bluuebunny/crossref_metadata_2025 huggingface dataset:
Maturation feeding and reproductive development in adult pine weevil, Hylobius abietis (Coleoptera: Curculionidae)
Authors: Wainhouse D. , Boswell R. , Ashburner R.
Published: February 2004

Maturation feeding on conifer bark by newly emerged Hylobius abietis(Linnaeus) is essential for reproductive development. When feeding occurs on young conifer transplants, this weevil causes significant economic damage. Between emergence and oviposition however, weevils feed on bark from different sources but of unknown nutritional ‘quality’. The factors influencing the rate of feeding by males and females and female reproductive development were determined in laboratory bioassays using two contrasting food sources – the bark on different species of seedling conifer and on logs of mature trees. The nutritional ‘quality’ of bark was characterized by the concentration of nitrogen, total sugars, total polyphenols and resin. Regression models were used to show that overall, the rate of feeding on the bark of both seedlings and logs increased with weevil size and was negatively related to nitrogen concentration. The nitrogen concentration in seedling bark (mean 1.1%) was about three times higher than that of logs (mean 0.4%). The rate of reproductive development increased with nitrogen intake during feeding and the preoviposition period for weevils feeding on seedlings and logs was ~ 13 days and 46 days, respectively. Analysis of weevil mortality and of the weight gain of surviving weevils suggests that a nitrogen content of around 0.3% may be limiting for H. abietis. The possibility that nutritionally adequate food resources may be limiting for H. abietis is briefly discussed.
Nudel functions in membrane traffic mainly through association with Lis1 and cytoplasmic dynein
Authors: Liang Yun , Yu Wei , Li Yan , Yang Zhenye , Yan Xiumin , Huang Qiongping , Zhu Xueliang
Published: February 2004

Nudel and Lis1 appear to regulate cytoplasmic dynein in neuronal migration and mitosis through direct interactions. However, whether or not they regulate other functions of dynein remains elusive. Herein, overexpression of a Nudel mutant defective in association with either Lis1 or dynein heavy chain is shown to cause dispersions of membranous organelles whose trafficking depends on dynein. In contrast, the wild-type Nudel and the double mutant that binds to neither protein are much less effective. Time-lapse microscopy for lysosomes reveals significant reduction in both frequencies and velocities of their minus end–directed motions in cells expressing the dynein-binding defective mutant, whereas neither the durations of movement nor the plus end–directed motility is considerably altered. Moreover, silencing Nudel expression by RNA interference results in Golgi apparatus fragmentation and cell death. Together, it is concluded that Nudel is critical for dynein motor activity in membrane transport and possibly other cellular activities through interactions with both Lis1 and dynein heavy chain.
Exogenous Pathogen and Plant 15-Lipoxygenase Initiate Endogenous Lipoxin A4 Biosynthesis
Authors: Bannenberg Gerard L. , Aliberti Julio , Hong Song , Sher Alan , Serhan Charles
Published: February 2004

Lipoxin A4 (LXA4) is a potent endogenous lipoxygenase-derived eicosanoid with antiinflammatory and proresolving properties. Supraphysiological levels of LXA4 are generated during infection by Toxoplasma gondii, which in turn reduces interleukin (IL) 12 production by dendritic cells, thus dampening Th1-type cell-mediated immune responses and host immunopathology. In the present work, we sought evidence for the structural basis of T. gondii's ability to activate LXA4 biosynthesis. Proteomic analysis of T. gondii extract (soluble tachyzoite antigen [STAg]), which preserves the immunosuppressive and antiinflammatory activity of the parasite, yielded several peptide matches to known plant lipoxygenases. Hence, we incubated STAg itself with arachidonic acid and found using LC-UV-MS-MS–based lipidomics that STAg produced both 15-HETE and 5,15-diHETE, indicating that T. gondii carries 15-lipoxygenase activity. In addition, T. gondii tachyzoites (the rapidly multiplying and invasive stage of the parasite) generated LXA4 when provided with arachidonic acid. Local administration of a plant (soybean) lipoxygenase itself reduced neutrophilic infiltration in murine peritonitis, demonstrating that 15-lipoxygenase possesses antiinflammatory properties. Administration of plant 15-lipoxygenase generated endogenous LXA4 and mimicked the suppression of IL-12 production by splenic dendritic cells observed after T. gondii infection or STAg administration. Together, these results indicate that 15-lipoxygenase expressed by a pathogen as well as exogenously administered 15-lipoxygenase can interact with host biosynthetic circuits for endogenous “stop signals” that divert the host immune response and limit acute inflammation.
Noncoding Sequences Conserved in a Limited Number of Mammals in the SIM2 Interval are Frequently Functional
Authors: Frazer Kelly A. , Tao Heng , Osoegawa Kazutoyo , de Jong Pieter J. , Chen Xiyin , Doherty Mark F. , Cox David R.
Published: February 2004

