Effects of Different Silvicultural Canopy-Gap Sizes on Soil Respiration and Red Spruce Regeneration at Roan Mountain, North Carolina

Thomas Hennessey^1,* and Beverly Collins¹

¹Department of Biology, Western Carolina University, Cullowhee, NC, 28723. *Corresponding author.

Southeastern Naturalist, Volume 23, Issue 1 (2024): 67–83

First published early online: 16 February 2024

Abstract
We measured soil CO₂ efflux in scarified and unscarified soil collars, soil temperature and moisture, and seedling mortality from June through October 2021 under intact canopy, in single-tree canopy gaps, and in multi-tree canopy gaps in a Picea rubens (Red Spruce) and Abies fraseri (Fraser Fir) stand at Roan Mountain, NC, to test whether canopy openings or soil disturbance created conditions that enhanced or inhibited seedling regeneration or soil activity. We measured soil CO₂ efflux, soil temperature, and soil moisture weekly and tracked seedling survival at 3 time points. Gap size alone did not significantly affect observed differences in soil CO₂ efflux but interacted significantly with soil scarification: edges of large gaps had significantly higher efflux (by about 0.7 μmol CO₂ m⁻² s⁻¹ on average) than centers of large gaps when soil was scarified. In general, gap creation did not affect seedling mortality, scarification suppressed soil CO₂ efflux, and large gaps had a negative effect on soil CO₂ efflux that diminished toward the gap edge. Though longer-time-scale monitoring will be required for definite management suggestions or conclusions regarding soil processes and carbon storage, the effects on soil temperature, soil moisture, and soil CO₂ efflux produced by the gaps did not cause short-term negative effects on seedlings.

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