Greater Disturbance Research Articles

Linking recreational disturbance to population size in a ground‐nesting passerine

Summary There is often a perceived conflict between recreational access and wildlife conservation. Although many studies have investigated the potential effects on birds, this is the first study to demonstrate an impact of recreational disturbance on population size. We studied the impact of disturbance on a woodlark Lullula arborea population on 16 heathland sites in southern England. These sites all had historical records of breeding woodlarks and together encompassed a range of visitor‐access levels. A logistic regression model of patch use was used to quantify the area of habitat suitable for woodlarks. Woodlarks favoured patches with substantial proportions of bare ground and short vegetation. Across heaths, woodlark density (per hectare of suitable habitat) was lower on sites with higher levels of disturbance. Within heaths with recreational access, the probability of suitable habitat being colonized was lower in those areas with greater disturbance and was reduced to below 50% at around eight disturbance events per hour. There was no relationship between disturbance and daily nest survival rates. Birds on heaths with higher levels of disturbance fledged more chicks (per pair) because of a strong density‐dependent increase in reproductive output. A model is presented that predicts the consequences for the woodlark population of a range of access scenarios. The impact on the population depends on both the numbers of people and their spatial distribution. Under current access arrangements, a doubling of visitor numbers has little effect, while the same number of people distributed evenly across all sites leads to a major negative impact on the population. Density‐dependent breeding success partially balances the negative effects of disturbance; however, we calculated that there is currently a 17% reduction in productivity compared with that predicted in the absence of disturbance. Synthesis and applications. Many previous studies have stressed the negative effects of recreational disturbance on birds’ behaviour, distribution and breeding success. However, from a conservation viewpoint, the impact at the population level is of paramount importance. Modelling the population‐scale consequences of alternative access scenarios will help policymakers develop appropriate mitigation measures.

Semeadura direta de forrageiras de estação fria em campo natural com aplicação de herbicidas: I. Produção de forragem e contribuição relativa das espécies

Os campos naturais apresentam estacionalidade na sua produção forrageira, a qual pode ser atenuada com a introdução de espécies de estação fria através de semeadura direta, aumentando a produção forrageira no inverno. Durante quatro anos, conduziu-se um experimento de semeadura direta de forragem de inverno, sobre campo nativo, em um Argissolo Vermelho-Amarelo, de textura superficial arenosa do norte do Uruguai. Em delineamento de blocos ao acaso com parcelas sub-subdivididas, foram testadas doses de herbicidas (glifosate 1L ha-1, glifosate 4L ha-1, paraquat 3L ha-1 e testemunha), como tratamento principal, aplicadas no ano 1994. A repetição ou não das mesmas doses no ano 1995 constituiu-se na subparcela, e a aplicação ou não das mesmas doses no ano 1996 constituiu-se na sub-subparcela. Os resultados mostraram que o maior distúrbio sobre a produção de forrageiras e contribuição das espécies do campo nativo foi provocado com a aplicação continuada de herbicidas sistêmicos na maior dose. Quando não foi aplicado herbicida (testemunha) havia onze espécies e com aplicação de glifosate 4L ha-1 havia seis espécies, bem como ocorreu uma substituição de espécies perenes por anuais. O herbicida paraquat e a dose baixa de glifosate mostraram efeitos intermediários entre o observado no campo nativo semeado com triticale e azevém sem tratar com herbicida e os provocados com glifosate na dose alta. Por outro lado, os rendimentos de matéria seca das espécies forrageiras invernais semeadas foram 63% maiores na dose mais alta de glifosate do que na testemunha, devido a um maior controle da competição que exercia o campo nativo.

