Survivorship.

Practical R for biologists: an introduction ◽

10.1079/9781789245349.0218 ◽

2021 ◽

pp. 218-226

Author(s):

Donald Quicke ◽

Buntika A. Butcher ◽

Rachel Kruft Welton

Keyword(s):

Statistical Models ◽

Grass Cover ◽

Native Grass ◽

Factors Affecting ◽

Charadrius Vociferus

Abstract This chapter describes the use of statistical models to determine the factors affecting the survival of killdeer (Charadrius vociferus) nests at gravelled oil pads and on native grass cover in western Oklahoma, USA.

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Study on the reduction of atmospheric mercury emissions from mine waste enriched soils through native grass cover in the Mt. Amiata region of Italy

Environmental Research ◽

10.1016/j.envres.2013.02.004 ◽

2013 ◽

Vol 125 ◽

pp. 69-74 ◽

Cited By ~ 9

Author(s):

L. Fantozzi ◽

R. Ferrara ◽

F. Dini ◽

L. Tamburello ◽

N. Pirrone ◽

...

Keyword(s):

Mine Waste ◽

Atmospheric Mercury ◽

Grass Cover ◽

Native Grass ◽

Mercury Emissions

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Integrated Management of Cheatgrass (Bromus tectorum) with Sheep Grazing and Herbicide

Agronomy ◽

10.3390/agronomy9060315 ◽

2019 ◽

Vol 9 (6) ◽

pp. 315 ◽

Cited By ~ 2

Author(s):

Erik A. Lehnhoff ◽

Lisa J. Rew ◽

Jane M. Mangold ◽

Tim Seipel ◽

Devon Ragen

Keyword(s):

Bromus Tectorum ◽

Multiple Stressors ◽

Integrated Management ◽

Plant Cover ◽

Ground Surface ◽

Sagebrush Steppe ◽

Grass Cover ◽

Sheep Grazing ◽

Native Grass ◽

Targeted Grazing

Cheatgrass (Bromus tectorum L.) is one of the most problematic weeds in western United States rangelands and sagebrush steppe. It responds positively to different forms of disturbance, and its management has proven difficult. Herbicide or targeted grazing alone often fail to provide adequate long-term control. Integrating both may afford better control by providing multiple stressors to the weed. We assessed herbicide application, targeted sheep grazing and integrated herbicide and grazing on B. tectorum and the plant community in rangeland in southwestern Montana from 2015 until 2017. Herbicide treatments included spring-applied (May 2015 and 2016) glyphosate, fall-applied (October 2015) glyphosate, imazapic and rimsulfuron, and spring-applied glyphosate plus fall-applied imazapic. Targeted grazing, consisting of four sheep/0.01 ha for a day in 5 m × 20 m plots (all vegetation removed to the ground surface), occurred twice (May 2015 and 2016). While no treatments reduced B. tectorum biomass or seed production, grazing integrated with fall-applied imazapic or rimsulfuron reduced B. tectorum cover from approximately 26% to 14% in 2016 and from 33% to 16% in 2017, compared to ungrazed control plots, and by an even greater amount compared to these herbicides applied without grazing. By 2017, all treatments except spring-applied glyphosate increased total plant cover (excluding B. tectorum) by 8%–12% compared to the control plots, and forbs were generally responsible for this increase. Bromus tectorum management is difficult and our results point to a potential management paradox: Integrating grazing and fall-applied herbicide decreased B. tectorum cover but did not increase native grass cover, while some herbicides without grazing increased native grass cover, but failed to control B. tectorum. Additional research is necessary to determine grazing strategies that will complement herbicide control of B. tectorum while also stimulating native grass recovery, but this initial study demonstrates the potential of integrated management of B. tectorum compared to grazing or herbicide alone.

