Previous version: Indicator – Extent, Quality and Protection of Ontario’s Rare Ecosystems_May, 2015

Ontario’s diverse ecosystems include some that are of conservation concern due to their limited distribution and high proportion of specialized species absent from most of the province, such as prairies and savannahs (prairies with scattered trees), alvars (flat open limestone or dolostone habitats with thin soil), and freshwater coastal dunes. Although they are generally small in size, these habitats support many of Ontario’s endemic and other provincially rare flora and fauna. As such, they are fundamentally important for the conservation of biodiversity in the province.

The extent of prairie and savannah habitat in Ontario has been greatly reduced; in the Mixedwood Plains Ecozone, only a fraction (2–3%) remains (2,200ha; Rodger 1998) and this is threatened by habitat loss, invasive alien species, and succession to forest due to fire suppression. Globally rare alvar communities occur only in the Baltic region of Estonia and Sweden, in western Russia, the northern peninsula on the island of Newfoundland, the west side of Great Slave Lake in the Northwest Territories, the Interlake region of Manitoba, Saskatchewan Delta , and within the Great Lakes Basin of North America (Brunton and Catling, 2017). Ontario contains 65–70% of the North American total, including sites on the Bruce Peninsula, Manitoulin and Pelee islands, and on the Napanee, Smith’s Falls and the Carden limestone plains. Alvar ecosystems in Ontario face similar threats as prairie and savannah habitats, but also conversion to quarries. Great Lakes sand dunes make up the world’s largest collection of freshwater coastal dunes (SOLEC 2009). Ranging from the high forested dunes and linear dune ridges commonly backing sand beaches, to active, moving dune fields, sand dunes can be found along the coasts of all the Great Lakes. Freshwater coastal dunes are fragile ecosystems that are easily affected by human activities.

The distribution and status of these rare ecosystems is tracked by  Ontario ’s Natural Heritage  Information Centre based on plant communities (assemblages of plant species with a consistent composition, structure and habitat). To date, more than 1,300 occurrences of vegetation communities that are considered to be globally rare by NatureServe have been documented in Ontario (Figure 1). Sixty percent of these globally rare communities occur within the Mixedwood Plains Ecozone. There are other globally rare communities that have been documented from Ontario that lack comprehensive information and are not included in this indicator.

This indicator assesses the total area and quality of prairie, savannah, alvar, and dune ecosystems in Ontario, and the area of each that is legally protected in the province.

Analysis for this indicator was based on detailed spatial data available through the  Natural Heritage Information Centre. The areas of rare vegetation communities were summed to assess the total area of prairie and savannah, alvar and dune ecosystems in Ontario (Figure 2). The boundaries of vegetation communities in these rare ecosystems was overlain with the boundaries of protected areas (Provincial and National Parks, National Wildlife Areas, and Conservation Reserves) using GIS to determine the proportion of each rare ecosystem type found in protected areas. Rare communities in protected areas are sometimes subjected to disturbance and threats from human use, but are generally not subject to development and the same level of threats as non-protected areas. The total area and proportion of protected area for alvar and freshwater coastal dune communities have been refined from data originally reported in the State of Ontario’s Biodiversity 2015 report based on new survey information and refined digitized polygons based on more recently available orthophotography.  Prairie/savannah communities assessed in this indicator are limited to those on deep soils and the analysis does not currently include prairie communities on shallow soils that are found in northwestern Ontario (‘Other Prairie’ category in Figure 1).

In addition to the total area and level of protection, the status of vegetation communities was assessed using element occurrence ranks that are based on an assessment by the Natural Heritage Information Centre. Extant plant communities were assigned element occurrence quality ranks from A – D (Table 1) based on NatureServe data standards. Ranks were based on an examination of the size, condition, and landscape context of vegetation communities (Table 2). A full description of the ranking methodology can be found in Henson and Bakowsky (2014). For each rare ecosystem type, the total number and area of element occurrences assigned to each quality rank were tallied and plotted to compare changes between 2015 and 2021 (Figure 3).

It is important to note that the proportion of each rare ecosystem in protected areas is based on provincially and federally protected areas and does not include conservation lands held by private conservation organizations, municipalities, or Conservation Authorities. These conservation lands account for important additional protection for some rare ecosystems, but have not been assessed due to the lack of consolidated, comprehensive information on their spatial boundaries. For instance, the Nature Conservancy of Canada continues to actively expand Canada’s network of protected areas, an assessment of alvar ecosystems in 2015 by the Nature Conservancy of Canada showed that conservation lands contribute to the protection of an estimated additional 960 ha, almost equal to the amount in legally protected areas (D. Kraus, Nature Conservancy of Canada, personal communication).

Table 1. Element occurrence quality ranks assigned to vegetation communities in Ontario’s prairie, savannah, alvar and dune ecosystems.

Table 2. Description of factors considered when assessing quality of vegetation community element occurrences (see Henson and Bakowsky 2014).

• Download summary data for rare vegetation communities

Web Links:

Natural Heritage Information Centre  https://www.ontario.ca/environment-and-energy/natural- heritage-information-centre

NatureServe Conservation Status Assessment https://www.natureserve.org/conservation-tools/conservation-status-assessment

Sask River Delta Conservation Initiative https://www.saskriverdelta.com/alvar

References:

Bakowsky, W.D., and B.L. Henson. 2014. Rare communities of Ontario: freshwater coastal dunes. Natural Heritage Information Centre, Ontario Ministry of Natural Resources, Queen’s Printer for Ontario, Peterborough, ON.

Brunton, D. F. and P.M. Catling. 2017. Thematic Collection: Alvars in Canada. Canadian Field Naturalist 131(1):75-79.

Henson, B.L., and W.D. Bakowsky. 2014. Plant community ranking methodology: alvars, dunes, prairies. Natural Heritage Information Centre, Ontario Ministry of Natural Resources and Forestry, Peterborough, ON. [Available at:  https://sobr.ca/_biosite/wp-content/uploads/Henson- and-Bakowsky-2014_Plant-Community-Ranking-Methodology-Alvars-Dunes-Prairies.pdf]

Ontario Biodiversity Council. 2015. State of Ontario’s Biodiversity [web application]. Ontario Biodiversity Council, Peterborough, Ontario. [Available at: www.sobr.ca]

Rodger, L. 1998. Tallgrass communities of southern Ontario: A recovery plan. Report prepared for World Wildlife Fund Canada and the Ontario Ministry of Natural Resources.

State of the Lakes Ecosystem Conference (SOLEC). 2009. State of the Great Lakes 2009. Technical report prepared by Environment Canada and the United States Environmental Protection Agency. [Available at:  http://www.epa.gov/solec/]