Combining carbon sequestration objectives with timber management planning

Abstract

This paper presents a new approach to assessing carbon (C) sequestration in commercial forests at spatial scales relevant to forest managers. The approach combines C-sequestration objectives with timber and non-timber (i.e., wildlife habitat) management objectives. As a demonstration, the approach is applied to a 105,000 ha special management area in northern New Brunswick, Canada over a simulated time horizon of 80 years. Carbon stock calculations are carried out by multiplying a series of simple wood volume-to-C conversion factors to wood supply projections generated with the Woodstock™ wood supply (RemSoft Inc.) and CWIZ™ linear programming software. Basic input requirements to the wood supply model include (i) current forest stand inventory and forest age structure, (ii) growth and yield curves for naturally developing stands, (iii) modified growth and yield curves to describe post-treatment stand response, (iv) non-timber objectives, and (v) specific harvesting prescriptions, including extent of application area and intensity. Spatial blocking of stands is carried out by importing the treatment schedule from the 80-year plan and by providing spatial constraints such as green-up delays and adjacency rules over a 25-year planning horizon. Model projection indicates that carbon stock in the forest of the special management area will increase in the next 40 years under the proposed harvesting plan and start to decrease thereafter. Under the no-disturbance scenario (both natural and man-made), the carbon stock in the forest will increase for the next 60 years and start to decline thereafter. For the whole planning period, C stock in the forest following current industrial practices will be less than naturally growing forest without any form of disturbance. Although model calculations are not exact, combining C objectives with timber management objectives provides a good framework for assessing C sequestration in commercial forests, given the excellent quality of the forest input data regarding above ground biomass. Improvements to modelled C-sequestration projections may take place as scientific information about the details of the C cycle in managed forests becomes available.