Brown Peatmoss
Sphagnum fuscum
Brown Peatmoss is typically the dominant vegetation cover in bogs.
Section 4.4
Status of Wetland-associated Mosses
Summary of the effects of human disturbance on moss species associated with wetlands in the boreal forest as measured by the Biodiversity Intactness Index.
Updated January 2025
The average intactness of wetland-associated mosses in the forested region was 94%. Intactness by wetland category was:
Bogs & Poor Fens
98%
intact
Rich Fens
96%
intact
Swamps & Marshes
92%
intact
Generalists
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90%
intact
This section was updated in January 2025 to reflect additional moss data, updated species models, and new human footprint results. The number of moss species reported on increased from 45 to 56. Overall, habitat suitability for most wetland-associated moss species remained largely unchanged.
Introduction
Mosses—technically classified as bryophytes, a group that includes mosses, liverworts, and hornworts—are among the most important indicators used to classify certain wetland types, playing a key role in defining their ecological characteristics, functions, and overall condition[1,2].
- In peat-forming wetlands, such as bogs and fens, mosses often dominate the ground cover and play a vital role in ecosystem processes. They are essential to organic matter accumulation (commonly known as peat), while also influencing nutrient cycling, water retention, decomposition, and acidification, all of which contribute to the distinct characteristics of these ecosystems[3].
- In swamps and marshes, the moss layer is typically less developed but remains ecologically important[4,5]. Mosses in these wetlands provide critical habitat for microorganisms and contribute to essential functions such as nitrogen fixation. Wet depressions within swamps, in particular, serve as rich habitats for diverse moss species, including leafy mosses such as Rhizomnium and Plagiomnium species, as well as spear mosses like Calliergon species.
- Due to their sensitivity to variations in water levels and chemical composition (e.g., nutrients, pH), individual moss species are valuable indicators for identifying microhabitats within different wetland types[1]. For example, Warnstorf’s Peat Moss (Sphagnum warnstorfii) thrives in nutrient-rich fens with a pH range of 5 to 7, and is typically found in lawns and low hummocks. Meanwhile, Marsh Leafy Moss (Plagiomnium ellipticum) commonly grows in wet depressions within wooded fens and forested swamps.
Oskar Gran
Warnstorf’s Peat Moss (Sphagnum warnstorfii)
Marsh Leafy Moss (Plagiomnium ellipticum)
In this section, we report on the status of wetland-associated moss species classified into four wetland types (bogs & nutrient-poor fens, rich fens, swamps & marshes, generalists) in the forested region of Alberta, using the Biodiversity Intactness Index. These results have been updated incorporating more data, updated species models, and human footprint as of 2021.
Foundation of Peatland Ecosystems
Mosses are keystone species of peatland ecosystems.
- Peatlands are wetlands where plant production is greater than decomposition, resulting in an accumulation of peat (partially decomposed plant material).
- Peatlands are the dominant category of wetland in Alberta, comprising 90% of our wetlands.
- Peatlands exist along a continuum from bogs that are acidic and nutrient poor, typically dominated by Sphagnum mosses, to rich fens that are neutral to alkaline and nutrient rich. Fens are characterized by different moss species depending on their nutrient status; poor fens feature Sphagnum species, while rich fens are dominated by brown mosses.
- Peatland communities occur along a gradient from hummocks (elevated mounds) to hollows (flatter and wetter habitat). The height of hummocks can range from a few centimetres to a metre.
- Peatlands are sensitive to changes in water chemistry, hydrology, and climate, making moss species good indicators of ecosystem health.
R Caners
Northern Peatmoss
Sphagnum capillifolium
Northern Peatmoss forms dense carpets in nutrient-poor, acidic fens.
Yellow Starry Fen Moss
Campylium stellatum
Brown mosses, like the Yellow Starry Fen Moss, are key indicators of nutrient-rich fens.
Bog Haircap Moss
Polytrichum strictum
Bog Haircap Moss is common across the forested region, and is strongly associated with shrubby bogs and treed fens.
Methods
The ABMI collects data on moss species and builds statistical models to identify how the relative abundance of species varies in relation to native land cover, human footprints, and spatial/climate variables. Wetland-associated species are identified based on expert review of the literature. For species with sufficient data (collected between 2003 and 2019), we determine cumulative effects of human footprint on species by comparing predictions under current landscape conditions (HFI 2021[6]) to predictions in reference landscapes where all human footprints have been removed (backfilled). We convert the difference in relative abundance between predicted current and reference abundances to a scaled Biodiversity Intactness Index.
