Estimating stemwood nutrient concentration with an increment borer: A potential source of error

Abstract

Two methods of sampling stemwood nutrients have been compared on 10 Pinus pinaster (Ait.) trees: the increment borer method (non-destructive but producing samples which are not weighed according to the tissues' proportion) and the disc method (destructive but producing weighed samples). The samples were divided into sapwood and heartwood, and nutrient concentrations were determined for major nutrients (N, P, K, Ca, Mg). Compared with the disc sampling method, the increment borer sampling method significantly underestimated N, P and K concentration in sapwood, whereas it overestimated Ca and Mg concentration in heartwood. The mean error ranged from -13 per cent (N and P in sapwood) to +14 per cent (Ca in heartwood). These results were in agreement with previous studies which showed horizontal variations in the nutrient concentration of stemwood. © Institute of Chartered Foresters, 2005. All rights reserved.