Forest Ecology and Management 469 (2020) 118132 Contents lists available at ScienceDirect Forest Ecology and Management journal homepage: www.elsevier.com/locate/foreco Disturbance-based silviculture for habitat diversification: Effects on forest T structure, dynamics, and carbon storage ⁎ Dominik Thoma,b,c,d, William S. Keetona,b, a Rubenstein School of Environment and Natural Resources, University of Vermont, 81 Carrigan Drive, Burlington, VT 05405, USA b Gund Institute for Environment, University of Vermont, 617 Main Street, Burlington, VT 05405, USA c Institute of Silviculture, Department of Forest- and Soil Sciences, University of Natural Resources and Life Sciences (BOKU) Vienna, Peter-Jordan-Straße 82, 1190 Vienna, Austria d Ecosystem Dynamics and Forest Management Group, School of Life Sciences, Technical University of Munich, Hans-Carl-von-Carlowitz-Platz 2, 85354 Freising, Germany ARTICLE INFO ABSTRACT Keywords: Disturbance-based silviculture is of increasing interest as an approach to provide multiple ecosystem services and Silviculture with Birds in Mind beta diversity in habitat conditions. One such approach increasingly employed in the eastern U.S. is a set of CARBON storage forestry practices developed to diversify forested bird habitats, called Silviculture with Birds in Mind (SBM). Disturbance-based forestry While strongly appealing to many private landowners, empirical data have not yet been reported regarding the Forest management effects of SBM treatments on forest structure and dynamics and how they compare to natural disturbances. Forest structure Moreover, the potential of bird-oriented silviculture like SBM to enhance co-benefits, for instance, by retaining Habitat Beta diversity high carbon stocks in managed forests, has not been investigated. The objectives of our study were thus (i) to Silviculture analyze the effects of SBM treatments on forests and compare them with natural disturbances, and (ii)toassess Wind disturbance the co-benefits of multiple habitat indicators and carbon storage within three years of silvicultural treatmentin 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 Bayesianmodels 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 in- termediate-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 be- come 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. 1. Introduction ‘disturbance-based’, ‘nature-oriented’, ‘ecological’, ‘close-to-nature’, ‘multi-functional’ or ‘retention’ forestry (Puettmann et al., 2015), share Recent decades have witnessed growing interest in the development the objective of perpetuating the full range of stand scale structures and of silvicultural approaches designed to mimic natural disturbances in landscape patterns which organisms require, assuming adaptation to many parts of the world (Brang et al., 2014; Franklin et al., 2007; the natural disturbance regimes driving stand and landscape dynamics Seymour et al., 2002). These approaches, often referred to as (Franklin et al., 2007). A further goal is to provide a broader array of ⁎ Corresponding author at: Rubenstein School of Environment and Natural Resources, University of Vermont, 81 Carrigan Drive, Burlington, VT 05405, USA. E-mail address: [email protected] (W.S. Keeton). https://doi.org/10.1016/j.foreco.2020.118132 Received 11 December 2019; Received in revised form 31 March 2020; Accepted 1 April 2020 0378-1127/ © 2020 Elsevier B.V. All rights reserved. D. Thom and W.S. Keeton Forest Ecology and Management 469 (2020) 118132 habitat conditions and ecosystem services than may be associated with breeding population in the region; and (iv) are relatively easy to practices, such as short rotation industrial forestry or over reliance on identify by non-professional observers. Habitat conditions supporting even-aged management, that tend to simplify and homogenize stand feeding and breeding of different species include, for instance, irregu- and landscape structures (Kuuluvainen and Grenfell, 2012; Puettmann larly sized and structured canopy gaps with early successional vegeta- and Tappeiner, 2014). Some disturbance-based silvicultural systems tion (e.g., American woodcock (Scolopax minor [Gmel.])), tall trees were specifically designed to encourage both stand structural com- (e.g., scarlet tanager (Piranga olivacea [Gmel.])), and downed (e.g., plexity and landscape patch diversity (Keeton, 2006; Bauhus et al., Canada warbler (Cardellina canadensis [L.])) and standing deadwood 2009; Stanturf et al., 2014). These approaches have great potential to (e.g., yellow-bellied sapsucker (Sphyrapicus varius [L.])) (Hagenbuch balance the interests of society in biodiversity and the supply of mul- et al., 2012). SBM treatments have been designed to collectively create tiple ecosystem services. For instance, management for structural these habitat conditions by mimicking disturbances of different seve- complexity in mixed northern hardwood forests of eastern North rities and sizes. America has been found to increase elements of late-successional bio- Some of the silvicultural approaches investigated here, such as diversity (Dove and Keeton, 2015; Gottesman and Keeton, 2017; variable density thinning (in SBM termed “variable retention thinning” McKenny et al., 2006) and carbon storage (Ford and Keeton, 2017) or VRT), have been employed in many different forest systems in North while, at the same time, providing wood products from timber harvests America (Carey, 2003; Stanturf et al., 2014), but have been poorly (Nunery and Keeton, 2010). studied in the eastern U.S. Others are better understood in terms of Disturbance-based approaches have struggled to gain traction implications for long-term stand development trajectories (see, for ex- within the forestry community in the eastern United States (Fahey ample, Halpin et al., 2017) but have not been assessed relative to other et al., 2018). However, recently interest has developed around silvi- disturbance based approaches. Though the subject of on-going mon- cultural approaches specifically tailored to promote a diversity of bird itoring, effects of the SBM treatments on bird populations are still lar- habitats (Sallabanks and Arnett, 2005), reflecting the nation-wide in- gely uncertain. Stand improvement thinning, a variant of one of the terest among non-industrial private landowners in birds as a primary SBM treatments, was successful at fostering songbird occupancy and motivation for owning forestland (Butler et al., 2007). A leading ex- abundance (Rankin and Perlut, 2015). In addition, Nareff et al. (2019) ample is a set of approaches collectively called Silviculture with Birds in found that territory densities and population abundances for Cerulean Mind (SBM), currently being demonstrated on a variety of ownerships Warblers responded positively to a range of retention-based, bird-or- in northeastern North America (Hagenbuch et al., 2012). Variants of iented silvicultural practices in Central Appalachian hardwoods. How- SBM are under development for other regions of North America as well, ever, the success of bird-oriented treatments at emulating natural dis- such as the U.S. Southeast and Pacific Northwest (see, for example, turbances, and their ability to achieve management objectives other Wood et al., 2013). In the Northeast, six innovative silvicultural treat- than bird habitat, have not been previously assessed. This also holds ments adapted to three stand development conditions have been pro- true for associations between silviculturally enhanced bird habitat di- moted, of which five had been implemented at the time of this study. versity and ecosystem services such as carbon storage. The treatments are largely based on disturbance-oriented concepts (see In this study, we quantify the co-benefits of disturbance-based Frelich and Lorimer, 1991; Seymour et al., 2002; Keeton, 2006; treatments oriented towards birds in terms of their effects on habitat Franklin et al., 2007), such as gap creation, legacy tree retention, conditions, stand structure associated with natural disturbance impacts, variable density thinning, and dead wood enhancement, and are ap- and carbon storage,