Harvard Forest Research

Assessing broad-scale patterns in susceptibility to beech bark disease

Principal Investigator: Posy Busby
Stanford University: Jun 25 2009 - Aug 15 2009:

Abstract:
In North America, exotic insect pests and pathogens pose one of the greatest threats to native forest ecosystems. Disease affecting ‘keystone’ species can be especially devastating by substantially altering forest succession and nutrient cycling. Despite the substantial risks associated with disease, we have a limited understanding of the factors controlling broad patterns in disease susceptibility. Population genetic structure is a likely factor influencing disease susceptibility. Specifically, greater genetic diversity is thought to confer a greater probability of resistance. This research will examine the relationship between Fagus grandifolia (American beech) population genetic structure and susceptibility to beech bark disease (BBD), an exotic scale-fungus pathogen. Modern beech populations established on historically cleared landscapes may have lower genetic diversity than those on adjacent continuously forested landscapes, perhaps as a result of founder effects. Land-use effects on soil fertility may also be important for BBD susceptibility. Landscapes historically cleared, plowed, and fertilized (w/ livestock manure) are characterized by higher soil nitrogen than both non-fertilized fields and continuously forest landscapes, even >50-100 years after agricultural abandonment. Historically fertilized landscapes may be more susceptible to BBD given greater nitrogen availability for the scale insect. :