Abundance and size distribution of permanent and temporary farm ponds in the southeastern Great Plains

Using aerial images from the US Department of Agriculture National Agriculture Imagery Program and the US Geological Survey National Hydrology Dataset, we estimated 577 654 farm ponds with surface areas from 0.005 to 1 ha in a 229 489 km(2) region of the southeastern Great Plains (2.52 ponds/km(2)). Ponds with surface areas from 0.005 to 0.1 ha were the numerically dominant size class in the study region. The distribution of farm pond sizes followed an inverse power law relationship. We estimated 376 209 permanent ponds and 201 445 temporary ponds were in our study area. The ratio of temporary to permanent ponds within a pond size class was inversely related to pond surface area; 47% of ponds with surface areas of 0.005-0.1 ha were temporary, whereas only 13% of ponds with surface areas of 0.91-1 ha were temporary. Because permanent and temporary farm ponds are abundant and have different physico-chemical properties and ecological communities, assessments of regional biogeochemical processes and biodiversity in the Great Plains must consider both types of ecosystems.