California Foothills Research Articles

California Oak-Woodland Overstory Species Affect Herbage Understory: Management Implications

Concerns for the future of California's oak-woodlands have intensified the need to better understand how different overstory species affect herbage standing crops and species frequencies. Data from over 8,000 plots harvested between 1961 and 1968 at the San Joaquin Experimental Range in the Sierra Nevada foothills of central California show that peak standing crops averaged 2,795 kg/ha in the open; 3,086 kg/ha under blue oak (Quercus douglasii); 1,840 kg/ha under interior live oak (Quercus wislizenii); 1,696 kg/ha under digger pine (Pinus sabiniana), and 1,917 kg/ha under buck brush (Ceanothus cuneatus). Overstory species affected standing crops differently on different range sites. On swales, standing crops were less under live oak and digger pine than in open areas. On open-rolling uplands, standing crops were less in the open and under live oak than under blue oak. On rocky-brush uplands, standing crops were less under all other overstory species than under blue oak. Data on species frequency suggest that herbage species of inter successional stages are more common under trees. The frequency of plant species varied with the species of overstory, and a diversity of overstory species may help to maintain adequate species diversity among understory species.

Growth Patterns of Perennial Grasses in the Annual Grassland Type of Southwest Oregon

AbstractSouthwest Oregon and northern California foothills are currently dominated by a variety of annual plant species. This study was designed to assess the potential of established perennial grasses to occupy two sites in the foothills ecosystem, Mediterranean/Maritime climatic regime, of southwest Oregon. Soils at Sites 1 and 2 are Darrow silty clay loam (fine, montmorillonitic, mesic Vertic Argixerolls) and Carney clay (fine, montmorillonitic, mesic Typic Chromoxererts), respectively, and annual precipitation at the sites averages 500 mm. Growth patterns of the perennial grasses were contrasted among each other and to the resident annual plants during fall, winter and spring growth periods. Of the perennial grasses, Idaho fescue (Festuca idahoensis Elmer), native to the area, and ‘Berber’ orchardgrass (Dactylis glomerata L.), introduced, most closely emulated the growth patterns of the resident annual grasses. These grasses initiated growth sooner, continued some growth through the winter and matured earlier than the other perennial grasses tested. Once established, Idaho fescue and Berber orchardgrass should be able to effectively compete with the resident annuals for resources and maintain their populations.

Sierra Foothill Range Field Station

The Sierra station, near Browns Valley in northern California, will be 30 years old this June:As can be seen from the air, the station's terrain is typical of much of California's foothill rangelands. Wooded, partially wooded, and cleared hills surround the headquarters and slope down to the Timbuctoo Bend of the Yuba River. The following eight reports indicate the variety of subjects covered by the research program at this center. (Cover photo by Charles Raguse)

Comparison of Actual and Predicted Blue Oak Age Structures

There is increasing interest in understanding the role of management on the current lack of blue oak (Quercus douglasii H. & A.) recruitment on California foothill rangelands. Age structure analysis has been suggested to relate when and how much recruitment occurred under past management as an indication of current management effects on recruitment. Previous estimates of blue oak age structure were based on unquantified correlations between age and diameter. Using regression analysis we found that diameter at breast height (DBH) accounted for 42-71% of the variation in tree age at 2 sites. Actual age structures were significantly different than age structures predicted from all regression equations at both sites. We suggest that the use of age structures to infer the role of management on blue oak population dynamics requires direct age measurement.

Conversion of Fertilized Annual Range Forage to Beef Cattle Liveweight Gain

AbstractA 3‐yr field experiment evaluated average daily (ADG) and total seasonal (LG) weight gains of growing beef cattle (Bos taurus) on fertilized California foothill annual range. Soils were a mixture of four series of alfisols. Nitrogen was applied alone at 45 or 90 kg ha−1, P and S were applied together at 34P 37S or 67P 74S kg ha−1, and the two N rates were combined with 34P 37S. Two 13.2‐ha replications were stocked with 215‐kg steers in late November, and stocking rates were increased twice during a grazing season averaging 190 d. Forage on offer (FL) varied from 400 to 2500 kg ha−1. Annual forage production (FP) varied from 2500 to 5700 kg ha−1 and differed (P<0.05) between treatments and years. Year‐to‐year and within‐year variations in rainfall influenced FP. Average daily gains over the season varied linearly from less than 0.2 to over 1.0 kg steer−1. Differences in ADG due to treatments were largely restricted to the first year and to treatments with N, P, and S or the higher level of PS, but 3‐yr trends were not significant. Average daily gain was not strongly influenced by either FL or legume content of the forage. Three‐year LG was highest for the two NPS and the higher PS treatment. Fertilization increased forage organic matter digestibility and N concentrations over the control. Results indicate that either N, P, and S or a sufficient level of P and S to stimulate production of legume N was required for high forage production.