Cross-species DNA sequence comparison is a fundamental method for identifying biologically important elements, because functional sequences are evolutionarily conserved, wheres nonfunctional sequences drift. A recent genome-wide comparison of human and mouse DNA discovered over 200,000 conserved noncoding sequences with unknown function. Multispecies DNA comparison has been proposed as a method to prioritize these conserved noncoding sequences for functional analysis based on the hypothesis that elements present in many species are more likely to be functional than elements present in limited numbers of species. Here, we perform a comparative analysis of the single-minded 2 (SIM2) gene interval on human chromosome 21 with horse, cow, pig, dog, cat, and mouse DNA. We classify conserved sequences based on the number of mammals in which they are present, and experimentally test sequences in each class for function. As hypothesized, conserved sequences present in many mammals are frequently functional. Additionally, we demonstrate that sequences conserved in a limited number of mammals are also frequently functional. Examination of genomic deletions in chimpanzee and rhesus macaque DNA showed that several putatively functional conserved noncoding human sequences were absent in these primates. These findings suggest that functional conserved noncoding human sequences can be missing in other mammals, even closely related primate species.
Age influences on the leadership styles and behaviour of managers
Authors: Oshagbemi Titus
Published: February 2004

This article explains reasons why the study of the relationship between leadership and age may be important and, using a questionnaire survey to collect data from over 400 UK managers, it identifies age influences on the leadership styles and behaviour of the managers. The findings suggest that younger and older managers have different profiles in their consultative and participative leadership styles. Older managers consulted more widely and favour more participation in comparison with younger managers. However the two groups of managers both practice directive and delegative leadership styles at about the same degree. On leadership behaviour, only idealised influence shows a significant F‐test between younger and older managers while the other measures show remarkable similarities between the two age groups. Some implications of the findings are discussed including the need to harmonise the positive contributions of both the younger and the older workers and giving respect to the contributions of both groups.
The myth of mutuality? Employee perceptions of partnership at Borg Warner
Authors: Suff Rachel , Williams Steve
Published: February 2004

Based on data generated from a case study investigation of a well‐known partnership company the implications of partnership for employees are examined. The partnership approach received the endorsement of employees and it does appear to have brought them tangible benefits. Nevertheless, an assessment of employee perceptions of four key ingredients of partnership – employee voice, job security, quality of working life and job satisfaction, and trust – demonstrates the inappropriateness of “mutuality” as a device for conceptualizing the employment relationship under partnership regimes. The reality of market relations and the imbalance of power in the employment relationship imply that genuine mutuality is likely to be unobtainable in practice.
Formalised individual agreements in Australia
Authors: Gollan Paul J.
Published: February 2004

There is considerable political and industrial relations debate in Australia concerning the value and merit of Australian workplace agreements (AWAs). However, formalised individual agreements are a relatively new phenomenon in the Australian industrial relations landscape, consequently, to date there has been limited assessment of the strategies, outcomes and processes involved in making and negotiating such agreements. This paper attempts to fill this gap by reviewing responses from 688 employers who had approved AWAs with the Office of the Employment Advocate (OEA) before February 2000. There are a number of issues that can be identified from this exploratory study. AWA employers were likely to be “individualistic” employers with more individual employee consultation and human resource practices. Individual employee and employer consultation arrangements were more likely to be used in establishing AWAs and generally communicating with the workforce as a whole. The survey also suggested that the majority of respondents intended to increase their use of AWAs in the future citing increased flexibility and the benefit of all employees being under one type of industrial relations instrument as the primary reasons for their introduction.
Five‐factor model traits and the prototypical image of the effective leader in the Confucian culture
Authors: Lim Leung Sing , Bozionelos Nikos
Published: February 2004

The association between the “five‐factor model” of personality and the prototypical image of the effective leader, and the extent to which that image was linked to the features of transformational leadership were examined in a questionnaire study that involved a sample of 101 Chinese origin individuals in Hong Kong. High levels of extraversion, conscientiousness, agreeableness, emotional stability and openness were perceived as characterizing effective leaders. In line with research on leader emergence in the Anglo‐Saxon culture but contrary to expectations, extraversion was the trait most potently associated with the prototypical notion of the effective leader. And that notion was linked to the features of transformational leadership. The findings also suggested that men and women may partly differ in the criteria they utilize to evaluate leaders. Additional research is necessary, but the findings imply that most of the conclusions on the relationship between personality traits and leader emergence drawn with Anglo‐Saxon samples are generalizable in Confucian societies.
The antecedents of customer‐contact employees’ empowerment
Authors: Melhem Yahya
Published: February 2004

Data from 517 service workers in 14 retail banks show positive and significant association between four empowerment antecedents (including trust, incentives, information and knowledge) and empowerment of customer‐contact employees. Particularly, the findings in this research suggest that trust, communication, knowledge and skills of customer‐contact employees may have a direct and strong impact on the empowerment of service employees. Empowerment antecedents (trust, incentives, communication, and knowledge) of customer‐contact employees accounted for significant variation in the levels of empowerment among customer‐contact employees in the banking industry. Implications for future research and for management practice are discussed.
US restaurant guides: how to avoid chain restaurants (an annotated bibliography)
Authors: Murphy Molly
Published: February 2004

