David A Orwig

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ecological change (Reid et al. 2005). Through habitat conversion, over-consumption of resources, and worldwide introductions of pests and pathogens, humans are causing species extinctions at a record rate: the sixth extinction crisis in the billion-year history of eukaryotic life on Earth (Eldridge 1998). The loss of a common or abundant foundation species(More)
Aim The hemlock woolly adelgid (HWA; Adelges tsugae Annand), a small, aphid-like insect native to Japan, is currently migrating northward through eastern North America and threatens to eliminate eastern hemlock [Tsuga canadensis (L.) Carriere], one of the most abundant, long-lived shade tolerant species, across its range. The major objectives of this study(More)
Exotic insect pests may strongly disrupt forest ecosystems and trigger major shifts in nutrient cycling, structure, and composition. We examined the relationship between these diverse effects for the hemlock woolly adelgid (HWA, Adelges tsugae Annand) in New England forests by studying its impacts on local canopy processes in stands differing in infestation(More)
 Radial growth responses to drought were examined in the tree-ring records of six species growing within two locations of differing land-use history and soil moisture characteristics, and in overstory and understory canopy positions in northern Virginia. Tree species experienced differential ring-width reductions during or immediately following four severe(More)
Hemlock (Tsuga canadensis) plays a unique role in Eastern forests, producing distinctive biogeochemical, habitat, and microclimatic conditions and yet has begun a potentially irreversible decline due to the invasive hemlock woolly adelgid (Adelges tsugae; HWA) that causes foliar damage, crown loss, and mortality of host trees. Understanding the regional,(More)
Aim This study compares the magnitude and trajectory of vegetation and ecosystem function dynamics associated with the direct impact of hemlock woolly adelgid (Adelges tsugae Annand; HWA) infestation vs. the indirect consequences of HWA-induced damage in the form of salvage and pre-emptive logging of hemlock [Tsuga canadensis (L.) Carriere] forests.(More)
Climate models project that by 2100, the northeastern US and eastern Canada will warm by approximately 3– 5 8C, with increased winter precipitation. These changes will affect trees directly and also indirectly through effects on ‘‘nuisance’’ species, such as insect pests, pathogens, and invasive plants. We review how basic ecological principles can be used(More)
Global change is impacting forests worldwide, threatening biodiversity and ecosystem services including climate regulation. Understanding how forests respond is critical to forest conservation and climate protection. This review describes an international network of 59 long-term forest dynamics research sites (CTFS-ForestGEO) useful for characterizing(More)
This study examined the impacts of hemlock woolly adelgid (Adelges tsugae Annand) (HWA), a small, invasive insect, on foliar chemistry, forest floor microclimate, and subsequent green foliage decomposition in eastern hemlock (Tsuga canadensis (L.) Carrière) forests. We investigated the direct effects of HWA feeding and indirect changes in microclimate on(More)
Aim This study examines changes in avian community composition associated with the decline and loss of eastern hemlock [Tsuga canadensis (L.) Carr.] resulting from chronic hemlock woolly adelgid (HWA; Adelges tsugae Annand) infestations. Location The study was conducted in a 4900-km study region extending from Long Island Sound northward to the southern(More)