Savanna

Late afternoon view across a more open part of Helen Allison Savanna. It's been a wetter than average summer and the lush grasses pictured here are testament to it. The mosquitoes also benefitted greatly from the wetter summer and were a serious nuisance on this visit.

 

Helen Allison Savanna is a Minnesota Department of Natural Resources Scientific and Natural Area, owned in part by The Nature Conservancy. The site supports a thriving oak savanna (mixed oak and grassland) that is home to a number of rare or uncommon woodland and grassland species of plants and animals.

 

This site is part of the Anoka Sand Plain, a large glacial outwash plain located north of the Twin Cities. While most of the sand plain is relatively flat, this area was reworked by wind and has some relatively large (for the area) sand dunes that probably formed mainly during the mid-Holocene dry period about 5,000 years ago. Some of the dunes are still mildly active today, with small blowout areas visible. The relatively steep topography probably saved this parcel of land from the plow.

 

The trees in the photo are bur oaks (Quercus macrocarpa) and other similar thick-barked, fire-resistant oak species. Fire plays a major role in establishing and maintaining most savanna ecosystems, killing off many species of trees and shrubs that would otherwise out-compete the native vegetation. Though mature, many of these trees only stand 15 to 20 feet high due to the limited water and nutrient status of these sandy soils. Some ash trees are also present on site.

 

DNR Scientific and Natural Areas are protected lands that have limited access to the public. Please see the Minnesota DNR SNA website for further information.

 

 

  • James_Shook 5y

    Fascinating to see this and to read your description. I have been reading about the recent ice ages, and hadn't known until now how much of the northern midwest and west, as well, of course, of Canada, was shaped by glacial actions, including catastrophic floods when ice dams broke or glacial lakes were breached. And, as here, by local ecosystems promoting desert conditions for relatively short periods of time after the retreat of the ice sheets.

    I think the role of fire in the maintenance of ecosystems is something that remains under-appreciated. Interesting to learn it is a factor here.
  • sedge808 5y

    I want to visit.
  • Tony Pulokas 5y

    Go nature! Looks like an awesome place to explore.
  • Anthony Levens 5y

    Great photograph! I know exactly the spot you were standing :)
  • MermaidAte 5y

    It could be England :-)
  • camilo 5y

    beautiful landscape , thanks for the explanation ';p
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Taken on July 20, 2010
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