Category: Ecological Research
Title: Monitoring Landscape-Scale Forest Structure and Potential Fire Behavior Changes Following Ponderosa Pine Restoration Treatments
Author: * Roccaforte, J.P.
Subject: Ponderosa pine (Pinus ponderosa), Ecological Restoration, Fire behavior, Landscape scale
Abstract: We evaluated landscape-scale forest restoration treatment implementation and effectiveness and assessed canopy fuels and potential fire behavior changes following landscape-scale forest restoration treatments in a ponderosa pine forest at Mt. Trumbull, Arizona. The goal of the project was to alter forest structure by thinning and burning to more closely resemble forest conditions prior to Euro-American settlement in 1870. We measured 117 permanent plots before (1996/97) and after (2003) treatments. The plots were evenly distributed across the landscape and represented an area of approximately 1200 ha, about half of which was an untreated control. The success of treatment implementation was variable. Most of the area originally planned for restoration was treated in some manner by 2003; however, only 70(percent) received the full planned treatment (thin and burn). Although pine density decreased significantly in the treated area, the projected residual density was exceeded by 111-256(percent). Despite contract amendments to terminate oak cutting, some oaks were still cut for several reasons. Thirteen percent of the presettlement pines died in the treated area by 2003 slightly exceeding the 10(percent) maximum allowable mortality outlined by managers; however, 9(percent) percent of the presettlement pines died in the control. One-third of large snags were lost, falling below the snag retention target, but new large snags were recruited, resulting in a net increase in snag density within the treated area. Implementation goals for large logs were achieved. Restoration treatments decreased canopy fuel load (CFL) and canopy bulk density (CBD) in the treated area, while slight increases occurred in the control. Predicted outcomes were consistent between the two fire behavior models (FlamMap and Nexus): under extreme drought and wind conditions, active crown fire hazard was reduced in the treated area. In contrast, the models show little change in active crown fire hazard in the control over the same time period. Although restoration treatments were not implemented perfectly, they were effective in attaining the overall project goal of restoring more open forest structure conditions while preserving most of the presettlement trees. Furthermore, canopy fuels and active crown fire hazard were substantially reduced, allowing for the reintroduction of low-intensity surface fires.
Source: Masters Thesis
Publisher: NAU School of Forestry, http://www.for.nau.edu