The green mountain massive sulphide deposit. Besshi-style mineralization within the california foothills copper-zinc belt

The Green Mountain massive sulphide deposit is located 50 miles north-northwest of Fresno, California. It is hosted by metasedimentary rocks + mafic volcanics of the Jurassic age central block, Mariposa Formation, one of three volcano-sedimentary domains hosting numerous massive sulphide occurrences within the Foothills copperzinc belt of central California. The 4.0 million ton (3.64 M tonnes) deposit is sheet-like in form and enclosed within epiclastic rocks of probably continental basement and volcanic-arc derivation that have been tightly folded about a steeply plunging, overturned anticline. Adjacent Sierran plutonism has imparted amphibolite facies metamorphic grades. The predominant sulphide is pyrrhotite with lesser sphalerite and chalcopyrite. The deposit is uniformly zoned with respect to copper and zinc with a prominent, but narrow, zinc-rich fringe. A blanket-like body containing anthophyllite and cordierite (±spinel) forms the comparative rock chemistry suggest that this zone was derived from the original sedimentary host through strong sodium depletion and magnesium enrichment within a seafloor exhalative system. It is proposed that the Green Mountain deposit and other sulphide occurrences within the Mariposa Formation are in a rift-related, marginal basin setting and have similarities to both the Besshi and Guaymas-type exhalative sulphide/sulphate occurrences.

Comparative water relations of adjacent california shrub and grassland communities.

Much of the coastal mountains and foothills of central and southern California are covered by a mosaic of grassland, coastal sage scrub, and evergreen sclerophyllous shrubs (chaparral). In many cases, the borders between adjacent plant communities are stable. The cause of this stability is unknown. The purpose of our study was to examine the water use patterns of representative grasses, herbs, and shrubs across a grassland/chaparrel ecotone and determine the extent to which patterns of water use contribute to ecotone stability. In addition, we examined the effects of seed dispersal and animal herbivory. We found during spring months, when water was not limited, grassland species had a much higher leaf conductance to water vapor diffusion than chaparral plants. As the summer drought progressed, grassland species depleted available soil moisture first, bare zone plants second, and chaparral third, with one chaparral species (Quercus durata) showing no evidence of water stress. Soil moisture depletion patterns with depth and time corresponded to plant water status and root depth. Rabbit herbivory was highest in the chaparral and bare zone as indicated by high densities of rabbit pellets. Dispersal of grassland seeds into the chaparral and bare zone was low. Our results support the hypothesis that grassland species deplete soil moisture in the upper soil horizon early in the drought, preventing the establishment of chaparral seedlings or bare zone herbs. Also, grassland plants are prevented from invading the chaparral because of low seed dispersability and high animal herbivory in these regions.

Fossil Plethodontid Salamanders from the Latest Miocene of California

Two salamanders, Aneides lugubris, and Batrachoseps sp., are reported from the latest Miocene (Hemphillian) upper Mehrten Formation of the western Sierra Nevada foothills of California. A record of Batrachoseps sp. is also reported here from the Pinole Tuff of the same age in the San Francisco Bay area of California. These are the second Tertiary records of plethodontid remains and the first from west of the Rocky Mountains. The minimum age of Aneides lugubris, and the Sierra Nevada population in particular, is established at approximately five million years. This is consistent with the estimated longevity of this species based on biochemical evidence and modifies a previous biogeographic speculation. Prior to Peabody's (1959) description of late Miocene trackways of Batracho- seps from near Columbia, California, the fossil record of plethodontid salaman- ders did not extend earlier than the Pleistocene. Since then there has been only one unquestionable plethodontid record from rocks older than the Pleis- tocene-four vertebrae from the early

A Case Study in Faunalturbation: Delineating the Effects of the Burrowing Pocket Gopher on the Distribution of Archaeological Materials

Excavation of a small single-component prehistoric campsite in the coastal southern California foothills has provided evidence concerning the patterns and approximate rates of redistribution of archaeological materials caused by the burrowing pocket gopher, Thomomys bottae. Investigation of bimodal vertical distributions of both historic and prehistoric archaeological materials shows a close correspondence to the burrowing habits of pocket gophers in coastal California. Comparison of these bimodal distributions with a site chronology based upon diagnostic artifacts and C-14 dating suggests that, under certain soil conditions, downward displacement of archaeological materials may occur at rates averaging over 5% per century. The broader implications of the effects of faunalturbation upon the interpretation of archaeological assemblages are briefly discussed.

