Masam – a flexible stand density management model for meeting diverse structural objectives in multiaged stands

Abstract

A flexible approach for density control of multiaged stands (stands with two or more age classes) managed with the single-tree selection system is presented. This density management approach divides stands into components such as age classes, canopy strata, or species, and allocates growing space among components to control stocking. Growing space is represented by leaf area. Users specify a total stand growing space occupancy, the number of desired components, number of trees per component, and the percentage of occupied growing space allocated to each component. A series of equations can be developed and assembled in a simple spreadsheet to design and assess density management alternatives. Organization of these equations is presented as the Multiaged Stocking Assessment Model (MASAM) and is used to design several example prescriptions for several species. Model outputs which aid in implementation of designed prescriptions include stand-level totals for basal area, stand density index, and average annual volume growth for a cutting cycle. Other outputs may include component totals for basal area, stand density index, average tree vigor, and quadratic mean diameter. This approach provides flexibility in designing density management regimes for multiaged stands with a variety of stand structural characteristics including two or more age classes or strata, or stands with a preponderance of large or small trees.