Date of Award

5-2007

Level of Access Assigned by Author

Open-Access Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Ecology and Environmental Sciences

Advisor

Robert G. Wagner

Second Committee Member

William A. Halteman

Third Committee Member

Malcolm L. Hunter, Jr.

Abstract

Click beetle (Coleoptera: Elateridae) assemblages were examined in three experiments in the Acadian forest of Maine. First, I used flight intercept traps to compare Elaterid assemblages in stands that developed after clearcut, shelterwood, and selection harvests. Click beetle richness was highest in stands managed under a selection system and lowest in stands regenerated using the clearcut method. The abundance of click beetle species was lower in stands managed by clearcutting than in stands managed using the shelterwood and selection methods. Hardwood basal area was the best environmental predictor for both species richness and species abundance. Second, I examined whether Elaterid assemblages in soil were associated with hardwood (Maple, Birch, Aspen, Blueberry, and Oak) and softwood (Spruce-Fir-Pine, Pine, Hemlock, and Fern-Hemlock) cover types. Elaterid diversity was generally higher in hardwood than softwood stands. Species richness was lowest in the Spruce-Fir-Pine and highest in the Oak cover type. Species abundance was lowest in the Spruce-Fir-Pine and Pine and highest in the Oak, Maple, and Hemlock cover types. Assemblages in hardwood stands were less similar to those in coniferous stands than they were to each other, with assemblages in oak stands being least similar to those in coniferous or other hardwood stands. Four species of click beetle were more abundant in softwood stands, and seven species were associated with increases in specific softwood tree and shrub species. Nine species of click beetle were more abundant in hardwood stands, and fifteen species were associated with increases in specific hardwood tree and shrub species, including six species associated with oak stands. Third, I examined how the species richness, abundance, diversity, and assemblage similarity of click beetles inhabiting coarse woody material (CWM) were affected by gap harvesting and characteristics of the CWM (diameter, degree of decay, and wood type) in Maine’s Acadian forest. Species assemblages varied between harvest treatments, canopy conditions, CWM wood type (hardwood vs. softwood), and especially between CWM decay classes and among diameter classes. Size of harvest gap did not influence the species abundance of click beetles across the small range of gap sizes studied (0.01 to 0.21 ha), and there were few differences between the two harvest treatments. Four of the most common species had higher abundances in closed canopy than harvest gaps. Click beetle species richness and species abundance were higher in CWM that had larger diameters and were more decayed. Click beetle diversity was higher in softwood than hardwood CWM.

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