Lichens of the San Joaquin Experimental Range, California

A preliminary checklist of lichens from the interior foothills of central California includes 76 species. Three seldom-collected species--Rhizoplaca marginalis, R. glaucophana and Peltula zahlbruckneri--are among the taxa listed. Although there have been a number of reports in the literature of lichens from Yosemite Valley (Tuckerman 1882, 1884; Hasse 1913), and the con- tiguous Sierra Nevada (Tuckerman 1866, 1872), few lichen collections from the foothills of the Sierra have been mentioned. Herre's (1945) study of Cal- ifornia lichens listed only low elevation (85 m) species for central California; and Herre's (1946) review of California Parmelia spp. showed few rec-

Deep intraplate seismicity in the western Sierra Nevada, central California

abstract A microearthquake monitoring program was conducted from 1976 to 1979 in the eastern San Joaquin Valley and Sierran foothills of central California. This program revealed one of the deepest occurrences of intraplate earthquakes observed in the conterminous United States. Earthquakes in the M L range of approximately 0 to 3.2 were confined to the lower crust of the Sierran block at depths from 12 to 38 km. The distribution of epicenters was diffuse and widespread with some clustering in space and time. Two particulary active areas that were consistent with the historical seismicity record were recognized: an area 15 km south of the town of Madera and an area 15 km south of Mariposa. No association of the seismicity with faults or other geologic structures expressed at the surface was apparent. Based on regional seismic monitoring by the U.S. Geological Survey and the detailed monitoring performed in this study, this occurrence of deep seismicity does not appear to extend farther north along the foothills than Jamestown, although two deep events have been observed near Oroville. The southern limit is not as well defined due to the lack of seismographic coverage. Focal mechanisms of these deep crustal earthquakes exhibited: (1) strike-slip faulting combined with some reverse and normal components; and (2) a regional tectonic stress field characterized by a maximum compressive stress generally trending north-south and a minimum compressive stress trending east-west. These observations support the view that (1) the Sierra Nevada represents a transition between a region of primarily shear deformation along the San Andreas fault zone and extensional tectonics of the Basin and Range province; and (2) the orientation of the tectonic stress field is generally uniform throughout the crust of the Sierran block.

Comparisons of Factors Affecting Preimaginal Production of Culiseta inornata (Williston) (Diptera: Culicidae) in Two Different Habitats of Central California

Preimaginal production of Culiseta inornata (Williston) was investigated in temporary fall-flooded breeding sources in the Suisun Marsh and Sierra Nevada foothills of central California. Sources sampled on Suisun Marsh supported significantly more abundant populations of mosquitoes and phytoplankton and associated macroinvertebrates, and fewer predators. Suisun Marsh sources were also characterized by having low dominant taxon diversity. Foothill sources supported fewer mosquitoes, but were trophically more diversified, less productive, and contained a significantly higher number of predator taxa. First-instar larvae of C. inornata comprised a significantly high proportion of the preimaginal population in foothill sources, few of which apparently survive to later instars. Experiments with larvae of C. inornata confined in screened buckets demonstrated that shorter development time and increased survival occurred in one source sampled on Suisun Marsh. Both C. inornata and Culex tarsalis Coquillett exhibited classical resurgence after the dredging of one source in the Sierra Nevada foothills.

