About the Inventories
The Native Prairie Vegetation Inventory (NPVI) came about because of a lack of fundamental native prairie information required to support the understanding and management of a variety of landscape planning issues. This first inventory was initiated in 1991, interpreting from 1:30,000 black and white aerial photography. The area of inventory included the Grasslands Natural Region (GNR) and portions of the Parkland Natural Region (PNR) adjacent to the GNR.
Native prairie was generally thought of as any vegetated landscape not disturbed by man. In order to establish an interpretation standard for describing the amount of native landscape, the Prairie Conservation Action Plan definition of Native Prairie was adopted:
“An area of unbroken grassland or parkland dominated by non-introduced species, and an area of previously broken grassland that has reverted back to native vegetation (30 to 60 years)”.
With this definition as a guide, the native portion of the landscape was categorized using six native cover types:
SHRUB - Native Shrubland
GRAMINOID - Native Grass
LAKE - Lake/Reservoir Area
RIPARIAN - Riparian Zones
TREED - Native Trees
WETLAND - Wetland Area
Guidelines put in place for interpreters included:
- Generally, anything not disturbed by man is considered native.
- Lakes are defined as areas of reasonable size containing permanent year round water. Dammed lakes are considered native.
- Wetlands are defined as low lying areas that contain standing water for at least part of the year.
- Riparian areas include the surface area of the flowing water and areas along the sides of rivers, creeks and streams that would likely be flooded during an average spring run-off. Generally it is easy to distinguish average flood levels from exceptionally high flood levels.
- Fields that appear to have been cut in the past are considered non-native as they may be improved pasture.
- Grass filled drainage gulleys that do not contain a defined central creek are classed as graminoid.
- A ring of shrubs growing around the perimeter of wetlands is typically included with the wetland classification.
- Small roads/railway lines are generally considered negligible and ignored.
The NPVI quarter section based inventory was well received and extensively used by Provincial land managers and industry. However, current and anticipated pressures from a prosperous Alberta economy and projected population increases placed increased pressures on the southern Alberta landscape. Though the NPVI information was beneficial, it was difficult to tie land management issues to a specific location on the ground. There grew a need for a high quality spatial dataset to support management issues surrounding biodiversity, species at risk, public land and disposition management, carbon accounting, sustainable ranching and the petroleum and power industries. Efforts, again initiated by Alberta’s Prairie Conservation Action Plan, brought forward suggestions for a more comprehensive and detailed GIS product to meet the growing pressures of properly managing the landscape.
In 2006-2007, under the Land Use Framework-Database component, Sustainable Resource Development initiated the Grasslands Vegetation Inventory (GVI) which can be generalized as a landscape (rangeland sites) and land use (agricultural, industrial and populated areas) inventory with emphasis being placed on native characteristics. This inventory is being interpreted using high resolution 3D Color infrared imagery allowing for precise line placement and interpretation of the landscape. GVI data is digitally captured on screen as polygon, line and point features and attributed using standard forms and drop-down menus.
This inventory separates the landscape into ‘Site Types’ which can be thought of as different habitat types or land uses. Upland polygons are captured to a minimum size of 5 hectares and wetland or riparian sites to a minimum of 1 hectare. Each site type, up to four (4) per polygon, is described by tree, shrub, water and herbaceous cover as well as distribution of these cover types within the polygon. Once complete, this multiyear landscape inventory will cover the Grasslands Natural Region.