Prior History of Physical and Sexual Abuse Among the Psychiatric Inpatient Population: A Comparison of Males and Females

Despite increasing attention given to the high prevalence and effects of abuse in the severely mentally ill, few studies have looked at its effects among males. While both male and female psychiatric patients report greater abuse history than the general population, studies have focused on females alone. The current study compared the effects of abuse history between 271 severely mentally ill males (n = 160) and females (n = 111). The mean age of participants was 33.7 years (SD = 9.73), and included 129 Caucasians, 120 African Americans, 15 Hispanic-Americans, and 7 "Other" (i.e., Asian and native American descent). Primary Axis I diagnoses included Bipolar disorder (23.2%) major depressive disorder (27.7%) schizophrenic disorder (26.6%), substance-related disorders (10.3%), and miscellaneous disorders (12.1%). Each patient completed a comprehensive assessment, including clinician ratings, self-report measures, clinical and structured interviews. Comparisons between genders revealed that females were more likely to report both physical and sexual abuse, and males were more likely to report no history of abuse. In addition, Caucasians were more likely to report abuse than were African Americans, and voluntary patients were more likely to endorse abuse history than those admitted involuntarily. Few gender differences were found in psychological symptoms among males and females. Satisfaction with the home environment was significantly lower for abused than nonabused females. This was not true for males. However, abused psychiatric patients were perceived by the physicians, nurses, and themselves as having greater emotional disturbance than were nonabused patients, regardless of gender. Clinical implications are discussed.

Disturbance caused by varying propagation delay in non-occluding hearing aid fittings

The disturbance caused by various short propagation delays to the perception of external sounds and own voice for a non-occluding hearing aid was investigated. Ten normal-hearing and 10 mildly hearing-impaired individuals listened to external sounds and their own voice while wearing non-occluding devices providing 10dB of linear gain. Participants rated the disturbance caused by delays of 2, 4 and 10ms to music, running speech, and their own voices. The results indicated greater disturbance for the longest delay for both subject groups when judging own voice, with the ratings of the hearing-impaired participants being lowest. Normal-hearing participants also judged the 10-ms delay as more disturbing for the external sounds. Owing to the listening conditions with constant gain from 800Hz and above, the results apply directly only to this experiment. Disturbance ratings for all delays were low, which suggests that any of those tested would be acceptable for this application.

Human chronic fascioliasis: a possible cause of unexplained abnormal liver tests

Fascioliasis is a cause of hepatic disease. Hepatitis B and C viruses are important causative factors in chronic liver disease. In this study, the frequency of hepatitis B (HBV) and/or hepatitis C (HCV) in cases of chronic human fascioliasis is studied. Egg count, indirect haemagglutination test (IHAT), haemoglobin level, total leucocyte and eosinophil counts, serum bilirubin, serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and acid phosphatase (ACP) are performed. Serum γ-glutamyltransferase (GGT), arylsulphatase (ASA) and lipid peroxide levels are determined. Results showed that levels of the latter group of enzymes were increased significantly in cases of chronic fascioliasis. Therefore, determination of GGT, ASA and lipid peroxide should be added to the list of liver function test used to diagnose this disease. Hepatitis B was not detected in any of the 27 chronic fascioliasis patients studied, while HCV was found in only two (7%) cases. However, greater disturbance of biochemical parameters was seen in patients with combined fascioliasis and HCV infection.

Binge eating disorder in extreme obesity

To determine whether extremely obese binge eating disorder (BED) subjects (BED defined by the Eating Disorder Examination) differ from their extremely obese non-BED counterparts in terms of their eating disturbances, psychiatric morbidity and health status. Prospective clinical comparison of BED and non-BED subjects undergoing gastric bypass surgery (GBP). Thirty seven extremely obese (defined as BMI > or = 40 kg/m(2)) subjects (31 women, six men), aged 22-58 y. Eating Disorder Examination 12th Edition (EDE), Three Factor Eating Questionnaire (TFEQ), Structured Clinical Interview for the Diagnostic and Statistical Manual-IV (SCID-IV), Short-Form Health Status Survey (SF-36), and 24 h Feeding Paradigm. Twenty-five percent of subjects were classified as BED (11% met full and 14% partial BED criteria) and 75% of subjects were classified as non-BED. BED (full and partial) subjects had higher eating disturbance in terms of eating concern and shape concern (as found by the EDE), higher disinhibition (as found by the TFEQ), and they consumed more liquid meal during the 24 h feeding paradigm. No difference was found in psychiatric morbidity between BED and non-BED in terms of DSM-IV Axis I diagnosis. The health status scores of both BED and non-BED subjects were significantly lower than US norms on all subscales of the SF-36, particularly the BED group. Our findings support the validity of the category of BED within a population of extremely obese individuals before undergoing GBP. BED subjects differed from their non-BED counterparts in that they had a greater disturbance in eating attitudes and behavior, a poorer physical and mental health status, and a suggestion of impaired hunger/satiety control. However, in this population of extremely obese subjects, the stability of BED warrants further study.

