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Competitive Balance (competitive + balance)
Selected AbstractsTHE ECONOMICS OF ACHIEVING COMPETITIVE BALANCE IN THE AUSTRALIAN FOOTBALL LEAGUE, 1897,2004ECONOMIC PAPERS: A JOURNAL OF APPLIED ECONOMICS AND POLICY, Issue 4 2004Ross Booth This paper summarises some key aspects of a theoretical and empirical analysis of whether various labour market devices and revenue-sharing rules used in the Victorian Football League/Australian Football League (VFL/AFL) since its inception in 1897 have increased competitive balance by reducing the inequality in the distribution of player talent between clubs. The history of labour market intervention and revenue sharing in the VFL/AFL is discussed, with six different periods between 1897 and 2004 identified for analysis. Fort and Quirk's (1995) model of US professional team sports leagues is used to analyse the effectiveness of the various devices that have been used in the VFL/AFL, but only after adapting the model to allow for VFL/AFL clubs being win maximisers (subject to a budget constraint) rather than profit maximisers. The various devices used by the VFL/AFL are assessed in terms of their likely impact on competitive balance, with some significantly different theoretical predictions than under profit maximisation. It is found that free agency results in a less equal distribution of player talent under win maximisation, whilst both gate sharing and increases in shared league-revenue tend to equalise playing strengths (which is not the case under profit maximisation). Moreover, the invariance principle, that the effect of a player draft will be undermined by the sale (and/or trade) of player talent, is found not necessarily to hold under win maximisation and can be reduced or eliminated with a team salary cap. Whether the trade of players and draft choices can undermine a player draft is also considered. The conclusion reached is that a player draft, a team salary cap, and revenue sharing is the combination most likely to succeed in achieving higher levels of competitive balance. The evidence of competitive balance in the VFL/AFL is consistent with these predictions. [source] Phorid fly parasitoids of invasive fire ants indirectly improve the competitive ability of a native antECOLOGICAL ENTOMOLOGY, Issue 5 2004Natasha J. Mehdiabadi Abstract., 1.,The red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae), is an invasive species of south-eastern U.S.A. Since its introduction from South America approximately 70 years ago, this pest has devastated natural biodiversity. 2.,Due to such ecological costs, Pseudacteon phorid fly parasitoids (Diptera: Phoridae) from South America are being introduced into the U.S.A. as a potential biological control agent. Here, the indirect effects of these specialised parasitoids on an interspecific native ant competitor, Forelius mccooki (Hymenoptera: Formicidae), are evaluated. 3.,Over the course of a 50-day laboratory experiment, the results show that the native ant improved aspects of exploitative, but not interference, competition when S. invicta -attacking flies were present compared with when they were absent. 4.,Forelius mccooki colonies from the phorid treatment had approximately twice as many foragers at food baits relative to controls; however, there was no significant difference in interference aspects of competition or native ant colony growth between the two treatments. 5.,These results suggest that the S. invicta -specialised parasitoids help shift the competitive balance more in favour of F. mccooki than if these flies were not present; however, this competitive advantage does not translate into increased colony growth after 50 days. These laboratory findings are interpreted with regard to the more complex interactions in the field. [source] THE ECONOMICS OF ACHIEVING COMPETITIVE BALANCE IN THE AUSTRALIAN FOOTBALL LEAGUE, 1897,2004ECONOMIC PAPERS: A JOURNAL OF APPLIED ECONOMICS AND POLICY, Issue 4 2004Ross Booth This paper summarises some key aspects of a theoretical and empirical analysis of whether various labour market devices and revenue-sharing rules used in the Victorian Football League/Australian Football League (VFL/AFL) since its inception in 1897 have increased competitive balance by reducing the inequality in the distribution of player talent between clubs. The history of labour market intervention and revenue sharing in the VFL/AFL is discussed, with six different periods between 1897 and 2004 identified for analysis. Fort and Quirk's (1995) model of US professional team sports leagues is used to analyse the effectiveness of the various devices that have been used in the VFL/AFL, but only after adapting the model to allow for VFL/AFL clubs being win maximisers (subject to a budget constraint) rather than profit maximisers. The various devices used by the VFL/AFL are assessed in terms of their likely impact on competitive balance, with some significantly different theoretical predictions than under profit maximisation. It is found that free agency results in a less equal distribution of player talent under win maximisation, whilst both gate sharing and increases in shared league-revenue tend to equalise playing strengths (which is not the case under profit maximisation). Moreover, the invariance principle, that the effect of a player draft will be undermined by the sale (and/or trade) of player talent, is found not necessarily to hold under win maximisation and can be reduced or eliminated with a team salary cap. Whether the trade of players and draft choices can undermine a player draft is also considered. The conclusion reached is that a player draft, a team salary cap, and revenue sharing is the combination most likely to succeed in achieving higher levels of competitive balance. The evidence of competitive balance in the VFL/AFL is consistent with these predictions. [source] Interactive effects of water table and precipitation on net CO2 assimilation of three co-occurring Sphagnum mosses differing in distribution above the water tableGLOBAL CHANGE BIOLOGY, Issue 3 2009BJORN