Arceuthobium -the dwarf mistletoes-is a clearly defined genus of hemi-parasitic plants in the family Viscaceae. The genus occurs throughout much of the Northern Hemisphere; however, the greatest concentration of species and subspecies occurs within coniferous forests of western North America, where considerable research was executed in the mid-to-late 20th century to determine their geographic distributions, host specializations, and taxonomic boundaries. However, the last monograph of Arceuthobium presenting morphological, phenological, phylogenetic, and physiological information for N. American dwarf mistletoes was published in 1996, and since that time, no subsequent publications have presented taxonomic information for the present classification of N. American Arceuthobium . Thus, herein, we provide updated phylogenetic and taxonomic data for 44 taxa of Arceuthobium indigenous to N. America while simultaneously addressing knowledge gaps and suggesting future research to improve our understanding of these ecologically and economically important forest tree parasites. The present classification systems for and recent treatments of N. American Arceuthobium are also discussed.

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The Cassia crossbill (Loxia sinesciuris) feeds exclusively on seeds held in serotinous cones of lodgepole pine (Pinus contorta latifolia). Its population, confined to 67 km² of pine in southern Idaho, declined by ~ 80% between 2003 and 2011 apparently because an increase in the occurrence of hot summer days (≥32 °C) caused the serotinous cones to open and shed their seeds. We hypothesized that the propensity for serotinous cones to open varies across the landscape depending on the maximum temperatures cones experienced. We tested a suite of abiotic variables for predicting the occurrence of open serotinous cones among 1547 trees at 170 sites. The best-supported model indicated that trees with open cones were less frequent on northeastern aspects and as slope increased. Fewer open cones were expected on northeast aspects because they receive less direct solar radiation. However, the decrease in trees with open cones as slope increased on southwest aspects was unexpected. Increased convection on slopes could reduce maximum cone temperatures and account for the decrease of open cones on steeper slopes, regardless of aspects. Although cones are less likely to open on steeper slopes, slopes with southerly aspects are likely the least favorable for pine recruitment and survival. The most favorable sites for both lodgepole pine and the persistence of closed cones are slopes on northeast aspects. Such locations are often dominated by subalpine fir (Abies bifolia). Reforestation of fir-dominated areas with lodgepole pine, therefore, provides a means to expand microclimatic refugia for Cassia crossbills.

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The Arizona Sky Island Arthropod Project (ASAP) is a new multi-disciplinary research program at the University of Arizona that combines systematics, biogeography, ecology, and population genetics to study origins and patterns of arthropod diversity along elevation gradients and among mountain ranges in the Madrean Sky Island Region. Arthropods represent taxonomically and ecologically diverse organisms that drive key ecosystem processes in this mountain archipelago. Using data from museum specimens and specimens we obtain during long-term collecting and monitoring programs, ASAP will document arthropod species across Arizona's Sky Islands to address a number of fundamental questions about arthropods of this region. Baseline data will be used to determine climatic boundaries for target species, which will then be integrated with climatological models to predict future changes in arthropod communities and distributions in the wake of rapid climate change. ASAP also makes use of the natural laboratory provided by the Sky Islands to investigate ecological and genetic factors that influence diversification and patterns of community assembly. Here, we introduce the project, outline overarching goals, and describe preliminary data from the first year of sampling ground-dwelling beetles and ants in the Santa Catalina Mountains.

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