Promote prescribed fire in fire-adapted wetlands

Fire is an important disturbance regime for certain wetland types. In sedge meadows, fire reduces accumulated leaf litter, resulting in enhancement of floral diversity, particularly by allowing recruitment of short-lived forbs. In emergent marsh, accumulation of roots, rhizomes, stems and leaves of cattails (Typha spp.) results in reduced water depth; implementing summer fire (particularly if combined with draining) can slow or reverse this trend. Fire can also be a helpful tool in limiting overabundance of woody vegetation, particularly when applied in conjunction with cutting and herbicide application. While wildfire has been an important disturbance regime in peatlands, the response of Sphagnum to fire varies greatly depending on landscape position, fire frequency and intensity, and Sphagnum moisture content. Drought and lowered water tables associated with climate change can strongly influence Sphagnum moisture content and thus the intensity and duration of fire, with intense and prolonged fires in peatlands that occur under dry conditions potentially resulting in catastrophic losses of peat and major compositional shifts. Climate change may necessitate adjustments in timing, frequency, and seasonality of burns in other wetland types too as suitable windows of opportunity shift or contract. For example, wetter springs and rapid green-up could require a shift in prescribed burning windows. Execution of burns may change as well, particularly if drought conditions increase the chances for smoke issues and air pollution. Warmer, drier conditions may also increase opportunities for burning in wetlands that may have typically been too wet to burn in the past.

This strategy outlines resistance and resilience approaches to manage wetlands facing altered water budgets (water inputs, storage capacity, and outputs) due to a changing climate. Hydrology is a leading driver of wetland character and function and so expected changes to hydrologic regimes, hydrodynamics, and water levels concern wetland managers. Projections in the Upper Midwest indicate that wetlands will be influenced both by extreme precipitation and flooding events and longer drought periods between rain events. Some wetlands will become dryer and others may become wetter than long-term averages. Thus, managers face challenges (i.e., extreme flooding; drought) and opportunities (i.e., restored flood pulses to wetlands disconnected from surface or groundwater flows) in managing wetlands in the context of climate change. Restoring hydrologic connectivity has historically been a primary tactic of management efforts to restore wetlands lost or degraded by filling or draining due to land-use conversion and water extraction, and many of those same tactics can be applied or amended by wetland managers to meet climate change adaptation objectives. Restoring hydrologic connectivity and ameliorating saturated, anoxic conditions that limit decomposition also supports the capacity of wetlands to actively remove and sequester atmospheric carbon and mitigates future carbon losses.