INTER-VARIETAL COMPETITION IN PERENNIAL RYEGRASS SWARDS     

A. L. Gardner  I. V. Hunt 《Grass and Forage Science》1963,18(4):285-291

Pure cultures and mixtures of equal numbers of plants of Irish. New Zealand and S23 perennial ryegrass were grown in artificially constructed swards under field conditions. They were cut every time they reached grazing height for three successive years. Counts of plant numbers and tiller numbers per plant made each November show that S23 suppressed both plant number and tiller number per plant of Irish ryegrass and to a lesser extent of New Zealand perennial ryegrass. Its own plant number and tiller number per plant were improved in these combinations. New Zealand perennial ryegrass suppressed plant and tiller numbers of Irish perennial ryegrass.
Varying the method of cutting to match the growth of each variety resulted in improved plant survival and tiller number per unit area of Irish perennial ryegrass when cut according to the growth of S23, i.e. late in the spring. The importance of the effect of experimental technique is discussed.  相似文献   

A revised concept of landscape equilibrium: Disturbance and stability on scaled landscapes   总被引：20，自引：0，他引：20  

Monica G. Turner  William H. Romme  Robert H. Gardner  Robert V. O'Neill  Timothy K. Kratz 《Landscape Ecology》1993,8(3):213-227

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International conference on FMD     

Dr Gardner Murray 《Australian veterinary journal》2002,80(1):21-21

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Sectional notes     

Frank W. Hussey  J. S. Gardner  C. H. Metzger 《American Journal of Potato Research》1934,11(1):23-25

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Epidemiology theory and disturbance spread on landscapes     

R. V. O’Neill  R. H. Gardner  M. G. Turner  W. H. Romme 《Landscape Ecology》1992,7(1):19-26

Abtract Epidemiology models, modified to include landscape pattern, are used to examine the relative importance of landscape geometry and disturbance dynamics in determining the spatial extent of a disturbance, such as a fire. The models indicate that, except for very small values for the probability of spread, a disturbance tends to propagate to all susceptible sites that can be reached. Therefore, spatial pattern, rather than disturbance dynamic, will ordinarily determine the total extent of a single disturbance event. The models also indicate that a single disturbance will seldom become endemic,i.e., always present on the landscape. However, increasing disturbance frequency can lead to a landscape in which the proportion of susceptible, disturbed, and recovering sites are relatively constant. Research supported by Ecological Research Division, Office of Health and Environmental Research, U.S. Department of Energy under contract No. DE-AC05-840R21400 with Martin Marietta Energy Systems, Inc. Contribution No. 10 to the Sevilleta LTER program. Environmental Sciences Division Publication No. 3812, ORNL.  相似文献   

Ellagitannins,flavonoids, and other phenolics in red raspberries and their contribution to antioxidant capacity and vasorelaxation properties     

Mullen W  McGinn J  Lean ME  MacLean MR  Gardner P  Duthie GG  Yokota T  Crozier A 《Journal of agricultural and food chemistry》2002,50(18):5191-5196

Analysis of extracts of Glen Ample raspberries (Rubus idaeus L.) by gradient, reverse phase HPLC with diode array and tandem mass spectrometry identified eleven anthocyanins, including cyanidin-3-sophoroside, cyanidin-3-(2(G)-glucosylrutinoside), cyanidin-3-glucoside, cyanidin-3-rutinoside, pelargonidin-3-sophoroside, pelargonidin-3-(2(G)-glucosylrutinoside), and pelargonidin-3-glucoside. Significant quantities of an ellagitannin, sanguiin H-6, with an M(r) of 1870 were detected along with lower levels of a second ellagitannin, lambertianin C, which has an M(r) of 2804. Other phenolic compounds that were detected included trace levels of ellagic acid and its sugar conjugates along with one kaempferol- and four quercetin-based flavonol conjugates. Fractionation by preparative HPLC revealed that sanguiin H-6 was a major contributor to the antioxidant capacity of raspberries together with vitamin C and the anthocyanins. Vasodilation activity was restricted to fractions containing lambertianin C and sanguiin H-6.  相似文献   

