Home About us Contact
|
Home About us Contact | ||
|
|
||
Year Effects (year + effects)
Selected AbstractsThe ecology of restoration: historical links, emerging issues and unexplored realmsECOLOGY LETTERS, Issue 6 2005T. P. Young Abstract Restoration ecology is a young academic field, but one with enough history to judge it against past and current expectations of the science's potential. The practice of ecological restoration has been identified as providing ideal experimental settings for tests of ecological theory; restoration was to be the ,acid test' of our ecological understanding. Over the past decade, restoration science has gained a strong academic foothold, addressing problems faced by restoration practitioners, bringing new focus to existing ecological theory and fostering a handful of novel ecological ideas. In particular, recent advances in plant community ecology have been strongly linked with issues in ecological restoration. Evolving models of succession, assembly and state-transition are at the heart of both community ecology and ecological restoration. Recent research on seed and recruitment limitation, soil processes, and diversity,function relationships also share strong links to restoration. Further opportunities may lie ahead in the ecology of plant ontogeny, and on the effects of contingency, such as year effects and priority effects. Ecology may inform current restoration practice, but there is considerable room for greater integration between academic scientists and restoration practitioners. [source] Commercial Runner peanut cultivars in the USA: Fatty acid compositionEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 2 2010Eui-Cheol Shin Abstract Though peanuts are classified as a high-fat food, they possess good proportions of fatty acids deemed as heart healthy. The fatty acid compositions of Runner peanuts were determined for commercially grown cultivars over two recent crop years. GC-FID analyses revealed that the fatty acid levels for Runner peanuts were significantly (p,<0.05) different among the normal, mid-, and high-oleic peanuts investigated. Oleic acid-to-linoleic acid (O/L) ratios were found to be 1.93,±,0.30, 5.25,±,1.12, and 16.9,±,5.20 for normal, mid-, and high-oleic peanut lipids, respectively. Tamrun OL01 possessed a fatty acid profile characteristic of a mid-oleic cultivar. From the sample set (n,=,151), mean %,weights for oleic acid and linoleic acid were 52.09,±,2.84 and 27.38,±,2.60 in normal, 69.33,±,3.18 and 13.66,±,2.35 in mid-oleic, and 78.45,±,2.05 and 5.11,±,1.67 in high-oleic peanuts, respectively. Cluster analysis segregated cultivars based on fatty acids into normal, mid-, and high-oleic groups. Factorial analysis revealed that cultivar effects were significant (p,<0.01) for all fatty acids, except for lignoceric acid. Cultivar effects were also highly significant (p,<0.001) for O/L, IV, unsaturated/saturated fatty acid (U/S) ratio, and %,saturation. Significant crop year effects were shown for palmitic, oleic, arachidic, gondoic, and lignoceric acids, as well as U/S ratio and %,saturation. Healthy unsaturated fats accounted for ,80% in all crop years and cultivars. [source] Fine root dynamics in a loblolly pine forest are influenced by free-air-CO2 -enrichment: a six-year-minirhizotron studyGLOBAL CHANGE BIOLOGY, Issue 3 2008SETH G. PRITCHARD Abstract Efforts to characterize carbon (C) cycling among atmosphere, forest canopy, and soil C pools are hindered by poorly quantified fine root dynamics. We characterized the influence of free-air-CO2 -enrichment (ambient +200 ppm) on fine roots for a period of 6 years (Autumn 1998 through Autumn 2004) in an 18-year-old loblolly pine (Pinus taeda) plantation near Durham, NC, USA using minirhizotrons. Root production and mortality were synchronous processes that peaked most years during spring and early summer. Seasonality of fine root production and mortality was not influenced by atmospheric CO2 availability. Averaged over all 6 years of the study, CO2 enrichment increased average fine root standing crop (+23%), annual root length production (+25%), and annual root length mortality (+36%). Larger increase in mortality compared with production with CO2 enrichment is explained by shorter average fine root lifespans in elevated plots (500 days) compared with controls (574 days). The effects of CO2 -enrichment on fine root proliferation tended to shift from shallow (0,15 cm) to deeper soil depths (15,30) with increasing duration of the study. Diameters of fine roots were initially increased by CO2 -enrichment but this effect diminished over time. Averaged over 6 years, annual fine root NPP was estimated to be 163 g dw m,2 yr,1 in CO2 -enriched plots and 130 g dw m,2 yr,1 in control plots (P= 0.13) corresponding to an average annual additional input of fine root biomass to soil of 33 g m,2 yr,1 in CO2 -enriched plots. A lack of consistent CO2× year effects suggest that the positive effects of CO2 enrichment on fine root growth persisted 6 years following minirhizotron tube installation (8 years following initiation of the