some were impacted by active or abandoned beaver ponds; some were undergoing active harvest, while others were harvested previously; and some were impacted by a combination of the previous factors. Harvest impacts on organic carbon, suspended sediments, and mercury fell within the range of variation seen at undisturbed sites, except where significant soil and water disturbance from stream crossings occurred upstream. Pond impacts were highly variable, but more strongly related to catchment characteristics than to pond characteristics. Though downstream impacts were found to be greatest at a new pond in a catchment undergoing active harvest, pond and harvest impacts were not consistently additive in catchments where both occurred. Understanding the impacts of beaver ponds in conjunction with forest harvest is important for predicting the ultimate effectiveness of management decisions aimed at protecting terrestrial-aquatic ecosystems commonly affected by both disturbances.
Location Name
Cedar
Full Address
Banff Park Lodge Resort Hotel & Conference Centre
201 Lynx St
Banff AB T1L 1K5
Canada
Abstract
Canada�s boreal forests provide many important ecosystem services and it is crucial that they are managed sustainably. In Ontario, sustainable forest management is largely based on emulating natural disturbances. With respect to stream biogeochemistry, beaver ponds are one of the most common and significant disturbances against which to compare. Thus, there is a need to further our understanding of how beaver ponds and forest management interact and modify the effects of one another. This study examined a suite of surface water chemistry variables, with a focus on the bioaccumulative neurotoxin methylmercury, in 28 headwater streams across 3 years in northwestern Ontario. Some catchments were undisturbed; some were impacted by active or abandoned beaver ponds; some were undergoing active harvest, while others were harvested previously; and some were impacted by a combination of the previous factors. Harvest impacts on organic carbon, suspended sediments, and mercury fell within the range of variation seen at undisturbed sites, except where significant soil and water disturbance from stream crossings occurred upstream. Pond impacts were highly variable, but more strongly related to catchment characteristics than to pond characteristics. Though downstream impacts were found to be greatest at a new pond in a catchment undergoing active harvest, pond and harvest impacts were not consistently additive in catchments where both occurred. Understanding the impacts of beaver ponds in conjunction with forest harvest is important for predicting the ultimate effectiveness of management decisions aimed at protecting terrestrial-aquatic ecosystems commonly affected by both disturbances.
Session Type
Breakout Session