Inner-City Children Living with an HIV-Seropositive Mother: Parent–Child Relationships, Perception of Social Support, and Psychological Disturbance

Despite ongoing concern about the well-being of HIV-seronegative children living in urban poverty with a seropositive mother, very little is known about this expanding population of children. In this cross-sectional study, the psychosocial adjustment of 60 ethnic minority children 11 to 16 years of age who were living with an HIV-seropositive mother was compared with that of 108 children attending public school in the same community. Results of three multivariate analyses of covariance indicated that, after allowance for differences associated with age, gender, ethnicity, and family structure, the HIV-affected group confirmed (a) greater disturbance in the parent–child relationship, (b) less social support, and (c) greater disturbance in psychological functioning. Secondary analysis of the multivariate findings indicated that the differences were characterized primarily by (a) perception of more indifference and hostility in the mother–child relationship, (b) perception of less social support available from parents, friends, and teachers, and (c) less self-esteem. The findings suggest that HIV infection and concurrent problems may compromise parent–child relationships and perception of social support in ways that leave older, seronegative children living with an infected mother at risk for psychological disturbance.

FLOW CHARACTERISTICS AROUND AN INCLINED ELLIPTIC CYLINDER IN A TURBULENT BOUNDARY LAYER

The flow characteristics around an inclined elliptic cylinder located near a flat plate were investigated experimentally. The axis ratio of the elliptic cylinder was AR=2. The pressure distributions along the surface of the cylinder and the flat plate were measured by varying the angle of attack of the elliptic cylinder. The velocity profiles behind the cylinder were measured using hot-wire anemometry. When the angle of attack varies, the peak pressure location on the windward cylinder surface moves towards the rear edge of the cylinder, while that on the leeward surface moves towards the front edge of the cylinder. The vortex-shedding frequency also gradually decreases, defining a critical angle of attack for each gap ratio. The location of the minimum pressure on the flat plate surface moves downstream for positive angles of attack, while it moves upstream for negative angles of attack. Negative angles of attack cause a greater disturbance in the boundary layer near the wall compared to positive angles of attack. This shows that the separated wall shear layer from the boundary layer and the lower shear layer of the cylinder wake are strongly merged compared to other cases.

Suicidal thoughts and acts in Irish adolescents

To determine the frequency of reported suicidal thoughts and acts in (a) a school-based sample of Irish adolescents, (b) adolescents attending a community child and family mental health service. The study population consisted of: (a) 195 adolescents aged 13-15 years attending ten secondary schools throughout Ireland. The schools were selected to represent a wide social and cultural spread: and (b) 66 adolescents aged 13-15 years attending a community child mental health service. The measures used were the Child Behaviour Checklist completed by the parents of the adolescents and the Youth Self Report completed by the adolescents. Within the school sample, the parents of 3% of adolescents reported that their child had talked of harming him/herself, but none reported acts of self-harm. Fifteen percent of the adolescents themselves reported that they had thoughts of harming or killing themselves, and 8% reported that they had tried to harm or kill themselves. Within the mental health clinic attenders sample, the parents of 33% of the adolescents reported that their child had talked of harming him/herself, and the parents of 27% reported that their child had tried to harm or kill themselves. Twenty-one percent of the adolescents themselves reported that they had thoughts of harming or killing themselves, and 21% percent reported that they had tried to do so. In both groups, adolescents with higher total problem, internalising and externalising scores on the questionnaires, indicating greater disturbance, were more likely to report thoughts and acts of self harm. Thoughts of suicide and acts of self harm are common in Irish adolescents and are not limited to those attending mental health services. Parents are frequently unaware of these thoughts. Further studies involving interviews with adolescents at risk are indicated to determine the significance of these thoughts and how adolescents deal with them.

