Forest Management Potential Recolonization Benefits of Retention Forestry Practices

Tree retention after forest harvest is often used to enhance biodiversity in forests that are otherwise managed using even-aged systems. It remains unclear to what extent scattered trees and residual patches (i.e., retained structures) actually facilitate recolonization of species in logged areas. For assessing recolonization benefits, it is necessary to consider both survival in retained structures postharvest and recolonization in cleared areas. We conducted a literature review to assess recolonization responses of birds, mammals, reptiles, amphibians, vascular plants, invertebrates, lichens/bryophytes, and mycorrhizal fungi. The clearest benefits of retention were for poorly dispersing plants. Seed dispersal type may be a key life-history trait relative to effectiveness of recolonization, with animal-dispersed seeds having the greatest dispersal range. We found that lichens/bryophytes are likely not dispersal limited (with possible exceptions) but are slow growing and require the development of moist microsite conditions. Significant literature gaps exist for amphibians, nonvolant invertebrates, and mycorrhizal fungi. Overall, recolonization success postharvest is taxon specific, where the benefits of implementing retention systems will depend on the region and species within that region. Species that require a long growth period (some lichens) or are poor dispersers (some herbaceous species) may benefit more from the creation of forest reserves than from retention practices.