Highway 403 – Mississauga Rd East 1 (Riverwood Conservancy)
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HIGHWAY 403 – MISSISSAUGA RD EAST 1 (RIVERWOOD CONSERVANCY) Region of Peel NAI Area # 3406, 4142 Credit Valley Conservation Authority City of Mississauga Size: 52 hectares Watershed: Credit River Range 4 NDS, Lots 4-7 Ownership: 100% Subwatershed: Credit public (Credit Valley River: Norval to Port Conservation) Credit General Summary This natural area is part of a string of natural areas along the valley of the Credit River as it runs through the City of Mississauga. This site is the portion of the valley on the east side of the river, between Hwy. 403 and Burnhamthorpe Rd., known as the Riverwood Conservancy. The site includes the floodplain east of the river, the valley walls and some tableland forest. The Credit River is a major species movement corridor used by wildlife including migratory fish and birds. This site is in good condition and has a high biodiversity of flora and fauna, in part due to its varied vegetation communities. It supports regionally rare vegetation types, several Species At Risk and rare species. Vernal pools and seepage areas are present. NAI biologists have not inventoried this natural area. Instead the data set has been compiled from a variety of sources. Vegetation communities, plant species and breeding birds were inventoried by consultants for the Mississauga Natural Areas Survey (NAS). The NAS surveys were conducted four times between 1996 and 2009. CVC’s Terrestrial Monitoring biologists have frequently and regularly visited a monitoring plot within this site from 2003 to the present. Their species observations from 2003 to 2009 are included in the data set reported on here (the CVC database is annually updated and thus will be the most current source at any point in time) although their data are restricted to the monitoring plot. Additional data that this summary draws upon comes from various individuals. Fish species were inventoried by CVC from upstream and downstream sampling stations (Table 1). As there are no barriers between the upstream station and this natural area, and between the downstream station and this natural area, the data from the upstream and downstream sites was extrapolated to this area. Table 1: CVC Field Visits Visit Date Inventory Type 23 May 2000 Fish 24 Aug. 2001 Fish Natural Feature Classifications and Planning Areas Life Science ANSI - regionally significant Credit River at Erindale ESA - Credit River - Eglinton to Dundas ESA Physical Features This area is in the Iroquois Plain physiographic region; characterized by a gentle slope toward Lake Ontario and a thin layer of sandy and silty sand soils. The shoreline of glacial Lake Iroquois was higher than the current Lake Ontario shoreline and this area was once an old lake bottom. The area is on the east side of the Credit River and includes floodplain, valley walls and tableland, all of it vegetated. Chappell Creek and MacEwan Creek join the Credit River at this site. A trunk sanitary sewer was installed on this site in the Credit River valley in the early 1970’s. Gabion baskets and Date of this Site Summary: July 2012 HIGHWAY 403 – MISSISSAUGA RD EAST 2 (RIVERWOOD CONSERVANCY) stones were placed along the river valley to reduce erosion and the Credit River was re-aligned at the south end of the area to protected the Burnhamthorpe bridge abutments (ENVision, 2003) Over time, the river water has carved out a valley leaving steep valley walls and exposing provincially significant fossils within the stratified bedrock. These fossils date back 415 million years to the Silurian Age (Riverwood Conservancy, 2011). Human History Archaeological digs carried out in 1989 and 2000 determined that Iroquois used part of Riverwood as a wildlife butchering site. Three hundred pieces of animal bones were found, including bone from Elk. It is believed the butchered meat was then transported to villages along the Lake Ontario shoreline. Ceramic fragments were also discovered, one piece dating back to between 1400 and 1500 A.D. (Landplan Collaborative, 2002). The nearby community of Erindale is located about three kilometres downriver near the intersection of Mississauga Rd. and Dundas St. W. It was first settled in the 1820’s when a saw mill, flour mill, church and post office were built. Erindale later had a dairy (Heritage Mississauga, 2009). From this we can infer that logging, crop-raising and livestock-rearing were common land uses in the surrounding countryside. Riverwood was settled and developed in the 1800’s as a farm and has a long farm history ending in the late 1970’s. The MacEwan House, on its property, was built c. 1840 and is believed to have been used as a pickle factory at one time. It was converted into a summer home in 1914 (Landplan Collaborative, 2002; ENVision, 2003). In 1910, the Credit River (downstream of this natural area) was