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

Abstract

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.

The Effects of Organic Mulches on Water Erosion Control for Skid Trails in the Hyrcanian Mixed Forests

“…Numerous studies have confirmed that soil erosion in skid trails was at its highest rate in the first years after machine traffic events and then decreased significantly, primarily due to vegetation regrowth [8,44,45]. For example, Boggs et al [46] studied the effect of forest harvesting on water quantity and quality in North Carolina, USA, and showed that the amount of sediment as well as the amount of nitrate in the water reached its maximum value two years after harvesting, and then its value decreased, probably as a consequence of the regrowth of tree and understory vegetation. Also, in Canada, Glaz et al [47] investigated the effect of forest harvesting on the water quality of lakes near harvested forests, and showed a significant difference in the amount of phosphorus in the control and logged samples one year after disturbance.…”

Terrestrial diet influences mercury bioaccumulation in zooplankton and macroinvertebrates in lakes with differing dissolved organic carbon concentrations

“…Increasing DOC concentrations derived from terrestrial sources can themselves potentially increase Hg bioaccumulation in estuarine ecosystem food webs (French et al, 2014;Jonsson et al, 2014;Jonsson et al, 2017). This is also relevant in boreal ecosystems as common forest harvest activities can enhance terrestrial OM input to lake (Meunier et al, 2016), resulting in increased DOC concentrations (O'Driscoll et al, 2006;Glaz et al, 2015), and sometimes higher Hg and/or MeHg input from terrestrial to aquatic ecosystems (Eklöf et al, 2013;Kronberg et al, 2016). This can increase Hg bioaccumulation in food webs (Bishop et al, 2009;Hongve et al, 2012;Wu et al, 2018).…”