Non-Forested Wetlands

Increasing temperatures may lead to more water loss through evaporation, altering delicate hydrologic balances. However, with similar to slightly increased precipitation and higher groundwater recharge projected, hydrologic changes may be minimal. If water levels do rise or drop over time, sites with floating "bog" mats may be able to fluctuate naturally. Nutrient enrichment through changing land use and groundwater pollution may be one of the greatest threats and could increase non-native invasive species. However, several factors may reduce vulnerability.

Warmer temperatures may increase water losses, but potentially increasing groundwater recharge could offset higher rates of evaporation. However, if drying does occur, either due to natural losses or due to groundwater withdrawals, peat decomposition is possible, along with cascading increases in available nitrogen, increasing the risk of invasive species. Although some characteristic plant species appear to tolerate warmer temperatures, most have strict hydrologic requirements.

In large peatland basins with no inlets or outlets, the balance of precipitation to evaporation is crucial. Warmer temperatures may increase water losses, and unless precipitation also increases, eventual drying could occur, touching off peat decomposition and increases in available nitrogen, increasing the risk of invasive species or encroachment by sedge meadow species. Risk of catastrophic wildfire may increase, and fires that consume subsurface peat would be detrimental, though less severe fires could be a benefit. Impact could be lessened by several factors.

Potential changes in hydrology are anticipated to have the greatest impacts to Northern Sedge Meadows, with either consistently lower or higher water levels leading to large changes in species composition. Exactly how precipitation, evaporation, groundwater infiltration, and other factors that influence water levels will change, however, is uncertain. On the positive side, many of the dominant plant species of Northern Sedge Meadows are widespread in Wisconsin, also occur well to the south and are adapted to fluctuating water levels.

Warmer temperatures may increase water losses, but potentially increasing groundwater recharge could offset higher rates of evaporation. However, if drying does occur, peat decomposition is possible, resulting in increases in available nitrogen, increasing the risk of invasive species. Black spruce is likely to experience a steep decline, and under high change scenarios, tamarack could decline as well. If tree species are lost entirely, community structure would be fundamentally changed.

Potential changes in groundwater and seepage lake levels could have severe consequences for these communities. Higher temperatures, longer growing seasons, and corresponding increases in evapotranspiration will result in more water leaving the system. This could be exacerbated by anthropogenic demand for groundwater resources. However, projected increases in annual precipitation may offset some of these losses. If water tables drop, tree and shrub invasion is likely along with conversion to non-wetland species.

Ephemeral Ponds are often defined based on the amphibians and invertebrates that use them, especially those for which ponds are their primary breeding habitat. Warmer temperatures, higher evapotranspiration rates and longer dry spells could lead to some ponds drying up earlier, which could adversely impact species that require inundation for larval development. Extreme precipitation events could also adversely impact species as well as increase the risk of invasion by non-native plants like reed canary grass.

More frequent, higher intensity storms are likely to exacerbate sedimentation and nutrient enrichment. While a detriment to many species, cat-tail, and other marsh generalists may benefit from these disturbances. However, invasive species, including narrow-leaf and hybrid cat-tail, may also benefit, possibly shifting species dominance to non-native cat-tail. Potentially changing precipitation patterns could increase the variability of water level fluctuations, however, Emergent Marsh is highly adapted to, and even benefits from natural fluctuation.

Potential changes in groundwater and seepage lake levels could have severe consequences for these communities. Higher temperatures, longer growing seasons, and corresponding increases in evapotranspiration will result in more water leaving the system. This could be exacerbated by anthropogenic demand for groundwater resources. However, projected increases in annual precipitation may offset some of these losses. If water tables drop, tree and shrub invasion is likely along with conversion to non-wetland species.

Potential changes to hydrology could have adverse impacts on Central Poor Fen. Higher temperatures, longer growing seasons, and corresponding increases in evapotranspiration will result in more water leaving the system. This could be exacerbated by anthropogenic demand for groundwater resources in some areas. However, projected increases in annual precipitation may offset some of these losses. If water tables drop, peat loss and tree and shrub invasion is likely, as is the risk of damaging wildfire. Invasive species are also an increasingly problematic threat.