Barrie Creeks, Lovers Creek, and Hewitt's Creek Subwatershed Plan

The Barrie Creeks, Lovers Creek and Hewitt’s Creek Subwatershed Plan
The most common forest types in the Barrie Creeks subwatershed are cultural woodlands
(which refers to young or early successional forests, often dominated by species such as
trembling aspen, eastern white cedar, or red cedar), and deciduous and mixed forests. Similarly,
the most common woodlands in the Lovers Creek subwatershed are deciduous and mixed
forests, and in the Hewitt’s Creek subwatershed are deciduous forests (Table 6-1). Deciduous
and mixed forests are found typically on well drained sandy loam sites. Deciduous forests are
found more typically on relatively flat ground around the crest of the glacial meltwater valley
extending from the tip of Kempenfelt Bay (Figure 2-22, Chapter 2 – Study Area), while mixed
forests are more common on areas with steeper slopes (including ravines, and the side of that
glacial valley) which have slightly cooler microclimates (Figure 6-3).
Relatively uncommon in these subwatersheds are coniferous woodlands (including forests,
swamps, and plantations), which account for only 17% of the total woodland. These uncommon
forest types provide habitat for unique wildlife communities, particularly those which prefer
coniferous woodlands, such as pine warbler (Dendroica pinus), Cooper’s hawk (Accipiter
cooperii), and blue jay (Cyanocitta cristata) (Bird Studies Canada et al., 2008).
Structural diversity of habitat is a key driver of biodiversity. In woodlands, habitat niches can
range from microhabitats such as the surfaces of fissured trunks, leaves, and rotting logs to
macrohabitat features such as the horizontal layers within the woodland (e.g. supercanopy,
canopy, subcanopy). In addition, woodlands are present in a wide variety of topographic
settings and soil and moisture regimes. For all of these reasons it is not surprising that many
woodland species are obligates (i.e. they are only found in woodlands), or that woodlands
provide habitat for a wide range of flora and fauna. They form important building blocks of the
natural heritage system.
The summary statistics reflecting the percentage of the watershed under forested cover cannot
address these more detailed issues related to the diversity and ecological integrity of individual
forest patches. These issues relate typically to factors such as forest size, forest age, proximity
to other natural areas, topographic heterogeneity, and structural diversity within the forest.
Policy 6.48 of the LSPP requires the MNR (in collaboration with the LSRCA, First Nations, and
Métis communities) to map and identify `high quality` natural areas in the Lake Simcoe
watershed. When this policy has been developed and mapping complete, more could be said
about the distribution of these site-specific quality measures in this study area.
Although the total extent of forest cover in a subwatershed is the primary driver for many forestdependent
ecological processes, some species are also sensitive to the size of remnant forest
patches (Robbins et al., 1989; Lee et al., 2002), the amount of ‘interior’ forest habitat (Burke and
Nol, 1998a; Burke and Nol, 2000), and the proximity or connectivity between remnant forest
patches (Nupp and Swihart, 2000).
Contiguous woodland areas have been calculated and the distributions of woodland patch sizes
are displayed in Figure 6-4, Figure 6-5, and Figure 6-6. While the total area of woodland
represents the amount of forest completely within the subwatershed, the number of patches
also includes any patches touching the subwatershed boundary. This methodology was used to
avoid underestimating the number of large patches. If only patches within the subwatershed
boundaries were considered, the number of large patches would be underestimated.
The Barrie Creeks subwatershed is characterized by a large number of small forest patches
(Figure 6-3, Figure 6-4). There are a total of 117 separate patches of woodland in this
subwatershed, 90% of which are small (less than 10 ha in size). Despite their small size,
collectively these small fragments represent half of the subwatershed’s total forest cover. The
Chapter 6: Terrestrial Natural Heritage 268