Boreal Subarctic Lake Water Quality, Zooplankton Communities, and Benthic Macroinvertebrate Communities in Areas Impacted by Wildfire

Wildfires are a natural phenomenon in the boreal forest, but recent studies suggest that there will be increases in the frequency and severity of fires in this region over the next century. When wildfires occur in lake catchments, they may affect water quality and invertebrate communities living in associated lakes. Invertebrates, including zooplankton and benthic invertebrates, play important roles in aquatic food webs, acting as conduits of energy from primary producers to larger organisms such as fish and water birds. Therefore, it is important to understand how these groups will respond to changes caused by fires. Unfortunately, few studies have been conducted in the northern boreal forest to examine how wildfires might impact lakes in this region. For my thesis, I collected data on water quality, macrophytes, zooplankton, and benthic invertebrates from 20 lakes in the Sahtú Settlement Area of the Northwest Territories, which has been impacted by recent fires. Nine of these lakes were affected by fires in their catchments 4-5 years prior to data collection, while eleven were not. My results showed that surprisingly few water quality variables were related to burn history, but lake colour and phenols were higher in lakes affected by burns, and pH and dissolved oxygen were lower in those lakes. Remote sensing data suggest that macrophyte biomass could have increased in lakes affected by burns following the 2014 fires, and macrophyte biomass was an important predictor of community composition for both zooplankton and benthic macroinvertebrates. In addition, burn history was an important predictor of zooplankton richness, and benthic macroinvertebrate richness and abundance. However, my analyses also revealed that natural variability in catchment and lake properties was more important for explaining differences in invertebrate communities among lakes than the effects of wildfires. Overall, my results suggest that shifts in the lake water quality and biology are still detectable 4-5 years after burns in their catchments, suggesting that increased frequency and severity of burns in the north could have long-term impacts on boreal lakes

Boreal Subarctic Lake Water Quality, Zooplankton Communities, and Benthic Macroinvertebrate Communities in Areas Impacted by Wildfire

Wildfires are a natural phenomenon in the boreal forest, but recent studies suggest that there will be increases in the frequency and severity of fires in this region over the next century. When wildfires occur in lake catchments, they may affect water quality and invertebrate communities living in associated lakes. Invertebrates, including zooplankton and benthic invertebrates, play important roles in aquatic food webs, acting as conduits of energy from primary producers to larger organisms such as fish and water birds. Therefore, it is important to understand how these groups will respond to changes caused by fires. Unfortunately, few studies have been conducted in the northern boreal forest to examine how wildfires might impact lakes in this region. For my thesis, I collected data on water quality, macrophytes, zooplankton, and benthic invertebrates from 20 lakes in the Sahtú Settlement Area of the Northwest Territories, which has been impacted by recent fires. Nine of these lakes were affected by fires in their catchments 4-5 years prior to data collection, while eleven were not. My results showed that surprisingly few water quality variables were related to burn history, but lake colour and phenols were higher in lakes affected by burns, and pH and dissolved oxygen were lower in those lakes. Remote sensing data suggest that macrophyte biomass could have increased in lakes affected by burns following the 2014 fires, and macrophyte biomass was an important predictor of community composition for both zooplankton and benthic macroinvertebrates. In addition, burn history was an important predictor of zooplankton richness, and benthic macroinvertebrate richness and abundance. However, my analyses also revealed that natural variability in catchment and lake properties was more important for explaining differences in invertebrate communities among lakes than the effects of wildfires. Overall, my results suggest that shifts in the lake water quality and biology are still detectable 4-5 years after burns in their catchments, suggesting that increased frequency and severity of burns in the north could have long-term impacts on boreal lakes

Development of integrated ecological standards of sustainable forest management at an operational scale

