Research
Publications


Management and Physiology of Hardwood Rangelands
Project:
 Environmental effects of land use and intensive range management: a Northern California example
Project Leader:
Albin-Smith, T.K., and C.A. Raguse
Summary:
 1984. Univ. of Calif. Calif. Water Res. Center, Contr. no.187: p. 33.
This paper presents criteria for assessing and mitigating environmental impacts of manipulating foothill rangeland to improve its capacity for livestock grazing. Environmental setting information provides the basis for impact analysis: baseline soil and vegetation types, hydrology, habitat, and land use history of the foothill environment was assessed for sensitivity to range improvements and land use; including vegetation-type conversion, facilities construction, grazing, and irrigation.

Project:
 Mineralogy and weathering processes in basic metavolcanic "greenstone" in the Sierra Foothill region of Northern California
Project Leader:
Allardice, W.R., R.A. Dahlgren, and M.J. Singer
Summary:
 1990. Amer. Soc. Agron. Annual Meet., San Antonio, TX (Abstr.) 1990 Div. S-9: p. 459.
Weathering processes were examined in Typic Haploxeralfs formed in upper Jurassic basic metavolcanic greenstone. The objective of our study was to examine the role of weathering processes and soil mineralogy as it pertains to nutrient cycling. Results indicate a weathering sequence of primary chlorite --> vermiculite-chlorite intergrade --> vermiculite and smectite. In the upper soil horizons, the vermiculite appears to be transformed to mica by K enrichment associated with biocycling. In contrast, in the lower portion of the profile where K levels are low, vermiculite weathers to smectite.

Project:
 Resampling VTM plots in blue oak cover type series
Project Leader:
Allen-Diaz, B.H., and B.A. Holzman
Summary:
 1993. Report for Forest and Rangeland Resources Assessment Program (FRRAP), Calif.Dept.of Forestry and Fire Protection, July 1993. p. 70.
Understanding recent change within the blue oak woodlands is the focus of this study. The transitional cover types such as Blue oak-Foothill pine/Grass and Blue oak/Buck brush/Grass persist on the landscape due to continuous changes in blue oak communities through time as well as in response to human disturbances such as harvesting and fire suppression. Grazing did not appear to significantly affect overstory vegetation change. Although it is the ecological changes that were of most interest in this study, it is the cultural impacts that will significantly determine the future of the blue oak woodlands in California. Ref.123\62.30.

Project:
 Determining forage diet quality by analyzing fecal matter with near infrared spectroscopy
Project Leader:
Barry, S.
Summary:
 1996. Proc., UC Sierra Foothill REC Beef and Range Field Day. pp. 27-30.
A relatively new technique developed by the Department of Range Ecology at Texas A&M University can quickly determine the nutritional status of cattle grazing rangeland or pasture. Cattle manure is analyzed using near infrared reflectance spectroscopy (NIRS). Manure samples have been collected from ranches throughout the Sacramento Valley and Sierra Foothill, etc. and analyzed using the NIRS process. Ref.278\64.14. .

Project:
 The effect of the application and subsequent removal of ammonium nitrate on the growth and nitrogen-fixing capability of subterranean clover (Trifolium subterraneum L.)
Project Leader:
Boursier, P.J.
Summary:
 1979. Thesis, Univ. of Calif., Davis Master of Science: pp. 1-16.
The review of the literature reveals considerable variation in recommendations involving the use of nitrogen fertilizer during the establishment of forage legumes. This study was performed to investigate the effects of the application of NH4NO3 and its subsequent removal upon the growth and nitrogen fixation of subterranean clover plants. The experiment was performed twice during different times of the year to determine the effects of variation in total sunlight received. Determinations were made at various times during the experiments for total dry weight, apparent nitrogen fixation, leaf area and reduced nitrogen concentration. Detailed measurements of total daily light intensity were maintained during each experiment.

Project:
 Growth and nitrogen-fixing responses of subterranean clover to application and subsequent removal of ammonium nitrate
Project Leader:
Boursier, P.J., C.A. Raguse, and K.L. Taggard
Summary:
 1989. Crop Sci. 29: pp. 758-763.
Considerable variation exists in recommendations for the use of N during establishment of forage legumes. Abundant literature documents the inhibition of N2 fixation by applied N, but few experiments determined the consequences of its subsequent removal. In this study the effects of NH4NO3 on the growth and N2 fixation of subterranean clover were investigated. The results suggest that low to moderate levels of N can be applied to an annual range community containing subterranean clover to attain specific fall-winter growth objectives without the risk of suppressing peak (spring) N2 fixation.

Project:
 Effects of seed aggregation, nutrient availability, and temperature on germination of subterranean clover (Trifolium subterraneum L.)
Project Leader:
Caminos, J., C.A. Raguse, and D.C. Sumner
Summary:
 1973. Agronomy J. 65: pp. 1002-1003.
Germination percentage was increased and emergence was accelerated when two or more subterranean clover seeds were planted in close physical proximity instead of singly. The effect was enhanced when nutrient solution was supplied. The influence of close seed spacing and improved nutrient availability were more pronounced at cool temperatures, they therefore could be of importance to stand establishment from new seedings in the California annual range when rainfall adequate to permit germination occurs later than normal.

Project:
 Livestock grazing and riparian habitat water quality: An examination of oak woodland springs in the Sierra foothills of California
Project Leader:
Campbell, C.G., and B.H. Allen-Diaz
Summary:
 Proc., Symp. on Oak Woodlands: Ecology, Management, and Urban Interface Issues. San Luis Obispo, CA., Mar 19-22, 1996.
Studies have suggested that livestock degrade riparian vegetation and stream channels, produce sediment, pathogen, and nutrient loading as pollutants which may result from grazing on or near streams. This study shows that moderate livestock grazing intensities do not detrimentally affect water quality at springs or ephemeral creeks in the oak woodland of California. Ref.253\64.01.

Project:
 Biogeochemistry in oak woodlands of the Sierra foothills
Project Leader:
Dahlgren, R., and M. Singer
Summary:
 1993. Proc., UC Sierra Foothill REC Beef and Range Field Day: pp. 29-30.
Our study has focused on nutrient cycling; the movement of nutrients in, out of, and within the ecosystem. The flow of nutrients through the oak woodland ecosystem has been studied for a four year period in the Schubert Watershed. Fluxes of nutrients in ecosystem waterflows (precipitation, canopy throughfall, soil solutions and stream water), plant uptake, and litterfall were monitored. These latter projects have demonstrated that oaks can be successfully established on hardwood rangelands if sufficient care is taken to plant, protect, and maintain them.

Project:
 Nutrient Cycling in Managed and Unmanaged Oak Woodland-Grass Ecosystems
Project Leader:
Dahlgren, R., and M.J. Singer
Summary:
 1991. Proc., Symp. on Oak Woodlands and Hardwoods Rangeland Mgmt., USFS Tech. Rep. PSW-126: pp. 337-341.
The influence of oak trees and grazing on nutrient cycling in oak woodland-grass ecosystems was examined at the Sierra Foothill Range Field Station in the northern-Sierra Nevada foothills of California. Nutrient concentrations in ecosystem waterflows (precipitation, canopy throughfall, and soil solutions) were monitored in a non-managed natural area and in an adjacent grazed area. Grazing increased soil solution concentrations of chloride and sodium, but had no effect on major nutrient levels. When comparing between oak and non-oak sites, the oak sites had enhanced soil solution concentrations and decreased levels of sodium.

