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Don Gayton, M.Sc, P.Ag Summerland, BC d.gayton@shaw

OKANOGAN/OKANAGAN GRASSLANDS. Don Gayton, M.Sc, P.Ag Summerland, BC d.gayton@shaw.ca. We are at the northern edge of the Pacific Northwest Bunchgrass region, which covers parts of southeastern Washington, northeastern Oregon, west-central Idaho and western Montana.

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Don Gayton, M.Sc, P.Ag Summerland, BC d.gayton@shaw

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  1. OKANOGAN/OKANAGAN GRASSLANDS Don Gayton, M.Sc, P.Ag Summerland, BC d.gayton@shaw.ca

  2. We are at the northern edge of the Pacific Northwest Bunchgrass region, which covers parts of southeastern Washington, northeastern Oregon, west-central Idaho and western Montana. The PNW Bunchgrass vegetation type is characterized by three main grasses, bluebunch wheatgrass, Idaho fescue, and rough fescue. Many other grasses, forbs, shrubs, lichens and mosses form part of this Vegetation type.

  3. This is a good example of diverse landscape “structure” – lichens/mosses, grasses/forbs, low shrubs/tall shrubs, trees etc. Structure is important for biodiversity.

  4. The White Lake Grasslands, near Penticton

  5. These small “aspect grasslands” are found on south slopes in forested communities. They are important sources of diversity, habitat and forage.

  6. PNW BUNCHGRASSES:THE HOLY TRINITY • BLUEBUNCH WHEATGRASS • Pseudoroegneria spicata • ROUGH FESCUE • Festuca campestris • IDAHO FESCUE • Festuca idahoensis

  7. BLUEBUNCH WHEATGRASS

  8. ROUGH FESCUE

  9. IDAHO FESCUE

  10. Only 30% of this grass biomass is aboveground: the other 70% is fine roots. About 1/3 of these roots will die each winter, and be replaced. The dead roots break down to become humus, making native grassland soils fertile, with very high moisture holding capacity. Unfortunately, this fertility is their undoing: most of the world’s grassland soils (also known as Chernozems) are now under cultivation.

  11. OTHER KEY PNW GRASSES • NEEDLEANDTHREADGRASS • COLUMBIA NEEDLEGRASS • JUNEGRASS • SANDBERG’S BLUEGRASS • SAND DROPSEED

  12. Good condition native grasslands have very high biodiversity values, and host many rare species. This one is known as Lyall’s mariposa lily.

  13. THE 5 DRIVERS OF NATIVE GRASSLAND LOSS • LAND CONVERSION • FOREST INGROWTH • SUBURBANIZATION • WEED INVASION • OVERGRAZING

  14. EXPANDING SUBURBS AROUND CITIES ARE EXTIRPATING MANY NATIVE GRASSLAND AREAS.

  15. Historically, frequent light fires maintained open forests and grasslands.

  16. HISTORICAL RANGE OF FIRE FREQUENCIES (HRV) IN INTERIOR DRY FOREST TYPES: (based on fire scar analysis): 5 TO 35 YEARS Modern fire suppression means open forests have become much denser (forest ingrowth) and trees are encroaching on to traditional grasslands (forest encroachment).

  17. As our climate warms, the Okanagan/Okanogan Valley will be an important corridor for newly adapted native species to migrate northward. We will need to consider migration pathways in our urban and rural land use planning.

  18. GAYTON’S “WATCH LIST” OF CULTIVATED GRASSES • DON’T USE IN OR NEAR NATIVE HABITAT: • SMOOTH BROME • CRESTED WHEATGRASS • KENTUCKY BLUEGRASS • CANADA BLUEGRASS • ORCHARDGRASS • TIMOTHY • REED CANARYGRASS • OK IN SPECIFIC SITUATIONS: • ITALIAN WILDRYE • CREEPING RED FESCUE • TALL FESCUE • HARD (SHEEP) FESCUE • INTERMEDIATE WHEATGRASS • BLUE GRAMA • BUFFALOGRASS

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