There’s no universally accepted definition of an ‘old growth forest’ – but most scientists agree they’re characterized by large old trees, multi-layered canopies, and dead wood that provides habitat for a variety of animals, from cavity nesting birds to invertebrates.
In the Northeast, less than 1% of our forests are old growth. And old is a relative term. Different trees have different life expectancies. As a general rule, old growth forests have some trees that are several centuries old. They show few signs of human disturbance. And they are messy, with forest floors covered in dead wood and a rich herbaceous layer. When subject to activities like logging, this understory complexity can take decades to recover.
A group of researchers recently found that land snails are a good indicator of old growth forests. Their presence or absence can be tied to land use patterns, with a number of species showing a preference for old growth environments.
Daniel Douglas is a professor at Eastern Kentucky University.
“Because they (land snails) are highly immobile and they have preferences for particular habitats within a forest like, for instance: coarse, woody debris, or that dead, decaying, woody matter, (or) high accumulations of leaf litter. Those are all characteristics of old growth forests. And because land snails don’t move that much and they are tied so closely to this micro-habitat, that’s what makes them good indicators of forests that have experienced very little human disturbance.”
The results will likely apply to forests through the temperate world, and give further support to the unique role old growth forests play in preserving biodiversity.
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Web Extra
Full interview with Daniel Douglas, a professor at Eastern Kentucky University
[audio:http://wamcradio.org/EarthWise/wp-content/uploads/2013/04/douglas_full_web.mp3|titles=douglas_full_web]
Web Links
Land Snails Diversity Can Reflect Degrees of Anthropogenic Disturbance
http://www.esajournals.org/doi/full/10.1890/ES12-00361.1
Photo, taken on February 6, 2012, courtesy of Geoff Gallice via Flickr.
Earth Wise is a production of WAMC Northeast Public Radio. Support for Earth Wise comes from the Cary Institute of Ecosystem Studies in Millbrook, NY, with partial support from the Field Day Foundation.