The effects of different pasture and rangeland ecosystems on the annual dynamics of insects in cattle droppings

A 2-yr study (1971-73) in the Sierra Nevada foothills of California consisted of: 1) a quantitative analysis of the differences in diversity and abundance of the insect fauna colonizing and inhabiting diurnally and nocturnally excreted cattle droppings in four different pasture and rangeland ecosystems (natural woodland range, partially cleared woodland range, totally cleared woodland range, cultivated irrigated pasture); and 2) a study of the relationship between the diversity and abundance of insect inhabitants per cowpat and the rate of pat degradation. The fauna consisted of three orders of insects containing 26 families and 102 species. There were 35 to 40 different kinds of Coleoptera, 50 of Diptera, and 12 of Hymenoptera, recorded from samples. Differences per pat in the mean number of species, number of individuals, and insect biomass among pastures, months, and years for the major taxa were analyzed and discussed. The pasture ecosystem and the season were most important in determining the diversity and abundance of insects colonizing droppings. Major differences among pastures in the number of individuals and species per pat were mainly due to a combination of interacting loco-and microclimatological factors associated with the environment of the different pastures. Most species of dung insects did not colonize pats dropped during the night. The most important insect species influencing biomass per pat was the scarab, Aphodius fimetarius (L.). The importance of considering species, individuals, and biomass in attempting to understand changes in community structure and function was demonstrated.

Growth of Subterranean Clover in a Range Soil as Affected by Microclimate and Phosphorus Availability. I. Field Studies1

AbstractRelationships between microenvironment and phosphorus availability are important to stand establishment and winter growth of introduced annual legumes in California's foothill rangelands.Ridge, furrow, north‐facing, and south‐facing microsites were established to create variations in light and temperature microenvironments in previously tilled soils of the Sobrante and Las Posas series. An additional microsite treatment, consisting of a simulated range drill seeding, with and without a litter cover, was made on adjacent untilled soil. Phosphorus rates, applied as single superphosphate, were 0, 40, 80, and 160 kg P/ha.Pellet‐inoculated seeds of subterranean clover (Trifolium subterranean L.) were sown in rows 15 cm apart perpendicular to the microsite ridges, slopes, and furrows.Soil (1 cm) and air (3 cm above soil) temperatures were monitored hourly with thermistors.Plant sampling was done at four times from November to March to determine morphological development, plant weight, and percent P per plant. At maturity, remaining plants were sampled to estimate seed production.Large diurnal temperature differences were associated with microsite treatments and were more pronounced for soil than for air.Percent P in shoot tissue generally reached highest values in January, indicating that plant growth was restricted more during winter than was P uptake. With warmer temperatures and higher light intensities in February, growth dilution resulted in a decrease in P percentage. Small modifications of microrelief significantly altered the microenvironment, especially soil temperature. Morphological development and plant weight responses were greatest on south‐facing slopes and at the highest P level. Seed production was not influenced by P fertilization.

DIVERSIFICATION AND SECONDARY INTERGRADATION OF TWO CHRYSOPA CARNEA STRAINS (NEUROPTERA: CHRYSOPIDAE)

AbstractAnalysis of larval and adult characters, as well as biological data from various geographic populations, indicates that Chrysopa mohave Banks and Chrysopa carnea Stephens represent two strains of a single species and C. mohave is therefore designated a new synonym of C. carnea. The carnea strain occurs allopatrically throughout eastern and midwestern North America and the mohave strain is probably indigenous to California.The pattern of variation found in larvae and adults from different populations suggests that the carnea strain was secondarily introduced into California where it interbred with the mohave strain. This hybridization resulted in genetically varied populations with predominantly carnea characteristics in California’s Central Valley. Populations of the mohave strain occur in the California foothill and coastal areas because adults of the mohave strain, unlike the carnea strain, can aestivate during the hot, dry summers when food is sparse. Summer irrigation increases the abundance of larval and adult food which the non-aestivating carnea strain needs. It appears that the native mohave strain will compete successfully only in those areas of California which are unmodified by agricultural practices.

Ecology, Morphology, and Systematics of Jepsonia (Saxifragaceae)

Aspects of flowering, leaf production, caudex and contractile root morphology, edaphic preferences, and systematics ofJepsonia (Saxifragaceae) are discussed. Although other authors have recognized as few as one species ofJepsonia, various lines of evidence suggest that three allopatric species can be recognized, which are morphologically distinct and separated from each other by barriers to hybridization. These species areJ. heterandra of the Sierra Nevada foothills of California,J. malvifolia of southern California’s offshore islands and the Mexican Guadalupe Island, andJ. parryi of mainland southern California and adjacent Baja California. Plants flower from late summer to early winter in response to environmental factors that have yet to be clearly identified. Flowers are heterostylous, and the species are self-incompatible. Pollination is by syrphid flies and halictid bees. Leaves are produced during or after flowering in response to rain. They persist through the winter until the onset of the dry season in the subsequent late spring. Plants perennate by a starchy underground structure, which is hypocotylar in origin and best termed a caudex. Young plants and many old ones also produce one or more very large, whitish, starch-free contractile roots that are annual in duration.Jepsonia heterandra characteristically is restricted to the crevices of slatelike rocks, although the other two species occur in a wider range of edaphic situations. Moisture and temperature conditions, as well as rodent predations, may determine the general and local distribution of the species. The relationships of the genus are briefly considered, and interspecific differences are described.