An examination of select recent (since 1995) US restaurant guidebooks. Although most provide basic information, they vary in areas they cover, intended audiences and types of restaurants included. Very few of them cover regional food or go much beyond the most basic information. This select annotated bibliography is an attempt to sort them out.
Reforming municipal services after amalgamation
Authors: McKay Ruth B.
Published: February 2004

The differing perspectives of decision makers in a newly‐amalgamated municipality may hinder the reduction of costs or introduction of efficient organizational change. Accepting differences may be essential, at least initially, to achieve efficiencies. During amalgamation the pursuit of uniformity of services in combination with a weak and/or chaotic change process (lack of committee structure, poor information, vague deadlines, shifting relationships and assertion of power) may undermine efforts to obtain efficiencies.
The characteristics of supermarket shoppers in Beijing
Authors: Mai Li‐Wei , Zhao Hui
Published: February 2004

Retail shopping establishments in the West have evolved through many different stages, in close association with Western lifestyles. The growth of supermarkets has been an important part of this trend, and in the 1980s, they were introduced in China. With their distinctive business environment, it is significant to study the success of the distribution technology transfer and how the Chinese consumers have received the Western shopping approach. This study examines supermarket shoppers in Beijing. The results provide an insight into the shopping patterns of Chinese consumers and identify potential problems for international retailers.
Alternative techniques for casting process simulation
Authors: Lewis R.W. , Ransing R.S. , Pao W.K.S. , Kulasegaram K. , Bonet J.
Published: February 2004

Over the past 20 years, casting process simulation has been an active area of research. The simulation techniques are either based on solving governing partial differential equations using numerical schemes such as the finite element or finite difference methods, or a variety of heuristically based geometry driven methods. Numerical methods are more accurate, but geometry driven methods are computationally less expensive. This paper explores two alternative techniques to overcome some of the limitations of traditional numerical simulation schemes for the casting process simulation. The first technique uses a geometric transformation method known as the medial axis transformation, to predict hot spots whereas the second technique, based on meshless methods, is used for simulating the mould filling process.
Viewpoint: Canadian competition policy: progress and prospects
Authors: Ross Thomas W.
Published: February 2004

Abstract.  This paper discusses the state of competition policy – in particular the economics of competition policy – in Canada today and considers its prospects going forward. It argues that: (i) the importance of competition policy has become accepted widely in Canada and indeed throughout much of the world; (ii) competition policy design and enforcement is in general well done in Canada; (iii) economists, including many Canadians, have played a central role in the development of an efficient and effective competition policy in Canada and elsewhere; and (iv) competition policy in Canada is today facing very serious challenges, and economists should be concerned.
“Moderate” Environmental Amenities and Economic Change: The Nonmetropolitan Northern Forest of the Northeast U.S., 1970‐2000
Authors: White Kristopher D. , Hanink M.
Published: February 2004

ABSTRACT  Population, employment, and income changes in a region comprised of eighteen nonmetropolitan counties of Maine, New Hampshire, Vermont, and New York are described using Bureau of Economic Analysis data covering 1970 to 2000. Changes at the county level are examined as net differences using pooled cross‐section time series analysis. The specific focus of the empirical analysis is the effect that environmental amenities have in population and economic change. Empirical results indicate that a county's relative endowment of environmental amenities has positive economic change effects, but only when the county is relatively accessible as well. Further, the environmental amenity effects vary in their temporal consistency, even when accessibility is taken into account. In general, however, the reported results support the proposition that even relatively moderate environmental amenities can hold positive effects for economic change.
Local Labor Market Adjustment to Immigration: The Roles of Participation and the Short Run
Authors: Johannsson Hannes , Weiler Stephan
Published: February 2004

ABSTRACT  While previous research has generally found that immigration raises unemployment for natives, effects are often more muted than expected. Anticipated out‐migration responses have been similarly difficult to discern. However, these findings may be byproducts of the long‐run nature of most inquiries, which furthermore do not account for changes in natives’ labor force participation. In response, this study evaluates the impact of the arrival of low‐skilled immigrants on low‐skilled natives in urban areas over a five year period. Initial static results from the Census Basic Monthly Survey clearly indicate that immigrants have a significant negative impact on natives’ labor force participation. Building upon these static panel results, characteristics of immigrants’ destination choices are examined along with the ensuing adjustment process through dynamic analyses of local markets. Surges of immigrants significantly reduce the labor force participation of low‐skilled natives, emphasizing this often neglected channel for labor market adjustment. Previous work may thus understate the true impact of immigrants on local labor markets by focusing on the longer term and ignoring adjustments through participation.
Retail Trade on the U.S.‐Mexico Border During the NAFTA Implementation Era
Authors: Adkisson Richard V. , Zimmerman Linda
Published: February 2004

