Testing the Lake States variant of FVS (Forest Vegetation Simulator) for the main forest types of northern Ontario

Abstract

The Lake States variant of the FVS (Forest Vegetation Simulator) model (LS-FVS), also known as the LS-TWIGS variant of FVS, was validated for black spruce (Picea mariana (Mill.) BSP), white spruce (Picea glauca (Moench) Voss), jack pine (Pinus banksiana Lamb.) and trembling aspen (Populus tremuloides Michx.) forests in northern Ontario. Individual-tree data from 537 remeasured sample plots were used. This dataset included different combinations of site index, stand density and age. It was possible to compare observations and predictions for different projection length periods. The validation exercise included a biological consistency analysis, the computation of mean percent difference (MPD) for stand density, stand basal area, top height and quadratic mean diameter (QMD) and the comparison of observed and predicted individual-tree dbh. The biological consistency analysis indicated that LS-FVS logically predicted the effect of site index on top height, stand basal area and QMD for black spruce and jack pine. However, the decrease in stand basal area at young ages was inconsistent with the normal development pattern of the forest stands under study and was attributed to deficiencies in the prediction of mortality. LS-FVS was found to underpredict stand density, stand basal area and top height and to overpredict QMD. Even though there were large errors in the prediction of change in stand density, LS-FVS was nevertheless consistent in the prediction of the shape of the dbh size distribution. pour la densité, la surface terrière, la hauteur maximale et le diamètre moyen quadratique (QMD) et la comparaison des diamètres à hauteur de poitrine (dhp) observés et prédits d'arbres individuels. L'analyse de cohérence biologique a indiqué que LS-FVS a prédit de façon cohérente les effets de l'indice de site sur la hauteur maximale, la surface terrière et le QMD pour l'épinette noire et le pin gris. Cependant, la diminution en surface terrière en bas âge s'est avérée inconsistante avec la tendance normale de développement des types forestiers sous étude. Cette situation a été attribuée à une faiblesse de LS-FVS au niveau de la prédiction de la mortalité. Il a été trouvé que LS-FVS a sous-estimé la densité des peuplements, la surface terrière et la hauteur maximale et surestimé le QMD. Même s'il y avait de larges erreurs dans la prédiction du changement dans la densité des peuplements, LS-FVS était néanmoins cohérent dans la prédiction de la forme de la distribution des classes de dhp.

How much birch (Betula papyrifera) is too much for maximizing spruce (Picea glauca) growth: a case study in boreal spruce plantation forests

“…This program represents the complex stand growth on the basis of its projections of tree lists, annual diameter increment and stand site index. Although we did not use long-term re-measurement data to evaluate the performance of this model, TWIGS was extensively validated by Lacerte et al (2004) at higher latitudes in Ontario and the performance was consistent with other studies where long-term re-measurement data were not used (Payandeh, Huynh 1991;Payandeh, Papadopo 1994). This model projection also provided confident prediction in boreal-northern forest transition of the Lakes States: MN, WI, MI Upper Peninsula (Miner et al 1988).…”

“…Some other investigations also reported that mixedwood stands showed greater productivity than single species stands (Man, Lieffers 1999;Legare et al 2004;Kelty 2006). This also lends confidence to the TWIGS projection even though the version used was for the boreal-northern forest transition of the Lakes States (Miner et al 1988) and higher latitude Ontario Canada (Payandeh, Papadopol 1994;Lacerte et al 2004). …”

Applying research for enhanced productivity on the Canadian Ecology Centre – Forestry Research Partnership forests

“…Growth and yield plots established on the NF in 2003, in conjunction with CEC-FRP and Forest Ecosystem Science Cooperative Inc. in red pine plantations planted prior to the 1970s are showing excellent growth potential. Yield projections of these plot data using FVS Ontario (Lacerte et al 2004(Lacerte et al , 2006 indicate red pine is reaching 5.8 to 9.4 m 3 •ha -1 •yr -1 . Accordingly, potential for enhancing productivity and yield on this forest is high.…”

Ontario's forest growth and yield modelling program: Advances resulting from the Forestry Research Partnership

“…The CEC-FRP spurred many G&Y-related activities such as further implementation of the plot network, the development of benchmark yield curves, the calibration of density management diagrams, the investigation of growth intercept models, and the evaluation and calibration of FVS Ontario (Lacerte et al 2004). FVS Ontario is the Ontario variant of the Forest Vegetation Simulator (FVS), the official growth model of the United States Forest Service.…”