Title

MODELED MIXED CONIFER FOREST DEVELOPMENT FOLLOWING A MOUNTAIN PINE BEETLE OUTBREAK

Presenter Information

Leo Brett

Presentation Type

Presentation

Abstract

Mountain pine beetle (MPB) outbreaks are large-scale disturbances which can alter the structure and successional trajectory of affected forest stands. In mid-elevation ponderosa pine /mixed-conifer communities in particular, little is known about how different levels of MPB mortality will affect successional trajectories of affected forest stands, even though this forest type comprises large percentages of the western forest landscape. These forest stands may have a unique response to MPB mortality events compared to pure pine stands, due to the significant presence of non-host (non-pine) species.

To examine the effects of MPB outbreak on this forest type, forest inventory data collected from several stands recently affected by MPB was used to run a series of 50-year simulations using the U.S. Forest Service Forest Vegetation Simulator. Each stand was “grown” for 50 years under four different scenarios: no host species mortality, observed host species mortality, double observed host species mortality, and full host species mortality.

Simulations indicated shifts in stand structure aligned along a gradient of MPB intensity and persisting through time. At 50 years, under different beetle mortality scenarios, stands showed lower tree density (trees ha-1) and decreased basal area (m2 ha-1) compared to no-mortality scenarios. Non-host trees showed higher density and higher basal area compared to no-mortality scenarios. These results indicate that MPB may be a significant driver of stand structure and composition in mixed-conifer systems. By increasing understanding of the role of MPB on forest development, this information will help inform future forest management decisions involving MPB outbreaks.

Category

Life Sciences

This document is currently not available here.

Share

COinS
 
Apr 15th, 10:40 AM Apr 15th, 11:00 AM

MODELED MIXED CONIFER FOREST DEVELOPMENT FOLLOWING A MOUNTAIN PINE BEETLE OUTBREAK

UC 331

Mountain pine beetle (MPB) outbreaks are large-scale disturbances which can alter the structure and successional trajectory of affected forest stands. In mid-elevation ponderosa pine /mixed-conifer communities in particular, little is known about how different levels of MPB mortality will affect successional trajectories of affected forest stands, even though this forest type comprises large percentages of the western forest landscape. These forest stands may have a unique response to MPB mortality events compared to pure pine stands, due to the significant presence of non-host (non-pine) species.

To examine the effects of MPB outbreak on this forest type, forest inventory data collected from several stands recently affected by MPB was used to run a series of 50-year simulations using the U.S. Forest Service Forest Vegetation Simulator. Each stand was “grown” for 50 years under four different scenarios: no host species mortality, observed host species mortality, double observed host species mortality, and full host species mortality.

Simulations indicated shifts in stand structure aligned along a gradient of MPB intensity and persisting through time. At 50 years, under different beetle mortality scenarios, stands showed lower tree density (trees ha-1) and decreased basal area (m2 ha-1) compared to no-mortality scenarios. Non-host trees showed higher density and higher basal area compared to no-mortality scenarios. These results indicate that MPB may be a significant driver of stand structure and composition in mixed-conifer systems. By increasing understanding of the role of MPB on forest development, this information will help inform future forest management decisions involving MPB outbreaks.