ABSTRACT  When NAFTA was implemented in 1994, there was a general expectation that it would hurt U.S. retailers along the U.S.‐Mexico border. This paper asks whether there was a significant change in the pattern of retail trade in border MSAs in the years surrounding NAFTA's implementation. Data from MSAs in the four border states are analyzed. After controlling for other potential influences on retail trade, there remained a statistically significant change in the pattern of retail trade between 1992 and 1997. The changes cannot be unquestionably attributed to NAFTA but do suggest that NAFTA had a negative influence on retail sales on the U.S. side of the border.
The Relationship Between Psychopathology and Shame in Secondary School Students
Authors: Ang Rebecca P. , Khoo Angeline
Published: February 2004

This study investigated the relationship between psychopathology and shame. Three hundred and thirty‐one Secondary 2 students from Singapore participated in the study. All students completed a self‐report questionnaire consisting of the Anxiety and Depression scales of the Behavior Assessment System for Children (BASC), the short version of the Aggression Questionnaire (AQ), and the Internalized Shame Scale (ISS). As predicted, students in the comorbid group at‐risk for anxiety, depression and aggression, had significantly higher shame scores compared with at‐risk students in all the other three single‐disordered groups (anxiety‐only, depression‐only, or aggression‐only) as well as students in the control group. Also, as expected, the control group scored significantly lower compared to all other single‐disorder groups and the comorbid group. Implications of these findings with regard to comorbidity of psychopathology and its relationship to shame, classroom interventions, as well as implications pertaining to teachers' and counsellors' work with at‐risk students will be discussed.
Transformations in the Couplings Among Intellectual Abilities and Constituent Cognitive Processes Across the Life Span
Authors: Li Shu-Chen , Lindenberger Ulman , Hommel Bernhard , Aschersleben Gisa , Prinz Wolfgang , Baltes Paul B.
Published: February 2004

Two-component theories of intellectual development over the life span postulate that fluid abilities develop earlier during child development and decline earlier during aging than crystallized abilities do, and that fluid abilities support or constrain the acquisition and expression of crystallized abilities. Thus, maturation and senescence compress the structure of intelligence by imposing age-specific constraints upon its constituent processes. Hence, the couplings among different intellectual abilities and cognitive processes are expected to be strong in childhood and old age. Findings from a population-based study of 291 individuals aged 6 to 89 years support these predictions. Furthermore, processing robustness, a frequently overlooked aspect of processing, predicted fluid intelligence beyond processing speed in old age but not in childhood, suggesting that the causes of more compressed functional organization of intelligence differ between maturation and senescence. Research on developmental changes in functional brain circuitry may profit from explicitly recognizing transformations in the organization of intellectual abilities and their underlying cognitive processes across the life span.
Show Your Pride
Authors: Tracy Jessica L. , Robins Richard W.
Published: February 2004

Three experiments provide converging evidence that pride has a distinct, recognizable expression. Experiment 1 showed that judges can agree in identifying a posed expression as showing pride and can reliably distinguish pride expressions from expressions of related emotions such as happiness. Experiment 2 showed that judges can identify the pride expression when the task uses an open-ended response format that does not cue them with the label “pride.” Experiment 3 showed that the pride expression includes a small smile, with head tilted slightly back, visibly expanded posture, and arms raised above the head or hands on hips. Overall, these findings challenge the assumption that all positive emotions share the same expression, and suggest that pride may be added to the pantheon of basic emotions generally viewed as evolved responses.
Women's Preferences for Male Behavioral Displays Change Across the Menstrual Cycle
Authors: Gangestad Steven W. , Simpson Jeffry A. , Cousins Alita J. , Garver-Apgar Christine E. , Christensen P. Niels
Published: February 2004

Women prefer both the scent of symmetrical men and masculine male faces more during the fertile (late follicular and ovulatory) phases of their menstrual cycles than during their infertile (e.g., luteal) phases. Men's behavioral displays in social settings may convey signals that affect women's attraction to men even more strongly. This study examined shifts in women's preferences for these behavioral displays. A sample of 237 normally ovulating women viewed 36 or 40 videotaped men who were competing for a potential lunch date and then rated each man's attractiveness as a short-term and a long-term mate. As predicted, women's preference for men who displayed social presence and direct intrasexual competitiveness increased on high-fertility days relative to low-fertility days, but only in a short-term, not a long-term, mating context. These findings add to the growing literature indicating that women's mate preferences systematically vary across the reproductive cycle.
Intravenous immunoglobulin treatment in autoimmune neurological disorders: pilot study on early effects on patients' quality of life
Authors: Padua Luca , Aprile Irene , Caliandro Pietro , Padua Roberto , Mazza Salvatore , Tonali Pietro
Published: February 2004

