Disturbance-based silviculture for habitat diversification: Effects on forest structure, dynamics, and carbon storage

Abstract Disturbance-based silviculture is of increasing interest as an approach to provide multiple ecosystem services and beta diversity in habitat conditions. One such approach increasingly employed in the eastern U.S. is a set of forestry practices developed to diversify forested bird habitats, called Silviculture with Birds in Mind (SBM). While strongly appealing to many private landowners, empirical data have not yet been reported regarding the effects of SBM treatments on forest structure and dynamics and how they compare to natural disturbances. Moreover, the potential of bird-oriented silviculture like SBM to enhance co-benefits, for instance, by retaining high carbon stocks in managed forests, has not been investigated. The objectives of our study were thus (i) to analyze the effects of SBM treatments on forests and compare them with natural disturbances, and (ii) to assess the co-benefits of multiple habitat indicators and carbon storage within three years of silvicultural treatment in mature northern hardwood-conifer forests. We derived 14 stand structural variables as well as carbon storage from 217 SBM inventory plots, and compared them with the effects of intermediate-severity wind disturbance using non-metric multidimensional scaling (NMDS). Subsequently, we applied multi-hierarchical Bayesian models to investigate SBM treatment effects on aboveground carbon storage, as well as on four key habitat indicators. We also used Bayesian models to derive the relationships between habitat indicators and carbon storage. SBM treatments created a diversity of post-harvest stand conditions and, while having lower values for some structural characteristics in comparison to controls, significantly enhanced the variation in individual structural elements. Moreover, the treatments were closer in ordinal space to the irregular structure associated with intermediate-severity wind disturbance than untreated control plots. However, the NMDS indicated that SBM treatments did not fully approximate partial wind disturbances. Carbon storage was positively associated with stand structural complexity. Disturbance-based approaches like SBM help diversify habitat conditions and we expect these effects to become more pronounced as stands respond to the treatments over time. If applied more broadly, treatments targeted at diversifying habitats would also help maintain high carbon stocking at landscape scales. However, as the treatments do not fully emulate the region’s natural disturbance regime, we propose widening the portfolio of multi-cohort, retention, and gap-based silvicultural approaches in landscape-scale management.