bluuebunny/crossref_metadata_2025_split huggingface dataset:
Potential indirect effects of shellfish culture on the reproductive success of benthic predators
Authors: Inglis Graeme J. , Gust Nick 
Published: December 2003

Summary

Environmental assessments of coastal aquaculture are concerned mostly with direct impacts on natural assemblages in the vicinity of shellfish or fin‐fish farms. As the size and density of farmed sea space increases, there is greater potential for indirect effects on food webs beyond the immediate culture area.
We investigated the potential indirect effects of long‐line mussel Perna canaliculus farms on the demography of an important benthic predator, the sea star Coscinasterias muricata. Surveys beneath four active farms, an abandoned farm and three unfarmed areas of seabed in Pelorus Sound, New Zealand, described the direct effects of mussel culture on the distribution and abundance of sea stars and other benthic consumers. These data were used to calibrate a model that simulated the fertilization success of sea star populations in farmed and unfarmed areas of the bays.
Deposits of living mussels and mussel shells covered up to 55% of the seafloor beneath farm sites, but were absent from soft sediments at unfarmed sites. Mean densities of sea stars were up to 39 times larger at active farm sites than in unfarmed areas and were correlated with the abundance of living mussels on the seafloor.
Within individual farms, the distribution of sea stars was highly aggregated at small spatial scales, with most (63%) individuals occurring within 2 m of their nearest neighbour. In unfarmed areas, sea stars were widely dispersed (< 1 80 m−2).
Our simulations indicate that, because of the extremely clumped distributions of sea stars, spawning individuals at farm sites would on average have substantially greater fertilization success (c. 90% of eggs) than those foraging in areas where farms are absent (<< 2% of eggs), and total zygote production could be as much as 1500 times greater than in unfarmed areas.
Synthesis and applications. This study demonstrates the potential for significant bottom‐up effects of aquaculture on surrounding ecological assemblages. If, as has been suggested, sperm limitation is a major constraint on recruitment of asteroids and other invertebrate predators, supplemental provisioning from increased farm development could result in occasional outbreaks of populations, over a broader area than the farmed location. Without appropriate monitoring such events are likely to be dismissed as rare, natural phenomena rather than a consequence of shellfish culture.
Dung and nest surveys: estimating decay rates
Authors: Laing S. E. , Buckland S. T. , Burn R. W. , Lambie D. , Amphlett A. 
Published: December 2003

SummaryWildlife managers often require estimates of abundance. Direct methods of estimation are often impractical, especially in closed‐forest environments, so indirect methods such as dung or nest surveys are increasingly popular.Dung and nest surveys typically have three elements: surveys to estimate abundance of the dung or nests; experiments to estimate the production (defecation or nest construction) rate; and experiments to estimate the decay or disappearance rate. The last of these is usually the most problematic, and was the subject of this study.The design of experiments to allow robust estimation of mean time to decay was addressed. In most studies to date, dung or nests have been monitored until they disappear. Instead, we advocate that fresh dung or nests are located, with a single follow‐up visit to establish whether the dung or nest is still present or has decayed.Logistic regression was used to estimate probability of decay as a function of time, and possibly of other covariates. Mean time to decay was estimated from this function.Synthesis and applications.Effective management of mammal populations usually requires reliable abundance estimates. The difficulty in estimating abundance of mammals in forest environments has increasingly led to the use of indirect survey methods, in which abundance of sign, usually dung (e.g. deer, antelope and elephants) or nests (e.g. apes), is estimated. Given estimated rates of sign production and decay, sign abundance estimates can be converted to estimates of animal abundance. Decay rates typically vary according to season, weather, habitat, diet and many other factors, making reliable estimation of mean time to decay of signs present at the time of the survey problematic. We emphasize the need for retrospective rather than prospective rates, propose a strategy for survey design, and provide analysis methods for estimating retrospective rates.
Abundance and composition of plant species along grazing gradients in Australian rangelands
Authors: Landsberg J. , James C. D. , Morton S. R. , Müller W. J. , Stol J. 
Published: December 2003

