Browsing by Subject "recruitment"

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    Fisheries management under climate and environmental uncertainty: control rules and performance simulation
    (Oxford University Press, 2014) Punt, Andre´ E; A’mar, Teresa; Bond, Nicholas A; Butterworth, Doug S; de Moor, Carryn L; De Oliveira, Jose´ A A; Haltuch, Melissa A; Hollowed, Anne B; Szuwalski, Cody
    The ability of management strategies to achieve the fishery management goals are impacted by environmental variation and, therefore, also by global climate change. Management strategies can be modified to use environmental data using the “dynamic B0” concept, and changing the set of years used to define biomass reference points. Two approaches have been developed to apply management strategy evaluation to evaluate the impact of environmental variation on the performance of management strategies. The “mechanistic approach” estimates the relationship between the environment and elements of the population dynamics of the fished species and makes predictions for population trends using the outputs from global climate models. In contrast, the “empirical approach” examines possible broad scenarios without explicitly identifying mechanisms. Many reviewed studies have found that modifying management strategies to include environmental factors does not improve the ability to achieve management goals much, if at all, and only if the manner in which these factors drive the system is well known. As such, until the skill of stock projection models improves, it seems more appropriate to consider the implications of plausible broad forecasts related to how biological parameters may change in the future as a way to assess the robustness of management strategies, rather than attempting specific predictions per se.
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    The Evolutionary Ecology of Sprouting in Woody Plants
    (2003) Bond, William J; Midgley, Jeremy J
    Woody plants may be killed by severe disturbance or resprout from vegetative tissue. Sprouters can persist at a site through several generations of nonsprouters. Differences in sprouting behavior are therefore important for understanding vegetation dynamics, extinction risks, and woody plant management. Although sprouting appears not to be uniquely correlated with many other intrinsic attributes, such as specific leaf area or breeding systems, a clear correlate is reduced seedling aboveground growth rates from sprouters allocating more to belowground structures. Consequently, sprouters tend to have low seedling recruitment rates, and saplings take longer to reach maturity. Sprouters also tend to have lower seed output than nonsprouters, but comparative studies have seldom taken other trait differences such as plant size into account. Added to these trade-offs between persistence and recruitment, sprouters are often multi stemmed and shorter than related nonsprouters and may be outcompeted by them when disturbances are rare. Since sprouters tend to have long generation times, damped demographic trends, and gene flow across generations, it has been suggested that their speciation rates would be low. The available data, primarily from fire-prone Gondwanan shrublands in South Africa, show no strong differences in speciation rates of related sprouters versus seeders. This indicates that ecological factors are important determinants of the evolution of fire life