How does forest fire affect water quality and invertebrates in subarctic lakes

Wildfire is one of the most impactful disturbances to Boreal water catchments where damaged forest vegetation increases runoff, erosion, organic material, and trace metals into water bodies. In 2014, severe megafires spread throughout the organic and mineral-rich peatlands of the Taiga Plains and Sahtú Settlement Area in Canada’s Northwest Territories (NWT), denuding watersheds for hundreds of small lakes. Lakes found in burned areas often experience large increases in nutrients which can have impacts on aquatic communities. To examine the impact of the 2014 fires on lakes in the NWT, biological data of zooplankton using a 64 µm mesh net (identified to genus), and benthic invertebrates using a 500 µm mesh D-net (identified and separated into functional feeding groups) were collected and enumerated from a mixture of 20 impacted and reference shallow lakes at three randomized sample stations per lake using a reference condition approach. Chlorophyll-a, conductivity, pH, and temperature were collected at each of the three stations and the centre of the lake. Surface sediment and soil samples were collected at each of the three random stations. Water chemistry and nutrients (TP, TN, DOC, and TOC) were collected through an integrated tube sampler in the centre of the lake. Physical attributes (surface area, watershed area, burned area, etc…) and macrophyte reflectance were obtained using satellite remote sensing. Sampling was conducted on August 2018/2019. A combination of Spearman correlations with the burned drainage ratio or hectares burned in the catchment/lake surface area (bDR), hierarchical partitioning, and multivariate analysis through principal component analysis and redundancy analysis was used to determine the physiochemical variables affected by forest fire and how these relate to biological differences in the lake ecosystems.

This data was collected to examine forest fire impact on water quality and invertebrates in subarctic lakes.

Taiga Plain
Sahtú Settlement Area
Northwest Territories