Tuesday, July 24, 2012

Nature Square

Have you ever gone out into a natural environment and looked to see how many different type of species you can find within a given area?  Observations of small areas can give you a better understanding of the interdependence each species has both with each other and with its environment.
Nature Square at Springbrook Prairie

Getting Outside
Today, I rode my bike to my local prairie preserve to get outside, get some exercise, and practice this skill of observation.  This study is performed by cordoning off an area one meter square, making notes of what you see, and observing their interactions.  Because my focus right now is on sustainability and resilience, I studied the transition area between the disturbed mowed path and the non-mowed prairie area and made notes about the differences in species composition at the different locations.  I wanted to see what, if any, effect this disturbance had on species composition.  

Disturbed versus Intact
The area that is regularly disturbed - the mowed portion nearest to the path - had much less diversity in plants, there was more bare soil, and pioneer invasive species such as Queen Anne's Lace, thistles, and crab grass were abundant.  I did see one spider, but no other wildlife was present.  In the undisturbed area adjacent to the mowed portion, the diversity of species was much greater.  I saw five species of grass, bee balm, a couple of other forbs I couldn't identify, grasshoppers, a bee, a monarch butterfly, clover, thistles, and even a woody shrub.  This transitional edge benefited from the rain runoff from the path, so it seemed more well watered than the other more inland areas.  

The Power of Diversity

This simple observation is an illustration of the power of diversity.  You can observe that disturbed areas have less diversity than those that are undisturbed, not only across classifications (grasses, flowers, insects, wildlife), but also within each group (a variety of grasses fulfilling different niches).  The intact system with a high level of diversity is therefor more prepared to retain its function through additional disturbance than the previously disturbed portion.  

Additional disturbances, such as the severe drought that has tested most portions of the Midwest, has taken a tole on the prairie.  The intact prairie looks very different than it looked last year when rainfall was abundant - the grasses are shorter and the species mix is different - but it's still a prairie.  The mowed portion of the prairie, although still a part of the system, no longer looks like a prairie and the land has been largely turned over to invasives.  

Key Takeaway
Resilient systems incorporate diversity by maintaining a variety of groups with different functions and cultivating variety within those groups.  They are therefor more able to maintain their function and identity throughout and following disturbance.  

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