Effects of silvicultural practices on carbon stores in Douglas-fir – western hemlock forests in the Pacific Northwest, U.S.A.: results from a simulation model

Abstract

We used a new model, STANDCARB, to examine effects of various treatments on carbon (C) pools in the Pacific Northwest forest sector. Simulation experiments, with five replicates of each treatment, were used to investigate the effects of initial conditions, tree establishment rates, rotation length, tree utilization level, and slash burning on ecosystem and forest products C stores. The forest examined was typical of the Cascades of Oregon and dominated by Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and western hemlock (Tsuga heterophylla (Raf.) Sarg). Simulations were run until a C steady state was reached at the landscape level, and results were rescaled relative to the potential maximum C stored in a landscape. Simulation experiments indicated agricultural fields stored the least (15% of the maximum) and forests protected from fire stored the greatest amount (93% of the maximum) of landscape-level C. Conversion of old-growth forests to any other management or disturbance regime resulted in a net loss of C, whereas conversion of agricultural systems to forest systems had the opposite effect. The three factors, in order of increasing importance, most crucial in developing an optimum C storage system were (i) rotation length, (ii) amount of live mass harvested, and (iii) amount of detritus removed by slash burning. Carbon stores increased as rotation length increased but decreased as fraction of trees harvested and detritus removed increased. Simulations indicate partial harvest and minimal fire use may provide as many forest products as the traditional clearcut -broadcast-burn system while increasing C stores. Therefore, an adequate supply of wood products may not be incompatible with a system that increases C stores.Résumé : Nous avons utilisé un nouveau modèle, STANDCARB, pour examiner les effets de différents traitements sur les réservoirs de carbone (C) dans le secteur forestier du Pacifique Nord-Ouest. Des expériences simulées, avec cinq ré-plications pour chaque traitement, ont été utilisées pour étudier les effets des conditions initiales, du taux d'implantation des arbres, de la longueur de la période de révolution, du niveau d'utilisation de l'arbre et du brûlage à plat sur les réserves de C dans l'écosystème et dans les produits forestiers. La forêt examinée était typique des Cascades de l'Oregon et dominée par le douglas de Menzies (Pseudotsuga menziesii (Mirb.) Franco) et la pruche de l'Ouest (Tsuga heterophylla (Raf.) Sarg.). Les simulations ont été arrêtées lorsque le niveau de C atteignait l'état d'équilibre à l'échelle du paysage. Les résultats ont été exprimés relativement au maximum de C pouvant être stocké dans un paysage. Les expériences simulées indiquent que les terres agricoles stockent le moins (15% du maximum) de C et que les forêts protégées du feu stockent la plus grande quantité (93% du maximum) de C à l'échelle du paysage. La conversion des vieilles forêts à tout autre régime d'aménagement ou de perturbation entraîne une perte nette de C, alors que la conversion des systèmes ag...

A Flexible Hybrid Model of Life Cycle Carbon Balance for Loblolly Pine (Pinus taeda L.) Management Systems

“…In contrast, when rotation lengths were shortened to 18 years, net C stock was reduced. Other reports for different conifer species [12][13][14] indicated similar effects of rotation length on C storage i.e., extended rotations increased C sequestration in conifer forest plantations. Longer harvesting cycles represent one of the major management strategies used to increase forest C density [80].…”

“…Rotation length is known to affect C stored in forest stands [10,11] and the use of extended rotations has been proposed as an effective way to increase C sequestration for different forest types such as scots pine (Pinus sylvestris L.) [12], Douglas-fir (Pseudotsuga menziesi (Mirb.) Franco) [13] or slash pine (Pinus elliottii Engelm. var.…”

The Fall River Long-Term Site Productivity study in coastal Washington: site characteristics, methods, and biomass and carbon and nitrogen stores before and after harvest.

“…Detailed characterization of initial study conditions is an important component of studies that test the effects of silvicultural and other management treatments on relevant site conditions and long-term site productivity (Harmon and Marks 2002). In this paper, we detail objectives and describe the experimental design and site-characterization methodology used in the long-term site productivity study at Fall River…”

Voluntary carbon credits from improved forest management: policy guidelines and case study

“…356,479.4 164,497.9 125,135.4 39,362.4 64,014 iForest -Biogeosciences and Forestry replacing the stock difference approach by a process-based flux computation. In particular, soil carbon typically represents about 50% of total ecosystem stored carbon , and its changes may become relevant when more than one rotation, or alternatives such as deforestation or clear-cutting, are included into the baseline or alternative management scenarios (Harmon & Marks 2002). The most promising approach for operational forest management and planning is represented by stand-scale empirical and semi-empirical simulators, which are still capable of tracking all carbon pools but rely on simple assumptions and do not require extensive calibration or parameterization by local forest managers (Kurz et al 2002).…”