Unusual Forests - Archive of Older Posts


Lee Frelich walks through a forest of rock elm and basswood, MN (photo by Mark Stennes)



Unusual Forests

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Unusual Forests

by Edward Forrest Frank

Places in which the trees are not spectacular, but represent an unusual assemblage or exhibit unusual character are something I feel is as important to document as are the big trees we measure.  Other examples, such as the the rock elm forest in Minnesota, are also worth documenting.  We may not know if all of the examples included in this section are significant in a broader context, but we will never know unless we catalogue and document these finds.

Dr. Lee Frelich wrote (December 6, 2008): "I think unusual forests are important because they may have covered millions of acres in the past, and may again in the future. For example the elm forest of Minnesota which probably now totals only a few hundred acres, covered the southern half of MN, WI, and most of IA, IL and IN 11,000 years before present. It may also be the forest of the future when the climate changes."

Forests in this section include:
1)  Unusual assemblages: This category would include forests with an unusual assemblage of trees and other plants. Lee Frelich has talked about the Rock Elm forest in Minnesota near the boundary between prairie and forest. Other such forests might include those growing in various types of barrens in which the assemblage is restricted by the geologic conditions. 

"Forest" in Sedona Canyon, AZ

2) Mixed Conditions: We should also consider those forests such as are growing in a mixed condition like trees in swamp setting or trees in desert setting. These are not what we would normally consider a forest, but they are a vital part of the ecosystem. The old growth post oak systems in the cross- timbers areas of Oklahoma and Texas are a good example of this type of assemblage.

  Stunted pines atop Mt. Everett, MA

3) Forests with character:  This is a somewhat subjective category, but a forest segment with these characteristics would likely be recognized by a wide number of people. The term  "aged with adversity" has been used and this is really the focus of this characteristic. Don Bertolette said, "some of the oldest trees of several species that come to mind (foxtail pine in the Sierra Nevada's, bristlecone pine in the Sierras and White Mtns., western juniper) are growing on relatively depauperate sites, in environmentally extreme climatic conditions." So we have the concept of trees that have character because they have been aged by adversity. This would include many of the stunted forests growing under harsh environmental conditions. The age of these trees may not be easily apparent hidden by their unusual form, and certainly they are not large for the species, but they do have character.
4) Forests with unusual structural complexity.. This structural complexity often comes in two forms: accumulated biomass and geologic. Older forests tend to have a tremendous amount of structure in the form of nesting cavities, snags, coarse woody debris, moss, tip-up mounds etc. Forests of any age growing on boulder fields or other rocky situations also have copious structure for wildlife to utilize. Structurally complex forests often are synonymous with "primary" and "old-growth" forests but not always. (Josh Kelly)

5) Relict woods.  These are forest patches with assemblages of species representative of a previous climatic regime.  These are characterized by disjunct populations separated from their typical range by a large distance. 
6) Understory:  Certainly the character and composition of the understory of the forests is also worth considering when suggesting that something is unusual or uncommon.  I want to include in this listing those forest sections that deserve consideration and discussion about whether they fit this category.