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| Ministry of Environment |
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| Sensitive
Ecosystems Inventories |
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Central Okanagan Grasslands (GR)
Grasslands in the Central Okanagan study area are dominated by bunchgrasses,
but scattered forbs occur throughout these sites. The grasslands of
the Central Okanagan represent a portion of the Pacific Northwest bunchgrass
grasslands that are centred in south-east Washington, north-east Oregon
and Idaho. Areas where grasslands occur are generally too hot and dry
for forests to establish. Often, grasslands occur on medium and finer
textured soils (typically chernozems). Moisture is effectively funnelled
by the conical shape of bunchgrasses and captured by extensive grass
roots in the upper horizons of the soil, thus leaving little moisture
available for tree seedlings. In comparison, trees are usually able
to establish on moist sites, and on coarse (sandy, gravely) soils where
moisture is available at depth. Additionally, grasslands are favoured
in environments where frequent, low-severity fires historically occurred.
Subtypes of Grasslands
For this SEI, grassland ecosystems were divided into distinct classes
(grassland and shrubland)
according to their environmental and vegetation characteristics.
Grassland Ecosystems
(GR:gr)
Bunchgrasses, most commonly bluebunch wheatgrass and rough fescue,
dominate healthy grassland ecosystems in the study area. Bunchgrasses
are designed to funnel moisture to the center of the plant, and have
extensive fine roots to capture moisture in the upper horizons of the
soil. Grassland soils are usually fine- or medium-textured, and soils
are topped by a thick, dark-coloured horizon enriched by organic matter
from the decomposition of grass roots.
Shrubland Ecosystems
(GR:sh)
Shrubs, most commonly snowberry and roses, dominate shrubland ecosystems
in the study area. Shrublands occur in grassland areas, but are moister
than the surrounding grasslands as they occur in depressions and moist
pockets that tended to collect snow and some run-off. Soils are dark
(high in organic materials), typically medium-textured, and very nutrient-rich.
Status of Grasslands
Grassland ecosystems were found to cover 1.5% (464 hectares) of the
study area. The majority of these were grasslands, but a large proportion
was shrublands. Many of these undisturbed grassland ecosystems were
restricted to rocky sites with poor access for cattle, and to higher
elevations where more moisture and high productivity enabled these sites
to recover more quickly than lower elevation sites.
All grassland ecosystems are a high priority for conservation considering
that many have been lost to agricultural and urban settlement, and many
sites have been invaded by non-native plants.
Grasslands with 20-50% non-native vegetation were included in the Disturbed
Grasslands category.
For more detail see the Technical Report.
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