Summary

The widespread provision of livestock drinking water in previously dry Australian rangelands has supported concomitant increases in cumulative grazing pressure. While the associated impacts on plants of pastoral importance have been well documented, far less is known about the rest of the flora.
To address this deficiency, we measured the frequency of occurrence of all plant species at sites along water‐centred grazing gradients in commercial paddocks located in the rangelands of central and southern Australia. Four gradients were in chenopod shrubland vegetation, and four in acacia woodlands. Each gradient extended to a reference site remote from all waters, where grazing by stock was minimal. Five further sites were sampled along each gradient, at locations progressively closer to the gradient's watering point.
Ground‐layer species far outnumbered those in upper layers (466 and 134, respectively). Most were geographically localized (72% found at one gradient only) and locally uncommon (46% per gradient occurred with a frequency < 5% per site).
Species showing trends of decreasing frequency with proximity to water significantly outnumbered those showing increasing trends. Significantly more species that were recorded only once occurred at the sites furthest from water, where long‐term grazing pressure was least. Some gradients also showed an overall decline in species richness with increasing proximity to water.
Most species were native, and among these there were no clearly identifiable ‘global winners’ (i.e. no widespread species advantaged by grazing and associated disturbances). In contrast, the majority of the few exotic species, including two of the three most widespread species found, showed increasing abundance with proximity to watering points.
Synthesis and applications. The results from this study indicate consistent and substantial changes in plant composition that are probably related to the accumulated long‐term impacts of water‐centred grazing. The consequences are potentially severe, because artificial watering points are now extremely widespread in the Australian rangelands. Identification and protection of representative, water‐remote refugia for the most grazing‐sensitive species should therefore be a high priority for regional conservation.
The effects of the intensification of agriculture on northern temperate dung beetle communities
Authors: Hutton Stephen A. , Giller Paul S. 
Published: December 2003

SummaryThere is growing concern that the intensification of agriculture within southern Ireland is having detrimental effects on Irish fauna through habitat loss, reduction in biodiversity and pollution‐related events. To assess the impact of farm management on one group of important insects, the dung beetles, their abundance, biomass, diversity and species richness were examined using dung‐baited pitfall traps in intensive, organic and rough grazing farms.We collected 39 631 dung beetles belonging to 24 different species. Eight species (Aphodius prodromus,A. sphacelatus,A. ater,A. rufipes,A. depressus,Sphaeridium lunatum,S. scarabaeoidesandMargarinotus carbonarius) accounted for 94% of the captures, but their relative dominance varied with farm type. 54% of total individuals captured were from organic sites, 30% from intensive sites and 16% from rough grazing sites.Organic farms had significantly greater beetle biomass, diversity and species richness compared to intensive and rough grazing farms.Aphodiusabundance on organic farms was significantly greater than on intensive and rough grazing farms in spring and autumn.Aphodiusbiomass on organic farms was significantly greater than on rough grazing farms in spring, late summer and autumn, and greater in autumn compared with intensive farms.A colonization experiment demonstrated that the variation in dung beetle abundance among different dung types depended on the farm type. This was not true for beetle biomass colonizing dung pads, where variation among different dung types and different farm types were independent. Multiple comparisons showed that under rough grazing and intensive management there was significantly greater beetle abundance and biomass found in dung from organic and intensive farms than from rough grazing farms. Dung from organic farms held a significantly greater beetle biomass than the intensive and rough grazing dung.Synthesis and applications. Intensive agricultural management including the use of chemical fertilisers, veterinary drugs (e.g. ivermectin) and removal of herbaceous field boundaries could be detrimental to dung beetle biodiversity and dung decomposition. Organic farming has beneficial effects on dung beetle communities. Patchy ecosystems characterized by a diversity of ungulate species increase dung beetle diversity and hence improve dung decomposition.
Predicting the response of farmland bird populations to changing food supplies
Authors: Stephens Philip A. , Freckleton Robert P. , Watkinson Andrew R. , Sutherland William J. 
Published: December 2003

SummaryAgricultural developments over recent decades have had significant negative effects on wildlife. Modern European agriculture faces many further developments in technology, finances and climate. A framework for predicting the consequences of these developments and for informing management that mitigates previous depredation of wildlife is essential.Field trials, monitoring and experimental approaches are all invaluable tools for predicting the consequences of proposed agricultural practices. However, such trials are time‐consuming and expensive, with limited spatial and temporal scope. Increasingly, it is recognized that predictive modelling using computer simulations is essential for assessing the likely impacts of novel management practices.Many agricultural developments are likely to have impacts on the availability of food for farmland wildlife. In this paper, we review modelling techniques that are available for predicting the consequences of changing food supplies for farmland birds, a group already shown to be sensitive to agricultural management.We focus on two broad types of simulation modelling: phenomenological approaches (using aggregative responses or full population models), and behavioural depletion models (including daily ration and functional response approaches). We assess the strengths and weaknesses of each, particularly with regard to available data.We conclude that given the constraints on current information, daily ration models probably represent the most useful form of simulation modelling for farmland birds. Few phenomenological population models link demography explicitly to food supply and collecting data on these links should be a priority of autecological studies. More empirical data on aggregative and functional responses is needed to identify the generality of these functions, and to confront uncertainties in their use.Synthesis and applications.Modelling techniques available for predicting the consequences of changing food supply for farmland birds have largely outstripped the availability of data required to parameterize them. We recommend the best available techniques given current constraints on data. Predictive models of biodiversity response should be more widely used when considering proposals for agricultural developments or agri‐environment schemes. Models will provide a basis for selecting between competing proposals, whilst their widespread usage will both permit more frequent model validation and aid in model development.
Soil seed banks and the potential restoration of forested wetlands after farming
Authors: Middleton Beth A. 
Published: December 2003

