. The Canadian field-naturalist. Natural history. 146 The C_\\'.\dlan Field-Natltl\list Vol. 109. FiCLTiE 3. Distribution of aivars (dots) in Great Lakes region (83 sites) for which information on species composition is available from Natural Resources. Heritase or Nature Conservancv offices, or from researchers. of natural vegetation suggesting open habitat prior to human influence. Relationships among regions in terms of their alvar tloras were evaluated using UPGMx\ (unweighted pair group method with arithmetic aver- aging) clustering of Jaccard's coeftlents and princi- pal coordinate analy
. The Canadian field-naturalist. Natural history. 146 The C_\\'.\dlan Field-Natltl\list Vol. 109. FiCLTiE 3. Distribution of aivars (dots) in Great Lakes region (83 sites) for which information on species composition is available from Natural Resources. Heritase or Nature Conservancv offices, or from researchers. of natural vegetation suggesting open habitat prior to human influence. Relationships among regions in terms of their alvar tloras were evaluated using UPGMx\ (unweighted pair group method with arithmetic aver- aging) clustering of Jaccard's coeftlents and princi- pal coordinate analysis with minimum spanning tree, both derived from the cumulative species lists for three or more sites within each region. Details on the statisticial procedures may be found in Pielou (1984). .Analyses were done with NTSYS-pc version L6(Rolfe 1990). Results and Discussion Distribution and Extent of Documented Ahars With the exception of small isolated areas ( western Lake Ontario, western Lake Erie, and Lake Champlain area), the aivars of the Great Lakes region occur near the contact line of the granitic Canadian Shield upland with the Ordovician Ume- stones and dolomites (Figure 3). The main area of occurrence extends from the nonh shore of Lake Michigan east to the islands of northern Lake Huron, such as Drummond Island, east across ManitouUn Island southeast to the south end of Georgian Bay. east to the Lake Simcoe area and the Garden lime- stone plain, discontinuously east to the Napanee limestone plain between Trenton and Kingston, then, following a gap due to the Frontenac axis of granitic rocks, and/or Lake Ontario, appearing again in New York State at the east end of Lake Ontario and on the Smiths Falls limestone plain in the Ottawa Valley. It is ver\' roughly estimated that 252-287 alvar sites currentiy exist in the Great Lakes Region. Additional field studies are required to provide more accurate figures (Table 1). .\lvar habitats probably always occupied a rela
Size: 1863px × 1341px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectnaturalhistory, booky