Project:
 Nutrient Cycling in Managed and Non-Managed Oak Woodland-Grass Ecosystems
Project Leader:
Dahlgren, R., and M.J. Singer
Summary:
 1994. Rep. to Integrated Hardwood Range Management Program. LAWR Paper #100028.: p. 91.
This research project examining oak woodland nutrient cycling shows that oak trees play a major role in maintaining the nutrient status of these ecosystems. Each year, a typical blue oak will return approximately 1, 0.1, 2, and 0.8 kg of nitrogen, phosphorus, calcium and potassium, respectively, to the soil surface in the form of litterfall (e.g. leaves, twigs and acorns) and canopy throughfall (canopy leaching). While these values may appear low, multiplying by all the oak trees in a watershed results in very large quantities of nutrients.

Project:
 Nutrient cycling in grazed and ungrazed oak woodland rangelands
Project Leader:
Dahlgren, R., and M.J. Singer
Summary:
 1995. Proc., UC Sierra Foothill REC Beef and Range Field Day: pp. 27-33.
Oak trees play a critical role in sustaining ecosystem productivity through their role in cycling nutrients to the soil surface, preventing nutrient leaching losses, increasing water infiltration, and attenuating water erosion and stream sediment concentrations. Moderate intensity grazing does not appear to have any serious detrimental effects on nutrient cycling in these oak woodland ecosystems. Oak tree removal will lead to a significant loss of nutrients from these ecosystems leading to a long-term decrease in ecosystem productivity. Careful removal of oaks does not significantly change stream flow patterns or amounts.

Project:
 Direct extraction of microbial biomass nitrogen from forest and grassland soils of California
Project Leader:
Davidson, E.A., J.F. Eckart, S.C. Hart, and M.K. Firestone
Summary:
 1989. Soil Biol. Biochem. 21: pp. 773-778.
The direct extraction method for estimating microbial biomass-N, which involves chloroform fumigation and extraction without an incubation step, affords the opportunuty to analyze soils for which the incubation step is problematic. We tested the direct extraction method on freshly sampled grassland and forest soils of California, which experience seasonal wetting and drying cycles and labile substrate inputs. Ref.295\64.31.

Project:
 Measurement of nitrous oxide dissolved in soil solution
Project Leader:
Davidson, E.A., and M.K. Firestone
Summary:
 1988. Soil Sci. Soc. Am. J 52: pp. 1201-1203.
Degassing of soil solution as soil water enters springs and streams may be a significant pathway of N2O release into the atmosphere. A simple method is presented to sample soil solution to include gases dissolved in solution. Small porous cup lysimeters connected to narrow diameter nylon tubing were flushed with N2 gas; a vacuum was applied with an evacuated serum bottle; and solution and gases were captured in the bottle. Concentrations of N2O in soil solution of a grassland in central California varied from below ambient to 13 times ambient. At a wet riparian zone site, N2O in soil solution appeared to be related to NO3- concentration, which can be determined from the same soil solution sample. Ref.301\64.37.

Project:
 Cattle grazing and oak trees as factors affecting soil emissions of nitric oxide from an annual grassland
Project Leader:
Davidson, E.A., D.J. Herman, A. Schuster, and M.K. Firestone
Summary:
 1993. ASA Special Publication 55: pp. 109-119.
Range management decisions are driven largely by considerations of animal productivity and land-use regulations, but range management may also impact exchange of trace gases between the biosphere and the atmosphere. The first objective of this work is to determine the effects of grazing and vegetation cover on NO emissions at a study site in the central valley of California. The second objective is to investigate the mechanisms which may explain differences in NO fluxes between grazed and ungrazed plots, between plots under oak canopies and plots in open grassy areas, and between wet and dry seasons. Ref.299\64.35.

Project:
 Microbial production and consumption of nitrate in an annual grassland
Project Leader:
Davidson, E.A., J. Stark, and M.K. Firestone
Summary:
 1990. Ecology 7(5): pp. 1968-1975.
Gross nitrification rates ranged from 12 to 46% of gross mineralization rates during the growing season of annual grasses. Microbial assimilation of NO3- occured at rates similar to previous estimates of plant uptake. Hence two common assumptions, that nitrifying bacteria are poor competitors for NH4+ and that microbial immobilization of NO3- is insignificant, are not correct for this grassland system. Spatial compartmentalization of sites of production and consmption of inorganic-N, along with diffusional constraints among such microsites, appear to be critical factors affecting N-cycling characteristics of the ecosystem. Ref.296\64.32.

Project:
 Effects of diurnal variation in light and temperature on the acetylene reduction activity (nitrogren fixation) of subterranean clover
Project Leader:
Eckart, J.F., and C.A. Raguse
Summary:
 1980. Agronomy J. 72(3): pp. 519-523.
Singly, or in combination, both light intensity or temperature can limit symbiotic N fixation. The present study determined N fixation response to variation in both light and temperature for an annual range legume which, during its normal growing season, may be subject to growth limiting levels of both environmental factors. The results show that diurnal changes in acetylene reduction by subterranean clover result more from fluctuations in temperature than from diurnal changes in light and suggest that N2 fixation by root nodules of this species is buffered against shortterm changes in photosynthate supply.

Project:
 Teamwork on the range
Project Leader:
Ellis, K.W.
Summary:
 1980. Proc., UC Sierra Foothill Range Field Station Beef and Range Field Day: pp. 53-55.
This outline describes the network of departments and people involved in the range livestock programs in Extension. The staff, both specialists and advisors, must continue to work with state and federal agencies who control the decision-making processes connected with these agencies now and in the future as a resource for decision making so that the best multiple use plans can be developed and prevail. Most of all, we must and will continue the close cooperation with those who own, operate, and stock California's rangeland in order to maintain the team effort that has proved beneficial and fruitful.

Project:
 Microenvironment of a dynamic annual community in relation to range improvement
Project Leader:
Evans, R.A., B.L. Kay, and J.A. Young
Summary:
 1975. Hilgardia 43: pp. 79-102.
Syntheses of microenvironments based on monitoring are needed for understanding complex phenomena of an ecosystem and for establishing benchmark or standard regimes of temperature, light, and soil moisture for laboratory experiments involving seed germination, seedling growth, and other plant responses. These studies, in turn, answer questions about the dynamics of a plant community. The microenvironment was monitored and vegetation was intensively sampled to interpret complex responses of an annual rangeland community to chemical weed control and reseeding.

Project:
 Influence of date of planting on emergence of cultivars of Trifolium hirtum All. and T. subterraneum L.
Project Leader:
Evans, R.A., B.L. Kay, and J.A. Young
Summary:
 1976. J. Range Manage. 29: pp. 333-337.
Emergence by seven cultivars of rose clover and eight cultivars of subclover was studied in relation to date of planting. Numerous planting dates were used for three growing seasons. Temperature in the seedbed was monitored hourly. The seeded clovers all germinated at the time of the first effective rains. Where seeds were exposed to high soil temperatures, early fall planting generally reduced seedling emergence in cultivars of rose clover, but enhanced or did not affect emergence in subclover. In 2 of the 3 years, seeding after the first rain gave significantly lower emergence. Maximum seedbed temperatures below 10C allowed only very limited emergence.

Project:
 Germination of winter annual species from a rangeland community treated with paraquat
Project Leader:
Evans, R.A., J.A. Young, and B.L. Kay
Summary:
 1974. Weed Sci. 22: pp. 185-187.
Three annual plant species, erect plantain, common chickweed, and silver hairgrass are commonly found and may dominate a unique flora on areas sprayed with paraquat (1,1'-dimethyl-4,4'-bipyridinium ion) in cismontane rangelands of California. The basis of this phenomenon is shown to be temperature-related germination requirements, novel seed characteristics, and lack of competition. Weed control-revegetation systems that use paraquat in establishing forage species on rangelands have been developed for arid Intermountain areas of the West and for areas of the Mediterranean climate in cismontane California.