Abstract We performed a multi‐perspective follow up in 25 patients with autoimmune neurological disorders treated with intravenous immunoglobulin (IVIg) to evaluate the early effects on patients' health‐related quality of life (HRQoL). Diagnoses were based on clinical picture, neurophysiological assessment, nerve biopsy, and therapeutic response. As patient‐oriented assessment, we used the Short Form 36 questionnaire (SF‐36), the most used generic health tool, and the disability of arm shoulder and hand questionnaire (DASH). Our data indicate that physical aspects of patients' HRQoL improve early and strongly after IVIg. This agrees with the muscle strength improvement previously reported. But, the mental aspects of the HRQoL are not influenced by the therapies. Traditional outcome assessment in neurological diseases has always been based on physician‐derived and instrumental findings. Over the last two decades, clinical researchers have underlined the need for a standardized evaluation of concepts such as HRQoL. We believe that this study represents a further step toward an evidence‐based therapeutic approach of some neurological diseases and that further fundamental steps should be taken.
Sensory manifestations in Charcot‐Marie‐Tooth disease
Authors: Gemignani Franco , Melli Giorgia , Alfieri Sara , Inglese Cristina , Marbini Adriana
Published: February 2004

Abstract  Involvement of sensory nerves in Charcot‐Marie‐Tooth (CMT) disease is well known, however, sensory symptoms are usually overlooked. To assess the frequency and features of sensory symptoms in a cohort of patients with CMT, we investigated in a prospective study 52 consecutive CMT patients, diagnosed on the basis of clinical, neurophysiological, and genetic features and classified in CMT type 1 (CMT1) (20 patients, including 14 with CMT1A) and CMT type 2 (CMT2) (32 patients). Positive sensory symptoms were reported by 28 patients (54%), including neuropathic pain in 6 patients. Pain, either neuropathic or nociceptive, was present in 29 patients (56%) and in 15 patients as a main symptom. Positive sensory symptoms were present in 24 of 32 CMT2 patients (75%) and in 4 of 20 CMT1 patients (20%) (p < 0.001); there was a presenting manifestation in 11/32 CMT2 patients vs. 1/20 in CMT1 patients (p = 0.018), and one of the main features in 6/32 CMT2 patients vs. 1/20 CMT1 patients. Frequency of positive sensory symptoms in CMT1A patients was similar to that of the entire CMT1 group. Within the CMT2 group, patients with positive sensory symptoms as a main or onset feature (11 patients) had significantly later onset (median 57 vs. 25 years; p = 0.042) and less severely impaired motor action potentials than CMT2 patients without positive sensory symptoms (8 patients). Nociceptive pain was especially frequent in CMT1A patients (10/14, 71%). Sensory manifestations in CMT seem more frequent than previously thought, especially in CMT2; however, their frequency may be different in the genetic subtypes of the disease and/or an expression of phenotypic variability. Sensory symptoms, and in particular pain, may represent an important issue in the management of CMT patients, especially in a physical medicine approach.
Cyclooxygenase‐2 (Cox‐2) in injured human nerve and a rat model of nerve injury
Authors: Durrenberger Pascal F. , Facer Paul , Gray Roy  A. , Chessell Iain P. , Naylor Alan , Bountra Chas , Banati Richard B. , Birch Rolfe , Anand Praveen
Published: February 2004

Abstract  Inflammation associated with nerve injury produces a number of pathogenic chemical mediators of which prostanoids are a potent component. Cyclooxygenases (Cox‐1 and Cox‐2) are the enzymes responsible for prostanoid production. We have investigated Cox‐2 immunoreactivity (Cox‐2‐IR) and glial activation in human injured (n = 16) and uninjured (n = 8) nerves and in the chronic constriction injury (CCI) model of nerve injury in the rat, using immunohistological and autoradiographic methods. Tissues were immunostained with antibodies to Cox‐2, CD‐68 (human macrophage marker), OX42 (rat microglial marker), or incubated with tritiated PK11195 (marker of glial activation), prior to image analysis. In human nerves, Cox‐2‐IR was detected in cells with morphology and distribution similar to macrophages/microglia – these were increased significantly in human nerve proximal to injury (p < 0.002), reaching a peak at 4–6 weeks after injury. In the rat CCI model, at 40 days after injury, microglia‐like cells with Cox‐2‐IR were increased significantly in the injured nerve (p < 0.004) and ipsilateral dorsal spinal cord (p < 0.008). PK11195‐binding results were similar for Cox‐2‐IR in chronic injured human nerve and rat tissues. These findings suggest that Cox‐2‐immunoreactive cells could play a role in processes associated with Wallerian degeneration, nerve regeneration, and the development of persistent pain. Selection of patients 4–6 weeks after nerve injury would be more likely to show any efficacy of Cox‐2 inhibitors.
Neotropical tadpoles influence stream benthos: evidence for the ecological consequences of decline in amphibian populations
Authors: Ranvestel Anthony W. , Lips Karen R. , Pringle Catherine M. , Whiles Matt R. , Bixby Rebecca J.
Published: February 2004

1. Few studies have assessed the role of tadpoles in tropical streams, although they are often abundant and conspicuous components of these systems. Moreover, amphibian populations are declining around the globe, particularly stream‐dwelling species in tropical uplands, and the ecological consequences of these losses are not understood.

