Long-term effects of silviculture on soil carbon storage: does vegetation control make a difference?

Abstract

Forests and the soils beneath them are Earth’s largest terrestrial sinks for atmospheric carbon (C) and healthy forests provide a partial check against atmospheric rises in CO₂. Consequently, there is global interest in crediting forest managers who enhance C retention. Interest centres on C acquisition and storage in trees. Less is directed to understorey management practices that affect early forest development. Even less is paid to the largest ecosystem reservoir of all – the mineral soil. Understorey vegetation control is a common management practice to boost stand growth, but the consequence of this on ecosystem C storage is poorly understood. We addressed this by pooling data from five independent groups of long-term studies in the western US. Understorey control increased overstorey biomass universally, but C contents of the forest floor and top 30 cm of mineral soil largely were unaffected. Net soil C increment averaged 1.3 Mg C ha^-1 year^-1 in the first decade. We conclude that soil C storage is not affected adversely by vegetation management in forests under a Mediterranean climate. However, understorey shrubs can profoundly affect stand susceptibility to wildfire. We propose that C accounting systems be strengthened by assessing understorey management practices relative to wildfire risk.

Citation

Powers, Robert F.; Busse, Matt D.; McFarlane, Karis J.; Zhang, Jianwei; Young, David H. 2012. Long-term effects of silviculture on soil carbon storage: does vegetation control make a difference? Forestry. doi:10.1093/forestry/cps067.