Project:
 Nutrient cycling in managed oak woodland-grass ecosystem
Project Leader:
Firestone, M.K., L.J. Halverson, and D.J. Herman
Summary:
 1995. Integrated Hardwood Range Management Program Oct(2): p. 56.
Covering an estimated 3 million hectares statewide, hardwood rangelands support diverse uses in California. These rangelands are used extensively as cattle pasture, so management practices implemented in the interest of cattle production widely affect all users. It is therefore in the interest of all users that an understanding be developed as to how various management practices affect ecosystem sustainability. One aspect of the long-term productivity of these systems is the cycling of nutrients among soil, flora, and fauna. This study investigates the effects of managing this land for cattle production on ecosystem nutrient cycling.

Project:
 Dynamics of nitrogen transformations in a California annual grassland: II. Microbial processes
Project Leader:
Firestone, M.K., L.E. Jackson, R.B. Strauss, and E.A. Paul
Summary:
 1985. Amer. Soc. Agron. Annual Meet. (Abstr.) 1985 43: pp. 155-156.
Competition for 15N-NH+4 and NO-3 was quantified in open grassland field cylinders over 24 h periods. During the period of most active plant N uptake, static NO-3 pools were not detectable and field rates of nitrification (by pool dilution assay) could supply about 1/3 of the plant N uptake. During this period of apparent competition for NO-3, denitrification was detectable in field soil only when plants were removed. Uptake of NH+4 by microbial biomass was about 4 times that of plant uptake.

Project:
 Understory - canopy relationships in oak woodlands and savannas
Project Leader:
Frost, W.E., J.W. Bartolome, and J.M. Connor
Summary:
 Proc., Symp. on Oak Woodlands: Ecology, Management, and Urban Interface Issues. San Luis Obispo, CA., Mar 19-22, 1996.
We summarize available information about the relationships between oak overstory and understory plants. Understory biomass productivity and plant species composition vary considerably in California's oak woodlands and savannas. Factors discussed include geographic location, overstory species composition, overstory density and distribution, and animal utilization. Management implications are summarized for different woodland types around the state. Ref.256\64.01.

Project:
 Grazing and Land Management Strategies for Hardwood Rangelands
Project Leader:
George, M.R.
Summary:
 1991. Proc., Symp. on Oak Woodlands and Hardwoods Rangeland Mgmt., USFS Tech. Rep. PSW-126: pp. 315-319.
Annual rangelands produce 84 percent of California's range forage which are used all year by sedentary ranching operations and seasonally by migratory operations. Environmental policy, energy and water costs may reduce traditional summer forage sources, resulting in increased grazing pressure on hardwood and annual rangelands. However, the landowner's production goals and society's environmental quality goals can still be attained by subdividing the ranch into management units based on the land's productive potential and resource value and by intensifying grazing management.

Project:
 Application of nonequilibrium ecology to management of Mediterranean grasslands
Project Leader:
George, M.R., J.R. Brown, and W.J. Clawson
Summary:
 1992. J. Range Manage. 45: pp. 436-440.
The state and transition model and the ball and cup analogy are used to organize the vegetation dynamics knowledge base for California's annual-dominated Mediterranean grasslands. These models help identify irreversible transitions and alternate stable states. Mechanisms that facilitate movement between successional stable states are categorized as demographic inertia, seedbank and germination, grazing impacts, establishment and competition, fire feedback, and irreversible changes in soil conditions.

Project:
 Correlation of degree-days with annual herbage yields and livestock gains
Project Leader:
George, M.R., C.A. Raguse, W.J. Clawson, C.B. Wilson, R.L. Willoughby, N.K. McDougald, D.A. Duncan, and A.H. Murphy
Summary:
 1988. J. Range Manage. 41: pp. 193-197.
On California's winter annual rangelands precipitation controls the beginning and end of the growing season while temperature largely controls seasonal growth rates within the growing season. Post-germination accumulated degree-days (ADD) account for the length of the growing season and variation of daily temperature. Simple correlations of ADD and herbage yield or resultant livestock gains were determined at 5 locations in annual type range in northern California. Degree day values were determined by summing daily degree-days from the beginning of the growing season after germinating rainfall until the clipping or weigh dates.

Project:
 Grazing compatible with blue oak regeneration
Project Leader:
George, M.R., and L.M. Hall
Summary:
 1991. Report for Forest and Rangeland Resources Assessment Program (FRRAP), Calif. Dept. of Forestry and Fire Protection, August 1991. p. 32.
Cattle have been implicated as a principal cause for poor oak regeneration in California's hardwood rangelands. The effects of stock density and season of grazing was evaluated on blue oak establishment. Seven hundred and twenty blue oak seedlings were planted on ten-foot centers in thirty plots in three annual grassland pastures at the Sierra Field Station. Steers were allowed to graze one plot per week at low, medium, and high stock densities during the months of January, April and July of 1990. It is clear that cattle damage to oak seedlings varies tremendously depending on season of grazing and, to a lesser degree, stock density. Ref.39\60.17.

Project:
 Computerized pasture inventory program
Project Leader:
George, M.R., L. Lasarow, and J. Clawson
Summary:
 1985. Proc., UC Sierra Foothill Range Field Station Beef and Range Field Day. pp. 13-16.
Many ranchers keep animal or herd performance records but do not keep pasture performance records. The pasture inventory program was developed to provide ranchers with an easy method of keeping pasture records. It includes a tutorial which introduces the concepts of pasture inventory and shows step by step how to use the program. The program is currently being tested at the Sierra Foothill Range Field Station. Newer versions will be documented and released as they are developed to meet the needs of the ranching community. Ref.209\63.20.

Project:
 Control of decomposition processes and nutrient flow in a California forest and grassland
Project Leader:
Hart, S.C.
Summary:
 1991. Ph.D. Thesis, University of California, Berkeley. 226 pages.
This dissertation work focused on two major factors that potentially control decomposition processes and nitrogen release from plant detritus in forests and annual grasslands with Mediterranean-type climates: substrate quality (degradability) and spatial compartmentalization of available carbon and N within the soil profile. Despite a low initial quantity of Pinus ponderosa needle litterfall in an old- compared to a nearby young-growth mixed-conifer forest, no difference in decomposition rates was found between litter types when incubated in either stand. The extremely low rates of decomposition in these forests appear to be due to the combined effects of low quality litter and seasonal displacement of warm temperatures from moist conditions in Mediterranean-type climates. Ref.293\64.29.

Project:
 Flow and fate of soil nitrogen in an annual grassland and a young mixed-conifer forest
Project Leader:
Hart, S.C., M.K. Firestone, E.A. Paul, and J.L. Smith
Summary:
 1993. Soil Biol. Biochem. 25: pp. 431-442.
A comparative study of N dynamics in an annual grassland and a young mixed-conifer forest, that occur on the same soil great group in California, was made by adding small amounts of 15NH4+ to mineral soils within field microplots and following changes in 15N recoveries in soil and plant pools over 12-16 months. Total 15N recovery was only about 54% 6 months after 15N addition, indicating a high potential for rapid N loss from the surface soil of this forest. Comparision of net changes in litter N and accmulation of 15N during decomposition suggests that N was mineralized from litter concurrently as N was immobilzed from the mineral soil in both sites. Ref.298\64.34.

Project:
 Patterns of growth and soil-water utilization in some exotic annuals and native perennial bunchgrasses of California
Project Leader:
Holmes, T.H., and K.J. Rice
Summary:
 1996. Annals of Botany Company 78: pp. 233-243.
We compared exotic cool-season annuals and native perennial bunchgrasses in terms of growth, biomass allocation, rooting distribution, root morphology, and soil water utilization. Exotic cool-season annuals completed their life cycle early in the dry season through rapid growth apparently made possible by a high proportional allocation to shoots in combination with the efficient production of roots of high specific root length. Further, annuals tended to concentrate root growth and soil water utilization in the upper soil profile. In contrast, native perennial bunchgrasses allocated a high proportionof their biomass to the production of a deep root system, which allowed them to continue soil-water utilization well into the dry season and contribute to the formation of a very dry soil profile. Taken together, these contrasting patterns suggest that the invasion of exotic cool-season annuals might have produced a corresponding increase in the amount of water present at depth in the soil profile during the dry season. Ref307/64.44.

