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Abstract Detail

Ecological Section

Catling, Pauline [1], Kenkel, Norman [2], Ford, Bruce [2].

The Classification and Management of Alvars in the Interlake Region of Manitoba, Canada.

Alvars are globally rare habitats that are characterized by thin soils over limestone or dolomite bedrock, in which some combination of drought, flooding, fire, wind and/or grazing maintains the openness. Alvar ecosystems are found in only a few northern European countries and in isolated localities throughout North America, including Manitoba's Interlake Region. Although the plants found in Manitoba alvars are often associated with prairie and boreal habitats, the species mixture is often different because of the unique soil conditions. In addition, a number of provincially, nationally, and globally rare species, including the ferns Pellaea gastonyi and Pellaea glabella subsp. occidentalis and the moss Grimmia teretinervis, are specifically associated with these habitats in Manitoba. As a contribution to the development of a conservation strategy for Manitoba’s Interlake, we conducted a quantitative assessment and classification of alvar plant communities. Our multivariate analyses (using clustering and ordination techniques) indicate that vegetation composition is dependent on both ecological features and disturbance. The amount of tree cover is a strong determinant of the species composition of alvar habitats. This could be due to increased presence of shade-loving species or simply that trees prefer different ecological conditions than those dominated by graminoid species. The amount of bare rock, soil depth and moisture availability are the dominant ecological features determining floristic composition. The Manitoban alvars are divisible into three main vegetation groups: graminoid alvars with no tree cover, shrubland alvars with very thin soil and high rock cover, and alvar savannahs. Graminoid alvars are further divided into heavily grazed alvar grasslands, rocky alvar grassland with more shrub cover and wet graminoid alvar. The shrubland alvar are divided into Dasiphora fruiticosa shrubland and dwarf shrubland, the latter characterized by Arctostaphylos uva-ursi and Juniper spp. Treed alvars are divided into Quercus macrocarpa/mixed deciduous savannah, Picea glauca savannah and Pinus banksiana savannah. Trends within these broad groupings based on the intensity of grazing were also evident. Plots that were geographically proximate to one another did not cluster together, indicating that a patch-work of variable condition exists throughout the Interlake region of Manitoba. The results from this study will be used to develop a prioritized list of areas for protection and conservation management.

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1 - University of Manitoba, Biological Sciences, Winnipeg, MB, CAN
2 - University of Manitoba, Biological Sciences, Winnipeg, MB, R3T 2N2, CAN

none specified

Presentation Type: Oral Paper:Papers for Sections
Session: 35
Location: Salon 6/The Shaw Conference Centre
Date: Tuesday, July 28th, 2015
Time: 9:15 AM
Number: 35006
Abstract ID:700
Candidate for Awards:None

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