Thinning Specification for Direct Contracts

THINNING SPECIFICATION FOR DIRECT CONTRACTS

Stands will be thinned following current thinning best practice and as described in Forestry Commission Field Book 2, ‘Thinning Control’ (1999).

Line Thinning

 First thin stands will be line thinned to provide access racks with the remaining matrix being selectively thinned. Line thinning will either be ‘with the rows’ or ‘across the rows’ (cross rack) depending on row spacing. The specification identifies the type of line thinning and the intensity.

 Where cross rack thinning is required the cross racks will be cut at 14 metre centres with a tolerance of +/- 1.5 metres. Rack widths will be 3.5m to a maximum of 4.5m. The contractor will be responsible for the layout of the racks to the correct spacing and width.

 In certain circumstances ‘cross racking’ may involve crossing rows of stumps windrowed after the first rotation clearfell operation. The Contractor may clear a path through stump rows, at the point at which the cross rack crosses the stump row. The Contractor may not clear any tree regeneration in order to pass along the stump rows unless agreed with the Commission.

Matrix thinning and subsequent thinning

 Where identified in the specification, the matrix (the remaining crop between the racks) of first thin stands will be selectively thinned. This will be a self-select operation (trees will not be marked). The matrix thinning will be a ’Low’ thinning concentrating on the removal of the lower canopy - suppressed and sub-dominant trees and trees of poor form.

 In sub thin stands (second and subsequent thinnings) the thinning operation will be a self-select ‘Selective Intermediate’ thinning.

 Thinning will be controlled by the contractor to achieve a target basal area for the stand (see specification for ‘Target Basal Areas’). The contractor will be expected to undertake basal area checks as the thinning progresses (following the procedure outlined in Field Book 2) and to submit basal area check records and harvested volume records to the Commission on completion of each sub compartment.