Project:
 Dynamics of nitrogen transformations in a Californian annual grassland: I. Plant uptake and transfers
Project Leader:
Jackson, L.E., M.K. Firestone, J.P. Schimel, and J.W. Bartolome
Summary:
 1985. Amer. Soc. Agron. Ann. Meet. 1985 (Abstr.): p. 157.
Uptake of N by annual plants in a natural grassland was greatest in early spring when soil moisture was high. At this time, litter, especially detrital roots, was decomposing at maximum rates (50 kg dry weight/ha/day). Plants took up approximately 1/10 of the NH+4 pool. A similar experiment later in the spring indicated that low soil moisture changed rates of plant uptake of NO-3 and NH+4.

Project:
 Short-term partitioning of ammonium and nitrate between plants and microbes in an annual grassland
Project Leader:
Jackson, L.E., J.P. Schimel, and M.K. Firestone
Summary:
 1989. Soil Biol. Biochem. 21: pp. 409-415.
We measured short term partitioning of 15NH4+ and 15NO3- into plants and microbes in a California annual grassland. High rates of microbial NO3- uptake may have resulted from the occurrence of microsites that were depleted in NH4+. Even though plants competed better for NO3- than for NH4+, microbial uptake was a major factor controlling NO3- availability to plants. The high rates of NH4+ and NO3- uptake by plants and microbes clearly demonstrate that the soil N pool bears little relationship to actual N availability. Ref.303\64.39.

Project:
 Plant and soil nitrogen dynamics in California annual grassland
Project Leader:
Jackson, L.E., R.B. Strauss, M.K. Firestone, and J.W. Bartolome
Summary:
 1988. Plant and Soil 110: pp. 9-17.
Seasonal changes in soil water and nitrogen availability were related to the phenology and growth of plants in California annual grassland. Plant accumulation of nitrogen was mainly confined to two short periods of the year: fall and early spring. This suggests inorganic nitrogen flux during the drought period. The "drought escaper" life history characteristics of annual grasses in California annual grassland, however, may prevent plants from utilizing available nitrogen during a large part of the year. Ref.265\64.02.

Project:
 Influence of tree canopies on grassland productivity and nitrogen dynamics in deciduous oak savanna
Project Leader:
Jackson, L.E., R.B. Strauss, M.K. Firestone, and J.W. Bartolome
Summary:
 1990. Agriculture, Ecosystems and Environment 32: pp. 89-105.
In oak and annual grassland savanna in the foothills of the Sierra Nevada, CA, soils under deciduous blue oak canopies have higher nitrogen turnover and inorganic N availabilty than surrounding open grassland soils. Over 3 years of study, annual above- and below- ground productivity and plant N accumulation in both communities were generally very similar. Although the two areas differ in species composition, rates of seedling establishment, seasonal phenology, and dry weight and N allocation patterns, these differences are not great enough to affect productivity at this site. Even if forage production in the blue oak savanna does not benefit from the presence of oak canopies, soils under oaks harbor a reservoir of soil organic N that could be rapidly lost or redistributed if oaks are removed for management purposes. Ref.302\64.38.

Project:
 Comparative effects of repeated cycles of water stress on growth and apparent dinitrogen fixation of Ladino and strawberry clovers
Project Leader:
Johnson, K.L., and C.A. Raguse
Summary:
 1985. Crop Sci. 25(2): pp. 299-306.
Water stress is a major environmental factor limiting growth and symbiotic N2 fixation of legumes. This study was conducted to determine the effects of repeated short-term cycles of water stress on growth and N2 fixation of Ladino clover and strawberry clover. In separate experiments, stolons of each species were trained into a calcined, under controlled conditions of ambient air and root temperature, and provided with N-deficient nutrient solution. The results of these experiments indicate that minor, short-term water stresses, if repeated, can result in significant decreases in productivity.

Project:
 Hardinggrass and annual legume production in the Sierra Foothills
Project Leader:
Kay, B.L.
Summary:
 1969. J. Range Manage. 22(3): pp. 174-177.
Seeding trials at the Sierra Foothill Range Field Station show that total forage production can be doubled by sowing annual clovers. Also increased were the quantity and quality of winter feed. Winter feed was increased further by planting hardinggrass with the legumes. Results were similar on the two soil types involved.

Project:
 Atrazine and Simazine increase yield and quality of range forage
Project Leader:
Kay, B.L.
Summary:
 1971. Weed Sci. 19(4): pp. 370-371.
Application of atrazine to intermediate wheatgrass increased forage yields, plant protein, and nitrate over a 4-year period. Atrazine or simazine applied to a sward of red brome, Arabian grass, and red-stem filaree increased dry-matter yields sixfold and also increased protein and nitrate nitrogen. Nitrate in plants treated with atrazine increased to near-toxic levels for livestock.

Project:
 Rose clover - a preferred quail food
Project Leader:
Kay, B.L.
Summary:
 1986. Proc., Joint Mtg. Soc. for Range Mgmt & Wildlife Soc., Sparks, NV. 22: pp. 39-41.
Diets of California quail were sampled from 1979 to 1981 during the fall and winter on cleared and seeded foothill ranges on the east side of the Sacramento Valley. Rose clover comprised 43% to 96% of the crop sample by dry weight. It was used both as seed and leaves, and in amounts proportionally greater than its occurence in the range cover. Quail are highly selective in choosing among the food sources present. Rose clover is clearly a preferred species as it is selected over the many non-seeded resident species which persist after the range clearing. This is not surprising as legumes are well recognized as a preferred food plant.

Project:
 Paraquat for range seeding in Cismontane, California
Project Leader:
Kay, B.L., and R.E. Owen
Summary:
 1970. Weed Sci. 18(2): pp. 238-244.
A technique was developed for seeding rangelands too steep or too rocky to seed by current methods. Hardinggrass and subclover were established by seeding immediately after spraying the resident vegetation with paraquat. Tested for seeding in sod were single-disk, double-disk, and hoe-type drill openers. No hardinggrass was established without some weed control. Spraying helped establish subclover but was not critical. Prolonged weed control made paraquat superior to cultivation by giving better weed control and a firmer seedbed.

Project:
 Curing standing range forage with herbicides
Project Leader:
Kay, B.L., and D.T. Torell
Summary:
 1970. J. Range Manage. 23(1): pp. 34-41.
Paraquat applied to standing annual range forage at anthesis of the grasses resulted in standing hay 57 to 77% higher in protein. Crude fiber was decreased and phosphorus increased. Forage production was generally lower with treatment, because the growing season was shorter. Palatability of dry forage was improved. Lambs on treated forage gained more rapidly. No physiological or pathological changes were found in the lambs. Spraying resulted in less grass and more clover in the year following spraying.

Project:
 Effect of Quercus douglasii (fagaceae) on herbaceous understory along a rainfall gradient
Project Leader:
McClaran, M.P., and J.W. Bartolome
Summary:
 1989. Madrono 36(3): pp. 141-153.
Variation in effect of approximately 50% Quercus douglasii (blue oak) cover on herbaceous understory biomass and composition was studied along a rainfall gradient between five sites. Biomass and composition were compared between understory and adjacent open grassland at each site to evaluate changes in canopy effect along the gradient. We conclude that variation in canopy effect on biomass resulted from changes in relative production between understory and open grassland, not from differences in relative composition. Ref.274\64.10.