dammed for a hydroelectric project just north of Erindale in present-day Erindale Park. Around the same time, upstream on the Credit River, another hydroelectric dam project was built at Streetsville (Enersource, 2008). These damming projects would have impacted the hydrology of the Credit River and impacted this natural area, particularly the floodplain vegetation. This natural area shows evidence of being logged and farmed and there are still remnants of an apple orchard. It was used for cattle grazing into the 1940’s (Dave Taylor, pers. comm.). In 1985, The Riverwood Conservancy (formerly the Mississauga Garden Council) started managing this natural area in partnership with the City of Mississauga and CVC. The ongoing management of this natural area includes restoration of habitat including native tree planting and invasive plant species removal (Taylor, 2009). Public gardens are also planned for the non-natural portion of the property. This area is a public passive recreational area with a network of hiking trails, including the Culham trail. The Culham Trail is an 18 km trail for pedestrians and cyclists that runs along the Credit River valley from Erindale Park, just downstream from this natural area, north to the City of Brampton. The trail network in this natural area receives moderate to heavy recreational use. Fishing is a common activity along the Credit River. This area is bordered by the Credit River on the southwest side, Burnhamthorpe Rd. on the southeast side and a railroad line on the northeast side. A cultural meadow community of over 2 ha in size flanks the area on the northwest side, itself bordered by Highway 403. A set of clearings containing the old estate houses and other Riverwood Conservancy facilities are maintained on the tableland surrounded by natural communities. Vegetation Communities For the most part, the vegetation community mapping generated by the Mississauga NAS coincides with the NAI natural area delineations in Mississauga although there are some small discrepancies. Part of this could be due to real changes in community boundaries between the years that the mapping and area delineation were done. Other factors that may contribute to discrepancies are Date of this Site Summary: July 2012 HIGHWAY 403 – MISSISSAUGA RD EAST 3 (RIVERWOOD CONSERVANCY) differing ways of defining edges of communities and differing levels of resolution in mapping. The Vegetation Communities map following this text illustrates the discrepancies. Values for community sizes making up the natural area are taken from the NAS mapping. Values of total natural area size are taken from the NAI area delineation. The general community types present here are deciduous forest (83%), mixed forest (2%), meadow marsh (0.9%), shallow marsh (0.1%), cultural meadow (19%) and plantation (0.2%). A total of 12 vegetation communities of seven different types were mapped by the NAS in this natural area (City of Mississauga, 2006; Table 2). The Fresh-Moist Sugar Maple - Hemlock Mixed Forest (FOM6-1) and the Dry-Fresh Oak - Hickory Deciduous Forest (FOD2-2) are regionally rare. One community was classified only to ecosite level. The Dry-Fresh Oak - Hickory Deciduous Forest (FOD2-2) community is an abundant producer of mast (nuts), capable of supporting a variety of wildlife species. The Cattail Organic Shallow Marsh (MAS3-1) community has formed in a dug pond. Forests are of varied age and include some older forests with trees over 100 years of age. Table 2: ELC Vegetation Communities Map Vegetation type Size in % of natural reference * hectares area FOD2-2 Dry-Fresh Oak - Hickory Deciduous Forest 6.08 11.62 FOD5 Dry-Fresh Sugar Maple Deciduous Forest Ecosite 19.91 38.04 Fresh-Moist Willow Lowland Deciduous Forest (2 FOD7-3 communities) 17.71 33.83 FOM6-1 Fresh-Moist Hemlock Mixed Forest 1.09 2.08 Reed-Canary Grass Mineral Meadow Marsh (3 MAM2-2 communities) 0.49 0.94 MAS3-1 Cattail Organic Shallow Marsh 0.05 0.09 CUM1-1 Dry-Moist Old Field Meadow (2 communities) 9.89 18.90 CUP3-E Norway Spruce Coniferous Plantation 0.12 0.24 TOTAL AREA INVENTORIED 55.34 * Note: The map reference code refers to the vegetation type shown on mapping for this area and also to the Appendix list of species typically encountered in this vegetation type. Species Presence Vascular Plants Plant biodiversity is high in this area. A total of 362 vascular plant species are recorded for this area, of which 223 (68%) are native. One of these species, Butternut ( Juglans cinerea ) is Endangered both nationally and provincially, as well as being provincially rare (S-rank S3?; Table 3). Ten Butternut trees were observed and all were infected with Butternut Canker. Nineteen additional plant species are regionally rare (Table 4). Birds A total of 81 bird species are recorded here, of which 78 (96%) are native. Most are believed to be breeding on site. Two of these are Species At Risk (Table 3).