J. M. ROBROEK Abstract Sphagnum cuspidatum, S. magellanicum and S. rubellum are three co-occurring peat mosses, which naturally have a different distribution along the microtopographical gradient of the surface of peatlands. We set out an experiment to assess the interactive effects of water table (low: ,10 cm and high: ,1 cm) and precipitation (present or absent) on the CO2 assimilation and evaporation of these species over a 23-day period. Additionally, we measured which sections of the moss layer were responsible for light absorption and bulk carbon uptake. Thereafter, we investigated how water content affected carbon uptake by the mosses. Our results show that at high water table, CO2 assimilation of all species gradually increased over time, irrespective of the precipitation. At low water table, net CO2 assimilation of all species declined over time, with the earliest onset and highest rate of decline for S. cuspidatum. Precipitation compensated for reduced water tables and positively affected the carbon uptake of all species. Almost all light absorption occurred in the first centimeter of the Sphagnum vegetation and so did net CO2 assimilation. CO2 assimilation rate showed species-specific relationships with capitulum water content, with narrow but contrasting optima for S. cuspidatum and S. rubellum. Assimilation by S. magellanicum was constant at a relatively low rate over a broad range of capitulum water contents. Our study indicates that prolonged drought may alter the competitive balance between species, favoring hummock species over hollow species. Moreover, this study shows that precipitation is at least equally important as water table drawdown and should be taken into account in predictions about the fate of peatlands with respect to climate change. [source] Where temperate meets tropical: multi-factorial effects of elevated CO2, nitrogen enrichment, and competition on a mangrove-salt marsh communityGLOBAL CHANGE BIOLOGY, Issue 5 2008KAREN L. McKEE Abstract Our understanding of how elevated CO2 and interactions with other factors will affect coastal plant communities is limited. Such information is particularly needed for transitional communities where major vegetation types converge. Tropical mangroves (Avicennia germinans) intergrade with temperate salt marshes (Spartina alterniflora) in the northern Gulf of Mexico, and this transitional community represents an important experimental system to test hypotheses about global change impacts on critical ecosystems. We examined the responses of A. germinans (C3) and S. alterniflora (C4), grown in monoculture and mixture in mesocosms for 18 months, to interactive effects of atmospheric CO2 and pore water nitrogen (N) concentrations typical of these marshes. A. germinans, grown without competition from S. alterniflora, increased final biomass (35%) under elevated CO2 treatment and higher N availability. Growth of A. germinans was severely curtailed, however, when grown in mixture with S. alterniflora, and enrichment with CO2 and N could not reverse this growth suppression. A field experiment using mangrove seedlings produced by CO2 - and N-enriched trees confirmed that competition from S. alterniflora suppressed growth under natural conditions and further showed that herbivory greatly reduced survival of all seedlings. Thus, mangroves will not supplant marsh vegetation due to elevated CO2 alone, but instead will require changes in climate, environmental stress, or disturbance to alter the competitive balance between these species. However, where competition and herbivory are low, elevated CO2 may accelerate mangrove transition from the seedling to sapling stage and also increase above- and belowground production of existing mangrove stands, particularly in combination with higher soil N. [source] Climate change can alter competitive relationships between resident and migratory birdsJOURNAL OF ANIMAL ECOLOGY, Issue 6 2007MARKUS P. AHOLA Summary 1Climate change could affect resource competition between resident and migratory bird species by changing the interval between their onsets of breeding or by altering their population densities. 2We studied interspecific nest-hole competition between resident great tits and migrant pied flycatchers in South-Western Finland over the past five decades (1953,2005). 3We found that appearance of fatal take-over trials, the cases where a pied flycatcher tried to take over a great tit nest but was killed by the tit, increased with a reduced interspecific laying date interval and with increasing densities of both tits and flycatchers. The probability of pied flycatchers taking over great tit nests increased with the density of pied flycatchers. 4Laying dates of the great tit and pied flycatcher are affected by the temperatures of different time periods, and divergent changes in these temperatures could consequently modify their competitive interactions. Densities are a result of reproductive success and survival, which can be affected by separate climatic factors in the resident great tit and trans-Saharan migrant pied flycatcher. 5On these bases we conclude that climate change has a great potential to alter the competitive balance between these two species. [source] Plant,soil feedback induces shifts in biomass allocation in the invasive plant Chromolaena odorataJOURNAL OF ECOLOGY, Issue 6 2009Mariska Te Beest Summary 1. ,Soil communities and their interactions with plants may play a major role in determining the success of invasive species. However, rigorous investigations of this idea using cross-continental comparisons, including native and invasive plant populations, are still scarce. 2. ,We investigated if interactions with the soil community affect the growth and biomass allocation of the (sub)tropical invasive shrub Chromolaena odorata. We performed a cross-continental comparison with both native and non-native-range soil and native and non-native-range plant populations in two glasshouse experiments. 