Predicting clinically significant response to cognitive behavior therapy for chronic insomnia in general medical practice: analysis of outcome data at 12 months posttreatment.

The clinical efficacy of cognitive behavior therapy (CBT) for chronic insomnia has been established, yet clinical effectiveness is less clear. This study presents data on 109 patients from general practice during a formal evaluation of clinical effectiveness. Two thirds achieved normative values of < or =30 min for sleep latency and wakefulness during the night after CBT. Furthermore, almost half of the sample reduced sleeplessness by > or =50%. Logistic regression revealed that initial severity did not contraindicate good outcome. Rather, greater sleep disturbance was positively associated with large symptom reduction, although lower endpoint scores were less likely. Similarly, symptoms of anxiety, depression, and thinking errors positively predicted good outcome. Hypnotic using patients responded equally well to CBT, and demographic factors were of no significant predictive value. It is concluded that CBT is clinically and durably effective for persistent insomnia in routine practice.

Management Approaches Employed by Teachers to Deal with Children's Behaviour Problems in Nursery Classes

The study was undertaken in Greece to investigate the management approaches employed by nursery teachers to deal with children's behaviour problems. In particular, the extent, frequency of use and effectiveness of behavioural, cognitive and punitive approaches were investigated with regard to conduct, emotional and developmental related problems. A questionnaire was developed and applied to a female teacher sample of 154 selected from nursery schools located in three distinct regions of Greece. The questionnaire was completed for 280 children from a total pupil sample of 3,091. The findings showed that teachers appear to mainly attend to and deal with conduct problems which cause greater disturbance in the classroom. However, emotional and developmentally related problems were also addressed revealing teachers' concerns about their pupils' well-being and development. Teachers seemed to mainly use positive ways in dealing with children's behaviour problems, but they did deliver punishments as well. Finally, the study indicated that teachers appear to be rather effect-oriented employing a variety of techniques of different theoretical orientation which have been perceived to be effective.

Patterns of seedling and overstory composition along a gradient of hurricane disturbance in an old-growth bottomland hardwood community

Disturbance patterns and species composition in the seedling and canopy layers were examined across the range of post-hurricane damage in an old-growth bottomland hardwood forest. Canopy coverage, tip-up number and area, snags, and coarse woody debris were quantified in plots along randomly oriented transects established in bottomland hardwood stands and mixed Pinus taeda L. - bottomland hardwood stands. Wilcoxon rank sum tests of these individual disturbance features indicated greater disturbance in plots containing the early successional species, Pinus taeda, than in mixed bottomland plots without it. Principal components analysis (PCA) using these features illustrated much overlap between the two assemblages and suggested a continuum of canopy and soil disturbance conditions from windthrows along axis I and a continuum of canopy disturbance due to snag formation along axis II. Woody seedlings and trees were inventoried in 30 plots spanning the range of disturbance. Seedling species richness exhibited a rank order increase along axis I. Floristic trends in both seedling and tree layers were significantly correlated with disturbance represented by PCA axis I scores. Removal from the canopy and lack of successful recruitment of Pinus taeda, a former canopy dominant, suggest that the hurricane has shifted this old-growth floodplain forest to a different successional state.

