Sierran mixed conifer forest wildfires: a biodiversity comparison between active and passive timber land management

Abstract

The mixed conifer forests of the Northern Sierras have great value in their biodiversity. Timber land management in this region varies by land owner and their objectives, including timber harvest and conservation. An increase in annual wildfires each year indicates a need to understand how different silvicultural strategies before and after fires affect the overall ecosystem biodiversity. Ecosystem functions and services can be affected by many factors involving anthropogenic activities in combination with fires. The aim of this study was to determine to what degree active (private timber company) and passive (United States Forest Service) management after a wildfire may affect plant biodiversity, and to compare those silvicultural approaches to active and passive pre-fire management. The study takes place within the vicinity of the 2012 Chips fire burn scar in Plumas County, California. Using tree canopy and plant species percent cover, in addition to presence and absence data, within frames and nested frames along 50 meter transects, statistical analyses revealed little significant difference between active and passive management. Analysis from data collected in this study concluded that tree canopy cover is significantly different under active post-fire management than under passive post-fire management and pre-fire conditions. There was not a significant difference in understory biodiversity (richness and evenness) among the four treatments. Dissimilarity in plant species composition was significant among the burned and unburned treatments, as well as between the two differently managed burned treatments. While the treatments were significantly dissimilar, there was not enough data collected to account for the high degree of variability seen in the data and so further data collection and analyses across multiple spatial and temporal scales would give better insight into the differences in biodiversity between treatments.