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Evaluating Factors Affecting Safety at Highway–Railway Grade Crossings

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/0361198105191800101 ◽

2005 ◽

Vol 1918 (1) ◽

pp. 1-9 ◽

Cited By ~ 2

Author(s):

Young-Jin Park ◽

Frank F. Saccomanno

Keyword(s):

Statistical Models ◽

Statistical Significance ◽

Cost Effective ◽

Interactive Effects ◽

Factors Affecting ◽

Explanatory Variables ◽

Grade Crossings ◽

Complex Relationships ◽

Four Quadrant ◽

The Cost

Various countermeasures can be introduced to reduce collisions at highway–railway grade crossings. Existing improvements to crossings include the installation of flashing lights or gates, the addition of extra warning devices such as four-quadrant barriers or wayside horns, and the enforcement of speed limits on the approaching highway. Statistical models are needed to ensure that countermeasures introduced at a given crossing are both cost-effective and practicable. However, in large part because of issues of colinearity, poor statistical significance, and parametric bias, many existing statistical models are simple in structure and feature few statistically significant explanatory variables. Accordingly, they fail to reflect the full gamut of factor inputs that explain variation in collision frequency at individual crossings over a given period of time. Before statistical models can be used to investigate the cost-effectiveness of specific countermeasures, models must be developed that more fully reflect the complex relationships that link a specific countermeasure to collision occurrence. This study presents a sequential modeling approach based on data mining and statistical methods to estimate the main and interactive effects of introducing countermeasures at individual grade crossings. This paper makes use of Canadian inventory and collision data to illustrate the potential merits of the model in decision support.

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Potential Effects of the Loss of Native Grasses on Grassland Invertebrate Diversity in Southeastern Australia

International Journal of Ecology ◽

10.1155/2014/202056 ◽

2014 ◽

Vol 2014 ◽

pp. 1-10 ◽

Cited By ~ 1

Author(s):

Roger Edgcumbe Clay

Keyword(s):

South Australia ◽

Grass Cover ◽

Native Plant ◽

Native Grass ◽

Native Plant Species ◽

Grassland Community ◽

European Settlement ◽

Southeastern Australia ◽

Invertebrate Diversity ◽

Invertebrate Biodiversity

Reduction in area of the southeastern temperate grasslands of Australia since European settlement has been accompanied by degradation of remaining remnants by various factors, including the replacement of native plant species by introduced ones. There are suggestions that these replacements have had deleterious effects on the invertebrate grassland community, but there is little evidence to support these suggestions. In the eastern Adelaide Hills of South Australia, four grassland invertebrate sampling areas, in close proximity, were chosen to be as similar as possible except for the visible amount of native grass they contained. Sample areas were surveyed in four periods (summer, winter, spring, and a repeat summer) using pitfall traps and sweep-netting. A vegetation cover survey was conducted in spring. Morphospecies richness and Fisher’s alpha were compared and showed significant differences between sample areas, mainly in the summer periods. Regression analyses between morphospecies richness and various features of the groundcover/surface showed a strong positive and logical association between native grass cover and morphospecies richness. Two other associations with richness were less strong and lacked a logical explanation. If the suggested direct effect of native grass cover on invertebrate diversity is true, it has serious implications for the conservation of invertebrate biodiversity.

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Efficacy of Exotic Control Strategies for Restoring Coastal Prairie Grasses

Invasive Plant Science and Management ◽

10.1614/ipsm-d-14-00031.1 ◽

2014 ◽

Vol 7 (4) ◽

pp. 590-598 ◽

Cited By ~ 10

Author(s):

Karen D. Holl ◽

Elizabeth A. Howard ◽

Timothy M. Brown ◽

Robert G. Chan ◽

Tara S. de Silva ◽

...

