James F. Fowler

Variables associated with the occurrence of Ips beetles, red turpentine beetle and wood borers in live and dead ponderosa pines with post‐fire injury

Recently, wildfires and prescribed burning have become more frequent in conifer forests of western North America. Most studies examining the impacts of insects on trees with post‐fire injury have focused on contributions to tree mortality. Few studies have examined fire‐caused injuries to estimate the probability of attack by insects. Scant data quantifying insect associations with one another, or with live and dead fire‐injured trees, are available. We examined live and dead trees with varying levels of fire injury in wildfires in Colorado, Montana, Arizona and the Black Hills aiming to determine fire injury associated with insect infestation, co‐occurrence between insects and insect association with live and dead fire‐injured trees. Bole scorch height estimated the likelihood of attack by Ips spp. Diameter at breast height, bole scorch height and crown scorch height estimated the likelihood of attack by Dendroctonus valens LeConte. Diameter at breast height and bole scorch height estimated the likelihood of attack by wood borers. Ips spp., Dendroctonus valens and wood borers were associated with one another. Ips spp. beetles and wood borers were associated with dead fire‐injured trees, whereas D. valens was often associated with live fire‐injured trees. Focusing on certain fire‐caused injuries may identify trees targeted by Ips spp. beetles, Dendroctonus valens and wood borers.

Development of post-fire crown damage mortality thresholds in ponderosa pine

Previous research has shown that crown scorch volume and crown consumption volume are the major predictors of post-fire mortality in ponderosa pine. In this study, we use piecewise logistic regression models of crown scorch data from 6633 trees in five wildfires from the Intermountain West to locate a mortality threshold at 88% scorch by volume for trees with no crown consumption. For trees with 440% crown consumption volume, linear regression indicates 485% mortality, but for trees with crown consumption volume o40%, there is a statistically significant, linear relationship between increasing crown scorch and increasing probability of mortality. Analysis of an independent 600þ tree dataset from Colorado produced similar results and supports the analysis approach. Crown scorch volume (485%), crown consumption volume (440%), and crown consumption between 5 and 40% combined with crown scorch volume 450% mortality thresholds could be incorporated into post-fire marking guidelines for forest management goals. Additionalkeywords: crown consumption,crown scorch,logisticregression, markingguidelines,piecewise regression, Pinus ponderosa, statistical models, wildfire.

Density and Elevational Distribution of the San Francisco Peaks Ragwort, Packera franciscana (Asteraceae), a Threatened Single-Mountain Endemic

Abstract Packera franciscana (Greene) W. A. Weber and A. Löve is endemic to treeline and alpine habitats of the San Francisco Peaks, Arizona, USA and was listed as a threatened species under the Endangered Species Act in 1983. Species abundance data are limited in scope, yet are critical for recovery of the species, especially in light of predictions of its future extinction due to climate change. This study defined baseline population densities along two transects which will allow the detection of future population trends. Packera franciscana ranged from 3529 to 3722 m elevation along the outer slope transect and densities were 4.18 and 2.74 ramets m−2 in 2008 and 2009, respectively. The overall P. franciscana 2009 density estimate for both transects was 4.36 ramets m−2 within its elevational range of occurrence, 3471–3722 m. The inner basin density was higher, 5.62 ramets m−2, than the estimate for outer slopes, 2.89 ramets m−2. The elevation of the 2009 population centroid for both transects was at 3586 (±10 SE) m with the inner basin centroid significantly lower than the outer slopes centroid: 3547 (±7 SE) m vs. 3638 (±7 SE) m, respectively. In mid-September, 6–9% of the P. franciscana ramets were flowering and/or fruiting in 2008–2009. These results and our estimate of >36,000 P. franciscana ramets in <2% of its range would suggest that the species is locally abundant, persisting and reproducing.

Snow duration effects on density of the alpine endemic plant Packera franciscana

Abstract. Packera franciscana (Greene) W.A. Weber and Á. Löve (Asteraceae) (San Francisco Peaks ragwort) is an alpine-zone endemic of the San Francisco Peaks in northern Arizona. Previous studies have shown that P. franciscana is patchily distributed in alpine-zone talus habitats. The purpose of this study was to describe the relationship between snow duration and P. franciscana abundance. We established trailside transects through P. franciscana habitat along the Weatherford Trail to estimate the abundance of P. franciscana ramets. Snow-free and snowbed sample segments were chosen based on a 17 May 2013 snow photograph taken from within the Inner Basin of the San Francisco Peaks caldera. The section of the Weatherford Trail under snow on 17 May 2013 had a 5-year arithmetic mean of 1.53 ramets ⋅ m-2 (SE 0.37)—much less dense than the snow-free section which had a 5-year arithmetic mean of 7.17 ramets ⋅ m-2 (SE 1.09). The steep upper portion of talus slopes is known to move downslope faster than mid- and lower slope portions due to gravitational processes working on surface particle size, slope angle, and frost heave/needle ice during moist periods. Needle ice is known to uproot seedlings in other species. Active talus shift may inhibit P. franciscana colonization and growth on upper talus slopes via high seedling mortality in the snowbed zone during spring snowmelt.