BIOL 2903 Lecture 7: Week 7 Notes
5 Mar 2017
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Precambrian (mostly granitic, some diabase), very old (~2. 5 billion yrs), surrounded by younger sedimentary limestone. Offer the only real source of relief in hbl diabase sills. Disjunct populations of plants e. g. , rock polypody (much more common near south), Greenland sandwort: greenland sandwort"s disjunct distribution in ontario = excellent example of importance of site conditions. Alpine brook saxifrage (dominant in tundra zone) South of hbl, there is a lot of relief & continuous forest. 25% of ontario, lies on canadian shield physiographic region. Old rocks (1-3 billion yrs old: most common minerals include silica & quartz, hard & generally acidic. Southern boundary = great lakes - st. lawrence forest region (characterized by mixture of northern & southern trees including white pine & red pine: both pines virtually absent from boreal forest, pines have needles in groups. Black spruce, white spruce, balsam fir: black spruce (loves water) not found in tundra b/c of permafrost. In some regions, jack pine = very common.