Keyword(s):

Soil Removal ◽

Agricultural Land ◽

Control Strategies ◽

Control Treatment ◽

Grass Species ◽

Grass Cover ◽

Native Grass ◽

Exotic Grasses ◽

Coastal Prairie ◽

Topsoil Removal

AbstractRestoration in Mediterranean-climate grasslands is strongly impeded by lack of native propagules and competition with exotic grasses and forbs. We report on a study testing several methods for exotic plant control combined with planting native grasses to restore prairies in former agricultural land in coastal California. Specifically we compared tarping (shading out recently germinated seedlings with black plastic) once, tarping twice, topsoil removal, herbicide (glyphosate), and a control treatment in factorial combinations with or without wood mulch. Into each treatment we planted three native grass species (Elymus glaucus, Hordeum brachyantherum, andStipa pulchra) and monitored plant survival and cover for three growing seasons. Survival of native grass species was high in all treatments, but was slightly lower in unmulched soil removal and control treatments in the first 2 yr. Mulching, tarping, and herbicide were all effective in reducing exotic grass cover and enhancing native grass cover for the first 2 yr, but by the third growing season cover of the plant guilds and bare ground had mostly converged, primarily because of the declining effects of the initial treatments. Mulching and tarping were both considerably more expensive than herbicide treatment. Topsoil removal was less effective in increasing native grass cover likely because soil removal altered the surface hydrology in this system. Our results show that several treatments were effective in enhancing native grass establishment, but that longer term monitoring is needed to evaluate the efficacy of restoration efforts. The most appropriate approach to controlling exotics to restore specific grassland sites will depend not only on the effectiveness, but also on relative costs and site constraints.

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Factors affecting bovine ketosis and its association with non-return rate

Agricultural and Food Science ◽

10.23986/afsci.72145 ◽

1983 ◽

Vol 55 (6) ◽

pp. 497-507

Author(s):

U. B. Lindström ◽

Marcus Von Bonsdorff ◽

Jouko Syväjärvi

Keyword(s):

Least Squares ◽

Statistical Models ◽

Return Rate ◽

Factors Affecting ◽

Return Rates ◽

Commercial Feed ◽

Prophylactic Measures

Data on 16406 cows (6025 recorded) from the area of the East & Central Al Society were analysed by least squares procedures. Ketosis incidence was determined from the milk by a commercial keto test reagent by AI technicians in connection with the ordinary first insemination of a particular cow. Ketosis incidence was on average 11.5 %, increased up to about the 4th - 5th parity and was significantly higher in larger herds. Breed did not significantly affect ketosis incidence. There was a tendency for higher incidence with increasing usage of commercial feed mixtures. Cows with ketosis milked less than unaffected ones and cows inseminated earlier than 60 days after calving had significantly higher incidence than cows inseminated later. The complete statistical models accounted for only 5 % (all herds) and 9 % (recorded herds) of variation in ketosis incidence, indicating the need for better measures of the herd environment. Heritabilities for ketosis incidence were not significantly different from zero. Cows with ketosis had significantly poorer non-return rates than unaffected ones, indicating the need for prophylactic measures.

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Factors affecting goat milk yield and its composition

Czech Journal of Animal Science ◽

10.17221/4333-cjas ◽

2011 ◽

Vol 49 (No. 11) ◽

pp. 465-473 ◽

Cited By ~ 8

Author(s):

G. Ciappesoni ◽

JPřibyl ◽

M. Milerski ◽

V. Mareš

Keyword(s):

Milk Production ◽

Milk Yield ◽

Statistical Models ◽

Goat Milk ◽

Dairy Goats ◽

Factors Affecting ◽

Stage Of Lactation ◽

Daily Milk Production ◽

Model Equations ◽

Daily Milk

The aim of the paper was to prove the accuracy of various statistical models of variance analysis for estimation of systematic factors that influence milk yield and fat and protein content in dairy goats. Data on daily milk production recorded by methods AT, AC or A4 for the population of Czech White Shorthaired Goats over 1992–2002 was used for calculations. A total of 78 736 test day from 6 234 goats were analysed. Average daily milk production was 3.09 kg with 3.72% of fat and 2.84% of protein. Variability of examined traits was significantly influenced by effects of herd-year or herd-test day, litter size, parity, season of kidding, stage of lactation and the combined effect parity-year-season of kidding. The variants of model equations in which complex effects of herd-year were replaced by effects of herd-test day showed higher values of reliability for the three traits analysed.  

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