Impacts of partial cuts on aboveground carbon stocks in esker forests

The impacts of partial cuts on carbon stocks remain uncertain due to elevated post-harvest windthrow mortality that may counteract the positive effects of thinning on stand growth. This study evaluated the effects of partial cuts and tree mortality on aboveground carbon stocks eight years after harvest in jack pine forests. The experimental design included 24 sites with varying harvest intensities: unharvested control, moderate (30–35 %), and heavy (40–50 %) thinnings. Dendrochronological analyses and allometric equations were used to quantify carbon in live and dead biomass (snags, broken, and uprooted trees). Increases in individual tree carbon stocks between the pre-harvest year and the eighth year post-harvest were lower in controls and similar among partial cut treatments. Eight years after harvest, live carbon stocks per hectare were 41 % lower in the heavy thinning than in unharvested stands but remained similar between moderate thinning and control treatments. Larger trees and those growing closer to skidding trails showed greater increases in carbon stock, with the latter exhibiting a 33 % higher increase on average. Mean total deadwood carbon stocks were 55 % higher in the control than in the partial cuts due to reduced snag carbon in harvested stands. Uprooting was influenced by harvest treatment and proximity to skidding trails, while stem breakage was driven by tree characteristics (height, age, and competition) and distance to trails. The proportion of snags was explained by mean annual wind speed. These findings suggest that moderate thinning could sustain forest carbon stocks with prescriptions aiming at maintaining snag carbon stocks. • Moderate thinning maintained live aboveground carbon stocks. • Tree carbon stock increases were greater under partial cut stands. • Larger trees and those near skidding trails showed greater carbon stock increases. • Partial cuts altered mortality patterns and reduced deadwood carbon stocks. • Mortality drivers differed among uprooted, broken, and snag trees.