Treesearch

Hemlock stands provide superior winter cover for white-tailed deer. When a site is suitable for the support of a hemlock community, a decision to undertake active management is appropriate, however the difficulty of securing adequate hemlock regeneration must guide and govern the timber management plan. The need to maintain deer wintering areas creates some limitations to the optimum application of silvicultural guides. Stand diversity caused by site quality variation, management history, or species composition can be exploited to improve quality of cover or to expand a wintering area. Up...

Eastern hemlock (Tsuga canadensis (L.) Carr.) is the second most abundant conifer species in the northeastern United States. It occurs both in almost pure stands and in stands where it is mixed with hardwoods and white pine (Pinus strobus L.). Recently, hemlock in the middle-Atlantic and southern New England states has become infested with the hemlock woolly adelgid (Adelges tsugae Annand). This insect pest can result in high levels of mortality, opening up the forest canopy and illuminating the forest floor to full sunlight. The effects of the mortality of overstory hemlock on forest...

Ninety-six bird and forty-seven mammal species are associated with the hemlock type in the northeastern United States. Of these species eight bird and ten mammal species are strongly associated with the hemlock type though none of these species are limited to it. Hemlock species richness appears to be lower than in other conifer or hardwood types. Avian habitat considerations include the distribution and variety of structural habitat features throughout managed and unmanaged stands in sustainable patterns. Sawtimber hemlock stands support significantly higher bird communities than young...

The effects of moose on eastern hemlock (Tsuga canadensis) natural seedling establishment in Algonquin Provincial Park, Ontario, were examined. Two thousand seedlings were tagged on 56 sites in 1992 and monitored for six years. Initial data collected included seedling height, browsing history and percent crown closure. At the end of the growing season of the following six years, heights of these seedlings were remeasured; damages on seedlings were assessed according to browsing, physical, logging and unknown factors. After six years, 10.4% of the seedlings had died. Browsing caused 60% of...

During an inventory to assess spruce bark beetle impact on the Kenai Peninsula in south-central Alaska, 5-year mortality estimates were made for all growing-stock trees on 0.6 ha areas, on 0.4 ha areas, and on a cluster of four 1/60-ha subplots. The analysis of the results of the comparison between cluster data and the larger plot data highlighted some of the problems associated with trying to assess tree mortality from small plots. Based on the large chi square values observed in these tests, there seems to be a strong case for taking a mortality plot that is larger than the four 1/60-ha...

Since 1969 Trent University researchers have been investigating the chemistry and biotic part of a small undisturbed lake near Minden, Ontario. Clear Lake is surrounded by old growth hemlock stands, some 400 years old. The research was later joined by personnel of the Ontario Ministry of the Environment, and the educational program in the Frost Centre. We are going to discuss changes in pH, phosphorus content and the reaction of aquatic macrophytes, Eriocaulon and Lobelia dortmana, to simulated acid rain conditions and increased ultraviolet radiation.

Several species of higher plants and mushrooms have been surveyed growing under the canopy of old stands of hemlock surrounding Clear Lake near Minden, Ontario. Some of the hemlock seedlings growing on fallen trunks together with debris in which they were growing were brought to a greenhouse in pots, and some of them were transferred into sandy soil. The conditions of growth involved a gradient of shading. As an analysis of the debris revealed a low pH, the soil in all pots was kept at a pH of 5.5. The best growing seedlings were in the most shaded areas in pots filled with plant debris...

Hemlock woolly adelgid (HWA) (Adelges tsugae), an introduced aphid-like insect from Asia, is expanding across the northeastern United States through the range of eastern hemlock (Tsuga canadensis (L.) Carr.) and has the potential to severely reduce or eliminate this important late-successional species. While infestation and unimpeded migration of HWA presents a tremendous management problem, it also has provided an unusual opportunity to examine the impacts of an introduced pest as it spreads. In order to develop insights into these management issues, we have developed a multi-faceted...

Eastern hemlock (Tsuga canadensis) is in decline throughout its range in the eastern US due to infestation by an exotic insect pest, the hemlock woolly adelgid (Adelges tsugae). In Shenandoah National Park, the hemlock woolly adelgid (HWA) rapidly killed many stands of hemlock after first appearing in the late-1980's, while having only minor impact in other stands.

Mortality of eastern hemlock (Tsuga canadensis (L.) Carriere) may be caused by a variety of agents, but hemlock trees of all sizes over a large geographic area are currently threatened by an outbreak of the hemlock woolly adelgid (HWA: Adelges tsugae Annand) in the eastern United States. In this paper, we review what is currently known about changes in nutrient cycling due to hemlock mortality, identify gaps in current knowledge, and describe research being conducted to better understand the influences of hemlock mortality on nutrient cycling. Recent research clearly demonstrates that...