Distribution of light and heavy fractions of soil organic carbon as related to land use and tillage practice   总被引：10，自引：0，他引：10  

Z. Tan  R. Lal  L. Owens  R.C. Izaurralde 《Soil & Tillage Research》2007,92(1-2):53-59

Mass distributions of different soil organic carbon (SOC) fractions are influenced by land use and management. Concentrations of C and N in light- and heavy fractions of bulk soils and aggregates in 0–20 cm were determined to evaluate the role of aggregation in SOC sequestration under conventional tillage (CT), no-till (NT), and forest treatments. Light- and heavy fractions of SOC were separated using 1.85 g mL⁻¹ sodium polytungstate solution. Soils under forest and NT preserved, respectively, 167% and 94% more light fraction than those under CT. The mass of light fraction decreased with an increase in soil depth, but significantly increased with an increase in aggregate size. C concentrations of light fraction in all aggregate classes were significantly higher under NT and forest than under CT. C concentrations in heavy fraction averaged 20, 10, and 8 g kg⁻¹ under forest, NT, and CT, respectively. Of the total SOC pool, heavy fraction C accounted for 76% in CT soils and 63% in forest and NT soils. These data suggest that there is a greater protection of SOC by aggregates in the light fraction of minimally disturbed soils than that of disturbed soil, and the SOC loss following conversion from forest to agriculture is attributed to reduction in C concentrations in both heavy and light fractions. In contrast, the SOC gain upon conversion from CT to NT is primarily attributed to an increase in C concentration in the light fraction.  相似文献   

Olfactory-based orientation in artificially imprinted sea turtles     

Grassman MA  Owens DW  McVey JP  M RM 《Science (New York, N.Y.)》1984,224(4644):83-84

Sea turtles (Lepidochelys kempi) are being artificially imprinted to Padre Island, Texas, in an effort to establish a new nesting population. These turtles spent more time per exposure in solutions made of Padre Island sand and seawater than in control solutions in a multiple-choice test. This is evidence that sea turtles may detect differences in natural water samples and remember olfactory cues to which they were exposed neonatally and that these differences may affect their orientation behavior. This suggests that imprinting could be used as a conservation technique for establishing new breeding populations of endangered sea turtles.  相似文献   

Boons to science     

Owens L 《Science (New York, N.Y.)》1991,254(5035):1233-1234

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Response: brain "identifier sequence"     

Owens GP  Chaudhari N  Hahn WE 《Science (New York, N.Y.)》1986,234(4779):1006

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The effect of algal symbionts on the accuracy of Sr/Ca paleotemperatures from coral     

Cohen AL  Owens KE  Layne GD  Shimizu N 《Science (New York, N.Y.)》2002,296(5566):331-333

The strontium-to-calcium ratio (Sr/Ca) of reef coral skeleton is commonly used as a paleothermometer to estimate sea surface temperatures (SSTs) at crucial times in Earth's climate history. However, these estimates are disputed, because uptake of Sr into coral skeleton is thought to be affected by algal symbionts (zooxanthellae) living in the host tissue. Here, we show that significant distortion of the Sr/Ca temperature record in coral skeleton occurs in the presence of algal symbionts. Seasonally resolved Sr/Ca in coral without symbionts reflects local SSTs with a temperature sensitivity equivalent to that of laboratory aragonite precipitated at equilibrium and the nighttime skeletal deposits of symbiotic reef corals. However, up to 65% of the Sr/Ca variability in symbiotic skeleton is related to symbiont activity and does not reflect water temperature.  相似文献   

Ecology and evolution. Sex differences in mortality rate     

Owens IP 《Science (New York, N.Y.)》2002,297(5589):2008-2009

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A Federal Enterprise: Inventing the NIH     

Owens L 《Science (New York, N.Y.)》1987,236(4804):985-986

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Juniper Consumption Does Not Adversely Affect Meat Quality in Boer-Cross Goats     

Matthew W. Menchaca  Cody B. Scott  Kirk W. Braden  Corey J. Owens  Loree A. Branham 《Strength and Conditioning Journal》2011,64(6):669-673

Goat browsing can be used as an alternative brush management option for redberry (Juniperus pinchotii Sudw.) and ashe (Juniperus asheii Buch) juniper instead of more expensive and invasive brush control methods, assuming consumption of juniper does not adversely affect the marketability of offspring. Some wildlife species reportedly retain juniper flavor when consumed. We determined if juniper consumption affected meat quality or flavoring of Boer-cross kid carcasses. Twenty recently weaned, Boer-cross wethers were randomly assigned to one of four treatments with treatments fed different amounts of juniper (0%, 10%, 20%, 30% juniper in the diet). All goats were fed juniper for 28 d at the Angelo State University (ASU) Management, Instruction, and Research Center. All goats were also fed a feedlot ration to meet maintenance requirements (2% body weight). Juniper intake varied (P < 0.05) between all treatments (0%, 10%, 20%, 30%) primarily because treatments were fed different amounts of juniper. Following a 28-d trial, goats were harvested at the ASU Food Safety and Product Development Laboratory. Carcass characteristics including live weight, hot carcass weight, dressing percentage, loineye area, body wall fat thickness, and leg circumference were similar (P > 0.05) among treatments. Sensory characteristics including tenderness, juiciness, flavor intensity, off-flavor, and overall acceptability were also similar (P > 0.05) among treatments. Landowners can utilize goats as a biological management tool without adversely affecting goat meat quality or flavoring.  相似文献   

Density stratification in ionically enriched Onondaga lake,U.S.A.     

Steven W. Effler  Emmet M. Owens  Keith A. Schimel 《Water, air, and soil pollution》1986,27(3-4):247-258

Denstity stratification was characterized in ionically enriched Onondaga Lake for a 7 mo period of 1980, based on paired profiles of temperature and cloride collected at 1 m depth intervals from a single deep water location on 54 different occasions. The lake was both thermally and chemically stratified. The chemical component represented 38.5% of the density stratification for the study period. It was most often the dominant component in establishing the depth of the upper mixed layer, which was unusually shallow in the lake. Further, the presense of the chemical component prolonged the stratification period. The chemical component of stratification decreased progressively through the study. The altered stratification characteristics of the lake may have negative effects on the level of biomass in the upper waters and the oxygen resources of the lower waters.  相似文献   

Radiographic aspects of cardiac pacemakers     

L P Tilley  M S Miller  J M Owens 《Seminars in veterinary medicine and surgery (small animal)》1986,1(2):165-171

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