PALUSTRINE WETLAND
Seasonal Pools
Did you know that Iowa was historically a very wet place? Before much of the state became farm land, the prairies and woodlands were dotted with wetlands. Referred to as ‘prairie potholes’, most of these pools of water were drained to make the land easier to manage for cultivating crops. Here at the Iowa Arboretum & Gardens, we are fortunate to have one of our very own wetlands that has been here from the beginning. The grounds of our cultivated 40 acres were only cleared of woodland vegetation in the 1960’s, leaving behind original topography. We celebrate the conservation of this remaining wetland and the benefits it brings to wildlife and the surrounding landscape.
A defining feature of these pools is that they are seasonal in nature. Moisture from winter snow and spring rain saturate the soil, any excess water then flows into these depressions in the landscape. Wetlands vary in depth, but most like this one are only a few feet deep. Once it fills up, the rest flows downhill to the nearest creek or river.
As temperatures increase in the spring, the pool comes alive. Creatures that were hibernating or laying dormant in the mud wake up and begin swimming around, including turtles, frogs, and invertebrates. Warm, nutrient rich water helps these creatures grow fast and reproduce quickly. Debris from the previous season like leaves and twigs begin to decompose, providing ample shelter and food. A chorus of frogs erupt from the wetland, later filling it with tadpoles. Migrating waterfowl often take breaks on their way northward, while some might choose this pool as a place to raise a family. It’s not uncommon to find raccoons hunting the shallow water, and other animals like foxes, opossums, and birds having a drink. By the middle of June, tadpoles have grown up and left to find shelter for the summer, insects will have grown wings to fly to more permanent water, and the water begins to disappear.
By mid-summer, the water is gone leaving behind rich mud for fast growing plant species to take root and grow. The stored water has soaked out into the soil of the surrounding landscape or slowly flows downhill underground. Some of the moisture has gone much deeper, replenishing ground water. The surrounding landscape is much more moist compared to areas without wetlands, helping reduce stress on trees late into the summer season. Once the mud dries, the bottom of the wetland is still green with plants growing, but with very little other life. Once rain returns in the fall, the mud will soften allowing species that hibernate to dig their burrows and get ready to settle in for winter once more.
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