Progress towards continuous cover woodland: Ipsden estate

Abstract

Increasing interest in continuous cover management of woodlands in Britain indicates the need for more study of the resulting wood production, since sales of wood remain the most important source of finance for established woodlands. Detailed enumeration data by 1 inch quarter girth (1″ QG = 3.23 cm diameter) classes and records of cut are available for 22 compartments of all-aged woodlands of the Ipsden estate, Oxfordshire, together with accounts compiled on a consistent basis since 1973. Predominant species are beech, oak, ash, cherry with, usually younger, European larch, Scots pine and other conifers managed on an irregular group selection system. Average growing stock volume of material over 5″ QG increased from 1080 hoppus feet per acre (96.3 m3 ha-1) in 1973 to 1800 h.ft per acre (160.4 m3 ha-1) in 2000. Cut amounted to 593 h.ft per acre (52.8 m3 ha-1). Total increment over the 27 years was 1312 h.ft per acre or 48.6 h.ft per acre per year (4.33 m3 ha-1 a-1). An 'ideal' stand is defined. The net annual income relative to value of standing timber of this is 1.8 per cent. The current absence of simulations of growth and potential yield in mixed-age, mixed-species stands makes forecasts of volume and money yield difficult. A plausible profile of future net income suggests that net present value of the current stock lies between £1450 per acre at 2 per cent and £750 at 3 per cent, both values being substantially lower than the standing value of timber of £1670 per acre: equality occurs at 1.7 per cent. This result should be set alongside the return, without grants, of growing even-aged broadleaved stands in Britain of a little over 1 per cent in real terms.