riparian vegetation | Don Gayton

(Note: this is the text of a letter sent to The Nature Trust of British Columbia, by myself and colleague Fred Marshall, in regards to livestock management in the White Lake Basin, an important ecological area in the South Okanagan.)

In a recent visit (May 8, 2020) to the Nature Trust’s White Lake Biodiversity Ranch, we noted some issues that disturbed us as Agrologists and as range managers. We would like to bring these to your attention.

Livestock Rotations

On May 8 we observed livestock in three different pastures: Observatory, Lower Parker and Welsh Lake. According to the 2014 Grazing Management Strategy for the White Lake Basin Biodiversity Ranch, the “even year” (2020) rotations are as follows:

Observatory: Sept. 11-Oct. 20
Lower Parker: Apr 20-May 31 & July 6-July 10
Welsh Lake: June 21-July 20

We are aware that rotations need to be adjusted from time to time, but we do question why two out of the three pastures are currently out of rotation.

Modern range management strategies emphasize larger herds grazing for shorter periods of time in a given pasture, with longer rest periods in between. This encourages non-selective grazing and adequate rest periods, allowing our slow-growing native grasses to recover. This is essential in the spring, a period when native grasses are particularly sensitive to defoliation. We do not see this strategy reflected in the Biodiversity ranch rotation schedule.

Invasives

The White Lake Basin has a long history of invasives, many pre-dating the Biodiversity Ranch. However, we are concerned that the current grazing practices are encouraging existing and new invasives. Observatory Pasture is one striking example. Diffuse Knapweed (Centaurea diffusa) populations are collapsing right across the southern Interior, due to successful biocontrol. Yet Diffuse Knapweed is extremely common in Observatory Pasture. Sulfur cinquefoil (Potentilla recta), a relatively new invasive, is now well established in the Basin.

Riparian Grazing Management

We were particularly distressed by the condition of lower Park Rill Creek (designated as “Riparian env” on the pasture map). Cattle have total access to this portion of the Creek, and they have destroyed all the riparian vegetation. As a result the Creek has downcut some two to three meters below the soil surface. This is inexcusable at the best of times, but even more so given the number of riparian and wetland-dependent species at risk in the White Lake Basin.