Figure 1
![Figure 1](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2F2046-9063-8-29/MediaObjects/12999_2012_Article_30_Fig1_HTML.jpg)
Location of the sampling sites in the northern Great Plains of Saskatchewan, with sample sites as open circles and major cities as open squares. Dashed lines indicate long-term isopleths of total precipitation minus total potential evapotranspiration (cm yr-1) [22]. Solid line denotes grassland transition. All lakes are in endorheic drainage basins.