Articles | Volume 12, issue 23
Biogeosciences, 12, 6999–7011, 2015
Biogeosciences, 12, 6999–7011, 2015

Research article 07 Dec 2015

Research article | 07 Dec 2015

Impact of forest harvesting on water quality and fluorescence characteristics of dissolved organic matter in eastern Canadian Boreal Shield lakes in summer

P. Glaz1, J.-P. Gagné2, P. Archambault2, P. Sirois3, and C. Nozais1 P. Glaz et al.
  • 1Département de biologie, chimie et géographie, Université du Québec à Rimouski, Rimouski (QC), Canada
  • 2Institut des sciences de la mer de Rimouski, Université du Québec à Rimouski, Rimouski (QC), Canada
  • 3Chaire de recherche sur les espèces aquatiques exploitées, Laboratoire des sciences aquatiques, Département des sciences fondamentales, Université du Québec à Chicoutimi, Chicoutimi (QC), Canada

Abstract. Forestry activities in the Canadian Boreal region have increased in the last decades, raising concerns about their potential impact on aquatic ecosystems. Water quality and fluorescence characteristics of dissolved organic matter (DOM) were measured over a 3-year period in eight eastern Boreal Shield lakes: four lakes were studied before, 1 and 2 years after forest harvesting (perturbed lakes) and compared with four undisturbed reference lakes (unperturbed lakes) sampled at the same time. ANOVAs showed a significant increase in total phosphorus (TP) in perturbed lakes when the three sampling dates were considered and in DOC concentrations when considering 1 year before and 1 year after the perturbation only. At 1 year post-clear cutting DOC concentrations were about 15 % greater in the perturbed lakes at ~ 15 mgC L−1 compared to 12.5 mgC L−1 in the unperturbed lakes. In contrast, absorbance and fluorescence measurements showed that all metrics remained within narrow ranges compared to the range observed in natural waters, indicating that forest harvesting did not affect the nature of DOM characterized with spectroscopic techniques. These results confirm an impact of forestry activities 1 year after the perturbation. However, this effect seems to be mitigated 2 years after, indicating that the system shows high resilience and may be able to return to its original condition in terms of water quality parameters assessed in this study.

Short summary
In this study, we showed that logging activities have a short-term impact (1 year after the perturbation) on water quality in boreal Eastern Canadian Shield lakes. However, this effect seems to mitigate 2 years after the perturbation. Further, the analysis of the absorbance and fluorescence data showed that while DOC concentrations did significantly increase in perturbed lakes, the DOM quality did not measurably change.
Final-revised paper