Role of Wind, Birds, Deer, and Humans in the Dispersal of Hemlock Woolly Adelgid (Homoptera: Adelgidae)

McClure, Mark S.

doi:10.1093/ee/19.1.36

Cited by 142 publications

(90 citation statements)

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“…Hemlock mortality rapidly followed the spread of HWA infestations in southern Connecticut when trees were stressed by drought and other pests during the next 15 years. The biology, impact and life cycle of HWA were closely studied in the late 1980s and early 1990s (McClure 1987(McClure , 1989(McClure , 1990(McClure , 1991. There are two annual generations of HWA on our hemlocks and the unique biology of the HWA sistens generation, which feeds during the fall and winter, together with its sessile habit which exposes the adelgid to weather extremes, makes this winter generation vulnerable to unpredictable winter conditions.…”

Section: Hwa Winter Mortality In Connecticut and Implications For Managmentioning

confidence: 99%

Predicting Hemlock Woolly Adelgid Winter Mortality in Connecticut Forests by Climate Divisions

Cheah

2017

Northeastern Naturalist

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Section: Hwa Winter Mortality In Connecticut and Implications For Managmentioning

confidence: 99%

Predicting Hemlock Woolly Adelgid Winter Mortality in Connecticut Forests by Climate Divisions

Cheah

2017

Northeastern Naturalist

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“…Despite decades of research examining various aspects of HWA biology (McClure 1989, 1990, 1991, Young et al 1995 and related forest impacts (Orwig and Foster 1998, Jenkins et al 1999, Eschtruth et al 2006, the pattern and rate of hemlock decline is still not well understood. Better knowledge of the regional, landscape, and site factors that control the impact of HWA and the subsequent response of forest ecosystems to its damage across a range of spatial and temporal scales is necessary to forecast future dynamics of forest change associated with this pest.…”

Section: Introductionmentioning

confidence: 99%

“…Better knowledge of the regional, landscape, and site factors that control the impact of HWA and the subsequent response of forest ecosystems to its damage across a range of spatial and temporal scales is necessary to forecast future dynamics of forest change associated with this pest. Since it entered Richmond, VA in the early 1950s (Souto et al 1996), HWA has spread via wind, birds, deer and humans rapidly to the north and recently to the more scattered stands in the south (McClure 1990, Morin et al 2009). Current rates of HWA dispersal are estimated to be between 8 and 13 km yr À1 (Evans and Gregoire 2007).…”

Section: Introductionmentioning

confidence: 99%

A foundation tree at the precipice:Tsuga canadensishealth after the arrival ofAdelges tsugaein central New England

et al. 2012

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Abstract. 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, landscape, site, and stand factors influencing HWA spread and impact is critical for predicting future landscape dynamics and directing effective management. Using aerial photographs, we documented hemlock distribution throughout central Massachusetts and subsampled 123 stands to examine the spatial pattern of HWA and its impact on tree vigor and mortality since its arrival in 1989. In the study region, over 86,000 ha of hemlock forest were mapped in 5,127 stands. White pine (Pinus strobus), red oak (Quercus rubra), red maple (Acer rubrum), and black birch (Betula lenta) were common overstory associates. Hemlock abundance increased from south to north, commonly on western and northwestern slopes. Average stand size was 55 ha, overstory basal area ranged from 23 to 55 m 2 ha À1 and overstory stem densities averaged 993 ha À1 .By 2004, 40% of sampled stands were infested, but most stands remained in good health overall; only 8 stands contained high HWA densities and only two had lost .50% overstory hemlock. Out of fifteen stand and landscape predictor variables examined, only latitude and winter climate variables were related to HWA density. Cold temperatures appear to be slowing the spread and impact of HWA at its northern extent as HWA infestation intensity and hemlock mortality and vigor were significantly correlated with average minimum winter temperature. Contrary to predictions, there was no regional increase in hemlock harvesting. The results suggest that regional HWA-hemlock dynamics are currently being shaped more by climate than by a combination of landscape and social factors. The persistence and migration of HWA continues to pose a significant threat regionally, especially in the northern portion of the study area, where hemlock dominates many forests.

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“…The hemlock woolly adelgid (HWA) is a small (1 mm adult) hemipteran native to Japan and China that was introduced near Richmond, Virginia in the 1950s; it had spread to southern New England by 1985 (McClure 1990). In the eastern United States, its invaded range now stretches from Massachusetts and New Hampshire in the north to Georgia in the south.…”

Section: Natural History Of the Systemmentioning

confidence: 99%

Exploitative Competition Between Invasive Herbivores Benefits a Native Host Plant

Preisser

Elkinton

2008

Ecology

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Abstract. Although biological invasions are of considerable concern to ecologists, relatively little attention has been paid to the potential for and consequences of indirect interactions between invasive species. Such interactions are generally thought to enhance invasives' spread and impact (i.e., the ''invasional meltdown'' hypothesis); however, exotic species might also act indirectly to slow the spread or blunt the impact of other invasives. On the east coast of the United States, the invasive hemlock woolly adelgid (Adelges tsugae, HWA) and elongate hemlock scale (Fiorinia externa, EHS) both feed on eastern hemlock (Tsuga canadensis). Of the two insects, HWA is considered far more damaging and disproportionately responsible for hemlock mortality. We describe research assessing the interaction between HWA and EHS, and the consequences of this interaction for eastern hemlock. We conducted an experiment in which uninfested hemlock branches were experimentally infested with herbivores in a 2 3 2 factorial design (either, both, or neither herbivore species). Over the 2.5-year course of the experiment, each herbivore's density was ;30% lower in mixed-vs. single-species treatments. Intriguingly, however, interspecific competition weakened rather than enhanced plant damage: growth was lower in the HWAonly treatment than in the HWA þ EHS, EHS-only, or control treatments. Our results suggest that, for HWA-infested hemlocks, the benefit of co-occurring EHS infestations (reduced HWA density) may outweigh the cost (increased resource depletion).

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Role of Wind, Birds, Deer, and Humans in the Dispersal of Hemlock Woolly Adelgid (Homoptera: Adelgidae)

Cited by 142 publications

References 0 publications

Predicting Hemlock Woolly Adelgid Winter Mortality in Connecticut Forests by Climate Divisions

Predicting Hemlock Woolly Adelgid Winter Mortality in Connecticut Forests by Climate Divisions

A foundation tree at the precipice:Tsuga canadensishealth after the arrival ofAdelges tsugaein central New England

Exploitative Competition Between Invasive Herbivores Benefits a Native Host Plant

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