Differences among women who exercise for ‘food related’ and ‘non-food related’ reasons

Young female subjects who engage in exercise to ‘work off’ food they have consumed (‘food related’ exercisers) were compared with other young female subjects who engage in exercise with other objectives (‘non-food related’ exercisers). Assessment of subjects' attitudes and behaviours indicated that the ‘food related’ exercisers exhibited more symptoms of obligatory exercise, eating disturbance, body dissatisfaction, and lower self-esteem, than did the ‘non-food related’ exercisers. A subset of women in the ‘food related’ group who reported exercising for the primary reason of working off food, losing weight, or changing their appearance (the ‘food related/body dissatisfied’ exercisers), indicated even greater disturbance on these measures. The role of exercise in relation to eating disorders is discussed. Copyright © 1998 John Wiley & Sons, Ltd and Eating Disorders Association.

Trophic relationships in the soil microfood‐web: predicting the responses to a changing global environment

AbstractIn this article, we evaluate how global environmental change may affect microfood‐webs and trophic interactions in the soil, and the implications of this at the ecosystem level. First we outline how bottom‐up (resource control) and top‐down (predation‐control) forces regulate food‐web components. Food‐web components can respond either positively or negatively to shifts in NPP resulting from global change, thus creating difficulties in developing general principles about the response of soil biota to global change phenomena. We also demonstrate that top‐down effects can be important in soil food‐webs, creating negative feed‐backs which may partially counter bottom‐up effects. Secondly, we determine how soil food‐webs and the processes they regulate respond to various global change phenomena. Enhanced atmospheric CO2 levels can have two main effects on plants which are relevant for the soil food‐web, i.e. enhanced NPP (often positive) and diminished organic matter quality (with negative effects, at least in the short term). Climate change effects resulting from elevated CO2 levels may be mainly secondary through alteration of vegetation, as shown by examples. Intensification of land management is usually associated with greater disturbance, which alters soil food‐web composition and key processes; this is particularly apparent in comparisons of conventionally tilled and nontilled agroecosystems. Global change involves shifts in plant species composition and diversity, possibly affecting soil food‐webs; we interpret this in terms of theories relating biodiversity to ecosystem function. We conclude that a more detailed understanding of interactions between NPP, soil organic matter and components of the soil food‐web, as well as their regulation of biogeochemical processes and ultimately ecosystem‐level properties, is essential in better understanding long‐term aspects of global change phenomena.

Extraction of non-timber forest products in the forests of Biligiri Rangan Hills, India. 5. Influence of dispersal mode on species response to anthropogenic pressures

We examined the response of forest tree species with different dispersal modes to anthropogenic pressure in a dry deciduous forest of South India. The species and their populations were sampled in two forest stands, one in proximity to a Soliga settlement (greater disturbance) and the other distant to the settlement (lower disturbance). Our results suggest that the populations of animal dispersed species than those of wind or passively dispersed species are more vulnerable to human disturbance. In fact wind dispersed species seem to be facilitated by human disturbances. The proximal site had a higher representation of understory plants and seedling belonging to wind dispersed species than that of animal dispersed species. We discuss the results in the context of the role of dispersal mode in shaping species response, and vegetation composition of forest to anthropogenic pressures.

Bladeploughing and Exclosure Influence Soil Properties in a Semi-Arid Australian Woodland

Runoff and sediment yield were evaluated on a sandplain dominated by woody perennial shrubs in north-western NSW, Australia. The site was bladeploughed; and some plots were grazed by sheep and cattle and others exclosed from grazing. Two years after ploughing and exclosure, grazed plots had significantly lower levels of aggregate stability and organic carbon compared with ungrazed plots, but there was no effect of ploughing. Surface pH levels were significantly greater on unploughed plots compared with ploughed plots. Two years after treatment, runoff and sediment yield were greatest on plots with the least disturbance (unploughed and ungrazed) and least on sites with the greatest disturbance (ploughed and grazed). We attribute differences in soil hydrology to the development of a thin physical soil crust on the unploughed-ungrazed plots, which restricted infiltration. On the ungrazed plots, increases in plant cover and biomass, and colonisation of the physical crust by biological elements, are hypothesised to lead to reduced runoff and sediment yield over time.

Assessment of Health Risks in Canteen Kitchens.