Project:
 49er fire revegetation activities
Project Leader:
McCreary, D.D.
Summary:
 1989a. Proc., UC Sierra Foothill Range Field Station Beef and Range Field Day. pp. 7-8.
In September, 1988 a fire swept through Western Nevada County, destroying 200 homes and burning over 35,000 acres of land. In terms of property loss, the 49er Fire was one of the most destructive in California history. It was also tremendously damaging to native woody vegetation, which was predominately oak trees. Soon after the fire was extinguished, efforts began to revegetate burned areas. By mid-March, nearly 800 pounds of acorns had been planted. While it is still too early to evaluate the success of Project Acorn in terms of oak tree establishment, the project was certainly successful in educating the public. Ref.228\63.39.

Project:
 The effects of different pasture and rangeland ecosystems on the annual dynamics of insects in cattle droppings
Project Leader:
Merritt, R.W., and J.R. Anderson
Summary:
 1977. Hilgardia 45(2): pp. 31-71.
Cattle droppings constitute a special microhabitat, including both organisms (biotic communities) and abiotic environment, each influencing the properties of the other. The interacting factors which influence both the diversity and abundance of insect species colonizing dung, and the rate of pat degradation, are summarized. Economic considerations are important criteria determining the type of pasture ecosystems for agricultural purposes. Our study showed that the establishment of totally cleared, dry grassland pastures in California resulted in a general reduction of the indigenous dung insect fauna.

Project:
 Seasonal Variation in the Nutritive Nature of California Range Forage for cattle
Project Leader:
Morris, J.G., and R.E. Delmas
Summary:
 1980. Proc., UC Sierra Foothill Range Field Station Beef and Range Field Day: pp. 16-20.
A fundamental characteristic of the world's rangelands is the variation in quantity and quality of forage it makes available to grazing animals. This variation results from responses of pasture plants to climatic variables, particularly temperature and rainfall. Data show that the organic matter digestibility and therefore, available energy from annual range forage falls to low levels in the summer-fall period. Thus, the forage ingested by range cattle varies markedly and predictably with the growth cycle of the range plants.

Project:
 Response of Subclover (Trifolium subterraneum L.) to phosphorus as influenced by soil phosphorus adsorption characteristics, mechanical disturbance of the soil profile, temperature and light
Project Leader:
Osman, A.
Summary:
 1974. Ph.D. Thesis, UCDavis: p. 88.
These studies were undertaken to evaluate the phosphorus requirement of subterranean clover grown on the Sobrante-Lasposas soil series and the growth response of the species with variations in light, temperature and soil disturbance.

Project:
 Growth of subterranean clover in a range soil as affected by microclimate and phosphorus availability
Project Leader:
Osman, A., C.A. Raguse, and D.C. Sumner
Summary:
 1977. II. Laboratory and phytotron studies. Agronomy J. 69: pp. 26-29.
Growth of subterranean clover seedlings on P-deficient soil was studied under controlled temperatures, photoperiod, and light intensities representative of winter in California's annual rangeland, with a Phosphorus treatment. Plant weights were significantly affected by P rates only at the 3.0 and 4.5 leaf stages. Total P per plant was a more consistent indicator of P availability than was % P. Shoot:root ratios, nodules per plant, and percent crude protein in shoot and root increased with P availability.

Project:
 Evolution of a pasture-range research program
Project Leader:
Raguse, C.A.
Summary:
 1980. Proc., UC Sierra Foothill Range Field Station Beef and Range Field Day: pp. 45-50.
This analysis has been written from the point of view of a co-project leader with over fifteen years of research history in the management of irrigated pasture and improved rangelands, principally as used by beef cattle. It includes an accounting of the pasture-range research program available and utilized at SFREC. The previous history and current activities of both the Hopland and Sierra Foothill Range Field Stations support the future projection of these facilities for research, teaching, and public service serving a broad array of societally-important objectives.

Project:
 Vegetation-type conversion at the Sierra Station - an historical review
Project Leader:
Raguse, C.A.
Summary:
 1987. Proc., UC Sierra Foothill Range Field Station Beef and Range Field Day: pp. 43-47.
Vegetation-type conversion may have several objectives, only one of which may be increase of range forage to support livestock production. With concerns about maintenance of environmental quality and wise management of renewable natural resources, complete type conversion has evolved to selective, prescribed manipulation of woody vegetation to maintain the natural mosaic pattern of the landscape. The UC Sierra Field Station's experiences in an ongoing vegetation-type conversion program will aid in development of a more universally acceptable approach to improving livestock production without unduly compromising aesthetic values and natural resources conservation needs.

Project:
 Thirty years of research: an overview
Project Leader:
Raguse, C.A., G.A. Beall, J.L. Hull, D. McCreary, and C.B. Wilson
Summary:
 1990. California Agriculture 44(2): pp. 4-7.
For the last 30 years, the Sierra Foothill Range Field Station has been an invaluable outdoor laboratory, classroom, and demonstration facility. The station will continue to serve society as research, teaching, and outreach evolve in response to changes in the broad geographical area it represents.

Project:
 Growth of subterranean clover in a range soil as affected by microclimate and phosphorus availability
Project Leader:
Raguse, C.A., and R.A. Evans
Summary:
 1977. I. Field studies. Agronomy J. 69: pp. 21-25.
The relationships between microenvironment and phosphorus availability were studied. Ridge, furrow, and aspect microsites were established to create variations in light and temperature microenvironments. Phosphorus was applied and subterranean clover sown in rows perpendicular to the microsite ridges, slopes, and furrows. Temperatures were monitored, and plant sampling was done to determine development, plant weight, and %P per plant. Large diurnal temperature differences were associated with microsite treatments and were more pronounced for soil than for air.

Project:
 Beef calf production from irrigated pasture, supplements and winter annual range in the Sierra Nevada foothills
Project Leader:
Raguse, C.A., J.L. Hull, and R.E. Delmas
Summary:
 1980. Proc., UC Sierra Foothill Range Field Station Beef and Field Day. pp. 5-15.
Animal data were analyzed by computing means and standard deviations for 1) cow weights at breeding, weaning and calving, and at beginning and end of supplementation, and 2) calf weights at birth and weaning (adjusted to 205 days). Using years as replications mean cow and calf weights for the two management systems were compared using the Student's "t" test. An Animal Unit Month (AUM), where used, was defined as one 1000-lb cow. A number of management options used in the study would be useful to part-time farmer-ranchers, especially where family labor and relatively-inexpensive irrigation water are available. Ref.191\63.02.

Project:
 Range fertilization: Results of a five-year research program
Project Leader:
Raguse, C.A., J.L. Hull, M.R. George, J.G. Morris, and K.L. Taggard
Summary:
 1987. Proc., UC Sierra Foothill Range Field Station Beef and Range Field Day: pp. 26-31.
For the geographic area in our study, plant and animal productivity may be enhanced by either of two fertilization strategies. The first, and probably preferable, is to apply adequate levels of phosphorus and sulfur sufficient to stimulate legume production and symbiotic nitrogen fixation capability. The second strategy is to apply moderate levels of nitrogen together with adequate levels of phosphorus and sulfur, which will both increase plant production and have a somewhat greater effect during the fall and winter seasons. With either strategy, maintenance of effective stocking rates is critical to efficient forage-to-animal transfer and conversion.