2. We chose a stream in the central Panamanian highlands, which has an intact fauna of stream‐breeding anurans, to examine the ecological consequences of amphibian losses. This site differs dramatically from sites in nearby western Panama and Costa Rica where anuran diversity and abundance have declined greatly in the last two decades.

3. We used an underwater electric field to create tadpole exclosures in runs, so that we could evaluate their influence on sediment dynamics and the abundance and community structure of algae and aquatic insects. Tadpoles reduced total sediments and both organic and inorganic fractions on substrata. Tadpoles also reduced algal abundance on substrata by approximately 50% and decreased algal biovolume. Gut content analyses showed that tadpoles consumed algae and sediments and we could see that algae and sediments were also displaced through bioturbation.

4. Atelopus zeteki, Rana warszewitschii, and Hyla spp. were the dominant larval anurans responsible for the effects observed. Visual surveys indicated that the densities of these taxa ranged from 23 (R. warszewitschii and Hyla spp. combined) to 43 m−2 (A. zeteki) in runs.

5. The abundance of baetid mayflies was lower in tadpole exclosures compared with controls, and this was attributed to tadpoles facilitating mayfly feeding by removing sediments and exposing underlying periphyton.

6. Tadpoles affect the abundance and diversity of basal resources and other primary consumers, and thus influence food web dynamics and energy flow in these tropical streams. Catastrophic decline in stream‐breeding anuran populations will influence the structure and function of neotropical stream ecosystems.
Simple traits do not predict grazing response in Australian dry shrublands and woodlands
Authors: Vesk Peter A. , Leishman Michelle R. , Westoby Mark
Published: February 2004

Plant species composition and species response to grazing are fundamental to the management of grazing lands. Reliable prediction of grazing responses from species’ traits would be a major step forward in generalizing knowledge and management beyond the locality. Recently results have been presented showing that plant species’ responses to grazing in subhumid grasslands in Argentina and Israel could be predicted from simple traits: height, leaf size, life history and specific leaf area (SLA). This study assessed whether those relationships between traits and grazing responses hold for Australian semi‐arid and arid shrublands and woodlands.

Eleven lists of grazing responses from five published grazing studies were matched with a plant trait data set. Trait distributions were compared between response groups pooled across studies. Relationships between traits and grazing response were also assessed, both within and across studies, using meta‐analysis.

Overall there was little evidence for predictability of grazing responses with simple traits in the semi‐arid and arid shrublands and woodlands. There were relationships between grazing response and life history and growth form, and some weak evidence for grazing increasers having high SLA.

Synthesis and applications. It was concluded that prediction of grazing responses with simple traits is less clear in semi‐arid and arid rangelands, which are characterized by openness at ground level and high diversity of growth forms, compared with subhumid grasslands that have structurally simple, continuous swards. The finding that species’ traits may have differing predictive capacity for grazing responses in different situations means that we need more empirical studies in different situations. The most important contrasts between situations for investigation are likely to be on axes of rainfall/productivity and evolutionary history of grazing.
The ecological implications of harvesting non‐timber forest products
Authors: Ticktin T.
Published: February 2004

The harvest of wild non‐timber forest products (NTFP) represents an important source of income to millions of people world‐wide. Despite growing concern over the conservation of these species, as well as their potential to foster forest conservation, information on the ecological implications of harvest is available only in disparate case studies.

Seventy studies that quantify the ecological effects of harvesting NTFP from plant species were reviewed, with the aims of assessing the current state of knowledge and drawing lessons that can provide guidelines for management as well as better directing future ecological research in this area.

The case studies illustrated that NTFP harvest can affect ecological processes at many levels, from individual and population to community and ecosystem. However, the majority of research was focused at a population level and on a limited subset of plant parts that are harvested.

Tolerance to harvest varies according to life history and the part of plant that is harvested. Moreover, the effects of harvest for any one species are mediated by variation in environmental conditions over space and time, and by human management practices.

In order to withstand heavy harvest, specific management practices in addition to gathering are necessary for many NTFP species. Management practices can be carried out at different spatial scales and some are highly effective in fostering population persistence.

Synthesis and applications. Substantial advances have been made towards identifying the ecological impacts of NTFP harvest. However, there is a need for longer‐term studies that focus on multiple ecological levels (ranging from genes to ecosystems), that assess the mechanisms underlying impacts and that validate current models. Researchers and forest managers need to work with local harvesters in designing and evaluating management practices that can mitigate the negative effects of harvest.
Regulation of shrub dynamics by native browsing ungulates on East African rangeland
Authors: Augustine David J. , Mcnaughton Samuel J.
Published: February 2004

Herbivores, edaphic features and fire are primary factors regulating the balance between woody and herbaceous vegetation in savannas. Many observational studies have evaluated the potential effects of browsing herbivores on woody plant dynamics in African savannas, but few experimental studies have compared the dynamics of African savannas with and without browsers.

A replicated herbivore exclusion experiment was used to assess the role that native ungulates play in regulating woody plant dynamics on commercial rangeland in central Kenya, where the indigenous fauna have been allowed to coexist with cattle.

