Selective feeding of pine voles on roots of tree seedlings

Abstract

Previous studies have implicated numerous physical and biotic factors as contributing to the failure of oak to regenerate successfully throughout substantial portions of eastern North America. Recent field evidence in southern Indiana implicated belowground herbivory by pine voles ( Microtus pinetorum (LeConte, 1830)) as a potentially important but overlooked mortality agent for oak seedlings. We used cafeteria-style feeding trials to determine whether selection of hardwood seedlings by captive pine voles differed according to species or age. White oak ( Quercus alba L.) was selected more frequently and experienced a greater proportion of root removal by pine voles than same-age seedlings of the other four species tested. Yellow poplar ( Liriodendron tulipifera L.) was never eaten. White oak seedlings 3 and 6 weeks of age suffered proportionately greater root removal than conspecific seedlings 12 and 15 weeks of age; pine voles removed roughly constant levels of root biomass irrespective of seedling age. Our results confirm that pine voles selectively feed on oak seedlings. In areas where pine voles are abundant, belowground herbivory could limit regeneration of oak by reducing seedling growth and survival. The importance of pine voles as factors influencing the success of oak regeneration warrants closer scrutiny in future field studies.