Within Canada, and internationally, an increasing demand that forests be managed to maintain all resources has led to the development of criteria and indicators of sustainable forest management. There is, however, a lack of understanding, at an operational scale, how to evaluate and compare forest management activities to ensure the sustainability of all resources. For example, nationally, many of the existing indicators are too broad to be used directly at a local scale of forest management; provincially, regulations are often too prescriptive and rigid to allow for adaptive management; and forest certification programs, often based largely on public or stake-holder opinion instead of scientific understanding, may be too local in nature to permit a comparison of operations across a biome. At an operational scale indicators must be relevant to forest activities and ecologically integrated. In order to aid decision-makers in the adaptive management necessary for sustainable forest management, two types of indicators are identified: those that are prescriptive to aid in planning forest management and those that are evaluative to be used in monitoring and suggesting improvements. An integrated approach to developing standards based on an ecosystem management paradigm is outlined for the boreal forest where the variability inherent in natural systems is used to define the limits within which forest management is ecologically sustainable. Sustainability thresholds are thus defined by ecosystem response after natural disturbances. For this exercise, standards are proposed for biodiversity, forest productivity via regeneration, soil conservation and aquatic resources. For each of these standards, planning indicators are developed for managing forest conditions while forest values are evaluated by environmental indicators, thus leading to a continuous cycle of improvement. Approaches to developing critical thresholds and corresponding prescriptions are also outlined. In all cases, the scale of evaluation is clearly related to the landscape (or FMU) level while the stand level is used for measurement purposes. In this view the forest should be managed as a whole even though forest interventions are usually undertaken at the stand level

The effects of a forest fires on water flow and quality in lakes surrounding a Northern Ontario mine

Water quality and quantity can be greatly impacted following a forest fire, but fire impacts can vary based on fire intensity, watershed topography, and post-fire precipitation events. Forest fires are an important contributor to the natural regeneration of forests. Watershed monitoring is important for gaining a greater understanding of forest fire impacts on water resources, thus helping to improve interpretations of overall fire effects. The aim of this study was to reveal fire disturbance impacts on water quality characteristics surrounding a mine site. The forest fire likely resulted in increases in dissolved organic carbon and ammonia concentrations, especially downstream of the mine site. However, no increased metal concentrations occurred after the fire. Increased flows and frequency of peak flow events in the watershed following the fire did occur, which can impact water quality in ways that were not measured

Riparian vegetation patterns and links with surface waters in the boreal forest

Riparian areas in the Canadian boreal forest represent the transition zone between terrestrial and aquatic ecosystems. Factors that influence riparian vegetation communities and the associated interactions with boreal streams were reviewed. Regional and local drivers (e.g., climate and site hydrology) that affect upland boreal vegetation also operate in riparian areas. However, the proximity of riparian areas to the stream channel not only modifies some of these drivers, but it means that the stream itself becomes a driver of riparian vegetation dynamics. For example, hydrological disturbances like flooding and ice scour affect soil texture and alter successional pathways, sometimes completely denuding streambanks of vegetation. Even in riparian areas unaffected by such catastrophic disturbances, saturated soil conditions can influence riparian forest composition and nutrient cycling

Étude Before-After Control-Impact (BACI) sur les effets des coupes forestières sur la biomasse et la structure en taille du zooplancton des lacs de l'écozone boréale au Québec

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal

Impact des coupes forestières sur l'alimentation et la croissance de l'omble de fontaine (Salvelinus fontinalis) dans des lacs du Bouclier boréal canadien