The ergonomic, occupational hygiene, and safety factors in canteen kitchen work were examined using worksite surveys and a questionnaire. Pain in the shoulders was found to be associated with the raised position of the upper limbs caused by excessively high working surfaces. Temperature, ventilation, and especially drafts caused the greatest disturbance at the workplace. Measurements revealed that variations in temperature during the day and between the neck and ankle caused the complaints. The most commonly occurring accident involved a wound to the fingers caused by a knife. However, employees reported burns to be the greatest accident risk. The two methods gave the most contradictory results concerning accidents and safety evaluations and the results corresponded best in ergonomic factors.

Effects of radial deformity on distal radioulnar joint mechanics

A cadaver experiment was performed to study the effects of radial deformity on the kinematics of the distal radioulnar joint and the anatomic configuration of the triangular fibrocartilage. Radial shortening caused the greatest disturbance in kinematics and the most distortion of the triangular fibrocartilage. Decreased radial inclination and dorsal angulation caused intermediate changes. Dorsal displacement produced minimal changes. Radial deformity did not produce distal radioulnar joint dislocation. These results provide biomechanical evidence of an important relationship between radial malunion and persistent symptoms in the distal radioulnar joint.

Psychodynamic aspects of delayed abortion decisions.

Multiple regression analysis of a wide range of variables for a sample of 58 women obtaining elective abortion identified psychodynamic factors as the only statistically significant explanations for seeking abortion at later gestational ages. Delay among these women was associated with greater disturbance in the basic sense of self as noted in indications of gender/sexual conflict on their drawings of a human figure, and lower achievement orientation ('striving') as expressed by lower levels of striving attributed to parents or other primary (early) caretakers. These findings are discussed as an active taking charge of an unintended pregnancy for women who present early for abortion; for those who delay, attempts to affirm a deficient feminine identification and/or reunite psychologically with the early caretaker are discussed as underlying dynamics.

Historical Vegetation, Fuel Loads, and Integrated Resource Information System for Bryce Canyon National Park

The composition and distribution of plant communities across a natural landscape is determined by a complex interaction of environment, interspecies relations and disturbance. Environmental factors associated with particular locations, such as precipitation and temperature regimes, limit the species which can occur at a given site to those with a metabolism suited to the environmental conditions. These environmental factors, while variable across the landscape, are relatively constant at a fixed point in space. Consequently, environment acts as a relatively constant constraint on vegetation distribution and composition. Within the usually large set of species which can exist at a given point, interspecies competition further limits the species present at a given time. The ecological characteristics of the species are also rather fixed, and the interspecies relations lead to a fairly directional and predictable change with time, i.e. succession. Disturbance reduces or eliminates some species directly, and leads indirectly to changes in composition through changes in the competitive hierarchy. In contrast to environmental and interspecies effects, the occurrence and effects of disturbance are highly variable, and depend in a complex way on previous disturbance and the current and previous vegetation. Historically, fire played an enormous role in determining the characteristics of vegetation in western forests. Additionally, fire suppression has preserved species which would have been reduced or eliminated under a regime of repeated burning, and has led to an increase in fuel loads in many natural communities. The high fuel loads cause relatively severe fires when fires do occur, causing relatively greater disturbance than occurred in the historical past. The results of these high intensity fires are very different from low intensity fires, with increased mortality of even fire-tolerant species, and occasionally catastrophic results. To evaluate the current landscape with reference to the historic landscape information is needed in several related areas. First, more baseline information is required on the historic vegetation mosaic. Specifically, what was the distribution of plant communities on the historic landscape, and what was the typical composition of these communities? Second, how does the pattern compare to the current pattern and how is this relation affected by the vegetation potential of the environment and the interspecies relations? How can natural ecosystem processes, including fire, be reintroduced so as to return the vegetation mosaic to one more similar to the historic vegetation mosaic? How can the guidelines which emerge from this information be implemented in an operational and spatially-explicit manner? These information needs are best met through a comprehensive information system incorporating the basic ecological relations of the vegetation and environment, fuel load accumulation, and fire behavior models.