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Abstract Detail



Bryological and Lichenological Section/ABLS

Jackson , Michelle Renee [1], Bellemare, Jesse [2].

Potential Effects of Eastern Hemlock Decline on the Hemlock-associated Liverwort Bazzania trilobata.

Bazzania trilobata is a relatively large, leafy liverwort typically found growing in close association with mesic Eastern Hemlock (Tsuga canadensis) forests across New England. As these Hemlock forests are increasingly invaded by two exotic insects, the Hemlock Wooly Adelgid (Adelges tsugae) and Elongate Hemlock Scale (Fiorinia externa), B. trilobata and other bryophytes associated with cool, mesic forest understory conditions might also be at risk of decline, in parallel with Hemlock. Several mechanisms might contribute to bryophyte declines, including changes in leaf litter composition and characteristics, greater exposure to light, heat, and drying conditions as dying Hemlocks open the forest canopy, and potential shifts in throughfall precipitation chemistry. These types of changes in the forest understory environment might impact the internal water status and physiological activity of bryophytes like B. trilobata, leading to deterioration or death if conditions become too extreme relative to intact Hemlock forests. In this ongoing project, we have initiated a multi-year transplant experiment testing B. trilobata survival and growth under forest canopies of varying Hemlock vs. deciduous tree species composition at Smith College’s MacLeish Field Station in western Massachusetts. Samples have also been placed in a recently logged forest with open canopy conditions, analogous to the pre-emptive and salvage logging taking place in some Hemlock stands threatened by the exotic insects.  In addition, we have begun a growth chamber experiment in the lab testing the abiotic boundaries of B. trilobata survival by manipulating temperature and moisture conditions.  Preliminary results indicate differential survival relative to temperature and water conditions, consistent with observations of high mortality of B. trilobata samples moved to clear-cut forest areas in the field experiment. In contrast, samples moved to intact deciduous forest areas have survived through Summer and Fall 2013, as have control samples under Hemlock canopies, but leaf litter accumulation might threaten long term survival in forests converted to deciduous canopies by Hemlock decline.  


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1 - Smith College, Biological Sciences, Box 8131, 1 Chapin Way, Northampton, MA, 01063, USA
2 - Smith College, Dept. Of Biological Sciences, Clark Science Center, 44 College Lane, Northampton, MA, 01063, USA

Keywords:
bryophytes
hemlock
hemlock wooly adelgid
Bazzania trilobata
invasive species.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Eyrie/Boise Centre
Date: Monday, July 28th, 2014
Time: 5:30 PM
Number: PBR003
Abstract ID:423
Candidate for Awards:None


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