Project:
 Foothill range management and fertilization improve beef cattle gains
Project Leader:
Raguse, C.A., J.L. Hull, M.R. George, J.G. Morris, and K.L. Taggard
Summary:
 1988. California Agriculture 42(3): pp. 4-8.
Substantial profit resulted from fertilization in a three-year study on foothill range concluded in the early summer of 1985. The work was done at the UC Sierra Foothill Range Field Station east of Marysville near Browns Valley. An earlier report (California Agriculture, May-June 1984) gave details of the experiment and a first-year summary of results. Our final results showed that fertilization with moderate to high levels of phosphorus and sulfur or with combinations of nitrogen, phosphorus, and sulfur was profitable on this cleared and legume-reseeded grassland.

Project:
 Range fertilization: Results of a five-year research program
Project Leader:
Raguse, C.A., J.L. Hull, M.R. George, J.G. Morris, and K.L. Taggard
Summary:
 1984. Proc., UC Sierra Foothill Range Field Station Beef and Range Field Day: pp. 26-31.
For the geographic area in our study, plant and animal productivity may be enhanced by either of two fertilization strategies. The first, and probably preferable, is to apply adequate levels of phosphorus and sulfur sufficient to stimulate legume production and symbiotic nitrogen fixation capability. The second strategy is to apply moderate levels of nitrogen together with adequate levels of phosphorus and sulfur, which will both increase plant production and have a somewhat greater effect during the fall and winter seasons. With either strategy, maintenance of effective stocking rates is critical to efficient forage-to-animal transfer and conversion.

Project:
 Range fertilization in Northern California - current experiments at the UC Sierra Foothill Range Field Station
Project Leader:
Raguse, C.A., J.L. Hull, M.B. Jones, J.G. Morris, M.R. George, K.D. Olson, K.L. Taggard, and R.E. Delmas
Summary:
 1984. Proc., 32nd Annual Calif. Fert. Conf., Fresno, CA.: p. 10.
This study weighed the average daily gain (ADG) of cattle on range nutrition. The application of nitrogen, phosphorus, and sulfur to annual legumes and grasses produced desirable results. When too much nitrogen was applied, potentially undesirable results included changes in botanical composition (more grasses and non-legume forbs, fewer legumes) and lowered quality of the forage, especially in spring as growth dilution lowers protein content. Where annual legumes such as subclover, rose clover, or bur clover can be established, they may provide an almost ideal solution to the problem of poor winter forage growth and low quality summer feed.

Project:
 Plant, livestock and economic responses to selective fertilization of Sierra Foothill rangeland with nitrogen, phosphorus and sulfur
Project Leader:
Raguse, C.A., J.L. Hull, M.B. Jones, J.G. Morris, M.R. George, K.D. Olson, K.L. Taggard, and R.E. Delmas
Summary:
 1986. Range Sci. Rep. No.8, UC Davis Agron. & Rg. Sci. Dept. 8: p. 11.
Field scale treatments of nitrogen-only, phosphorus plus sulfur, and all three elements together were aerially applied in early October of 1982 on a 520-acre site at the UC Sierra Foothill Range Field Station, and the experiment was conducted for three consecutive years without additional fertility adjustment. Assessment of soil nutrient status was made and climatic data, especially precipitation and temperature, were used as aids in interpretation of results. The best animal gains were from the multiple-element (NPS) and the higher-level PS treatments.

Project:
 The Forbes Hill range fertilization experiment
Project Leader:
Raguse, C.A., R. Hull, M.B. Jones, J.G. Morris, M.R. George, and K.L. Taggard
Summary:
 1985. Proc., UC Sierra Foothill Range Field Station Beef and Range Field Day: pp. 17-19.
Normal costs of fertilizer materials and application were recovered in the first grazing season (in a good year) following fall application. Best results were from the multiple-element (NPS) treatments. An extremely important element in recovery of fertilization benefits is the ability to adjust stocking rates to sometimes large seasonal changes in levels of forage production. Stocker steer average daily gains were higher for fertilized fields, indicating significant benefits of fertilization to forage quality.

Project:
 Plant, livestock and economic responses to selective fertilization of annual rangeland with nitrogen, phosphorus and sulfur
Project Leader:
Raguse, C.A., J.L. Jones, J.G. Morris, M.R. George, K.D. Olson, K.L. Taggard, and R.E. Delmas
Summary:
 1986b. Proc., 34th Annual Calif. Fert. Conf., Fresno, CA: pp. 53-60.
Field-scale treatments of nitrogen-only, phosphorus plus sulfur, and all three elements together were aerially applied in early October of 1982 and the experiment was conducted for three consecutive years without additional fertility adjustment. Esophageal-fistulated animals were used to collect forage samples from which treatment and season related changes in quality could be assessed. In addition to data collected for plant and animal levels of the system, an initial assessment of soil nutrient status was made and climatic data, especially precipitation, were used as an aid in interpretation of results.

Project:
 Range fertilization studies
Project Leader:
Raguse, C.A., M.B. Jones, M.R. George, and K.D. Olson
Summary:
 1983. Proc., UC Sierra Foothill Range Field Station Beef and Range Field Day: pp. 17-24.
Field fertilizer treatments: Using urea as the N source and a 1:1 mixture of 0-25-0-10S and 0-20-0-12S as P and S sources, NP and S were applied by helicopter on October 5 and 6, 1982, in various combinations and concentrations. Data collected: Animal level - average daily gain; weight gain per animal per grazing period; digestibility and protein content of forage collected by fistulated steers; animal grazing days. Plant level - changes in botanical composition; forage levels prior to each weigh date; NPS content of selected forage samples; observations on legume growth and vigor, including nodulation. Economic analysis and projections.

Project:
 Conversion of annual range forage to beef in the Sierra Nevada foothills
Project Leader:
Raguse, C.A., J.L. Jones, J.G. Morris, M.R. George, K.D. Olson, K.L. Taggard, and R.E. Delmas
Summary:
 1986a. Proc., Calif. Plant & Soil Conf., Sacramento, CA. pp. 91-98.
Conversion of plant to animal product in a Mediterranean annual grassland was studied in a type-converted oak woodland, annual-legume-reseeded, lower foothill area of the Sierra Nevada. Major objectives were to assess both short- and long-term biological and economic responses to additions of selected levels and combinations of nitrogen, phosphorus, and sulfur where soils were known to be limiting in all three elements. Seasonal grazing was done by stocker steers. Esophageal-fistulated animals were used to collect forage samples from which treatment and season related changes in quality could be assessed. Ref.116\63.77.

Project:
 Developmental morphology of seedling subterranean and rose clover leaves
Project Leader:
Raguse, C.A., J.W. Menke, and D.C. Sumner
Summary:
 1974. Crop Sci. 14: pp. 333-334.
Ten morphologic stages of leaf development were described for seedling subterranean clover and rose clover. The system is relatively simple to apply and has proved useful in field, greenhouse, and controlled-environment studies that require a rapid, nondestructive means of monitoring growth responses to changes in plant environment. If plant development is slow because of cold or other environmental stress, this index is supplemented with one describing growth from emergence to full expansion of the unifolilate leaf.

Project:
 Correlation of steer average daily gain with diet quality and forage phenology in an improved annual grassland
Project Leader:
Raguse, C.A., J.G. Morris, and V.N. Landry
Summary:
 1989. J. Range Manage. 42: pp. 415-420.
Objectives of this study were to construct a model to describe seasonal changes in steer average daily gain (ADG); to observe changes in nitrogen concentration and in vitro organic matter digestibility related to time of season and ADG; and to relate the phenological progress of maturation of rose clover to ADG, nitrogen concentration and in vitro organic matter digestibility. Ref.85\61.40.

