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Harvard Forest Symposium Abstract 2016

• Title: Long-term Forest-Wildlife Interactions in Southern New England
• Primary Author: Stephen DeStefano (USGS Massachusetts Cooperative Fish and Wildlife Research Unit)
• Additional Authors: Edward Faison (Highstead, Inc.); David Foster (Harvard University); David Wattles (University of Massachusetts at Amherst)
• Abstract:

  Animal populations are undergoing shifts in abundance and distribution on a global scale. About half of all mammal species are experiencing some level of threat. In North America, most large mammals have undergone extensive reductions in population size and range during the past 2-3 centuries. New England has lost a number of species, but the remaining assemblage of larger mammals that have recovered from low population levels are now doing quite well (e.g., white-tailed deer, beavers). Some are increasing their range within the region (e.g., black bears, fishers, bobcats) and adapting to changes in forest conditions and urbanization as human activity and climate change alter fundamental niche space. Nonetheless, we have entered an era in which common or abundant animals are no longer buffered against becoming threatened or endangered. Examples of once common species experiencing dramatic population declines (e.g., some bats, moose in some regions) – often due to changes in climate and associated responses of parasites and diseases – are becoming more prevalent.
  
  
  Our research on large mammals began in 2006 and has involved 3 species (deer, moose, and bears) and 2 broad approaches. With experimental exclosures we examine the effect of ungulate browsers on forest vegetation, which supports the HF LTER goal of understanding long-term dynamics of forest ecosystems; and with GPS-technology we document movements and landscape use by moose and bears, which supports the HF LTER goal of large-scale, regional conservation planning.
  
  
  The first phase of exclosure research (2008-2014) focused on herbivore effects on the re-establishment of vegetation in patch or small clear cuts. After 6-7 years, moose + deer reduced stem densities and basal area by 2-3-fold, whereas deer alone had relatively minor effects. By reducing the woody overstory and creating more open grown stand conditions, moose + deer browsing promoted herb and shrub assemblages characteristic of open/disturbed habitats and greater herbaceous species richness. Analysis of GPS-collared moose and bears is revealing habitat use and movements in a fragmented and human-dominated landscape. Major highways can act as barriers to movements, while adjacent topography and cover types can influence crossings on state highways. Moose tend to avoid areas with suburban development, while bears are often drawn to and integrated into them.
  
  
  The second phase of the exclosure research (2016-20) will focus on woody vegetation exceeding the browse zone and the beginning of competitive exclusion effects in the regenerating harvests. We are interested in whether stem density, basal area, and composition will converge in the treatment plots, or if browsing legacies will persist into later stages of stand development. Also, we have noted significant changes in tree morphology from browsing and are interested in measuring those effects and speculating on their ecological importance. Lastly, we will begin to resample exclosure and control plots at the HF Hemlock Removal Expt. and in uncut sites. We are also hoping to collaborate with visiting researchers on studies related to seed banking, non-browsing disturbance, and vegetation refugia on boulders. As analyses progress on the GPS data, we are seeking ways to incorporate results into regional conservation plans and into management of human-wildlife interactions.
  
  
  
  

• Research Category: Conservation and Management
  Large Experiments and Permanent Plot Studies
  Physiological Ecology, Population Dynamics, and Species Interactions