3. ,Results are interpreted in the light of three prominent hypotheses that explain the dominance of invasive plants in the non-native range: the enemy release hypothesis, the evolution of increased competitive ability hypothesis and the accumulation of local pathogens hypothesis. 4. ,Our results show that C. odorata performed significantly better when grown in soil pre-cultured by a plant species other than C. odorata. Soil communities from the native and non-native ranges did not differ in their effect on C. odorata performance. However, soil origin had a significant effect on plant allocation responses. 5. ,Non-native C. odorata plants increased relative allocation to stem biomass and height growth when confronted with soil communities from the non-native range. This is a plastic response that may allow species to be more successful when competing for light. This response differed between native and non-native-range populations, suggesting that selection may have taken place during the process of invasion. Whether this plastic response to soil organisms will indeed select for increased competitive ability needs further study. 6. ,The native grass Panicum maximum did not perform worse when grown in soil pre-cultured by C. odorata. Therefore, our results did not support the accumulation of local pathogens hypothesis. 7. ,Synthesis. Non-native C. odorata did not show release from soil-borne enemies compared to its native range. However, non-native plants responded to soil biota from the non-native range by enhanced allocation in stem biomass and height growth. This response can affect the competitive balance between native and invasive species. The evolutionary potential of this soil biota-induced change in plant biomass allocation needs further study. [source] Influence of nests of leaf-cutting ants on plant species diversity in road verges of northern PatagoniaJOURNAL OF VEGETATION SCIENCE, Issue 3 2000A.G. Farji-Brener Correa (1969,1998) Abstract. It has been suggested that ant nests are the most frequent small-scale disturbance that affect vegetation patterns. However, their effects on plant diversity are little studied. We document effects of nests of the leaf-cutting ant Acromyrmex lobicornis on physical-chemical soil properties and their influence on plant diversity near road verges in a desert steppe in NW Patagonia, Argentina. We analysed nest soils and controls for nitrogen, phosphorus, organic matter, moisture retention capacity and texture. We also analysed the vegetation on 42 nests (30 active and 12 abandoned or without life) and 42 areas without nests. Soil around nests had a greater nutrient content and capacity to retain moisture than control soils, which is mainly due to the presence of organic waste that the ants deposit on the soil surface. We found no association between the occurrence of nests and specific groups of plants, but plant diversity was higher at nest-sites than at nearby non-nest sites. This increased diversity , which is also found on abandoned nests , is mainly due to the occurrence of a larger number of native and exotic plant species on nest-sites that are uncommon elsewhere in the study area. The most abundant plant species showed similar cover values at nest and non-nest sites. This suggests that changes in diversity are associated to edaphic changes caused by nests rather than by changes in competitive balance caused by dominant species exclusion. We propose that the nests of Acromyrmex lobicornis, through increasing the availability of resources, generate favourable microsites that can function both as ,refuges' for less frequent native species, and as,stepping stones' for less frequent exotic plant species. [source] College football conferences and competitive balanceMANAGERIAL AND DECISION ECONOMICS, Issue 2 2004James Quirk First page of article [source] Linking physiological traits to impacts on community structure and function: the role of root hemiparasitic Orobanchaceae (ex-Scrophulariaceae)JOURNAL OF ECOLOGY, Issue 1 2005G. K. PHOENIX Summary 1The hemiparasitic Orobanchaceae (ex-Scrophulariaceae) are characterized by a distinctive suite of ecophysiological traits. These traits have important impacts on host plants and non-host plants, and influence interactions with other trophic levels. Ultimately, they can affect community structure and functioning. Here, we review these physiological traits and discuss their ecological consequences. 2The root hemiparasitic Orobanchaceae form a convenient subset of the parasitic angiosperms for study because: they are the most numerous and most widely distributed group of parasitic angiosperms; their physiological characteristics have been well studied; they are important in both agricultural and (semi)natural communities; and they are tractable as experimental organisms. 3Key traits include: high transpiration rates; competition with the host for nutrients and haustorial metabolism of host-derived solutes; uptake of host-derived secondary metabolites; dual autotrophic and heterotrophic carbon nutrition; distinct carbohydrate biochemistry; high nutrient concentrations in green leaf tissue and leaf litter; and small (often hairless and non-mycorrhizal) roots. 4Impacts on the host are detrimental, which can alter competitive balances between hosts and non-hosts and thus result in community change. Further impacts may result from effects on the abiotic environment, including soil water status, nutrient cycling and leaf/canopy temperatures. 5However, for non-host species and for organisms that interact with these (e.g. herbivores and pollinators) or for those that benefit from changes in the abiotic environment, the parasites may have an overall positive effect, suggesting that at the community level, hemiparasites may also be considered as mutualists. 6It is clear that through their distinctive suite of physiological traits hemiparasitic Orobanchaceae, have considerable impacts on community structure and function, can have both competitive and positive interactions with other plants, and can impact on other trophic levels. Many community level effects of parasitic plants can be considered analogous to those of other parasites, predators or herbivores. [source] | ||||||||||