Performance of planted native seedlings in felled strips within <i>Pinus radiata</i> plantation forest
<p dir="ltr">Introduction: Exotic plantations could facilitate restoration of native forests. Canopy manipulation of plantations creates more favourable light conditions for establishment and growth of woody natives, which could become canopy trees and assume dominance over the plantation.</p><p dir="ltr">Objectives: To explore the influence of canopy gap creation and herbivore exclusion in Pinus plantation on planted seedlings of three native species.</p><p dir="ltr">Methods: We compared growth and survival of planted seedlings using a randomised split-plot block design with three replicates of strip harvesting treatments and an unharvested control in a mid-rotation (14-year-old) Pinus radiata plantation in the Hawke’s Bay region of New Zealand. Felled strips were 50 m long and of three widths (9 m, 18 m, and 27 m), the unharvested controls were 50 m × 9 m. Ungulates were excluded using a deer fence around half of each strip along the short-axis. Height and root collar diameter of Podocarpus totara, Leptospermum scoparium, and Fuscospora solandri seedlings were measured at establishment and after 2.5 years. Survival and browse were monitored at six-monthly intervals.</p><p dir="ltr">Results: The removal of plantation trees enhanced the growth of planted native seedlings. All species had significantly greater height, root collar diameter growth, and survival in strip treatments compared to the control. However, no strip treatment produced greater seedling growth or survival across all species. Leptospermum scoparium and F. solandri seedlings with ungulate exclusion in medium and wide strips experienced reduced growth due to increased competition with exotic grasses without grazing pressure. However, seedlings of F. solandri and P. totara that were browsed were also more likely to die.</p><p dir="ltr">Conclusions: Removing plantation trees improves growth and survival of planted native species. Smaller gaps could be more effective where exotic grasses are common and grazing pressure from feral ungulates is low.</p><p dir="ltr">Implications for Practice: Canopy gap creation improves the growth and survival of native seedlings, with no clear difference between gap treatments. Ungulate exclusion negatively influenced the growth of some seedlings, likely due to increased competition with exotic vegetation without browsing pressure. Weed control and smaller gaps to reduce competition is likely to improve growth and survival of planting seedlings.</p>
