|Abstract or Summary
- The interactive impact of overstory canopy closure, understory brush control, and simulated white-tailed deer
(Odocoileus virginianus Zimmermann) herbivory (i.e., clipping) on growth and survival of underplanted white pine (Pinus strobus L.) seedlings was examined. Clipping was conducted in April 1996 and 1997 at three intensities (control, 0% previous year’s growth removed; lightly clipped, terminal and 50% previous year’s growth removed, and heavily clipped: 100% of previous-year’s growth removed) and three frequencies (never clipped, clipped once, clipped 2 years in a row). Decreasing overstory canopy closure and brush competition generally increased growth of seedlings
under all clipping regimes, with heavily clipped seedlings showing the least benefit of reduced competition. Although
first-year height growth was stimulated after light-intensity clipping, this effect did not persist the following year, and
these trees still were significantly shorter than controls at the end of the experiment. Diameter growth was reduced at
any clipping intensity or frequency, and remained below controls throughout the experiment. Seedling mortality was higher without brush control and after clipping. Results suggest that increased overstory and understory competition reduced seedling growth and survival. In regards to clipping, initial height growth stimulation may result from (i) resource reallocation away from diameter and root growth and (or) (ii) hormonal redistributions from loss of apical control in the seedling. Since both high competition levels and increased herbivory reduced seedling vigor, we suggest that understory brush control and deer protection (e.g., budcapping) go hand in hand to regenerate white pine.