Ecological dynamics

In its reference state, this site is dominated by wetland obligate graminoids such as Cusick's sedge (Carex cusickii), bladder sedge (Carex utriculata), densely-tufted sedge (Carex lenticularis), few-flowered spikerush (Eleocharis quinqueflora), and clustered field sedge (Carex praegracilis). Common forbs (and fern allies in the case of horsetail) found on this site may include largeleaf avens (Geum macrophyllum), slender cinquefoil (Potentilla gracilis), western polemonium (Polemonium occidentale), american bistort (Polygonum bistortoides), common camas (Camassia quamash ssp. Breviflora), and common horsetail (Equisetum arvense). Common grass species may include slender muhly (Muhlenbergia filiformis), tufted hairgrass (Deschampsia caespitosa), tall mannagrass (Glyceria striata). Bareground is low and litter cover is high. In aerated soils with cobbly or stony subsurface horizons, or slight raises in wetland areas, complexes of gray alder (Alnus incana) are commonly found. Willow species (Salix spp.) may also be found in aerated soils and along streambanks.

Historically, the ecological dynamics of the site would have been influenced largely by climate cycles affecting seasonal snowpack, runoff, droughts and flood. These processes would have been partly controlled by the type and cover of upland and forest vegetation throughout the watershed which would have modified water capture, storage and sediment supply. These upland dynamics would have been altered by historical fire regimes and subsequently vegetation succession, erosion and runoff. Beaver also had widespread impacts on water table depth and seasonality, frequency and duration of ponding and flooding, and stream channel structure.

Much of this site is unsuitable to livestock use for much of the year due to saturated soils. However, grazing may be accessible especially during mid to late summer. When soils are moist they may be more prone to compaction. Vegetation may be susceptible to damage by tramping, especially during reproductive. Prolonged disturbance by grazing animals will favor an increase in forbs and an altered composition of graminoids, with facultative wetland species such as baltic rush (Juncus balticus), and grazing resistant species such as Nebraska sedge (Carex nebrascensis), often increasing relative to other sedges. With continued improperly managed grazing, non-native meadow grasses such as Kentucky bluegrass (Poa pratensis), common timothy (Phleum pretense), and meadow foxtail (Alopecurus pratensis) commonly increase. Prolonged improperly managed livestock grazing will increase bareground, erosion and pedestalling, and decrease litter cover.

Where sites are connected to stream networks, these impacts may lead to decreased streambank stability and eventually degradation of stream channels. Overtime, with increased depth and incision of channels, water tables may recede and floodplains may become disconnected from stream courses. If these effects are not mitigated, a decrease in water table depth will favor a shift toward communities without the potential to sustain obligate wetland sedges and are instead dominated facultative wetland grasses such as tufted hairgrass or Kentucky bluegrass. High energy runoff events will accelerate this transition if banks have been destabilized by loss of vegetation. Site hydrology may also be altered by modifications to the stream channel by disturbances such as impoundment, removal of beaver, flow alteration for irrigation, channel realignment or terrace modifications for agricultural use. Chanel straightening, deepening and drainage practices may be implemented to convert the site to agricultural use or facilitate transportation corridors. These impacts may be less common in these higher elevation meadows compared to low elevation bottom lands. When implemented, these land uses often increase stream gradients, decrease sinuosity and increase channel depths, leading to disconnected floodplains overtime.

Emerging evidence suggests that montane meadows are experiencing conifer encroachment within the last century. Hypotheses for processes driving these vegetation changes range from climate cycles, alterations in fire regime and reductions in sheep grazing. While much of this site have soil moisture too high to accommodate significant conifer encroachment, populations of conifers such as lodgepole pine (Pinus contorta) and Engelmann spruce (Picea engelmannii), species somewhat tolerant of saturated soils, may become established due to climate or altered disturbance regimes.

This site may be vulnerable to alterations in surface and ground water hydrology as a result of climate change. Snowpack is expected to decline across the mountains of Oregon with a warming climate (Mote et al. 2005) and shifts from snow to rain is expected to be most pronounced at middle elevations of the Cascade and Blue Mountains. Research suggests that expected shifts in precipitation timing and type will have far reaching effects on blue mountain riparian, wetland and ground-water-dependent ecosystems and that wet meadows may experience shifts in dominant vegetation as a result of altered water tables (Dwire et al 2018). The state and transition model below does not take into account the potential impacts of a changing climate and instead represents an approximation of ecological dynamics resulting from a simplified model of this meadow system. Further work is needed to better understand community response to climate shifts as well as the existence of alternative states and plant communities that may exist within these states.