Value of Eastern Hemlock on the Landscape



eastern hemlock stands on the high Allegheny plateau
are threatened by hemlock wooly adelgid

 With Hemlock Wooly Adelgid (HWA) moving across Pennsylvania there is a real threat of it impacting hemlock on the high Allegheny plateau.  Recently, a group called the High Allegheny Hemlock Conservation Project has formed to look into hemlock conservation in the region.  The group is headed by The Nature Conservancy but numerous state, federal and private entities are involved.  One of their first tasks has been to develop an in-depth list of various attributes that make hemlock valuable, or what makes certain areas of hemlock valuable. 

The following is a list of the valuation aspects the Steering Committee feels are most important when considering the value of hemlock on the landscape:
Wildlife Habitat
Rare Habitats: Including old-growth, rare, threatened, and endangered species
Water Quality
Human “Use”:  Includes recreation, spiritual and aesthetic aspects, and can be used as a proxy for the amount of money gained from tourism, and amount of money that would be spent on removal of hazard trees

Other attributes that may make a stand of hemlock more valuable include: 
1. Access to the site - which directly relates to the ability to use treatments on the ground

2. Connectivity of hemlock stands or patches on the landscape

3. Diversity of hemlock age classes and associated species (may lead to increased resiliency following HWA infestation)

This list is not in any particular order and any feedback would be greatly appreciated.......it’s completeness or incompleteness, or suggestions on what data to use or where to look for data, would be appreciated.

The steering committee is currently gathering spatial data relevant to each of these aspects.  The attributes will be able to be viewed and used to prioritize stands where treatmenst can then be applied.

Lastly, I have provided a link to a bookhlet entitled Silvicultural Options for Managing Hemlock Forests Threatened by Hemlock Wooly Adelgid.  The booklet was written by David Orwig, Harvard forest, and David Kittredge, UMass Extension.  It was developed for landowners to learn about HWA and their options concerning management of hemlock.  With HWA so near the High Allegheny Plateau it is imperative to get the word out to as many as possible, so people can be looking for the insect and reporting what they are seeing.

For more information you can contact Sara Johnson (sejohnson@tnc.org) at The Nature Conservancy directly.