Project:
 Growth of subterranean clover in a range soil as affected by microclimate and phosphorus availability. III. Comparative growth of subterranean and rose clovers at cold soil temperatures
Project Leader:
Raguse, C.A., and K.L. Taggard
Summary:
 1979. Agronomy J. 71(4): pp. 523-528.
The biological yield potential of winter annual range legumes is influenced by the timing of rainfall adequate to ensure germination. Three controlled-environment experiments were conducted to compare the seedling growth of rose clover and subterranean clover on a P-deficient soil simulating winter conditions of cold soils and low light. Results suggest that while the practical soil threshold temperature for overall growth is near 5 C, some intraplant growth processes may proceed, but only at adequate availability levels of mineral nutrients. Ref.97\63.69.

Project:
 Irrigation of foothill annual rangeland: a means of augmenting fall/winter forage
Project Leader:
Raguse, C.A., K.L. Taggard, and R.E. Delmas
Summary:
 1983. In: Hannaway, D.B., ed. Foothill for food and forests. Beaverton, OR: Oregon State Univ. Symp. Series No. 2. pp. 345-349.
Winter annual legumes have low fall and early winter forage yields in California's Mediterranean-type climate. A 2-year field study was conducted to determine the effect of late summer irrigation on forage yield potential of subterranean clover, rose clover, and bur clover. Under climatic conditions similar to those in the present experiment, early fall irrigation will ensure vigorous plant growth at temperatures under which maximum root development and nodulation of legumes can occur. This increase in plant material in early fall allows earlier and longer grazing periods, and up to 6,000 to 7,500 kg/ha of high quality forage can be produced. Ref.105\63.72.

Project:
 Growth of subterranean clover in a range soil as affected by microclimate and phosphorus availability. III. Comparative growth of subterranean and rose clovers at cold soil temperatures
Project Leader:
Raguse, C.A., and K.L. Taggard
Summary:
 1979. Agronomy J. 71(4): pp. 523-528.
The biological yield potential of winter annual range legumes is influenced by the timing of rainfall adequate to ensure germination. Three controlled-environment experiments were conducted to compare the seedling growth of rose clover and subterranean clover on a P-deficient soil simulating winter conditions of cold soils and low light. Results suggest that while the practical soil threshold temperature for overall growth is near 5 C, some intraplant growth processes may proceed, but only at adequate availability levels of mineral nutrients.

Project:
 Plant/microbial competition for nitrogen in a california forest and grassland
Project Leader:
Schimel, J.P.
Summary:
 1987. Ph.D. Thesis, Univ. of Calif., Berkeley. 156 pages.
I examined the role of NH4+ vs. NO3-, and of spatial compartmentalization in controlling plant/microbial competition for N in annual grassland and mixed conifer forest soils. Control of N-incorporation by the forest floor biota was examined by slurrying samples in 15N containing solutions. NH4+ uptake was rapid. An inhibitor of glutamine synthetase, MSX, reduced NH4+ uptake, suggesting that a portion of the microbial population was NH4+ limited. Ref.292\64.28.

Project:
 Control of nitrification and denitrification in a California annual grassland
Project Leader:
Schimel, J.P., L.E. Jackson, and M.K. Firestone
Summary:
 1986. Proc., IV ISME : pp. 645-649.
We have begun to examine the importance of nitrification and denitrification in an oak-grass savanna in the foothills of the Sierra Nevada in California. In these soils the concentrations of NO3- are generally very low. However NO3- appears to be quite dynamic; we have found that NO3- accumulates rapidly in lab incubations and in field cylinders from which plants are removed. Nitrification may enhance nitrogen availability because grassland plants may compete better for NO3- than for NH4+ . Ref.300\64.36.

Project:
 Spatial and temporal effects on plant microbial competition for inorganic nitrogen in a California annual grassland
Project Leader:
Schimel, J.P., L.E. Jackson, and M.K. Firestone
Summary:
 1989. Soil Biol. Biochem. 2(8)1: pp. 1059-1066.
The changes in N-dynamics which occur after the start of autumn rains, following an extended summer drought, were examined in a California annual grassland. Competition for NH4+ and NO3- were assessed in intact soil microcosms periodically watered to stimulate autumn rains. Nitrification benefitted plants by increasing accessible N. Spatial factors were critical in controlling N-dynamics. Microsites free of NH4+ were presumably responsible for for the extensive microbial NO3- uptake. Of the activities measured in the top 9 cm of the soil, the surface 5mm accounted for almost half of mineralization and plant NH4+ -uptake, but only 11% of microbial NH4+ -uptake .Ref.297\64.33.

Project:
 Plant cover helps control rangeland erosion
Project Leader:
Singer, M.J., J. Blackard, and G.L. Huntington
Summary:
 1980. California Agriculture 34(10): pp. 8-10.
Soil erosion by water is a two-part process. First, the impact of raindrops detaches soil particles from the main mass of soil. Then, water flowing over the soil surface transports this loose soil from the site of detachment. Proper range management can prevent large erosion losses by ensuring that an adequate plant cover exists during the rainy season. This means that grazing pressure must be controlled and that type conversion practices such as mechanical brush removal, burning, and cultivation need to be timed so that the soil is not bare during the rainy periods of the year. Further research is needed to quantify the relationship between soil chemical properties and erodibility.

Project:
 The role of oak trees in nutrient cycling
Project Leader:
Singer, M.J., and R.A. Dahlgren
Summary:
 In press. Proc., Symp. on Oak Woodlands: Ecology, Management, and Urban Interface Issues. San Luis Obispo, CA., Mar. 19-22, 1996.
Many oak woodland ecosystems are grazed and many are being cleared for oak firewood to enhance grazing. Nutrients removed from an ecosystem at rates greater than they can be made available by natural processes such as rock weathering, nitrogen fixation, and atmospheric deposition lead to decreased productivity of the ecosystem. In grassland soils, nutrients leached below the shallow rooting zone of annual grasses are removed from the ecosystem into stream or ground waters. In contrast, the deeply rooted oak trees are able to capture the majority of the nutrients before they are lost from the ecosystem by leaching. Ref.262\64.01.

Project:
 Land use and intensive range management in the Sierra Nevada Foothills -- A contemporary analysis
Project Leader:
Smith, T.K.
Summary:
 1977. M.S. Thesis, UCDavis: p. 91.
The purpose of this investigation was to examine some range improvement practices commonly used in beef cattle production. The physical & biological environment at UC Sierra Foothill Range Field Station in Yuba County (our model) is representive of approximately nine million acres of Sierra Nevada foothill land. Soil erosion was found to be the major category for prevention efforts, for it can be both a cause and effect of environmental degradation in rangeland. Other categories of impact include direct removal of wildlife habitat through vegetation-type conversion and indirect impacts on the cultural and biological resources.

Project:
 Guidelines for managing California's hardwood rangelands
Project Leader:
Standiford, R., technical coordinator
Summary:
 1996. Oakland, CA: Univ. of Calif. DANR Publication 3368. 173 pages.
The purpose of this book is to help landowners and managers of hardwood rangeland properties develop management plans that maintain the profitability of their properties, while at the same time sustaining the ecological values provided by their land. There is no one best management system or one best set of guidelines. These guidelines will lead the reader through a close evaluation of their goals and objectives for their personal lives and their properties, and present a variety of management strategies to achieve these goals and objectives. This book is a revision of The Preliminary Guidelines for Managing Hardwood Rangelands, released in 1986 by the University of California. Ref.289\64.25.

Project:
 Environmental factors versus ammonia-oxidizer population characteristics as dominant controllers of nitrification in an oak woodland - annual grassland soil
Project Leader:
Stark, J.
Summary:
 1991. Ph.D. Thesis, Univ. of Calif., Berkeley. 146 pages.
Environmental variables and kinetic characteristics of ammonia-oxidizer populations were examined to determine which factors were most important in controlling seasonal and spatial variation in gross nitrification rates in a California oak woodland-annual grassland soil. Soil NH4+, NO3-, moisture, total N and C, and nitrification potential were higher in soils beneath the oak canopies than in open grassy areas between oaks and higher in the 0-1 than 1-9 cm soil layer. Mean soil temperatures and fluctuations in temperature and moisture were higher in open areas. Physiologically distinct ammonia-oxidizer populations coexisted within the oak woodland annual grassland soil. Populations from open sites had temperature optima that were 5 Co higher than those from canopy sites. Michaelis-Menten constants appeared different; however, high variability prevented drawing conclusions about population differences. Ref.294\64.30.

