How do natural disturbances and human activities affect soils and tree nutrition and growth in the Canadian boreal forest?

Abstract

There are concerns about the effect of increasing resource extraction and other human activities on the soils and vegetation of the boreal zone. The review covers published papers between 1974 and 2012 to assess the effects of natural disturbances and human activities on soils and tree nutrition and growth of the Canadian boreal zone. Changes in soil and foliar nutrients following disturbance were also analyzed by meta-analysis. When sufficient replicated studies were not available for a given disturbance or nutrient, response assessments or narrative summaries are presented. The majority of fertilization studies in the boreal zone showed a positive tree growth response to nitrogen (N) and phosphorus (P) fertilization either individually or in combination. Large amounts of N may be lost through volatilization following fire depending on the severity and frequency of the fire. This may contribute to N limitation in the boreal zone. Available soil P and extractable calcium (Ca) and magnesium (Mg) increased in the surface horizons following fire. In contrast, extractable P decreased following harvest. Harvesting had no effect on total or inorganic N except in mixedwoods where total N decreased in the surface organic horizon following harvest. These are potential areas of concern given tree growth responses to N and P fertilization. Potassium (K) in the forest floor did not change following fire or harvesting; thus, K availability for tree nutrition should not be at risk, since its cycle is rapidly restored. Mercury (Hg) cycling may be altered in the boreal zone as a result of flooding and if fire return intervals and intensities increase. Interactions of multiple disturbances may increase the risk of nutrient depletions, but there is currently little information on these interactions in the boreal zone. Evidence to date suggests the soils of the Canadian boreal zone have not been adversely affected except in localized areas. However, there is the risk of nutrient loss if soils are not considered in our forest management strategies, particularly where multiple disturbances may interact. The potential for off-site movement of nutrients and contaminants into the atmospheric and aquatic ecosystems, in addition to on-site environmental issues, is also a concern.

Impacts and prognosis of natural resource development on water and wetlands in Canada’s boreal zone

“…The surficial deposits of the boreal zone are generally dominated by glacial till blanket and veneer, with glaciolacustrine deposits distributed throughout and glaciomarine deposits surrounding the Hudsons Bay Lowlands (Fulton 1995). The soils overlying these deposits vary substantially across the boreal zone (see Maynard et al 2014).…”

Ecosystem management in paludified boreal forests: enhancing wood production, biodiversity, and carbon sequestration at the landscape level

“…Simard et al (2001) found that in the black spruce forest of the Clay Belt, soil burns reduced organic carbon content compared to logging. Nitrogen losses (especially through volatilization) have been frequently reported in various ecosystems (e.g., Johnson and Curtis 2001;Wan et al 2001;Boerner et al 2009;Nave et al 2011;Maynard et al 2014), and several studies have shown that base cation (i.e. K + , Ca ++ , Mg ++ ) concentrations are usually higher in the forest floor following fire than after logging Thiffault et al 2007).…”

Reclamation of boreal forest after oil sands mining: anticipating novel challenges in novel environments

“…), and tamarack (Larix laricina (Du Roi) K. Koch) (Beckingham and Archibald 1996). Biodiversity patterns and biogeochemical cycles are shaped by the region's subhumid and subarctic climate, its predominant brunisol and luvisol soils, and the occurrence and distribution of natural (i.e., wildfire) and anthropogenic disturbances (i.e., logging) (Bergeron et al 2002;Brandt et al 2012;Kishchuk et al 2015;Maynard et al 2013).…”