CO2 fumigation). Although CO2 -enrichment contributed to extra flow of C into soil in this experiment, the magnitude of the effect was small suggesting only modest potential for fine root processes to directly contribute to soil C storage in south-eastern pine forests. [source] Seabird predation by great skuas Stercorarius skua, intra-specific competition for food?JOURNAL OF AVIAN BIOLOGY, Issue 2 2007Stephen C. Votier Competition for food is widely cited as an important cost of coloniality among birds and much of the evidence in support of this hypothesis comes from studies of colonial piscivorous seabirds. However, for generalist seabirds able to switch between different prey types, the role of food availability in relation to colony size is unclear. Here we investigate patterns of the consumption of seabird prey in relation to colony size in a generalist seabird, the great skua Stercorarius skua, in Shetland, UK. At the population level skuas feed mainly on sandeels Ammodytes marinus and fishery discards, but respond to declines in fish availability to facultatively prey on other seabirds. By comparing the consumption of seabirds among seven different sized colonies, including one colony with artificially reduced numbers of skuas (Fair Isle), we investigate whether consumption of seabird prey is influenced by skua population size, while simultaneously measuring seabird prey availability. Data from five years also enables us to investigate the influence of annual variation in environmental conditions on seabird consumption. Using measures of body condition and reproductive performance we investigate the consequences of living in different sized colonies, which may provide insight into ultimate costs of nesting at high population density. Skua diets varied among colonies and the proportion of seabird prey in the diet was inversely related to skua colony size, despite similar per capita numbers of seabirds across colonies. At the colony where their numbers were artificially suppressed, skuas consumed a greater proportion of seabirds per capita. Highly significant year effects in seabird predation were observed but the pattern among colonies remained consistent over time. Two measures of adult body condition (pectoral muscle index and mean corpuscular volume) revealed that adult great skuas were in poorer condition at the largest colony (Foula), but reproductive performance did not alter significantly among colonies. This study provides evidence that intra-specific competition among skuas may limit opportunities for obtaining seabird prey, which may be particularly important during periods of poor availability of sandeels and fishery discards, and has implications for assessing the impact of skuas on seabird populations. [source] Genetic and environmental effects on morphology and fluctuating asymmetry in nestling barn swallowsJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 3 2000Cadée A barn swallow Hirundo rustica partial cross-fostering experiment with simultaneous brood size manipulation was conducted in two years with contrasting weather conditions, to estimate heritable variation in tarsus, tail and wing size and fluctuating asymmetry. Environmental stress had contrasting effects depending on trait type. Significant heritabilities for tarsus, tail and wing size were found only in enlarged broods irrespective of year effects, while tarsus asymmetry was significantly heritable in the year with benign weather conditions irrespective of brood size manipulation effects. Tail, wing and composite (multicharacter) asymmetry were never significantly heritable. The environment with the higher heritability generally had higher additive genetic variance and lower environmental variance, irrespective of trait type. Heritability was larger for trait size than for trait asymmetry. Patterns of genetic variation in nestlings do not necessarily translate to the juvenile or adult stage, as indicated by lack of correlation between nestling and fledgling traits. [source] The Impact of Income on the Taste for RevoltAMERICAN JOURNAL OF POLITICAL SCIENCE, Issue 4 2004Robert MacCulloch The question of how the level of development affects revolutionary support in society is of fundamental importance. One approach to provide an answer has been to study the relationship between actual civil conflict and income at the national level. This article takes a different approach. It uses microdata sets based on surveys of revolutionary support across one-quarter of a million people and identifies how the responses vary with their incomes. We find that a rise in GDP of $US 1,600 per capita in 2001 values decreases the chances of supporting revolt by 2.4 percentage points which represents a 41% drop in the proportion of people wanting a revolution. For a person who jumps from the bottom to top income quartile within their country, the probability declines by a similar amount. The results are robust to controlling for country and year effects, country-specific time trends and take account of the potential endogeneity of GDP. [source] | ||||||||||