Soil carbon pools and fluxes following the regreening of a mining and smelting degraded landscape

• Published in: The Science of the total environment Vol. 904; p. 166734
• Main Authors: Levasseur, Patrick A., Aherne, Julian, Basiliko, Nathan, Emilson, Erik J.S., Preston, Michael D., Sager, Eric P.S., Watmough, Shaun A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.12.2023
• Subjects: Canada; canopy; carbon; chronosequences; ecosystems; environment; Erosion; fine roots; Forest floor; forest litter; forest soils; forests; Jack pine; landscapes; Litter decomposition; mineral soils; Pinus banksiana; Pinus resinosa; Red pine; root growth; soil carbon; Soil respiration; soil temperature; stand age; trees; Canada; Jack pine; Litter decomposition; Soil respiration; Red pine; Erosion; Forest floor
• DOI: 10.1016/j.scitotenv.2023.166734
• ISSN: 0048-9697; 1879-1026

Increasing forest cover by regreening mining and smelting degraded landscapes provides an opportunity for global carbon (C) sequestration, however, the reported effects of regreening on soil C processes are mixed. One of the world's largest regreening programs is in the City of Greater Sudbury, Canada and has been ongoing since 1978. Prior to regreening, soils in the City of Greater Sudbury area were highly eroded, acidic, rich in metals, and poor in nutrients. This study used a chronosequence approach to investigate how forest soil C pools and fluxes have changed with stand age in highly “eroded” sites with minimal soil cover (n = 6) and “stable” sites covered by soil (n = 6). Encouragingly, the relationship between stand age and soil C processes (litterfall, litter decomposition, soil respiration, fine root growth) at both stable and eroded sites were comparable to observations reported for jack pine (Pinus banksiana Lamb.) and red pine (Pinus resinosa Ait.) plantations that have not been subject to over a century of industrial impacts. There was a strong “home-field advantage” for local decomposers, where litter decomposition rates were higher using a site-specific pine litter compared with a common pine litter. Higher soil respiration at eroded sites was linked to higher soil temperature, likely because of a more open tree canopy. Forest floor C pools increased with stand age while mineral soil C and aggregate C concentrations decreased with stand age. This loss of soil C is small relative to the substantial increases in aboveground tree and forest floor C pools, leading to a sizeable increase in total ecosystem C pools following regreening. [Display omitted] •Regreening degraded land improves tree growth but effect on soil carbon is unclear.•Soil carbon fluxes at regreening sites were similar to “healthy” pine plantations.•Decomposers have a “home-field advantage” as site-specific litter decomposed faster.•Total and aggregate mineral soil carbon concentrations decreased with stand age.•Ecosystem carbon increased due to large increases in forest floor and tree carbon.