La récolte forestière modifie les écosystèmes terrestres, mais a également un effet indirect sur les écosystèmes aquatiques. Jusqu'à maintenant, beaucoup d'études ont examiné l'impact des coupes forestières sur les écosystèmes lotiques. Toutefois, les effets sur les milieux lacustres et la faune ichtyenne ont été moins étudiés. De ce fait, il est très important de documenter davantage les impacts des coupes forestières afin de mieux comprendre leurs effets sur les espèces piscicoles en lac. Ces connaissances sont nécessaires pour permettre aux compagnies forestières et aux gouvernements d'améliorer la gestion de cette ressource renouvelable, tout en assurant aux pêcheurs sportifs de bénéficier d'une bonne qualité de pêche dans les zones d'exploitation forestière. L'objectif de cette étude était de déterminer les impacts à court terme des coupes forestières sur l'alimentation et la croissance de l'omble de fontaine (Salvelimis fontinalis) dans les lacs oligotrophes du Bouclier boréal canadien. Pour atteindre cet objectif, des ombles ont été capturés au cours de trois années (juillet 2008-2010), dans quatre lacs dont le bassin versant n'avait subi aucune perturbation et dans quatre lacs perturbés par les coupes forestières après la première année. Afin de vérifier l'effet d'une telle perturbation environnementale sur la diète du salmonidé, l'analyse des contenus stomacaux a été effectuée. Ces analyses n'ont pas permis de déceler des changements quant aux assemblages, aux indices de diversités et l'abondance des types de proies dans l'alimentation des individus âgées de 3 et 4 ans + capturés-suite à la récolte forestière. La variabilité entre les lacs est plus importante que celle attribuable aux coupes forestières. Les otolithes ont été utilisés pour mesurer la croissance chez les ombles de fontaine âgés de trois et quatre ans. Les récoltes forestières n'ont provoqué aucune modification des taux de croissance. Finalement, les résultats suggèrent que malgré une augmentation en phosphore total et en carbone organique dissous dans les lacs perturbés par la coupe forestière, aucune différence n'a été détectée dans l'alimentation et la croissance des ombles de fontaine. Cette étude supporte l'hypothèse selon laquelle l'effet des coupes forestières est dilué chez les espèces situées au sommet du réseau trophique comme l'omble de fontaine adulte dans les lacs de la forêt boréale

Effects of shoreline logging on the epilithic algal community in small Canadian Shield lakes with logged catchments

Study area : Coldwater Lakes experimental watersheds area within the boreal-Great Lakes transition forest on the Precambrian shield 200 km northwest of Thunder Bay and 70 km northwest of Atikokan, northwestern Ontario. Lakes L26, L39 and L42. Chlorophyll 'a' was used to index algal biomass ; carbon, nitrogen and phosphorus were used to measure nutritional status, and community characteristics were evaluated using areal densities of taxonomic classes. Littoral zones were described using water turbulence index, littoral wind measurements, and mass measurements of epilithic material, etc.Chlorophyll a, nutritional status and community characteristics of epilithic algae in littoral zones of three small Canadian Shield lakes with logged watersheds were assessed. Sites were chosen with different shoreline treatments, logged or unlogged shoreline forest, to estimate impacts of shoreline logging on epilithic algal communities. All three lakes had logged watersheds, and L42 and L39 had experienced some shoreline logging. No shoreline logging had been done on L26, but two sites were used with characteristics similar to logged and unlogged shoreline forest. Chlorophyll a (chi a) was used to index algal biomass; carbon (C), nitrogen (N) and phosphorus (P) were used to measure nutritional status; and, community characteristics were evaluated using areal densities of taxonomic classes. Littoral zones were described using a water turbulence index and littoral wind measurements, mass measurements of epilithic material including organic and inorganic components and changes in light (theoretical) and tem perature (actual) environments following shoreline logging. The only significant differences in measured variables were found at sites in L39, with higher levels of total and organic material, chi a, C and N at the site with logged shoreline forest. Further, Chlorophyceae, Bacillariophyceae, Xanthophyceae and Dinophyceae were higher and Cyanophyceae were lower in L39 a t the site with logged shoreline forest. No differences were found between treatment sites in L42, or between sites in L26. Differences found in L39 may have been due more to inter-site variation than to shoreline logging. Overall, data did not show evidence of impacts to epilithic algal communities or littoral environments from shoreline logging, however, results were not conclusive given the preliminary nature and short time-span of the study