Montana Field Guide

This group is composed of herbaceous-dominated wet meadows (wet prairie) and fens as well as localized areas of riparian shrub communities throughout areas of the Great Plains region. This is a minor group in Montana with a sporadic distribution and relatively poor documentation. The wet meadows (wet prairie) component of this group occurs along drainages, in basins and lowland sites in areas flooded for brief periods during the growing season via runoff or that flood after snowmelt or heavy rains. These lowland sites often have standing water for several weeks each year and they are commonly dominated by Sedges (Carex spp), Western Wheatgrass (Elymus smithii), Prairie Cordgrass (Spartina pectinata), or Switchgrass (Panicum virgatum). Fen habitats on the plain in Montana are rare but occur where mineral-rich groundwater emerges at the ground's surface; these sites are usually occupied by species such as Sedges (Carex spp) and Few-flower Spikerush (Eleocharis quinqueflora). These areas remain saturated throughout the growing season, permitting the development of organic peat. Wet or riparian shrublands usually dominated by Sandbar Willow (Salix exigua, Salix interior) are found along rivers and streams, typically in alluvial sand or gravel. Heights of these shrubland communities are less than 15ft tall. They also occur along irrigation ditches, and other low wet areas that are not subject to frequent flooding and scouring.

This Group encompasses portions of the Emergent Marsh and the Great Plains Closed Depressional Wetland Ecological Systems.

Wetlands; Wet Prairie, Wet Meadows, Fens, Riparian Shrublands; Herbaceous or Shrub Dominated; Great Plains Region; Seasonally, Vernally or Permanently Saturated

Typical Dominants: Sedges (Carex spp), Western Wheatgrass (Elymus smithii), Prairie Cordgrass (Spartina pectinata), Switchgrass (Panicum virgatum), Spikerushes (Eleocharis), Sandbar Willow (Salix exigua, Salix interior)

This wetland group occurs sporadically throughout the Great Plains Region in Montana, excluding areas in or adjacent to the island mountain ranges that are more appropriately classified as G521, G526, or G531.

In Montana, G975 occurs in Level III Ecoregions: 42 (Northwestern Glaciated Plains) and 43 (Northwestern Great Plains).

In Montana, G975 occurs or potentially occurs within these Major Land Resource Areas: 52 - Brown Glaciated Plains, 53A - Northern Dark Brown Glaciated Plains, 53B - Central Dark Brown Glaciated Plains, 54 - Rolling Soft Shale Plain, 58A,B,C,D - Northern Rolling High Plains, 60A,B - Pierre Shale Plains.

Small Patch

The wet meadows (wet prairie) component of this group occurs along drainages, in basins and lowland sites in areas flooded for brief periods during the growing season via runoff or that flood after snowmelt or heavy rains. These lowland sites often have standing water for several weeks each year. The water may be fresh or mildly saline. Soils can be mineral but mucks often form through the buildup of organic material (Looman 1982).

Great Plains fen habitats are localized in areas where mineral-rich groundwater emerges at the ground's surface. These areas remain saturated throughout the growing season, permitting the development of organic peat. These communities may have small pools which have precipitates of calcium carbonate and other minerals.

Wet or riparian shrublands usually dominated by Sandbar Willow (Salix exigua, Salix interior) are found along rivers and streams, typically in alluvial sand or gravel. They also occur along irrigation ditches, and other low wet areas that are not subject to frequent flooding and scouring.

Vegetation communities in herbaceous fens are short to medium-tall. Open to dense graminoids less than 1 m tall comprise the majority of the vegetation. Common species in these habitats are Sedges (Carex spp) and Few-flower Spikerush (Eleocharis quinqueflora). There may areas of taller vegetation, dominated by species such as Carex aquatilis and Schoenoplectus pungens.

The wet meadows (wet prairie) component of this group are commonly dominated by short to tall species such as Sedges (Carex spp), Western Wheatgrass (Elymus smithii), Prairie Cordgrass (Spartina pectinata), or Switchgrass (Panicum virgatum). The vegetation of these communities is usually moderate to dense and the dominant vegetation is typically 0.5-1.0 m tall. Forbs can be common, but shrubs are rarely found in this type. In wetter sites, the most abundant species are often Calamagrostis stricta, Carex pellita, Carex sartwellii, Anemone canadensis, Apocynum cannabinum, Symphyotrichum lanceolatum, Eleocharis spp, Juncus arcticus ssp. littoralis, Phalaris arundinacea, Polygonum amphibium, and Schoenoplectus americanus. These wetter sites are similar to G325 Great Plains Freshwater Marsh but have standing water for a much shorter amount of time each year.

Sandbar Willow (Salix exigua, Salix interior) is the dominant shrub and often the only woody species present. Other shrubs that may be present include Salix eriocephala (syn S. famelica, S. lutea) and Cornus sericea. Stands can have other woody species such as saplings of Salix amygdaloides and Populus deltoides. The understory is usually moderate to lush but can be sparse if subject to a recent major flood. The herbaceous layer is typically dominated by mid and tall graminoids such as Carex spp., Western Wheatgrass, Switchgrass, Prairie Cordgrass, and Schoenoplectus spp. in wetter areas. Other common herbaceous species include Horsetails (Equisetum hyemale), Xanthium strumarium, Polygonum spp., and Ambrosia artemisiifolia.

In Montana, this group is represented by vegetation communities classified into 5 Alliances and 8 Associations within the National Vegetation Classification.

Communities in this group are dependent on hydrological factors from groundwater recharge, snow melt, surface flows and rain events during the growing season.

Focus on maintaining hydrology of these sites and minimizing or eliminating on-site impacts should be the primary consideration. Additionally, impacts to and activities on adjacent sites may detrimentally impact these communities via changes in hydrology, exposure to pollutants through increased run-off, or increased chances of spread of invasive species onto these sites.

Information on restoration considerations is lacking at this time.

Tremblay et al. (2023)

S. Mincemoyer

12/6/2024