Exclusion of native browsing ungulates for just 3 years showed that they have dramatic effects at every scale from individual twig growth rates to overall rates of woody biomass accumulation in the ecosystem.

At the scale of individual Acacia twigs, browsers significantly reduced leaf density, leaf biomass and growth rates of twigs < 50 cm above‐ground (within the foraging height of dik‐diks Madoqua kirkii), but browsers had no effects on twig leaf density or leaf biomass at a height of 1·0–1·25 m above‐ground.

Reductions in the growth rate of twigs within the foraging height of dik‐diks was associated with a 6‐fold reduction in the rate at which shrubs < 0·5‐m tall were recruited into the 0·5–1·5 m height class. This reduced recruitment combined with measured rates of shrub mortality in larger height classes shows that browsers reduced the rate of increase in shrub density nearly to zero (7·1 ± 10·2 shrubs ha−1 year−1) compared to the rapid rate of increase in the absence of browsers (136·9 ± 13·6 shrubs ha−1 year−1).

Damage to shrub canopies by elephants Loxodonta africana caused large, significant reductions in cover of A. mellifera and Grewia tenax, but lesser reductions in cover of A. etbaica. For Acacias, elephant damage was focused on shrubs > 2·5 m tall, such that Acacias in intermediate height classes (0·5–2·5 m) experienced minimal browser impacts. Elephants influenced shrubland dynamics by altering shrub height‐class distributions, shifting species composition from broad‐leaved Grewia tenax to fine‐leaved Acacia species, and suppressing woody biomass accumulation; but elephants had little influence on changes in shrub density.

Synthesis and applications. Our results suggest that a community of native browsers that includes both small, selective species (e.g. dik‐diks) and large, bulk‐feeding species (elephants) can provide an important ecosystem service by suppressing shrub encroachment on commercial rangeland.
Disease transmission between and within species, and the implications for disease control
Authors: Caley Peter , Hone Jim
Published: February 2004

Disease transmission can occur between and within species for diseases with multiple hosts. If these diseases are undesirable, for economic or health reasons, then the relative importance of each type of transmission should be determined. Bovine tuberculosis (Tb) caused byMycobacterium bovisis one such undesirable disease.

In parts of New Zealand,M. bovisinfection is highly prevalent in feral ferretMustela furopopulations, and there is concern they may be acting as a reservoir of infection for domestic livestock, similar to the role played by brushtail possumsTrichosurus vulpecula. We undertook a manipulative large‐scale field experiment to test for and quantify interspecific transmission ofM. bovisfrom brushtail possums to feral ferrets, and intraspecific transmission ofM. boviswithin feral ferret populations.

Age‐specific prevalence data obtained from cross‐sectional surveys was modelled to estimate the effect of experimental reductions in possum population density on the force ofM. bovisinfection in ferrets. A simple analysis estimated the force ofM. bovisinfection in ferrets to be reduced by 88% at sites previously subjected to a possum population density reduction. A more detailed analysis, incorporating ferret survey data from both before and after possum population density reduction and controlling for the effect of ferret sampling, estimated that possum population density reduction decreased the force ofM. bovisinfection in ferrets by 29% at sites of high ferret density, and 88% at sites of low ferret density, compared with experimental control sites.

There is clearly substantial possum‐to‐ferret transmission ofM. bovis, and controlling possum populations is the logical first step to managingM. bovisinfection in ferret populations, especially at sites with low ferret density. Intra‐specific transmission is virtually absent in low density ferret populations though evident at higher densities.

Synthesis and applications.These results have management implications for other multiple‐host diseases around the world, such as bovine tuberculosis and rabies. Control of within‐species transmission may not be as effective for disease control as a reduction in between‐species transmission. The management decision should be based on empirical estimates of the magnitude of each form of transmission.
The challenge of managing multiple species at multiple scales: reptiles in an Australian grazing landscape
Authors: Fischer Joern , Lindenmayer David B. , Cowling Ann
Published: February 2004

Understanding the ecological effects of processes operating at multiple spatial scales on multiple species is a key challenge in ecology. It underpins both basic research and the increasing recognition of scale‐dependence in conservation biology.

Organisms are affected by ecological processes operating at multiple spatial scales. Hence the study of multiple species and spatial scales is a key challenge in ecology.

A spatially nested experimental design was used to investigate the habitat relationships of reptiles in a grazing landscape in southern New South Wales, Australia. Regression modelling was used to relate the presence of species and species richness to habitat variables.

Different species were predicted by different habitat variables, and some species reflected habitat structure at one, but not all, spatial scales. The four‐fingered skink Carlia tetradactyla was associated with box woodlands, areas with few rocks and many spiders, and areas with a northerly aspect and high tree cover. Boulenger's skink Morethia boulengeri was more likely to be found in areas with many ants and beetles, and also in areas with a northerly aspect and high tree cover. The striped skink Ctenotus robustus and olive legless lizard Delma inornata were significantly more likely to be detected in areas with a simple microhabitat structure. Species richness was highest in box woodlands (Eucalyptus albens and Eucalyptus melliodora) and at sites characterized by a high variability of habitat structure.