SummaryChanges in farming practice provide an opportunity to restore once extensive forested wetlands on agricultural land. In some parts of the world, however, it has proved difficult to restore the full complement of plant species through natural regeneration. Similarly, the restoration of forested wetlands by replanting has often resulted in ecosystems of low diversity. Better methods of restoring these important ecosystems are now required and baldcypress swamps provide an opportunity to investigate alternative approaches to the restoration of forested wetlands. This study examined the composition of seed banks of farmed fields to determine their value in restoring swamps in the south‐eastern United States.A seed bank assay of soils from baldcypress swamps was conducted to determine the extent to which seeds are maintained during farming for various lengths of time. Soils from swamps that were farmed for 0–50 years were collected near the northern boundary of the Mississippi Alluvial Valley along the Cache River, Illinois. Soils were placed in a glasshouse setting in flooded and freely drained conditions, and the numbers and species of seeds germinating were recorded.Woody species including trees, shrubs, and vines were poorly represented in seed banks of both farmed and intact sites (51 and 9 sites, respectively). Missing dominants in the seed banks included tree species with short‐lived seeds such asTaxodium distichumandNyssa aquatica.Cephalanthus occidentalisconstituted the most abundantly dispersed seed of all woody species.Herbaceous species were well represented in the seed banks of both farmed and intact swamps (species richness of 207 vs. 173 species, respectively) suggesting that herbaceous species may live longer than woody species in seed banks. Few of the herbaceous species decreased in seed density in seed banks with time under cultivation, although seed density was lower at sites that had not been farmed. Species that relied on vegetative organs for dispersal were absent in the seed banks of farmed sites includingHeteranthera dubia,Hottonia inflata,Lemna minor,Lemna trisulcaandWolffia columbiana. These species may require active reintroduction during restoration.Synthesis and applications.Both restoration ecologists and managers of nature conservation areas need to be cognisant of seed bank and dispersal characteristics of species to effectively restore and manage forested wetlands. In the case of baldcypress swamps, critical components of the vegetation are not maintained in seed banks, which may make these floodplain wetlands difficult to restore via natural recolonization. Ultimately, the successful restoration of abandoned farm fields to forested wetlands may depend on the re‐engineering of flood pulsing across landscapes to reconnect dispersal pathways.
Meeting the ecological challenges of agricultural change: editors’ introduction
Authors: Ormerod S. J. , Marshall E. J. P. , Kerby Gillian , Rushton S. P. 
Published: December 2003

Summary

The global need for agricultural production has never been greater. Nor has it ever been more complex due to the needs to balance global food security, optimum production, technological innovation, the preservation of environmental functions and the protection of biodiversity. The role of ecologists in finding this balance is pivotal.
In support of this role, ecologists now have very substantial experience of agricultural systems. We can understand, recognize and sometimes predict, at least qualitatively, the effects of pesticide applications, fertilizer use, drainage, crop choices and habitat modifications on farmland organisms, agro‐ecosystems or other ecosystems influenced by agricultural land.
In instances of greater uncertainty, for example under changing climates, where environmental stresses on ecosystems are interactive, and where ecosystem management or restoration must adapt to new technologies, the investigative skills and experience of ecologists are even more crucial in problem solving.
There are, nevertheless, contrasting examples of good and bad practice in knowledge‐transfer between ecologists and the communities who need our knowledge. The UK farm‐scale evaluations of genetically modified crops, for example, involved ecologists at all stages from design and data collection to advocating policy. By contrast, many European agri‐environment projects appear to have been developed and evaluated with only modest ecological advice. We advocate fuller involvement of ecologists in the development and evaluation of the European Union Common Agricultural Policy.
This special profile of seven agriculturally related papers illustrates effectively the array of approaches used by applied ecologists in addressing agricultural questions: modelling, meta‐analysis, surveys, transect studies, classical experiments, seedbank assays and process studies based on modern ecological methods. With over 20% of recent papers in the Journal of Applied Ecology reflecting agricultural issues, agro‐ecology continues to represent one of the pre‐eminent areas of applied ecology that is unlikely to diminish in importance.
Monetary Policy Announcements and Money Markets: A Transatlantic Perspective
Authors: Ehrmann Michael , Fratzscher Marcel 
Published: December 2003

