Loamy Savannah

Description

The Reference State represents the historical natural range of variability that dominated the dynamics of this ecological site. Since European settlement, however, fires have been significantly reduced, while other disturbances such as timber harvesting and grazing by domestic livestock have increased. As a result, the historical disturbance regime no longer exists, and communities representing the Reference State are no longer present.

On both temporal and special scales, this state would have historically supported woody vegetation and/or open grassland resulting from the variability in precipitation, fire, and other disturbances. The tree most characteristic of the wooded communities was bur oak, known for its fire and drought tolerance. Associated trees included quaking aspen and green ash. Common shrubs included both beaked hazel and American hazel, chokecherry, Saskatoon serviceberry, rose, and western snowberry. Graminoids were predominantly cool-season species, such as green needlegrass, needleandthread, western wheatgrass, bearded wheatgrass, prairie Junegrass, Canada wildrye, and sedges. Big bluestem, little bluestem, and blue grama were common associated warm season grasses. American vetch, veiny pea, Canada anemone, candle anemone, northern bedstraw, and blackeyed Susan constitute the more common forbs.

Characteristics and indicators

(i.e. Characteristics and indicators that can be used to distinguish this state from others). Because of changes in disturbances and other environmental factors (particularly the widespread occurrence of exotic species), the Reference State is considered to no longer exist.

Resilience management

(i.e. management strategies that will sustain a state and prevent a transition). If intact, the reference state should probably be managed with current disturbance regimes which has permitted the site to remain in reference condition as well as maintaining the quality and integrity of associated ecological sites. Maintenance of the reference state is contingent upon a monitoring protocol to guide management.

Submodel

Description

This state forms outside the historical disturbance regime, largely because of the long-term elimination of fire sufficient to establish a bur oak dominated forest similar to that of 1.3, and the introduction of exotic cool-season grasses. This state may be described as a bur oak dominated woodland with green ash and quaking aspen as the principal associates. The shrub component may include American and beaked hazel, chokecherry, Saskatoon serviceberry, rose, and snowberry. Kentucky bluegrass and/or smooth brome are the main cool-season exotic grasses, while the native graminoid component is largely limited to Sprengel’s sedge and perhaps rough ricegrass. Common associated forbs include wild sarsaparilla, early meadow-rue, veiny pea, and starry false lily of the valley.

Presently the distribution of common buckthorn in MLRA 55A has been relatively limited. However, it is spreading, and due to its invasive nature and habit of displacing native understory species is a threat to biodiversity. As a result, periodic monitoring for the species is recommended, and if the plant is encountered, control measures implemented.

Characteristics and indicators

The presence of trace amounts of exotic cool-season grasses. The presence of exotic biennial or perennial forbs (e.g. common dandelion, red clover, white clover, and black medic may not, on their own, indicate a transition from State 1: Reference State to State 2: Native/Invaded State but may facilitate that transition.

Resilience management

The invasion of these exotic grasses is associated with long-term elimination of fire allowing bur oak and green ash to dominate. These fire tolerant species will not be significantly impacted by implementation of prescribed fire. To maintain State 2.0 Native/Invaded State prescribed fire and prescribed grazing should be implemented.

Submodel

Description

This state results from clearing of woody vegetation on the site regardless of technique, and perhaps followed by a successful seeding of the site to native and/or introduced grasses, with or without introduced legumes or native forbs.

Characteristics and indicators

The plant community is a result of successful woody vegetation clearing or after pasture and hayland or rangeland planting. Exotic grasses, native grasses, exotic legumes, and or native forbs are used for grazing or forage production.

Resilience management

To slow or limit the invasion woody species, it is imperative that managerial options (e.g. prescribed grazing, prescribed burning) be carefully constructed and evaluated with respect to that objective).

Grazing management should be applied that enhances the competitive advantage of native grass and forb species. This may include: (1) grazing when exotic cool-season grasses are actively growing and native cool-season grasses are dormant; (2) applying proper deferment periods allowing native grasses to recover and maintain or improve vigor; (3) adjusting overall grazing intensity to reduce excessive plant litter (above that needed for rangeland health indicator #14 – see Rangeland Health Reference Worksheet); (4) incorporating early heavy spring utilization which focuses grazing pressure on exotic cool-season grasses and reduces plant litter provided that livestock are moved when grazing selection shifts from exotic cool-season grasses to native grasses.

Prescribed burning should be applied in a manner that maintains or enhances the competitive advantage of native grass and forb species. Prescribed burns should be applied as needed to adequately reduce/remove excessive plant litter and maintain the competitive advantage for native species. Timing of prescribed burns (spring vs. summer vs. fall) should be adjusted to account for differences in annual growing conditions and applied during windows of opportunity to best shift the competitive advantage to the native species.

Submodel

Description

This state typically results from the abandonment of cropland, hayland, or residences/farmsteads. Vegetation is typically dominated by Kentucky bluegrass and smooth brome. Common associates include western snowberry, wild rose, northern bedstraw, common dandelion, Canada goldenrod, common yarrow, and Canada thistle. Sprouts from adjacent stands of aspen or beaked hazel often encroach onto the site, as well as seedlings of adjacent green ash.

Characteristics and indicators

Tillage has destroyed the native plant community, altered soil structure and biology, reduced soil organic matter, and resulted in the formation of a tillage induced compacted layer which is restrictive to root growth. Noxious weeds, if present, will need to be managed.

Resilience management

Continued tillage will maintain the state. Control of noxious weeds will be required.

Submodel

Description

This plant community is most commonly associated with the cessation of cropping without the benefit of pasture/forest seeding or planting, resulting in a “go-back” situation