Different habitat variables varied over different spatial scales. For example, invertebrate abundance varied mostly over tens of metres, while grass/forb cover varied mostly over hundreds to thousands of metres.

Synthesis and applications. The multitude of species’ responses and spatial habitat variability highlighted the potential limitations of the fragmentation paradigm because it may oversimplify ecological complexity. On this basis, conservation in variegated grazing landscapes may need to consider changes to livestock management across entire landscapes, rather than concentrate solely on the preservation of particular patches.
Expansion of invasive species on ombrotrophic bogs: desiccation or high N deposition?
Authors: Tomassen Hilde B. M. , Smolders Alfons J. P. , Limpens Juul , Lamers Leon P. M. , Roelofs Jan G. M.
Published: February 2004

In many ombrotrophic bog areas the invasion of grass (e.g.Molinia caerulea) and tree (e.g.Betula pubescens) species has become a major problem. We investigated whether the invasion of such species is due to high atmospheric nitrogen (N) deposition by conducting a fertilization experiment.

The effects of experimentally increased N input onMolinia,BetulaandEriophorum vaginatumwere studied in desiccated bog vegetation in Ireland, where there is relatively low background N deposition. Four different N treatments were applied for 3 years: 0 (control), 2, 4 and 8 g m−2 year−1.

Ammonium and nitrate concentrations in the peat moisture increased at high N addition rates, leading to significantly higher carbon : nitrogen (C : N) and nitrogen : phosphorus (N : P) ratios in the top layer of the peat. The potential CO2production rate of the peat was not stimulated at high N addition rates due to severe acidification of the peat.

Despite high tissue N : P ratios (above 40), above‐ground biomass production byMoliniawas stimulated at high N addition rates, and foliar nutrient concentrations were unaffected. In contrast toMolinia,BetulaandEriophorumwere unable to increase their above‐ground biomass, probably due to P limitation. Regrowth of the lichenCladonia portentosawas suppressed at high N addition rates.

Synthesis and applications.We conclude that the invasion of bogs byMoliniaandBetulais likely to be less affected by desiccation than by increased N availability. Apparently,Moliniais well adapted to P‐limiting conditions, which may explain its success in regions with increased N deposition levels. The high availability of P in many Dutch bogs compared with Irish bogs, together with prolonged high N deposition levels, may explain the strong increase in bothMoliniaandBetulaobserved in the Netherlands. As long as N and P availabilities in Dutch bogs are too high to prevent invasion ofBetulaand/orMolinia, management measures stimulating growth ofSphagnummosses could probably reduce the negative effects of high N deposition levels.
Competitive control of invasive vegetation: a native wetland sedge suppresses Phalaris arundinacea in carbon‐enriched soil
Authors: Perry Laura G. , Galatowitsch Susan M. , Rosen Carl J.
Published: February 2004

Invasive plants pose a major threat to native plant communities around the globe. Current methods of controlling invasive vegetation focus on eradication of existing populations, and are often effective only in the short term. Manipulating resource availability to give native species a competitive advantage over invasive species could reduce ecosystem vulnerability to invasion and might more effectively control invasive vegetation. We evaluated this approach for controlling invasions of sedge meadow communities by Phalaris arundinacea, a widespread invasive grass in North American wetlands.

To test whether lowering nitrogen (N) availability would allow a wetland sedge, Carex hystericina, to suppress Phalaris competitively, we examined Carex and Phalaris competition under a range of inorganic N concentrations (25–400 mg kg−1) in a glasshouse. We lowered N availability in wetland soil using carbon enrichment and repeated harvests of a cover crop, and then created a N gradient by applying NH4‐N to the N‐depleted soil.

In soil without carbon added, competition with Phalaris reduced Carex biomass by 91%, while competition with Carex did not influence Phalaris, as is commonly observed in sedge meadows. Phalaris biomass was five times Carex biomass in mixed stands. Conversely, in soil depleted of available N via carbon enrichment, competition with Carex reduced Phalaris biomass by 82%, while competition with Phalaris reduced Carex biomass by only 32%, indicating that Carex is the superior competitor for N. Carex biomass was six times Phalaris biomass in mixed stands in the carbon‐enriched soil.

Carbon enrichment lowered soil inorganic N by 10–30 mg kg−1. NH4‐N addition mitigated the negative effects of carbon on Phalaris growth and competitive ability, indicating that carbon enrichment altered competitive outcomes by lowering N availability. Greater Carex N uptake efficiency under N‐poor conditions appeared to account for the Carex competitive ability for N.

Synthesis and applications. Carex dominance in carbon‐enriched soil strongly suggests that lowering soil inorganic N to < 30 mg kg−1 in restored wetlands would allow establishing sedge meadow communities to suppress Phalaris invasions. Low‐N soils might be achieved via carbon enrichment, vegetation harvests and reduced N inputs. Reducing community vulnerability to invasion by manipulating resource availability appears to be a promising approach to invasive species management.