Here we calculate intactness for moss species associated with four wetland categories, including bog/poor fens, rich fens, swamps/marshes, and generalists. These groups were defined by their ecological affinity (primarily water and nutrient levels) for these different wetland types. Mosses were classified into these four groups using a two-step process:
- Wetland-associated species were first associated with upland vs lowland (wetland) habitats based on habitat coefficients.
- Those species associated with lowland habitats were then further classified into the four categories of wetland association based on literature and expert knowledge.Three species are associated with two wetland types and are therefore included in both categories: Blunt Pincerwort (Cephalozia pleniceps) is associated with both bogs/poor fens and rich fens, and Polygamous Hook Moss (Drepanocladus polygamus) and Common Green Bryum Moss (Ptychostomum pseudotriquetrum) are both associated with both rich fens and swamps/marshes.
Habitat associations for some moss species may change as more data are collected, potentially leading to adjustments in species models. Additionally, some commonly found wetland species may be absent from the results due to insufficient detections by the ABMI for modeling purposes; however, this may change as more data become available.
For field sampling protocols see ABMI 2015[7], for lab processing protocols see ABMI 2010[8], and for analysis methods see ABMI 2017[9] and Sólymos et al. 2019[10].
Krista Williams
Collection of moss samples to be identified in the lab.
Caveats/Limitations
- Some explanatory variables may be confounded with each other. The ABMI collects observation data—we do not manipulate levels of habitat and human footprint types at our sites. This means that some variables may be confounded, such as the effects of latitude and agricultural footprint on occurrence.
- Our species distribution models are created through batch processing by taxonomic group. This means that all species within a given taxonomic group (e.g., amphibians, mosses) are modeled using the same combination of environmental variables (e.g., habitat types, human footprint types, climate), even though there may be a more appropriate combination for specific species.
- The vegetation and soil layers we use in our models are based on GIS analysis. No GIS product has 100% accuracy. Errors in classification could lead to inaccuracies in our predictions of species’ distributions.
- We currently do not include effects outside of direct habitat loss in our models. We know that many species respond to impacts such as edge effects, grazing, pollution, or alteration in groundwater flows. We are continuing to improve our species–habitat models to include additional effects, but our models are unable to include all possible impacts on species abundance.
- Intactness only shows the predicted effects of visible human footprint on habitat suitability. Species' populations change for many other reasons. A "decreaser" species—one with lower abundance in human footprint—may in fact have an increasing population trend, if other aspects of its environment are improving. And vice versa for an "increaser" species. Measuring the actual trends of species is a long-term goal of ABMI monitoring.
- Intactness maps show the predicted average effect of the types of footprint in each area. We do not have information on the exact effects of footprint in each specific area, and we do not monitor actual changes in species in every location.
- Our models only reflect the immediate local effects of human footprint. There may be additional large-scale effects that we do not account for. For example an extensive network of linear features and other human footprint may allow a species that prefers disturbed areas to spread through a region.
Results
Status of Mosses Associated with Wetlands
The status of 56 wetland-associated moss species in the forested region as measured by the Biodiversity Intactness Index:
94%
Intactness of the four moss groups averaged:
Bogs & Poor Fens
98%
Intact
Rich Fens
96%
Intact
Swamps & Marshes
92%
Intact
Generalists
90%
Intact
Highlights
- At 90% intact, habitat suitability was lowest for generalist wetland moss species that are not restricted to wetland habitats—these are species that while common in lowlands, can also be found in a variety of upland forested habitats.
- Some human development activities (e.g., forestry) occur more often in upland habitats, resulting in greater impacts to generalist species such as Elegant Beaked Moss (Eurhynchiastrum pulchellum; 77% intact), Knight's Plume Moss (Ptilium crista-castrensis; 83% intact), and Common Broom Moss (Dicranum scoparium; 83% intact).
- Intactness for species associated with swamps and marshes was 92%; habitat suitability is reduced for all but two species in this group. Three of the species with intactness of less than 90% were Hookleaf Fern Moss (Thuidium recognitum; 80% intact), Common Tree Moss (Climacium dendroides; 84% intact, and Heart-leaved Spear Moss (Calliergon cordifolium; 89% intact). These mosses are typical of nutrient-rich and moist microhabitats. Insufficient moisture conditions could lead to lower habitat suitability, and these species are negatively impacted by human footprint.
- Intactness for mosses associated with bogs and poor fens—mainly Sphagnum moss species and brown mosses—was highest, at 98% intact, on average. Intactness for mosses associated with rich fens was also high at 96%, with intactness at least 90% for all species.
- Human footprint is lower in fens and bogs compared to other habitat types, resulting in higher intactness for species associated with these wetland types.
Summary of Results Update
- The number of moss species associated with wetlands increased from 45 to 56 in the most recent analysis.This increase is attributed to the inclusion of additional moss data, allowing for new species models to be created for the forested region of Alberta.
