Forest fire cycles and life tables: a case study from interior Alaska
The negative exponential and Wiebull distributions were used to estimate stand survivorship curves for forested sites in the Porcupine River drainage of interior Alaska. The survivorship curve of Piceaglauca (Moench) Voss sites was best described by a Wiebull function, while both functions adequately described the Piceamariana (Mill.) Britton, Sterns & Poggenburg hardwood and all sites stand survivorship curve. Fire cycles calculated from the Wiebull distribution were 43, 113, 36, and 26 years for the entire study area, P. glauca, P. mariana, and hardwood sites, respectively. Fire frequencies estimated from a life table analysis were 48, 105, 43, and 30 years, respectively. The relationship between fire cycle and fire frequency calculations is discussed and various management implications are given.
The analysis in this article provides an update on the southern forest sector economic activity after the downturn experienced in 2008 –2009. The analysis was conducted using Impact Analysis for Planning (IMPLAN) software and data sets for 2009 and 2011 and results from the USDA Forest Service Timber Products Output latest survey of primary wood processing mills. Although improving economic conditions are reflected by increased mill roundwood consumption during 2011, the forest industry’s economic contribution improved slightly but not across all states. At the regional scale, the sector displayed a downward trend in employment, value added, and number of active primary mills.