AbstractThis paper investigates how money markets in the USA, Germany (up to 1998) and the euro area (since 1999) react to monetary policy announcements by the Federal Reserve, Bundesbank and ECB. We find that interest rates respond strongly to domestic monetary policy throughout, whereas the response to foreign monetary policy varies across markets and over time: both the German and the euro area market react to Federal Reserve announcements, whereas US markets do not generally respond to European monetary policy. Whereas announcements by the Bundesbank increased the volatility of German money markets, such effects are rarely found for the ECB, and have basically disappeared for the Federal Reserve. Moreover, the general linkage of money markets has increased considerably over time: interest rate developments and volatility in either the USA or the euro area are generally mirrored in the other market to a much larger extent than prior to EMU. We interpret these results as evidence that euro area and US markets not only have become more interdependent over time, but that the markets' understanding and anticipation of monetary policy decisions have improved over time.
Standing Facilities and Interbank Borrowing: Evidence from the Federal Reserve's New Discount Window
Authors: Furfine Craig 
Published: December 2003

AbstractStanding facilities are designed to place an upper bound on the rates at which financial institutions lend to one another overnight, reducing the volatility of the overnight interest rate, typically the rate targeted by central banks. However, improper design of the facility might decrease a bank's incentive to participate actively in the interbank market. Thus, the mere availability of central‐bank‐provided credit may lead to its use being greater than what would be expected based on the characteristics of the interbank market. By contrast, however, banks may perceive a stigma from using such facilities, and thus borrow less than what one might expect, thereby reducing the facilities' effectiveness at reducing interest rate volatility. We develop a model demonstrating these two alternative implications of a standing facility. Empirical predictions of the model are then tested using data from the Federal Reserve's new primary credit facility and the US federal funds market. A comparison of data from before and after recent changes to the discount window suggests continued reluctance to borrow from the Federal Reserve.
Forecast‐Based Monetary Policy: The Case of Sweden
Authors: Jansson Per , Vredin Anders 
Published: December 2003

AbstractCentral banks are dominant players in financial markets and economic policy. For both democratic and efficiency reasons, it is important that central banks' actions can be understood, predicted, and evaluated. Inflation‐targeting central banks that publish their forecasts provide unique opportunities for detailed studies of monetary policy based on real‐time data. This paper demonstrates how a central bank's forecasts can be used to identify two different forms of discretionary monetary policy: ‘policy shocks’ (deviations from systematic policy) and ‘judgements’ in forecasting.
Does Exchange Rate Policy Matter for Growth?
Authors: Bailliu Jeannine , Lafrance Robert , Perrault Jean‐François 
Published: December 2003

AbstractPrevious studies on whether the nature of the exchange rate regime influences a country's medium‐term growth performance have been based on a tripartite classification scheme that distinguishes between pegged, intermediate and flexible exchange rate regimes. This classification scheme, however, leads to a situation where two of the categories (intermediate and flexible) characterize solely the exchange rate regime, whereas the third (pegged) characterizes both the exchange rate regime and the monetary policy framework. Our study refines this classification scheme by accounting for different monetary policy frameworks, classifying monetary arrangements based on the presence of an explicit monetary policy ‘anchor’, such as the exchange rate or other targeted nominal variable. We estimate the impact of exchange rate arrangements on growth in a panel‐data set of 60 countries over the period 1973–1998. We find evidence that exchange rate regimes characterized by a monetary policy anchor, whether they are pegged, intermediate, or flexible, exert a positive influence on economic growth. We also find evidence that intermediate/flexible regimes without an anchor are detrimental for growth. Our results thus suggest that it is the presence of a monetary policy anchor, rather than the type of exchange rate regimeper se, that is important for economic growth. Furthermore, our work emphasizes the importance of considering the monetary policy framework that accompanies the exchange rate arrangement when assessing the macroeconomic performance of alternative exchange rate regimes.
Do Collective Action Clauses Influence Bond Yields? New Evidence from Emerging Markets
Authors: Richards Anthony , Gugiatti Mark 
Published: December 2003

AbstractThis paper provides empirical evidence relevant to the debate over the desirability of reforms to the way that financial markets and the international community deal with sovereign debt crises. We present new evidence showing that the use of collective action clauses (CACs) in sovereign emerging markets issuance has been wider than previously believed. In addition, we provide results on the way that financial markets have priced the use or non‐use of CACs, both before and after the path‐breaking issue by Mexico in February 2003. We interpret recent developments as indicating that US investors now accept that the use of well‐designed CACs is not inconsistent with protection of creditor rights.