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Full-Text Articles in Life Sciences

Cost-Effective Fire Management For Southern California's Chaparral Wilderness: An Analytical Procedure, Chris A. Childers, Douglas D. Piirto Oct 1988

Cost-Effective Fire Management For Southern California's Chaparral Wilderness: An Analytical Procedure, Chris A. Childers, Douglas D. Piirto

Natural Resources Management and Environmental Sciences

Fire management has always meant fire suppression to the managers of the chaparral covered southern California National Forests. Today, Forest Service fire management programs must be cost effective, while wilderness fire management objectives are aimed at recreating natural fire regimes. A cost-effectiveness analysis has been developed to compare fire management options for meeting these objectives in California's chaparral wilderness. This paper describes the analytical procedure using examples from a study currently being conducted for the Los Padres National Forest, and discusses some preliminary results.


Chromosome Studies In Asteraceae From The United States, Mexico, The West Indies, And South America, David J. Keil, Melissa A. Luckow, Donald J. Pinkava May 1988

Chromosome Studies In Asteraceae From The United States, Mexico, The West Indies, And South America, David J. Keil, Melissa A. Luckow, Donald J. Pinkava

Biological Sciences

Chromosome counts of Asteraceae are reported from Mexico, the United States, the West Indies, Peru, and Bolivia. First counts are reported for 27 species, eight infraspecific taxa, and three interspecific hybrids in Brickellia , Chrysanthellum, Cirsium, Egletes, Erigeron, Flaveria, Gnaphalium, Heterotheca, Hieracium, Hymenothrix, Koanophyllon, Layia, Lessingia, Pectis, Sclerocarpus, Stuessya, Tagetes and Wedelia. Counts are also reported for 196 taxa or hybrids for which chromosome numbers have been published previously. Of these, nine are new numbers. Taxonomic implications of certain counts are discussed.


Late Fall Fertilization Of Kentucky Bluegrass, David J. Wehner, Jean E. Haley, Dennis L. Martin May 1988

Late Fall Fertilization Of Kentucky Bluegrass, David J. Wehner, Jean E. Haley, Dennis L. Martin

Office of the Dean (CAFES) Scholarship

Many turfgrass managers apply a portion of the total yearly N to cool-season turfgrasses in the late fall (November). The purpose of this field study was to compare fertilization programs with and without N applications in November using both slow-release and soluble N sources. Turfs of two different cultivars of Kentucky bluegrass (Poa pratensis L. cv. Baron and cv. Newport) growing on a Flanagan silt loam (fine, montmorillonitic, mesic Aquic Argiudoll) received 10 fertilization programs utilizing urea, isobutylidene diurea (IBDU), or sulfur-coated urea (SCU). Urea was applied four times per year with either a spring application or a late-fall application ...


The Estimation Of Free Aluminium And The Competition Between Fluoride And Humate Anions For Aluminium, G. S.P. Ritchie, M. P. Nelson, M. G. Whitten May 1988

The Estimation Of Free Aluminium And The Competition Between Fluoride And Humate Anions For Aluminium, G. S.P. Ritchie, M. P. Nelson, M. G. Whitten

Food Science and Nutrition

Three equations for estimating the concentration of free aluminium, [Al3+], from the activity of free fluoride, (F-), were compared to assess their suitability for estimating [Al3+] in acid soil solutions and in competition studies. We then studied the ability of humic acids to compete with F for Al by comparing the behaviour of the humic acids in the presence of F and Al with that of several carboxylic acids under the same conditions. All three methods of estimating [Al ] were limited in their applicability to acid soil solutions but were uitable for estimating [Al3+] in competition studies ...


A Preliminary Evaluation Of Resin Extractable Molybdenum As A Soil Test, G. S.P. Ritchie Apr 1988

A Preliminary Evaluation Of Resin Extractable Molybdenum As A Soil Test, G. S.P. Ritchie

Food Science and Nutrition

Resin extractable Mo explained 72% of the variation in yield of wheat (Triticum aestivum) grown on ten acid soils as measured by the relative yield of the tops or by the uptake of Mo by the youngest emerged blade.


Makaira Sp., Cf. M. Nigricans Lacepede, 1802 (Teleostei: Perciformes: Istiophoridae) From The Eastover Formation, Late Miocene, Virginia, And A Reexamination Of Istiophorus Calvertensis Berry, 1917, Harry L. Fierstine Mar 1988

Makaira Sp., Cf. M. Nigricans Lacepede, 1802 (Teleostei: Perciformes: Istiophoridae) From The Eastover Formation, Late Miocene, Virginia, And A Reexamination Of Istiophorus Calvertensis Berry, 1917, Harry L. Fierstine

Biological Sciences

An incomplete, disarticulated skull (USNM 375733) is described and referred to Makaira sp., d. M. nigricalls, and a rostrum, tIstiophonls call'ertensis Berry. 1917 (USNM 9344. holotype). is re-identified as IstiopllOrus sp., cf. I. platypterus. Both specimens are from the Eastover Formation (early late Miocene, Virginia) and are the oldest records in. deposits bordering the western North Atlantic Ocean. Istioplwrus sp.. cf. I. p/atvpterus (= tlstiophorus ca/vertensls ) IS the oldest record of the specIes. Based on ecological requirements of Recent species. the prescnce of Istiophorus sp., cL I. p/arypterus and Makaira sp., cf. M. nigricans in the Eastover ...


