Section 2.4
Wetlands in the Mountain Region
Summary of the area of wetlands in the mountain region by wetland class with a description of the most common classes.
Total area of wetlands in the mountain region: 3.2%
- Swamp is the most common wetland class covering 1.0% followed by open water (0.9%), fen (0.7%), and marsh (0.5%).
- Half of the total wetland area in the mountain region is in protected areas.
Introduction
Wetlands are uncommon and typically small in the Rocky Mountain Natural Region compared to other natural regions in Alberta, with topography playing a large role in constraining their distribution.
Montane wetlands are characterized by the following features:
- Wetlands in the mountain region tend to occur in floodplains of major valleys because these are the areas of convergence of streams and seepage from melting snow; these flatter areas can maintain water at the surface.
- Montane wetlands mainly consist of small glacial ponds in alpine areas; wet meadows, marshes, fens, and beaver ponds in valleys; and narrow strips along ponds, rivers and streams.
- While wetlands cover a small area in the mountains, they support a high diversity of wildlife and plants[1,2].
- Beavers commonly use mountain wetlands and can play an important role shaping wetland areas by increasing the area of open water[3] and slowing the movement of water. Wetlands with beavers can also have higher wetland plant species richness than wetlands without beavers[2].
- In the Rocky Mountains, wetland ecosystems are more intact because of lower amounts of human development and larger areas of protection.
- These montane wetland ecosystems are part of the headwaters that are the key source of freshwater for much of Alberta.
In this section, we summarize wetland class and percent area in the mountain region of Alberta. We also highlight key wetland characteristics and species associated with the most common wetland classes.
Methods
- The mountain region wetland inventory includes the Rocky Mountain Natural Region of Alberta.
- Wetland locations were delineated using open source data and machine learning. Three classes of wetlands[4] were identified (fen, marsh, and swamp) plus open water habitat. The open water habitat category includes shallow open water wetlands—i.e., areas that are less than two metres deep—but also includes open water areas, like lakes, that are deeper than two metres. Upland areas were also identified.
- Steps to identify and classify wetlands in the mountain region of Alberta are listed below. For detailed methods see ABMI 2021[5].
- Protected areas are defined as provincial protected areas (a list of the eight categories can be found here) and national parks.
Steps to identify and classify wetlands in the mountain region:
- Open data sources of satellite imagery and a digital surface model, as well as known locations of classified wetlands from ABMI data[6], were used as computer inputs. There are relatively few wetlands in this region thus few training sites; therefore, the study area was extended into the Foothills Natural Region. A few additional sites from Google Maps photosphere were also used as computer inputs.
- Using these data inputs, the computer “learned” the characteristics associated with each wetland class, such as topographic position and vegetation properties, based on known wetland locations.
- Based on these characteristics for each wetland class, the computer created rules that were used to identify other possible wetland locations in the mountain region. These rules were applied across the region to create an inventory of wetlands.
- Before finalizing the mountain wetland inventory, known terrestrial areas as identified in the Human Footprint Inventory[7] were reclassified as upland. Finally, the inventory was reviewed to fix obvious errors such as missing lakes that had been confused with shadows.
Limitations and constraints
- The Rocky Mountain (mountain region) Wetland Inventory is based on open source satellite imagery of 10-m2 spatial resolution from the year 2020. It has a minimum polygon size of 400 m2, but the effective Minimum Mapping Unit is closer to 1000 m2.
- The Rocky Mountain Wetland Inventory classification has an overall accuracy of 85% compared to photo-interpreted validation data; however, most of the accuracy is from the distinction between upland and wetland, which is assessed at 90%.
- Bogs are rarely found in this natural region, and were not represented in the training data, thus only the wetland classes of marsh, swamp, fen and open water were classified for this region. The most common areas of confusion between classes in the Rocky Mountain Wetland Inventory are between treed fen and swamp vs. upland, and between fen vs. swamp. Refer to the technical documentation for more details on class accuracies.
Wetlands in the mountain region are mostly located in valley bottoms.
Results
Area of Wetlands in the Mountain Region
Total area of wetlands in the mountain region: 3.2%
Highlights
- In the mountain region, wetlands are uncommon, covering 3.2% of the area.
- Swamp is the most common wetland type covering 1.0% followed by open water (0.9%), fen (0.7%), and marsh (0.5%).
- Half of the total wetland area in the mountain region is in protected areas (781 km2 out of 1,560 km2)
- Open water habitats have the highest representation in protected areas at 71.7%, followed by swamps (42.5%), marshes (42.4%), and fens (39.1%).
Distribution of wetlands in the mountain region of Alberta. Click on the legend to turn wetland types on and off. Note: wetlands cover less area than what is displayed in the map.
More about wetlands
Click on a tab for a description of the most common wetlands in the mountain region. For more detailed descriptions of each wetland class, refer to the Alberta Wetland Classification System Field Guide[4].
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About marshes and fens in the mountain region
- Montane marshes and fens are typically found along floodplains in flat areas or gentle slopes, as well as in small depressions. Both types of wetlands can occur in the same area.
- Marshes occur on predominantely mineral soil and less than 40 cm of organic matter while fens occur on soils where at least 40 cm of organic matter has accumulated.
- Water levels are highly associated with snowmelt so these areas are often flooded in the spring and early summer by slow-moving waters. Water inputs come from a range of sources including groundwater, overland flow, streams, and precipitation.
- Some of these wetlands are seasonally wet, drying by late summer. However, many marshes can have pockets of standing water supporting aquatic species (e.g., aquatic invertebrates, amphibians, waterfowl).
- Vegetation cover is often dominated by grass and sedge species, particularly fens where species like the Small Bottle Sedge (Carex utriculata) can form continuous mats.