Annual hydrologic response to watershed conversion from oak woodland to annual grassland

A 12‐acre experimental watershed in the Sierra Nevada foothills of central California has been subjected to intensive range management practices after a six‐year calibration. The treatment consisted of chemically killing a dense stand of oak trees and brush to improve forage production. An adjacent untreated watershed, which is geologically and hydrologically similar, provides a means of evaluating the annual hydrologie response. Streamflow comparison shows an average annual increase of 4.5 inches in water yield. Inflow‐outflow analysis shows a corresponding decrease in consumptive use from an average of 20 inches per year to 15 inches per year. The change in consumptive use is demonstrated in an annual water yield prediction model and in the relationship of consumptive use to precipitation. Estimates of annual potential evapotranspiration from climatological data are higher than measured consumptive use. Two methods for predicting annual consumptive use show close agreement with measured values for both the oak woodland and the annual grassland.

Meditteranean Ecosystems and Vegetation Types in California and Israel

A comparison of climate, soils, vegetation, and biotic history of mediterranean ecosytems revealed closest ecological equivalence between the blue oak grassland in California and the vallonea oak grassland in Israel, both mediterranean oak savannas in which overall environmental resemblance seems closest. Ecological amplitude and syndynamics in most other comparable types are similar, but the chamise chaparral on non—calcic brown upland and lithosols differs from its maqui counterpart by its adverse influence on the ecosystem. Annual grasslands in California foothills are comparable to seral batha dwarfshrub and grassland in Israel as human—induced degradation stages of chaparral and maqui. For such ecological comparisons a holistic ecosystem approach seems more suitable than any preconceived phytoclimatic and climax concepts.

The Selective Origin of Incompatibility Barriers in the Plant Genus Gilia

Nine species of annual Gilias in Pacific North America and South America, belonging to the same section of the genus-the Leafy-stemmed Gilias, fall into two classes with regard to geographical distribution. Five species in the California foothills and valleys are sympatric. Four maritime species on the coasts of North and South America are completely allopatric in relation to one another and either completely or mainly allopatric in relation to the foothill-and-valley species. The sympatric foothill species are isolated from one another by very strong incompatibility barriers, forming an average of 0.2 hybrid seeds per flower pollinated in interspecific crosses, whereas the allopatric maritime species can be crossed inter se with the greatest of ease, forming an average of 18.1 hybrid seeds per flower. A somewhat similar geographical distribution pattern of crossing barriers is found in another branch of the genus, the Cobwebby Gilias, which occur in western North America and are also annual herbs. The sympatric species from the central part of the distribution area of this group yield an average of 3.4 hybrid seeds per flower in interspecific crosses. By comparison, crosses between central and peripheral species yield an average of 7.6 hybrid seeds per flower. The species hybrids are highly sterile in all combinations in the two groups of annual Gilias. The formation of such sterile hybrids represents a loss of reproductive potential on the part of their seed parents in the parental species population, a loss which must be especially disadvantageous in short-lived annuals. The inverse correlation between interspecific geographical and crossing relationships provides critical evidence in the case of the Leafy-stemmed Gilias, and supporting evidence in the case of the Cobwebby Gilias, for the hypothesis of a selective origin of hybridization-preventing mechanisms in annual plants under conditions of sympatry. It is proposed to name the process of selection for reproductive isolation the Wallace effect.

A New Species of Fremontodendron (Sterculiaceae) from the Sierra Nevada Foothills, California

The discovery of a new species of Fremontodendron i the Sierra foothills of California is of special interest, as the species of this genus are few in number and restricted in distribution. Specimens were first collected in 1956 by Beecher Crampton (Crampton 3524, UC) who noted on the label that the plant was a "sprawling semi-prostrate shrub" with a striking red-orange to reddish yellow flower.