Agriculture

Potential changes in precipitation patterns and groundwater infiltration could alter hydrologic regimes. Tamarack and many of the dominant tree species are projected to decline, although red maple may be more adaptable. However, tamarack is a pioneer species and has the ability to regenerate rapidly when conditions are favorable, and the community may persist in more northern sites or in climate refugia. It will likely fare less well in southern locations and in isolated stands in fragmented landscapes with limited connectivity to other natural communities.

Changes in surface water hydrology are likely, with a projected increase in both droughts as well as the frequency and intensity of floods, along with associated sedimentation and nutrient enrichment. Changes to groundwater regimes are possible as well, although both an increase in groundwater recharge as well as decreases in ground water levels are possible. For both surface and groundwater-driven sites, increased nutrient enrichment is likely and could fuel an expansion of invasive species.

All global climate models agree that there will be changes in precipitation patterns across the assessment area, but there is large variability among projections of future precipitation. Most climate models project increases in total annual preciptation, with most of the precipitation occurring in winter and spring. Projections of summer and fall precipitation vary more widely, with many models projecting decreased precipitation or only very slight increases (<15%).

More frequent large rain events could increase sedimentation and soil disturbance, leading to increases in non-native invasive species. Nutrient loading of both groundwater and surface water could also fuel invasives. Potential changes in precipitation patterns and groundwater infiltration could alter hydrologic regimes. Although shrub-carr is generally adapted to short-term water level fluctuations, high water over the long-term could convert some sites to the marsh.

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.

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.