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Natural History


The foothills of the southern Sierra Nevada experience a warm-summer mediterranean climate. Mean annual precipitation is 9.37’’. The average frost-free season ranges between 225 to 300 days. July is the hottest month with an average high temperature of 97.7°F. The coldest month is December with an average high of 57.6°F.


Winter accumulation of snow in the high mountains supplies seasonally available surface and groundwater for many of the foothill streams. An earthen dam forms a pond on the northern end of the property near the main entrance. In addition to the pond overflow, a nearby spring provides water for the seasonal creek along the northern edge of the ranch. There is also a perennial spring in the south-central part of the property. In a year with sustained winter rains, vernal pools form in the West Field #1, East Field #11 traps, and Pond Trap #3. The vernal pools provide valuable habitat and water for wildlife and cattle.


Circle-J Norris Ranch is located in the lower Sierra Nevada foothills, which are dominated by Blasingame and Auberry soils of sandy loam, with other minor soils present. These soils are formed from coarse, moderately weathered granite rock. Blasingame soils are moderately deep, with slopes ranging from 9 to 50 percent. These soils have a surface area of slightly acidic sandy loam, and subsoil of neutral loam, clay loam, and sandy clay loam. Auberry soils are deep, with slope ranging from 9 to 50 percent. These soils generally have a surface area of slightly acidic sandy loam, and a subsoil of slightly acid loam, medium acid loam, and sandy clay loam. These major soil types are well to moderately suited to rangeland, with good forage production in years of adequate moisture ranging from 1200 - 1920 lbs per acre of forage production. The ranch’s elevation ranges from 1,700ft to 2,050ft.


Circle J-Norris Ranch has some of the remaining vernal pool habitat in California. Vernal pool complexes were once widespread in the Central Valley and Sierra Foothills, but were compromised by industrial and agricultural development, invasion of non-native species, and alteration of hydrological patterns. Vernal pools form from several days of consistent rainfall. The pools do not form until the soil is saturated to the hardpan. Vernal pools in the Southern Sierra Foothills are primarily of the Northern Hardpan or Northern Basalt Flow types, which can exist as typical vernal pools within mima mound topography, or more irregularly clustered. Some Northern Claypan vernal pools also exist in the region, which may present in mima mound topography, or more shallow in alkali playa. Some pools may be connected by intermittent drainages called vernal swales.

There are many rare and endangered flora and fauna associated with vernal pool complexes, including the federally listed Vernal Pool Fairy Shrimp. Fairy shrimp cysts become embedded in mud at the end of spring and may remain dormant but viable for decades until the ideal vernal pool conditions exist for their survival. Low to moderate levels of plant litter are ideal for the formation of an open canopy, which is favored by flowering vernal pool plants. In shallow vernal pools, hoof prints may actually increase diversity, and can provide refugia for fairy shrimp to complete their life-cycle during a drought year.