Tom's Blog

Saturday, February 15, 2014

Using Google Earth in restoration ecology work

The quality of images used in Google Earth varies with year and with location, but currently the air photo used in our area is outstanding, provided the brightness and contrast are adjusted using Photoshop. According to the label, the area was "flown" on 10/8/2013. Although there is a 2013 air photo available for download from the National Agriculture Imagery Program (NAIP; flown 09/27 (check the Wisconsin Cartography Office for details), the quality is vastly poorer than the Google Earth image.

I haven't used Google Earth for several years so I don't know when enhancements have been made, but the current version has a fascinating "history" slider. For the area I was interested in (Black Earth Rettenmund Prairie), 7 different images were available: 4/1992, 4/2000,  9/2005, 9/2006, 9/2008, 11, 2010, and 10/2013. By clicking the slider arrow, you can seamlessly move from one date to the next. Since Kathie and I started managing restoration at BE Rettenmund in 2000, the work we have done passed before my eyes as I clicked the slider.

The best image is the newest (10/2013), which is shown here. As can be seen, the vegetation stands out clearly, and our trails and mowed fire break really show. Hopefully, a version of this image might be available that could be georeferenced in ArcGIS.

Black Earth Rettenmund is a fine remnant prairie, but at the time the Nature Conservancy purchased it (1986) it had seriously deteriorated. About half the 16 acre prairie and been overcome with trees and brush, including two major aspen clones and lots of sumac, gray dogwood, and honeysuckle. Despite frequent fire (mostly biennial), we are still fighting the legacy of those days. Note the location of the former aspen clone in the photo. The green there now is not aspen, but prairie willow and  hazel (both native, but still invasive). Other areas of the preserve have patches of gray dogwood. Sumac was once an even worse scourge, but after our four years of heavy work, it is no longer a problem. See this link from my blog for details on how we dealt with sumac.

The Gateway Prairie shown here was a cropped area when TNC bought the site, and was ignored for 20 years. When Kathie and I started restoration it was a monoculture of Bromus inermis. Judicious treatment with glyphosate in early April, and lots of overseeding has turned the area into a fine planted prairie. Not as good as the remnant, but better than a field of smooth brome!

Another nice thing about Google Earth is that you can save a JPEG of any area on the screen. (The labels on the image here were put on later with Photoshop.)

Google Earth is also available as a mobile app for the iPad. Although the mobile version lacks some of the options available in the desktop version (the historical slider, for instance), the quality of the image is very high, especially with the screen on the new iPad Air. 


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