- Although the area of human footprint expanded between 2018 and 2021 in the forested region, the overall increase was minimal, particularly in wetland habitats. As a result, habitat suitability for most wetland-associated moss species has remained largely unchanged between the previous analysis and the most recent update.
Intactness for moss species associated with wetlands. This graph shows the predicted deviation in species abundance from intact reference conditions (100%) for moss species associated with four wetland types: bogs/poor fens, rich fens, swamps/marshes, and generalists. Solid line indicates no change in habitat suitability between the current landscape with human footprint and the modelled reference landscape without human footprint. Both positive (predicted increases) and negative (predicted decreases) deviations from reference result in lower intactness. Each dot represents an individual species; hover over a dot to view individual species intactness values.
Status of wetland-associated mosses in the forested region. The status of moss species associated with wetlands in Alberta's forested region is assessed using the Biodiversity Intactness Index. Moss species are classified into four wetland categories: bog/poor fens, rich fens, swamps/marshes, and generalists. Three species—Blunt Pincerwort (Cephalozia pleniceps), Polygamous Hook Moss (Drepanocladus polygamus), and Common Green Bryum Moss (Ptychostomum pseudotriquetrum)—are associated with two wetland types and are therefore included in both categories. Species are ranked from lowest to highest intactness, and the Habitat Suitability column indicates whether habitat suitability has increased or decreased due to human footprint. Click on a species to view its profile for Alberta in the ABMI's Biodiversity Browser.
Conclusion
- Habitat suitability of moss species with general habitat preferences as measured by intactness is largely driven by their ability to inhabit both upland and a range of lowland habitats.
- Ground-covering mosses restricted to wetlands in the forested region (e.g., Sphagnum species, brown mosses) vary slightly in response to human footprint as a group, but individual species’ responses are important in explaining how habitat suitability changes with human footprint.
- The ABMI continues to collect moss data, working to improve our understanding of species' distributions in Alberta, as well as habitat associations and impacts of human footprint on these often overlooked species.
R Caners
Rusty Peat Moss (Sphagnum fuscum) is very common in bogs in the boreal forest.
References
1.
Vitt, D.H. 2014. A key and review of bryophytes common in North American peatlands. Evansia 31(4):121-158.
2.
Vitt, D.H. and M. House. 2021. Bryophytes as key indicators of ecosystem function and structure of northern peatlands. Bryophyte Diversity and Evolution 043 (1):253–264. Available at: https://doi.org/10.11646/bde.43.1.18
3.
Wieder R.K., D.H. Vitt, and B. Benscoter. 2006. Peatlands and the boreal forest. Pp. 1-8 in: Wieder, R.K. and D.H. Vitt (eds.). Boreal Peatland Ecosystems. Springer-Verlag, Berlin-Heidelburg-New York. Available at: https://doi.org/10.1007/978-3-540-31913-9_1
4.
Zoltai, S.C. and D.H. Vitt. 1995. Canadian wetlands: environmental gradients and classification. Vegetation 118:131-137.
5.
Turetsky, M.R. 2003. The role of bryophytes in carbon and nitrogen cycling. The Bryologist 106(3):395-409.
6.
Alberta Biodiversity Monitoring Institute. 2023. Wall-to-wall human footprint inventory—year 2021. Dataset. Last modified August 16, 2023. Available at: https://abmi.ca/data-portal/46
7.
Alberta Biodiversity Monitoring Institute. 2021. Terrestrial field data collection protocols (abridged version). Available at: https://abmi.ca/publication/601
8.
Alberta Biodiversity Monitoring Institute. 2010. Laboratory protocols for processing bryophytes. Available at: https://abmi.ca/publication/330
9.
Alberta Biodiversity Monitoring Institute. 2017. ABMI species website manual, version: 2017-10-06. Available at: https://abmi.ca/publication/505
10.
Sólymos, P., E.T. Azeria, D.J. Huggard, M-C. Roy, and J. Schieck. 2019. Chapter 4. Predicting species status and relationships. In ABMI 10-year science and program review. Available at: https://abmi10years.ca/10-year-review/resources/
Contributors
Krista Williams, Lead Scientist, Bryophytes, Alberta Biodiversity Monitoring Institute (ABMI)
Krista has been exploring the world of bryophytes since 2007, and with the ABMI since 2014. She can usually be found scouring the woods for bryophytes or with eyes glued to a microscope assigning names to these miniature plants.
If you have questions about the ABMI's bryophyte monitoring program, please get in touch: krista.williams@ualberta.ca
We are grateful for the support of the ABMI's delivery partners.
We would like to acknowledge the organizations and sponsors highlighted below who financially supported the development of this report.
