Year of Publication

2014

Degree Name

Master of Science (MS)

Document Type

Master's Thesis

College

Agriculture, Food and Environment

Department

Entomology

First Advisor

Dr. Lynne Rieske-Kinney

Abstract

Hemlock woolly adelgid is an invasive herbivore causing extensive mortality of eastern hemlock, an important foundation species that provides stable conditions influencing biological communities. Hemlock is often found in riparian areas and following its decline, broadleaved species, including birch, beech, and rhododendron, will replace it. These plants differ from hemlock in patterns of canopy cover and leaf properties, which influence conditions and resources within streams.

My goal was to evaluate potential impacts of adelgid-induced alterations to riparian canopies and litter on benthic communities and litter breakdown in streams. I characterized benthic invertebrate communities, litter colonization and litter breakdown in streams with hemlock- or deciduous-dominated riparian canopies. Riparian canopy influenced abundance of some invertebrates, but litter species influences a range of benthic colonizers. Rhododendron and beech litter generally support more invertebrates and decomposes more slowly than birch or hemlock. When invertebrates are excluded, broadleaved litter breakdown is more hindered than hemlock breakdown. My findings suggest that invertebrates may be more affected by future increases in broadleaved litter inputs to streams than by hemlock litter loss. This is significant because benthic invertebrates are important for in-stream litter processing and are linked to aquatic and terrestrial food webs.

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