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Natural Succession

Natural succession, also known as ecological succession, is the process by which biological communities replace each other in a relatively predictable sequence, based on environmental changes that occur within the habitat.  Gradually, a climax, or final community, is established and could remain in perpetuity until another disturbance, such as fire, agriculture or glaciation, returns the habitat to a relatively barren state. 

A typical sequence in succession is bare soil being colonized by annual grasses and forbs.  This pioneer community is gradually replaced by woody vegetation - first shrubs, then fast-growing shade-intolerant trees, such as conifer trees, aspens and birch, and eventually shade-tolerant, slower-growing maples, basswood, and elm.  A climax community, however, is not an unchanging community and older trees mature and die off producing snags and logs which can provide their own microhabitats. When a forest reaches this state it is referred to as an old-growth forest.

Here at Anoka-Ramsey, the receding glaciers of the Wisconsin glaciation 12,000 years ago left a barren soil along the Mississippi River called the Anoka Sand Plain.  An open oak and prairie habitat was maintained in this area by fire set by Native Americans and lightning strikes until about the 1600s when a cooler, moister climate reduced the frequency of fires.  This allowed the Big Woods to replace the prairie with maples, American elm, and basswood, though patches of prairie and oak savanna still remained.

Europeans brought their own form of disturbance as they cleared woods for timber and plowed prairies for agriculture.  The Big Woods was broken up into smaller fragments and woodlots. When Anoka-Ramsey bought the property on which it stands now, the land was mostly plowed field with small woodlots and shelterbelts. (see aerial photos).  The northern part of the property was set aside for a Natural Area and has been allowed to succeed, for the most part unimpeded, except a small portion being managed for prairie.  As one compares the aerial photos, one can see the increase in areas with trees between 1960, 1977 and 2006.  Further documentation can be seen with ground photos.

 

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Last Updated -August 12, 2016

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Melanie Waite-Altringer or Joan McKearnan or Terry Teppen