© 2001 by Institute of Chartered Foresters
Planting in open tapering conical cavities made in peat plough ribbons improves stability and growth
1 Applied Plant Science Division, Department of Agriculture and Rural Development for Northern Ireland, Newforge Lane, Belfast 9, Northern Ireland 2 Forest Service, Department of Agriculture and Rural Development for Northern Ireland, Dundonald House, Belfast 9, Northern Ireland
It was noted when planting conifers on peat plough ribbons using a semicircular spade that they often ended up at an angle to the vertical. For Pinus contorta of south coastal provenance (SCPC) this leaning, combined with wind action, resulted in most having a serious defect known as bowing (or basal sweep) of the lower part of the stem. In an attempt to help overcome such a serious defect a novel planting method was developed. Using a conical spade a deep, wide, downward tapering cone of peat was removed and not replaced. Gripping the stem of a ‘bare root’ plant the root-ball was simply pushed down firmly into the tapering cavity. The open cone supported the plant vertically. The spade used to make the cone had a tapering spike at its tip, helping new roots to penetrate vertically below the ribbon. The method was tested using a wide variety of planting stock, ranging from 2+1 transplants to 1-year bare-root seedlings, to Kopparfors and tubed seedlings. The latter were positioned at the base of the cone, using their specific planting tool. All controls were planted on top of the plough ribbons. The cone method gave shelter and successfully reduced early-onset bowing. Survival was increased, the potential planting season extended and rooting below the ribbon enhanced. Cone-planted trees suffered less damage from hares and thus fewer had multiple stems. However, the most important result for forestry was that cone planting gave a mean height advantage of 20 per cent in the three SCPC experiments and a similar result combined with a 71 per cent weight increase in an experiment using Sitka spruce (Picea sitchensis Bong. Carr.). For tubed seedlings, mycorrhizal inoculation with Thelephora terrestris was beneficial when compared with no inoculation of the compost used to fill the tubes. On the other hand, inoculation using Hebeloma populinum appeared detrimental, a possible reason being given in the discussion.
Received 23 February 2000.