An analysis framework for linking regeneration standards to desired future forest conditions

Abstract

This paper highlights the potential for moving from stocking standards as simple tools for administering contractual or policy-based stocking requirements to regeneration standards that play an active role in forest management. A framework is introduced for developing simplified models on which regeneration standards can be based. A case study for boreal mixedwoods is presented in which simplified models based on quadrat stocking summaries are used to predict total yield and species composition for various admixtures of white spruce and trembling aspen. It is suggested that these values can be used to satisfy both the evaluation of basic reforestation obligations and cut block level contributions to landscape level species composition objectives.Key words: regeneration standards, stocking standards, surveys, simulation, mixedwood management, forest management objectives RÉSUMÉCet article fait état de la possibilité de passer de l'utilisation des normes de densité relative en tant que référence usuelle de gestion d'un contrat ou d'une directive portant sur le nombre de semis par unité de surface, à des normes de régénération ayant un rôle actif en aménagement forestier. Un cadre de référence pour le développement de modèles simplifiés est présenté et pour lesquels les normes de régénération peuvent être retenues. Une étude de cas sur les forêts boréales mixtes est présentée pour laquelle des modèles simplifiés établis à partir de sommaires de stocking par quadrant sont utilisés pour prédire le rendement total et la composition en espèces dans le cas de différentes compositions d' épinette blanche et de peuplier faux-tremble. Il est suggéré que ces valeurs peuvent être utilisées pour répondre à la fois à l' évaluation des exigences de base en matière de régénération et pour le niveau de contribution d'un bloc de coupe aux objectifs de composition par espèce dans l' écosystème.

The Validation of the Mixedwood Growth Model (MGM) for Use in Forest Management Decision Making

“…The model was developed to assist decision makers in estimating growth and yield outcomes for a range of management practices. Recent publications by Pitt et al [2], Comeau et al [3] and Farnden [4] demonstrate the use of MGM as a tool to link stand interventions or surveys to future yield. As MGM was developed, various growth and mortality relationships were published, typically accompanied by tree-level and stand-level validation [5].…”

Observations on relationships between regeneration stocking and yield

“…In the context of assessing forest regeneration success, the concept of stocking is often used to describe a range of conditions relative to one where all of the available resources needed by trees to grow and thrive are or will be effectively accessed. Foresters working in many jurisdictions have put great effort into the quantification of stocking in regenerated stands (Farnden, 2009). One of the primary reasons for this work is the implicit recognition that stocking has a large impact on yield (Bella, 1976;McWilliams and McWilliams, 2009).…”

“…In this type of exercise, point pattern generators such as STRUGEN (Pretzsch, 1997) or the stand generator described by Farnden (2010) are used to establish either realistic or meaningfully abstract tree spatial distributions. Those distributions serve as a stem map both for the initiation of growth simulations and as the basis for regeneration survey simulations (Farnden, 2009). In this manner, each survey outcome can be linked explicitly to a yield prediction, and simulations for a large number of stand variations can be used to elicit general trends.…”

“…Therefore, a greater understanding of the links between stocking measures and anticipated yield is desirable. In addressing this problem, the current study follows the decision framework outlined by Farnden (2009): a set of simulated juvenile stands is generated which in turn is the basis for both growth simulations to determine yields and sampling simulations to generate silviculture survey summary statistics. Models are then constructed from the outcomes, whereby survey statistics are used to predict future yields.…”

How many plots are needed to estimate sapling density and stocking in temperate forests?

“…The ideal would be to know with certainty which variables have the most influence on the stand's long-term yield. However, this type of information is rarely available, due to the very longtime horizon necessary to obtain the results (Brand et al 1991;Farnden 2009;Walters et al 2022). Several authors have proposed standards to determine the desirable regeneration threshold, but they are often arbitrary (Farnden 2009).…”