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A West Island Forest

The following information is abstracted from an article originally published under the title West Island Forests: Rooted in time, growing toward an uncertain future by Jim and Helen Fyles. Dr Fyles is the current Academic Director of the Morgan Arboretum.

Where our forest came from

The strong impact of European settlement and use of the land for agriculture and forestry obscures our current picture of the West Island. The long-term pollen record speaks of migrations of plant species from as far south as North Carolina following the retreat of the glaciers, warming climate and emergence of land areas from the sea. Eight thousand years ago, spruce and pine dominated a forest perhaps reminiscent of the modern coniferous forests of central and northern Quebec. Hardwood trees, such as maple and beech arrived, between 6000 and 4000 years ago. The prevailing concept of the forest 'association' typical of the West Island is based on the field research and descriptions of Granter from the 1950's which characterized the 'Erablière á Caryer' on rich soils as a diverse mixed forest of sugar maple with bitternut hickory, white ash, basswood. Considerable uncertainty remains, however, about the composition of the 'climax' or 'old growth' forest before European settlement. One of the intriguing questions about the pre-European forest is the role that aboriginal peoples played in determining its character. Although no written records exist, the oral tradition held by Mohawk elders suggests that the extent and diversity of the hardwood forests may have been the product of intentional modification of the forest to promote species valued for food, fibre and medicine. Both the aboriginal oral record and written accounts of early European explorers describe large and long-established aboriginal communities with highly developed agricultural systems. The oral tradition recalls the removal of forest using fire and the intentional establishment of beaver colonies in stream valleys to flood the forest. Flooding not only killed the trees, making their removal relatively easy, but also led to the accumulation of sediments which increased the fertility of the soils once the pond was drained and converted to agricultural fields. Nut trees, such as hickory, and fibre species, such as black ash used in basket making, were commonly planted. Although the extent of the use of these 'management' techniques in the forests of the West Island is unknown, our concept of the history of these forests should include this important human component potentially reaching back thousands of years.

Land tenure and the 'back-forty'

The Seignurial land-tenure system that was introduced early in the period of French colonization had a significant effect on the pattern of colonial settlement and agricultural land development, and thus on the forest that was cleared to make way for these activities. In this tenure system, farmers were guaranteed access to the river, which was the primary transportation route. Farm buildings were usually built near the river, with agricultural fields behind and uncut forests remaining farther inland. When lots were divided, among inheriting sons for instance, the right to river frontage was maintained, thus perpetuating the pattern of farms near the river and forests further inland. This approach to land development ensured that the floodplain and riverbank forests were cut first. In many areas of the West Island, this occurred as early as the 1600's, and few of these forests remain intact today. Farmers used the inland forests for timber and firewood production or for free-range grazing by cattle and they were not converted to other ecosystem types. The location of these forests on soils derived from the ancient sandbars or poorly drained clay sediments, and undesirable for agriculture, strengthened the pattern of land use. Early land-use patterns are still readily apparent on maps of the West Island which show significant areas of old forest only in central sections of the area, including the Morgan Arboretum of Ste Anne de Bellevue and Senneville, Cap St Jacques, and Ile Bizard.

A fragmented forest

At one time, the forests of the West Island stretched in an unbroken blanket from Lac St Louis to Riviere des Prairies, divided only by streams and wetlands. Human activity has broken the forest into smaller and smaller pieces separated by tracts of agricultural fields, roads and suburban developments. Where once plants and animals could disperse through unbroken habitat, there now are barriers of asphalt, concrete and chain-link. Dispersal is a key process that maintains a diversity of species in ecosystems and of genes in a population. Research on islands has shown that smaller islands can support fewer species as do islands that are farther from the mainland. Once forest patches become islands in a sea of non-forest, the patches behave the same way, and the number of species that can be supported drops. Narrow corridors along road edges or fence lines become crucial for travel between patches. The distribution of spring flowers in many West Island forests show clearly the effects of how fragmentation and barriers can affect biodiversity. The trilliums are a case in point. Trillum seeds are dispersed by ants and therefore if these plants are exterminated from a forest stand, by cattle grazing for instance, their reestablishment from adjacent areas is very slow. Ants never travel far and seldom cross roads so that even woodland trails can act as barriers to trillium seed dispersal. In a landscape criss-crossed by pavement, dispersal is impossible.

Last Updated: Tuesday, 04 May 2010 19:01