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Grass Valley Reservoir





Plate 714X. Grass Valley Reservoir 1943 – 1948 – 1953 – 1958 – 2004 This Photo Plot Transect was sited to monitor range conditions in the mountain brush type southeast of Grass Valley Reservoir. Cottam, who established this transect in 1943, noted that the area had “been terribly overgrazed. The birchleaf mahogany seems to have suffered most. Many plants are dead. Most of the live ones have more than 50 percent dead branches, and the striking fact that no new shoots seem to have appeared this year attests to the extreme low vitality of these shrubs. All mahogany shrubs are closely cropped…” Cottam reported that oakbrush and Utah serviceberry were also heavily browsed. “Grasses are in general sparse and are already 80 percent utilized. They are in a low state of vigor. The soil on this transect shows very serious impoverishment, and unless drastic reduction in grazing is effected, both cattle and deer a decade hence will see little vegetation or soil left.” Cottam remeasured the transect in 1948 but found little improvement. “[Birchleaf mountain mahogany] seems definitely on its way out because of deer and stock overuse. One seedling of Cercocarpus montanus was observed in one of the plots. Reproduction of this shrub is very rare. There has been considerable soil movement. Much of the soil remains in terrace-like banks on the uphill side of shrubs while much of it has been carried to the valley below. The silting in the Grass Valley reservoir attests to this fact…there are many evidences of deer overabundance in this area.” Irwin Johnson measured the transect in 1953 but reported the range was still in poor condition. “There are several things which stand out on this Pine Valley summer range. First, is the unsatisfactory condition of the browse. The key species Cercocarpus montanus (birchleaf mahogany) is closely hedged, many dead branches in the shrubs that are alive and completely dead individuals are common. I did not find any seedlings and only a few plants that could be classed as young. Mostly the birchleaf mahogany is in the mature age class. Gambel oak is badly hedged in spots...The second condition that is conspicuous is the extend of sheet erosion….there are ample earmarks of active soil movement on the slopes; for example, recent alluvial deposits and accumulations on the uphill side of plants, pedestalled and undercut grasses and forbs, also rill marks. The surface soil is quite loose and easily disturbed. The effects of splash erosion are noticeable on the more level spots. Erosion pavement is dense on a lot of this range, especially on the more open places away from protection of oakbrush. Litter is very inadequate to protect the soil.” Johnson reread the transect five years later but found that little had changed. “My observation notes of July 28, 1953 are largely applicable today. The very poor condition of Cercocarpus montanus and the extensiveness of sheet erosion are perhaps the most noticeable features of the sampled area. Many shrubs of the above browse species are dead. They show the effects of years of repeated close hedging. The birchleaf mahogany yet alive are closely hedged. Many of them have 75 percent and more of dead wood. Some have just one or two green shoots….this range is in poor condition. Utilization of cattle to date is light because of deferred use. So far, just a few cattle on the transect area and vicinity. Deer signs, both old and new, are numerous….around palatable shrubs deer droppings often are dense. Sheet erosion continues to be a problem. Pavement is dense for the most part. Much evidence of considerable soil movement in recent years. Alluvial deposits in depressions, accumulation of debris above plants and undercutting are prevalent. Herbaceous litter practically nil.” Jim Bowns remeasured the transect in 1979 and found that range conditions had improved. “This range is presently a cattle allotment, but was grazed with sheep.

Vegetative Community:

Mountain Brush, Sagebrush, Pinyon, Juniper


South West

January 2018