Project:
 Effects of varying root/shoot temperatures on early growth of subterranean clover
Project Leader:
Sumner, D.C., C.A. Raguse, and K.L. Taggard
Summary:
 1972. Crop Sci. 12: pp. 517-520.
We sought to determine the individual contributions of ambient root and shoot temperatures to rate of plant development, dry matter accumulation, and root/shoot ratio. Subterranean clover was grown from seed in the following chronological sequences: (i) plants were grown at 20 C from seed to the two-leaf stage; (ii) root, shoot, or overall temperature was then lowered to 10 C and growth was allowed to progress until the five-leaf stage; and (iii) temperature was returned to 20 C and growth was continued to the 7- to 10-leaf stage. Shoot ambient temperature appeared to be less important than root ambient temperature as a determinant of growth rate.

Project:
 Late summer irrigation and establishment of winter annual legumes in a mediterranean-type climate
Project Leader:
Taggard, K.L., R.E. Delmas, and C.A. Raguse
Summary:
 1976. Agronomy J. 68: pp. 674-677.
A 2-year field study was conducted to determine the effects of late summer irrigation on seedling development, forage yield potential, and management problems of subterranean clover, rose clover, and bur clover. By irrigation prior to fall rains, we subjected six successive seedings to higher temperatures and longer fall-growth periods than usual. In the 1972-73 season, rose clover showed the largest differences in growth rates between planting dates. In the 1973-74 season, late-flowering subclover had the fastest growth rate; there were no differences between clovers following late irrigation.

Project:
 Evaluating dryland legumes and native perennial grasses as plant materials for use in sustainable agriculture systems
Project Leader:
Williams, W.A., C.D. Thomsen, and W.L. Graves
Summary:
 1994. SAREP FINAL REPORT: p. 19.
We evaluated dryland legumes and native perennial grasses for use in pasture, range, vineyard, and farming systems in northern California with respect to adaptability, persistence, weed suppression, and management requirements. Specific components of this project included field trials with dryland legumes at Sierra Foothill REC.

Project:
 Grazing productivity on seeded annual ryegrass in the California foothills
Project Leader:
Wilson, C.B.
Summary:
 1980. Proc., UC Sierra Foothill Range Field Station Beef and Range Field Day: pp. 51-52.
Increasing the carrying capacities of annual type ranges in the winter has been an important objective in livestock production research in California. By introducing annual ryegrass and supplemental irrigation, carrying capacities of five to six times that of typical winter rangelands were obtained. cattle were able to gain on the ryegrass in mid-December and early January. Normally, cattle on rangeland in the Sierra foothills do not start gaining weight until mid-February or March. This early high quality feed, therefore, provided a grazing alternative to increase livestock production from a basic range forage system.

Project:
 Germination of cultivars of Trifolium subterraneum L. in relation to matric potential
Project Leader:
Young, J.A., R.A. Evans, and B.L. Kay
Summary:
 1970. Agronomy J. 62: pp. 743-745.
The germination of 11 cultivars of subclover in relation to matric potential was dependent on the texture of the soil substrate. Germination terminated or was virtually zero at minus 5, 8 and 12 bars, respectively, on sand, loam, and clay substrates. Germination on soil beds in the greenhouse was dependent on substrate texture and the amount of seed coverage. In all tests in which germination was more than minimal, variability among the cultivars was marked.

Project:
 Germination of caryopses of annual grasses in simulated litter
Project Leader:
Young, J.A., R.A. Evans, and B.L. Kay
Summary:
 1971a. Agronomy J. 63: pp. 551-555.
A technique was developed for germinating grass caryopses in simulated litter, without the base of the caryopses in contact with a liquid moisture-supplying substrate. Germination of five annual species of bromegrass and medusahead differed markedly in response to temperature from 10 to 25 C, compared to germination of the same species in petri dishes. The species also differed in their rates of root elongation and root persistence under repeated drying cycles at incubation temperatures from 10 to 25 C. The differences in litter germination may be the basis for dominance of one species over another under specific temperature regimes.

Project:
 Response of medusahead to paraquat
Project Leader:
Young, J.A., R.A. Evans, and B.L. Kay
Summary:
 1971b. J. Range Manage. 24(1): pp. 41-43.
Medusahead plants from 23 sources were susceptible to paraquat at Davis, California, but resistant to application of this herbicide at Reno or Stead, Nevada. Differences in response were not due to ecotypic variability among the sources. Our purpose was to determine if ecotypic variability in medusahead was the cause of differential response of this species to paraquat application in different areas of western United States.

Project:
 Temperature requirements for seed germination in an annual-type rangeland community
Project Leader:
Young, J.A., R.A. Evans, and B.L. Kay
Summary:
 1973. Agronomy J. 65: pp. 656-659.
Germination as affected by constant and alternating temperatures was investigated in four species of annual grasses, soft chess; ripgut; slender oat and foxtail fescue, and in their replacement forage species, seven cultivars and one naturalized population of rose clover; hardinggrass; and perlagrass. The annual grasses germinated under a very broad range of temperatures; rose clover cultivars germinated at lower temperatures. Rose clover from a naturalized population had lower germination at low temperatures and higher germination at high temperatures than the seven cultivars tested.

Project:
 Dispersal and germination dynamics of broadleaf filaree, Erodium botrys (Cav.) Bertol
Project Leader:
Young, J.A., R.A. Evans, and B.L. Kay
Summary:
 1975a. Agronomy J. 67: pp. 54-57.
Dispersal, self-burying, and seed germination of the indehiscent fruits of broadleaf filaree were investigated. Field dispersal and laboratory germination in relation to temperature and germination enhancement experiments were conducted. Dormancy can be overcome artificially by soaking fruits in concentrated sulfuric acid or by exposing the seeds to diurnal fluctuations of temperature and relative humidity. Seeds that will imbibe water have an optimum germination at relatively cool temperatures, but considerable germination occurs with warm day temperatures and extreme diurnal fluctuations.

Project:
 Germination of Italian ryegrass seeds
Project Leader:
Young, J.A., R.A. Evans, and B.L. Kay
Summary:
 1975b. Agronomy J. 67: pp. 386-389.
We studied the germination of seeds of Italian ryegrass under constant and alternating temperatures, and simulated litter as a germination substrate. Italian ryegrass germinated over a wider range of temperatures and at more extreme diurnal fluctuations than did other annual grasses from the same environment. Germination of the naturalized population was highest at both relatively cool nights and warmer days. The limited temperature range at which Italian ryegrass germinates and the inability of roots to resist drying or to regenerate after drying may limit it ecologically.

Project:
 Germination of cultivars of Trifolium subterraneum L
Project Leader:
Young, J.A., B.L. Kay, and R.A. Evans
Summary:
 1970. Agronomy J. 62: pp. 638-641.
Germination of seeds of 11 cultivars of subclover grown in California was depressed by high temperatures and low temperatures, or remained dormant or non-sensitive in relation to incubation temperatures. Non-sensitive cultivars were least responsive to manipulations of the germination environment; while germination of temperature sensitive cultivars was stimulated by treatments such as, activated charcoal substrate, CO2 enriched atmosphere, inclined plates, or KNO2 solution. Pellet inoculation of seeds did not stimulate germination except with "Dwalganup".




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