Element mass balances for South Carolina Coastal Plain watersheds     

Leonard Robert Gardner 《Water, air, and soil pollution》1981,15(3):271-284

Element mass balance estimates for South Carolina Coastal Plain watersheds indicate that fertilizers and liming materials are the major sources for inputs of Ca, Mg, K, Cl, and HCO₃ whereas precipitation is the major input for Na and SO₄. Stream flow is the chief mode of output for all of these elements. A balance between input and output is evident only for Cl. Retentions of 50% or more are shown by Ca, Mg, K, HCO₃ and SO₄ whereas Na shows an apparent net loss. The retention of Ca, Mg and HCO₃ suggests that less than 25% of the dolomitic liming materials applied to the landscape actually dissolve and that the carbonate chemistry of Lower Coastal Plain streams is therefore probably largely controlled by seepage of groundwaters from underlying calcareous aquifers. The retention of K and the loss of Na may be due to cation exchange reactions on soil clays whereas the apparent retention of SO₄ is probably due to reduction to H₂S in floodplain environments and soil adsorption.  相似文献   

Purification and identification of linoleic acid hydroperoxides generated by soybean seed lipoxygenases 2 and 3     

Fukushige H  Wang C  Simpson TD  Gardner HW  Hildebrand DF 《Journal of agricultural and food chemistry》2005,53(14):5691-5694

It has been known that lipoxygenase (LOX) isozymes exhibit differences in product formation, but most product information to date is for LOX 1 among soybean (Glycine max) LOX isozymes. In this study, LOXs 2 and 3 were purified and used to generate hydroperoxide (HPOD) products in an in vitro system using linoleic acid as a substrate in the presence of either air or O2. The products were analyzed to determine their stereoisomeric characteristics. The control (no enzyme) showed only low levels of hydroperoxide production and no stereoisomeric specificity. LOX 2 shows high specificity in product formation, producing roughly 4 times more 13-HPOD than 9-HPOD, nearly all of which was 13-S(Z,E)-HPOD. LOX 3 produced more 9-HPOD than 13-HPOD at approximately a 2:1 ratio. No single stereoisomer was predominant among LOX 3 products. These results demonstrate that different isozymes of LOX have characteristic product profiles in in vitro reactions.  相似文献   

Winter flocking behaviour of speckled warblers and the Allee effect     

Janet L Gardner 《Biological conservation》2004,118(2):195-204

The aggregation of individuals into foraging flocks is one behavioural trait that, if disrupted, can cause the Allee effect, which is a slowing in population growth at low density or small population size, and this can greatly increase the risk of extinction. Here, I describe intraspecific flocking behaviour of a colour-banded population of speckled warblers, Chthonicola sagittata, a species that has declined across a large part of its range in the fragmented temperate woodlands of Australia. I make predictions about the context in which the Allee effect might be expressed and the consequences for the viability of populations living in small habitat remnants. Speckled warblers lived in discrete, stable social groups throughout winter, the nucleus of which was the residents from one or more adjacent breeding territories. The timing and mode of flock formation and the size of flocks varied between two winters, apparently in response to the severity of conditions; thus flocking probably facilitates increased foraging efficiency and predator detection, potentially leading to increased survival in harsh conditions. Because flock territories were up to 30 ha each, and larger territories are likely, birds living in remnants smaller than 40 ha may suffer increased mortality if there are too few birds available to form flocks of an appropriate size to facilitate the benefits of grouping when conditions are most extreme. Further, in small remnants where survival is reduced, dominance behaviour and male-male competition may act to compound the Allee effect by reducing reproductive success. Regardless of these predictions, speckled warbler populations may only be viable in remnants that are large enough to support multiple flocks, to enable rapid recruitment to breeding vacancies and thus provide adequate numbers of birds for flocking.  相似文献   

The pacific century     

Gardner DP 《Science (New York, N.Y.)》1987,237(4812):233

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