Influence of Adjacent Uplands and Groundwater on the Hydrology and Invertebrate Community Composition of Seasonal Forest Ponds in North Central Minnesota
Abstract
Seasonal ponds are common throughout northern Minnesota's forested
areas. Seasonal ponds typically flood due to snow-melt and high precipitation
rates in early spring, then dry by mid-late summer. The dynamic hydroperiods of
seasonal ponds create a unique fishless habitat hosting an abundance of many
endemic aquatic species. Hydroperiod has long been considered a major
controller of biological communities in seasonal ponds, but few data are available
for testing hydrological linkages among seasonal ponds, their surrounding
watersheds and their resident invertebrate communities. To identify hydrological
pond function, I placed peizometers and monitoring wells in 8 sites in the Buena
Vista State Forest in Beltrami County, MN, and 8 sites in the Paul Bunyan State
Forest in Hubbard County, MN (16 sites total). Water levels were monitored
weekly (2006-2009) from spring melt until ponds dried and water tables fell below
readable depths. Invertebrate communities were also sampled weekly during 2008
and 2009. Results indicate that high but variable water exchange occurs between
seasonal ponds and ground water. Hydrological patterns of seasonal ponds were
related to several physical parameters including hydrological function, maximum
depth, and canopy cover. Most relationships appear to be consistent between the
2 forest areas; however, some differences are notable, such as soil characteristics
and influence of pond surface area on hydroperiod. Patterns in pond invertebrate
communities were also related to hydrological function and hydroperiod, and these
patterns appear consistent between the 2 forest areas, suggesting that many
invertebrates are generalist users of these areas.