Optimal planting times for freshly lifted bare-rooted conifers on the North York Moors

Abstract

Two-year-old Picea sitchensis (Queen Charlotte Islands and Oregon provenances), Pseudotsuga menziesii, Larix kaempferi, Larix eurolepis, Pinus sylvestris and Pinus nigra var. maritima were lifted at intervals during two winters and planted within 24 h on a nearby second rotation site. Physiological condition at planting, measured by root growth potential and fine root electrolyte leakage, and outplanting performance were significantly influenced by lifting date. There were consistent differences in the species' response to lifting date. Planting out in September resulted in poor survival. Survival of P. sitchensis lifted in October until April was >90 per cent. Pinus sylvestris and P. nigra had survivals of >90 per cent when lifted in November and January respectively until March. There was no clear pattern in P. menziesii performance. Both L. kaempferi and L. eurolepis had two periods of good survival—October and March—with significantly poorer survival and growth associated with mid-winter planting. The double peak in larch performance was closely related to root growth potential; low mid-winter establishment was associated with root growth potentials of <5 even though the nursery root systems were in excellent condition as assessed by electrolyte leakage.