Phosphorus Leaching In Sandy Soils. I. Short-Term Effects Of Fertilizer Applications And Environmental Conditions, D. M. Weaver, G. S.P. Ritchie, G. C. Anderson, D. M. Deeley Jan 1988

Phosphorus Leaching In Sandy Soils. I. Short-Term Effects Of Fertilizer Applications And Environmental Conditions, D. M. Weaver, G. S.P. Ritchie, G. C. Anderson, D. M. Deeley

Food Science and Nutrition

The consequences of previous as well as current environmental conditions and management practices on the potential for phosphorus (P) to be lost by drainage from sandy soils in the short term (< 1 year) were studied in the laboratory and the field. The potential for P losses by drainage was estimated by measuring soil solution P levels and rapidly released P. Rapidly released P was measured by determining the concentration of dissolved inorganic P contained in filtered (µm) soil solutions after incubating soil at saturation for 15 min at ambient temperature. In the laboratory, sandy soils were incubated with ordinary superphosphate, coastal superphosphate (a granulated mixture of equal parts of superphospate, rock phosphate and elemental sulfur) or lime-superphosphate (a lime-reverted superphosphate with 18% kiln dust) and sequentially desorbed with deionized water. The effects of the extent of leaching, fertilizer type, application rate and the time of contact with the soil on soil solution P levels were investigated. The influence of annual pasture death and summer rainfall on rapidly released P in soils that had been pre-treated by leaching were also investigated.

Phosphorus concentrations decreased logarithmically in the successive supernatants of the sequentially desorbed soils. More P was desorbed from soils incubated with superphosphate and lime-superphosphate than soil incubated with coastal superphosphate. At each level of pre-leaching, the P concentrations in the soil solution increased with increasing time. The level, to which the P concentration in the soil solution increased at each time, decreased with increased extent of pre-leaching. The addition ...


Denitrification Losses From Kentucky Bluegrass Sod, C. F. Mancino, W. A. Torello, David J. Wehner Jan 1988

Denitrification Losses From Kentucky Bluegrass Sod, C. F. Mancino, W. A. Torello, David J. Wehner

Office of the Dean (CAFES) Scholarship

Denitrification may represent an important mechanism in the fate of N applied to turf. Denitrification losses were directly measured from fertilized 'Baron' Kentucky bluegrass (Poa pratensis L.) sod samples sealed in acrylic chambers using the acetylene inhibition technique. Losses were correlated with soil texture, percent soil saturation (SAT), and temperature. Losses from turf on a Hadley silt loam soil and Hadley silt soil (both coarse-silty, mixed, nonacid, mesic Typic Udifluvents) incubated at 22°C did not exceed 0.4 and 0.1%, respectively, of the applied potassium nitrate fertilizer (4.5 g N m-2) when soil water levels were ...


A Late Miocene Marlin, Makaira Sp. (Perciformes, Osteichthyes) From San Diego County, California, U.S.A., Harry L. Fierstine, Bruce J. Welton Jan 1988

A Late Miocene Marlin, Makaira Sp. (Perciformes, Osteichthyes) From San Diego County, California, U.S.A., Harry L. Fierstine, Bruce J. Welton

Biological Sciences

Fossil bones collected in the latest Miocene (= either late Clarendonian or early Hemphillian North American Land IvIammal Age), San Mateo Formation, near Oceanside, San Diego County, California, C. S.A., belong to a single specimen of the genus Makaira, species undetermined, and is part of the San Luis Rey River Local Fauna. For the genus, this represents the fifth discovery in fossil deposits bordering or within the Pacific Ocean region, and the third discovery in southern California, The specimen is within the known geochronological distribution of the genus (Late Miocene to Recent), provides further evidence that the coastal palaeoclimate of ...


Effect Of Temperature, Moisture, And Soil Texture On Dcpa Degradation, J. S. Choi, T. W. Fermanian, David J. Wehner, L. A. Spomer Jan 1988

Effect Of Temperature, Moisture, And Soil Texture On Dcpa Degradation, J. S. Choi, T. W. Fermanian, David J. Wehner, L. A. Spomer

Office of the Dean (CAFES) Scholarship

Turf managers sometimes experience poor or early loss of control of targeted weeds, even when herbicides are applied at recommended rates. This study was conducted to determine the influence of soil temperature and moisture on the rate of DCPA (dimethyl tetrachloroterephthalate) degradation in soil. The effect of six soil temperatures, three soil moistures, and three soil textures on the degradation of DCPA was measured in the laboratory through HPLC analysis. Soil temperature influenced the rate of DCPA degradation in the following order: 10<<15<<20<25=30>35°C. The average half-life ranged from 92 d at 10°C to 18 d at 30 ...


Phosphorus Leaching In Sandy Soils. Ii. Laboratory Studies Of The Long-Term Effects Of The Phosphorus Source, D. M. Weaver, G. S.P. Ritchie, G. C. Anderson Jan 1988

Phosphorus Leaching In Sandy Soils. Ii. Laboratory Studies Of The Long-Term Effects Of The Phosphorus Source, D. M. Weaver, G. S.P. Ritchie, G. C. Anderson

Food Science and Nutrition

Long-term phosphorus (P) losses and gains in sandy soils continuously fertilized with either ordinary superphosphate or coastal superphosphate (a granulated mixture of superphosphate, rock phosphate and elemental sulfur) or previously fertilized with superphosphate were investigated under leaching conditions in columns in the laboratory. The soils were subjected to 10 consecutive cycles designed to simulate the mediterranean weather conditions in the Harvey region of the Coastal Plain of Western Australia. Each cycle consisted of a wet phase during which the equivalent of 850 mm of rainfall was leached through the soil and a drier phase during which the soil was incubated ...