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The distribution of hemlock woolly a...

Evans, Alexander M.

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The distribution of hemlock woolly adelgid in trees, forest stands, and regions.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	The distribution of hemlock woolly adelgid in trees, forest stands, and regions./
Author:	Evans, Alexander M.
Description:	181 p.
Notes:	Adviser: Timothy G. Gregoire.
Contained By:	Dissertation Abstracts International67-12B.
Subject:	Agriculture, Forestry and Wildlife. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3243623
ISBN:	9780542994951

The distribution of hemlock woolly adelgid in trees, forest stands, and regions.
Evans, Alexander M.

The distribution of hemlock woolly adelgid in trees, forest stands, and regions. - 181 p.

Adviser: Timothy G. Gregoire.

Thesis (Ph.D.)--Yale University, 2006.

Eastern hemlock trees, Tsuga canadensis, provide wildlife habitat, supply timber, moderate climate, and form part of many old growth forests in eastern North America. The hemlock woolly adelgid (HWA), Adelges tsugae, is an invasive exotic insect that threatens to kill all eastern hemlock trees. As HWA and hemlock mortality have spread through eastern North America, it has generally been assumed that HWA population densities and rates of range expansion have been uniform. Those assumptions have led to potentially inaccurate crown sampling methods, obscured possibilities for mitigation, and prompted unnecessary pre-emptive salvage logging.

ISBN: 9780542994951Subjects--Topical Terms:

783690
Agriculture, Forestry and Wildlife.

The distribution of hemlock woolly adelgid in trees, forest stands, and regions.
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020 $a 9780542994951
035 $a (UMI)AAI3243623
035 $a AAI3243623
040 $a UMI $c UMI
100 1 $a Evans, Alexander M. $3 1269277
245 1 4 $a The distribution of hemlock woolly adelgid in trees, forest stands, and regions.
300 $a 181 p.
500 $a Adviser: Timothy G. Gregoire.
500 $a Source: Dissertation Abstracts International, Volume: 67-12, Section: B, page: 6794.
502 $a Thesis (Ph.D.)--Yale University, 2006.
520 $a Eastern hemlock trees, Tsuga canadensis, provide wildlife habitat, supply timber, moderate climate, and form part of many old growth forests in eastern North America. The hemlock woolly adelgid (HWA), Adelges tsugae, is an invasive exotic insect that threatens to kill all eastern hemlock trees. As HWA and hemlock mortality have spread through eastern North America, it has generally been assumed that HWA population densities and rates of range expansion have been uniform. Those assumptions have led to potentially inaccurate crown sampling methods, obscured possibilities for mitigation, and prompted unnecessary pre-emptive salvage logging.
520 $a This dissertation examines variation in HWA population density and range expansion at multiple scales. It does so by establishing and applying appropriate sampling methods, measuring HWA populations in natural stands over multiple years, studying seedling infestation, and modeling the geographic variability of spread. The results of this research show that assumptions of uniformity are unfounded for both HWA density at the stand scale and for rates of range expansion at the regional scale. Some forest stands maintain significantly lower HWA populations than others and these differences remain consistent over multiple years. The probability of seedling infestation by MXA follows the same pattern across stands as overstory infestation. At the regional scale, HWA is spreading at a median rate of 12.5 km per year, but range expansion is significantly slower in areas with an average annual minimum temperature less than -26°C. Other significant results from this dissertation show that Chinese hemlock, T. chinensis, is a better candidate for reforesting hemlock stands than western hemlock, T. heterophylla . HWA densities are greater in the lower crowns of hemlock trees. However in trees with low HWA populations, the density trend appears to be reversed and lower crown populations are sparse, which suggests the need to adjust HWA sampling methods.
520 $a The multiple scales of analysis in this dissertation reveal ecologically significant patterns and highlight the spatial variability in an exotic invasion. The combination of consistent, low HWA densities in some forest stands and very slow spread in colder regions presents the opportunity for silviculture to encourage hemlock.
590 $a School code: 0265.
650 4 $a Agriculture, Forestry and Wildlife. $3 783690
650 4 $a Biology, Biostatistics. $3 1018416
650 4 $a Biology, Ecology. $3 1017726
650 4 $a Biology, Entomology. $3 1018619
690 $a 0308
690 $a 0329
690 $a 0353
690 $a 0478
710 2 $a Yale University. $3 515640
773 0 $t Dissertation Abstracts International $g 67-12B.
790 $a 0265
790 1 0 $a Gregoire, Timothy G., $e advisor
791 $a Ph.D.
792 $a 2006
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3243623