Effects of Forest Harvesting and Fire on Fish Assemblagesin Boreal Plains Lakes: A Reference Condition Approach

Abstract

To assess the impacts of forest harvesting and fires on lentic fish assemblages in the Boreal Plains ecoregion (Alberta, Canada), we applied a reference condition approach to 37 lakes in burned, logged, or undisturbed catchments. Fish assemblages in the reference lakes were classified into two types: those dominated by large‐bodied piscivores and those dominated by small‐bodied fishes. A discriminant function analysis with only two environmental descriptors (lake maximum depth and average slope of the catchment) could correctly predict assemblage type in 84% of reference lakes. Depth likely reflects the influence that winter oxygen concentrations have on fish assemblage type, whereas catchment slope is correlated with a variety of landscape‐level features. Although potential effects of forest harvesting and fire can increase the susceptibility of lakes to winter hypoxia (via nutrient enrichment) and alter connectivity to the regional drainage network (via altered hydrology), fish assemblages in 93% of the disturbed lakes did not deviate from the discriminant function predictions, suggesting little, if any, assemblage‐level effects of the disturbances over the 1–2‐year time period of our study. Indeed, the level of disturbance in a catchment could explain less than 3% of the variation in assemblage structure, although a slight increase in the catches of white sucker Catostomus commersoni and a greater proportion of small individuals in white sucker populations may have reflected a modest enrichment effect in burned lakes. Current levels of landscape disturbance on the Boreal Plains appear to have minimal effects on lake fish assemblages but, because of the susceptibility of these lakes to winterkill, higher levels of terrestrial disturbance could prove detrimental.

Effects of Forest Fire on Young-of-the-year Northern Pike, <em>Esox lucius</em>, in the Northwest Territories

“…Recent literature on the effect of forest fires on lacustrine environments have focused on contaminants transfer (Allen et al 2005;Garcia and Carignan 2005;Kelly et al 2006) and fish-community interactions (St-Onge and Magnan 2000; Tonn et al 2003;. No specific information exists on the effects of forest fire on spawning and rearing Northern Pike, or their habitats in the Northwest Territories (NWT).…”

Impacts des coupes forestières sur l'alimentation de l'omble de fontaine (Salvelinus fontinalis) et la structure trophique de lacs en forêt boréale /

“…A lower proportion of small yellow perch {Perca flavescens) and white sucker (Catostornus commersoni) is associated with treated lakes (StOnge and Magnan 2000). Fish productivity and 1 + yellow perch growth seemed to remain almost unchanged after logging (Tonn et al 2003). An increase in young-of-the-year yellow perch abundance in response of higher DOC concentrations has been noticed in treated lakes (Bertolo and Magnan 2007).…”

Effects of Climate, Limnological Features and Watershed Clearcut Logging on Long-Term Variation in Zooplankton Communities of Boreal Shield Lakes

“…Generally, the impacts of watershed logging on water quality of boreal lakes are enhanced by high precipitation and runoff [12]. However, most of these impacts are short-term (<3 years) and have subtle bottom-up effects on zooplankton [12,17,[21][22][23] and fish communities [24][25][26][27][28]. A slight increase in crustacean zooplankton density has been observed in Finnish lakes after watershed logging [18,29].…”

“…Scaling up in food webs, post-harvest enhancements in nutrients, and dissolved organic carbon likely favor early growth of yellow perch due to better feeding conditions on zooplankton prey [28,30], only slightly affect littoral fish [25], and do not influence the habitat of the lake trout [24] in Boreal Shield lakes. Watershed logging increases the depletion of oxygen under ice cover in shallow lakes of the Boreal Plain and can enhance fish winterkill [27].…”