SBS Tuesday Seminars

Speaker:                    Barry Logan, Associate Professor of Biology, Director of Biochemistry Program, Bowdoin College, Brunswick, Maine

Date:                       Tuesday 23rd March 2010
Time:                       12 noon - 1pm
Venue:                     Victoria University, Hugh McKenzie HMLT003
Title:                        Decline of mistletoe-infected spruce forests along the New England coast: mechanisms of mortality and the legacy of land use

Abstract:
Intensive deforestation for livestock grazing and subsequent land abandonment along the Atlantic coast of North America led to the replacement of red spruce- and fir-dominated forests with white spruce-dominated forests.  White spruce is acutely vulnerable to infection by eastern dwarf mistletoe, a native xylem- and phloem-tapping parasite, and white spruce stands along the Atlantic coast in Maine (USA) experience severe damage and increased mortality caused largely by eastern dwarf mistletoe infection. 

Infection leads to hormonal, developmental and physiological host responses that preserve the longevity of needles on infected branches.  However, this host response may actually serve to increase the overall negative impact of infection on whole-tree growth and survival by prolonging the survival of infected branches with poor or possibly even negative carbon balance and by allowing those branches to serve as a source of parasite seed for further infection. 

I describe the effects of infection on host hormone metabolism, needle morphology, gas exchange, stem hydraulic conductivities, and branch and whole-tree dendroecology to show that insights into the mechanism by which mistletoe infection hastens the death of host white spruce can be obtained through examination of this parasite-host interaction at differing scales along the organism hierarchy.

All Welcome