Iowa: Plants and Wildlife
As evaporation increases with temperature and lake levels decrease, the concentration of pollutants and toxicants will increase and degrade water quality. This is not expected to be mitigated by pulse floods caused by precipitation events, as these events will cause an increase in runoff, introducing pollutants from adjacent agricultural, urban and industrial landscapes. A decrease in lake levels is expected to cause a loss of valuable habitat, including spawning grounds, for many species. Decreasing lake levels will also concentrate pollutants and toxicants, which will further harm fish species.
Warmer temperatures and reduction in summer water levels is expected to cause wetlands to dry more often, and earlier in the season, with many expected to dry permanently resulting in a loss of wetland habitat for native fish and wildlife populations. Warmer water temperatures could alter seasonal mixing patterns in lakes, which provide oxygenated water to the deeper strata of the lake. In such a situation, this stratification could completely cut off oxygen supply to the bottom of the lake, creating low or no-oxygen zones, or “dead zones”, which kill fish and other aquatic organisms. An increase in air and water temperature is expected to cause populations of coldwater fish, such as brook trout, lake trout and whitefish, to decline and be replaced by non-native invasive fish species.
Forest ecosystems are expected to shift in geographic range and species composition following northward trends in climate. With drier summer conditions, forested acres could be converted to grassland or pasture, while hotter, wet weather would encourage encroachment of southern pines. Drier summer conditions in forest ecosystems increases the likelihood of forest wildfire, which is further exacerbated by low moisture availability in soil and increased evaporation from plants. Forest ecosystems already stressed by drought conditions and wildfire are more susceptible to insect pest infestation, such as Gypsy Moth, which would normally be controlled by cold winter die off. Instead, these pests as well as non-native trees and plants, will be able to capitalize on warmer temperatures and milder winters and increase their populations. Initially high levels of atmospheric CO2 are expected to benefit forest growth, however increasing levels of ground-level ozone, which is toxic to plants, is expected to contribute to an overall decline in forest production. Iowa’s forest are expected to decline in size with climate change.
Prairie Pothole wetland ecosystems have become increasingly fragmented with development and urban sprawl. Further stress resulting from climate changes with limited migration corridors in the highly fragmented landscape could result in population declines and local extinctions of several threatened and endangered species of water fowl, invertebrates, fish and amphibians. Increased seasonal flooding is expected to cause declines, and possibly local extinctions, of wildlife species ill-adapted to flood conditions. For example, Iowa’s wood turtle nests on riverine gravel bars in mid-summer, habitat which is likely to disappear in most areas with increased washing out due to the increased frequency of high water events.
