Ministry of Environment
Sensitive
Ecosystems Inventories
Seasonally Flooded Agricultural Fields of East Vancouver Island and the Gulf Islands
Seasonally Flooded Agricultural Fields are lands that have been modified for agricultural use, but have important wildlife habitat value during specific times of the year.
These fields are located primarily in low-lying areas such as valley bottoms and deltas of large alluvial rivers and creeks. In some cases they are found on moisture-receiving sites, usually in association with lake shores, or lowlands adjacent to coastal bays. They are often former wetlands, and in many cases, are located adjacent to surviving wetlands such as marshes, swamps, and wet meadows. In such cases, other environmental factors such as poor drainage or a high water table contribute to flooding during the winter, fall and rainy season.
Why are Seasonally Flooded Agricultural Field ecosystems considered ecologically important?
- FS ecosystems provide surrogate wetland habitat – With the
historical loss of natural wetland ecosystems, FS ecosystems are playing
an increasingly important role by providing surrogate wetland habitat
for wildlife. The SEI study area is located along the Pacific Flyway,
which is the migratory path for bird species traveling between their
northern summer breeding grounds and southern wintering grounds. These
FS fields are an important area for migration stops and over wintering
grounds for birds and waterfowl.
- FS ecosystems provide for high biodiversity – These flooded
fields can support high numbers of different bird species for the
area they occupy, depending on the previous season’s agricultural
use and the weather. Many FS fields are adjacent to natural riparian
and wetland ecosystems, which increases habitat diversity within the
larger landscape mosaic. This increased diversity attracts a greater
variety of species, each with unique habitat needs. Also, many species
depend on one ecosystem for part of their life cycle (i.e. breeding),
and surrounding areas for another (e.g. birthing). This means wildlife
may extend use of the area into other seasons if the FS fields lie
adjacent to ecosystems that provide habitat requirements for another
part of its life cycle.
- FS ecosystems provide linkages and travel corridors - Hedgerows
that have developed along fence lines, that form the boundaries between
land holdings, create linkage opportunities in addition to those provided
by adjacent natural wetland and riparian habitats.
- FS ecosystems provide a forest/field edge effect – The edge between a woodland/forest and an FS field ecosystem is also an ecologically important landscape component. This transition zone provides a flow of energy, nutrients and species between these ecosystems. The movement of species both along and across these edges makes them places of intense species interactions, thus molding the composition of plant and animal communities within both the ecosystems. This edge effect results in greater habitat diversity and numbers of species.
What are some conservation concerns of Seasonally Flooded Agricultural Field ecosystems?
The overlapping of FS fields with a unique combination of topography, climate, and hydrology has resulted in the development of important wildlife habitat that supports unusually high densities of waterfowl, shorebirds, and raptors during the winter. Urban encroachment is the biggest threat, and has the most direct impact on both agricultural and wildlife use of Seasonally Flooded farm fields.
Examples of some of the larger Seasonally Flooded Agricultural Field ecosystems within the SEI study area: Courtney Flats and south of the Comox Airport, Martindale Flats, and near the estuaries of the Chemainus and Nanaimo Rivers.
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