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The Center for Native Grasslands Management

Title: Factors influencing vegetation and avian species responses to oak savanna restoration in the Mid-South
Year: 2010
Author(s): Barrioz, S., Keyser, P., Harper, C., Buehler, D., Buckley, D.
Source Title:
Source Type: Proceedings
pages: 40
Original Publication:  
Abstract: Oak savannas are among the most imperiled ecosystems in the United States as a result of land-use conversion, incompatible silviculture, and disrupted fire regimes. Consequently, associated vegetation and avian communities have also declined. Restoration of savanna communities may be an important strategy for conserving avian species that depend on early successional habitat, which is underrepresented on regional landscapes. Therefore, we evaluated savanna restoration strategies through a meta-analysis of twelve case studies in Tennessee and Kentucky. Specifically, we looked at factors influencing vegetation and avian response following mechanical overstory thinning and dormant‐season fire. We measured herbaceous and woody understory groundcover, and woody stem density. We conducted point counts to assess breeding bird use of the sites. Vegetation strata and breeding bird abundance were analyzed using hierarchical linear modeling. Total grass cover (0-74%) was negatively related to canopy cover (0-100%). Total forb cover (0‐56%) was negatively related to total basal area (0-40 m2/ha). Oak regeneration density (0-25 stems/m2) was positively related to canopy cover (0-100%). Grass and forb cover and herbaceous species richness were not related to topographic variables. With respect to breeding birds, forest species persisted within case studies that were two years post-disturbance. Only three grassland obligate bird species, Tyrannus tyrannus, Aimophila aestivalis and Spiza Americana, were observed on any sites. Presence of Passerina cyanea was positively related to ground layer development; whereas, Melanerpes erythrocephalus was positively related to basal area of dead trees. Based on our results, combinations of canopy reduction and late growing-season fire targeted at oak savanna restoration should be evaluated in future research.
Publisher: Proceedings of the Seventh Eastern Native Grass Symposium. Knoxville, TN, October 5-8, 2010
Editor(s): C. Harper