Alexander K. Stewart

Signal strength in sub-annual tree-ring chronologies from Pinus ponderosa in northern New Mexico

Abstract The creation of chronologies from intra-annual features in tree rings is increasingly utilized in dendrochronology to create season-specific climate histories, among other applications. A conifer latewood-width network has recently been developed for the southwestern United States, but considerable uncertainty remains in understanding site and species differences in signal strength and sample depth requirements. As part of the 22nd annual North American Dendroecological Fieldweek, the first Pinus ponderosa earlywood-width (EW) and latewood-width (LW) chronologies were developed for the Jemez Mountains in northern New Mexico. The aim was to extend an existing total ring-width (TW) chronology and to assess the potential for creating long LW chronologies. Analysis of chronology signal strength suggests that large sample size requirements remain a considerable hurdle for creating P. ponderosa LW chronologies longer than 400 years. At the Cat Mesa site, twenty-three sample trees were required to capture a statistically acceptable common signal in adjusted latewood (LWa), whereas only four samples were required for EW. This is significantly higher than sample depth requirements for LWa from the few other chronologies in the region where this statistic has been reported. A future priority should be to develop a conceptual guide for site and tree selection in order to maximize the potential for enhancing LW signal and for creating a robust network of multi-century LW chronologies.

Military base growth in Afghanistan: a threat to scorpion populations?

Abstract Coalition military bases in Afghanistan are increasing in area, infrastructure and population due to increased military efforts. From 2004 to 2010, a 40-hectare base in Ghazni, Afghanistan transitioned from a montane shrubland to a small, modern “village.” This shift comprised an over 50-fold increase in hardcover and a 20-fold increase in the human population. I searched the base with UV light (n  =  43.6 h) for scorpions, especially Mesobuthus Vachon 1950, an established, opportunistic scorpion found in Ghazni City, 5 km north. I completed my searches along two tracks (> 5 km total length) and considered all habitats for this scorpion. Anthropogenic microhabitats comprised concrete walls, concrete barriers, gabions or sandbags, each in contact with a dirt or gravel substrate (eight possible); all were thermally appealing (mean  =  2.3°C warmer than ambient temperature). Despite the population of Mesobuthus caucasicus Nordmann 1840 in Ghazni City and the increase in thermally attractive microhabitats on the base, I found no scorpions. I propose that the rapid anthropogenic change due to base improvements outpaces the capacity of this scorpion to disperse to a new, albeit satisfactory, environment. Here, I report my observations of scorpion diversity and abundance in east-central Afghanistan and the Hindu Kush Mountains, with a focus on the impact of increasing anthropogenic change upon the environment.

U.S. Army Agriculture Development Teams, Afghanistan: The Role of the Geoscientist

In the spring of 2008, the National Guard Bureau and the U.S. Army began employing a new counterinsurgency tool in Afghanistan—Agriculture Development Teams (ADT). These specialized, egalitarian U.S. Army teams, consisting of 12 soldier-expert hybrids, work directly with Afghanistan officials and farmers to support their agricultural needs. ADTs provide agriculture-related education, training and sustainable projects, which are U.S. funded and locally operated and maintained.