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Yosemite Valley Campground - Raspberry Trimming for Human-Bear Conflict Abatement
Yosemite National Park » Yosemite Valley Campground - Raspberry Trimming for Human-Bear Conflict Abatement » Document List
This project is proposing a reduction in raspberry fruits (through mechanical reduction) to mitigate incidences of human-bear conflict in Yosemite Valley campgrounds.
Proposal: Raspberry plants are perennial, but will produce canes that live for two years. The first year the cane is vegetative - no fruit. The second year that cane will produce fruit and die back in the fall. Management in the form of weed-eating and brush cutting would need to occur every other year to halt fruit production (proposing two years initially to see if this method works to reduce bear presence in the campgrounds). Manual mechanical reduction (weed-eating, mowing, and/or brush cutting) at 6-12 inches above the soil will allow for keeping native plant cover (resilient to non-native plant invasion) while significantly reducing berry production. Mechanical cutting of raspberry bushes will occur within 50 yards of Valley campgrounds (since park visitors are advised to stay a minimum of 50 yards from bears and other wildlife). No ground disturbance is anticipated. Pruning work will occur in the spring/early summer prior to fruit production. Spring removal could ensure activities are timed ahead of any bird nesting. Work is funding dependent but will ideally start in the Spring 2022.
Permanent removal of the raspberry plants with herbicide application is a less desirable option since they are a native plant and permanent removal would require revegetation of the area with native plants - and revegetating a site subject to frequent human disturbance is difficult, time consuming, and costly. Additionally, the berry plants are likely dispersed by native wildlife species (birds, small mammals, and bear) so reoccurrence of the raspberries is likely.
Any encounters with Himalayan and cut-leaf blackberry will be recorded and if time and staffing allows those will be treated with chemical herbicide (per the Invasive Plant Management Plan), which will serve to reduce the overall berry production and the length of time berries are produced near the campgrounds. Blackberries tend to produce later into the summer season than raspberries, so these treatments will reduce the length of time berries are available in Yosemite Valley campgrounds to attract the bears.
Proposal: Raspberry plants are perennial, but will produce canes that live for two years. The first year the cane is vegetative - no fruit. The second year that cane will produce fruit and die back in the fall. Management in the form of weed-eating and brush cutting would need to occur every other year to halt fruit production (proposing two years initially to see if this method works to reduce bear presence in the campgrounds). Manual mechanical reduction (weed-eating, mowing, and/or brush cutting) at 6-12 inches above the soil will allow for keeping native plant cover (resilient to non-native plant invasion) while significantly reducing berry production. Mechanical cutting of raspberry bushes will occur within 50 yards of Valley campgrounds (since park visitors are advised to stay a minimum of 50 yards from bears and other wildlife). No ground disturbance is anticipated. Pruning work will occur in the spring/early summer prior to fruit production. Spring removal could ensure activities are timed ahead of any bird nesting. Work is funding dependent but will ideally start in the Spring 2022.
Permanent removal of the raspberry plants with herbicide application is a less desirable option since they are a native plant and permanent removal would require revegetation of the area with native plants - and revegetating a site subject to frequent human disturbance is difficult, time consuming, and costly. Additionally, the berry plants are likely dispersed by native wildlife species (birds, small mammals, and bear) so reoccurrence of the raspberries is likely.
Any encounters with Himalayan and cut-leaf blackberry will be recorded and if time and staffing allows those will be treated with chemical herbicide (per the Invasive Plant Management Plan), which will serve to reduce the overall berry production and the length of time berries are produced near the campgrounds. Blackberries tend to produce later into the summer season than raspberries, so these treatments will reduce the length of time berries are available in Yosemite Valley campgrounds to attract the bears.