bluuebunny/crossref_metadata_2025_split huggingface dataset:
Between‐observer variation in the application of a standard method of habitat mapping by environmental consultants in the UK
Authors: Cherrill Andrew , McClean Colin 
Published: March 2003

Summary 1. In the UK, Phase 1 survey is a standard method of habitat mapping that has been used widely for environmental assessment and management planning. In this paper we make the first rigorous test of the precision with which environmental consultants apply the technique. 2. Six ecologists surveyed independently the same upland site in northern England. In pairwise comparisons between maps, spatial agreement was found to average 25·6% (with a range of 17·3–38·8%) of the area of the study site. The numbers of land cover types that were identified ranged from 13 to 21. Four or more surveyors agreed on the classification of 19% of the study site, while the area of land upon which all six agreed was only 7·9% of the study site. Spatial errors in the positioning of habitat boundaries occurred, but were a relatively minor source of the differences between maps. The majority of differences between maps were due to classification errors. Land cover types with similar species compositions were most frequently confused. 3. Spatially referenced field ‘target notes’ giving additional information on the vegetation mapped in each survey varied in number between 18 and 56. The contents of target notes were inadequate to allow a retrospective assessment of mapping decisions. The total numbers of species listed in target notes varied between surveys from 25 to 145. Sorenson's similarity for species lists derived from pairs of surveys ranged from 18·8% to 63·7%, and was not related to spatial agreement between surveys. 4. Time spent at the field site was not a correlate of any aspect of the results or cost of the survey. Three surveys conducted by members of a professional institute for ecologists were the most expensive, and also recorded larger numbers of target notes and species than the other surveys. However, their maps were no more similar than other pairs of maps. 5. Analysis of the survey results and comparisons with other methods of vegetation mapping suggest that mapping precision could be increased by (i) placing a greater emphasis on use of aerial photographs and other extant map data prior to (and during) field work; (ii) making greater provision for mapping of mosaics and increasing the level of floristic information in habitat definitions; (iii) recording a greater number of more detailed target notes in the field; and (iv) providing office‐based support to assist in the interpretation of aerial photographs, and the cross‐checking of field surveyors’ preliminary classifications against the contents of target notes and habitat definitions. The current application of the Phase 1 approach by environmental consultants places too great a reliance on decision‐making by the (frequently) unsupported lone surveyor whilst in the field.
Releasing genetically modified organisms: will any harm outweigh any advantage?*
Authors: Beringer John E. 
Published: March 2003

Summary 1.  The public debate about genetically modified organisms has concentrated largely on concerns about food safety and potential risks to the environment. In both cases there appears to be an assumption that existing crops and animals are safe. I discuss the experience we have to date from traditional methods and conclude that most concerns about environmental harm are more relevant to existing crops. 2.  The flow of genes among species, and even within different genera, is discussed with due attention being paid to the need for inherited genes to confer a selective advantage on hosts. 3.  A reason why so many people are critical of intensive agriculture and biotechnology is that virtually all changes in agricultural practice have an adverse impact on wildlife, particularly when such change leads to increased intensification. The problem of deciding how to manage agriculture to ensure that we maintain or enhance species diversity of wild plants and animals is discussed against the background that most of the UK environment is the result of human intervention. 4.  Nature and dense human populations cannot coexist without the former suffering. Our objective should be to develop and exploit our understanding of ecology to provide the information required to enable us to develop a far more enlightened future for agriculture and wildlife.
The impacts of non‐native species on UK biodiversity and the effectiveness of control
Authors: Manchester Sarah J. , Bullock James M. 
Published: March 2003

1. The introduction of non‐native species continues to cause ecological concern globally, but there have been no published reviews of their effects in the UK. Impacts in the UK are therefore reviewed, along with current legislation and guidelines relating to the introduction and control of such species. 2. A large number of non‐native species have been introduced to the UK, both deliberately and accidentally, but only a small number of introduced non‐native species have established and caused detrimental ecological impacts. However, general declines in UK biodiversity, and the potential effects of future climate change, may increase the susceptibility of ecosystems to invasions. 3. Detrimental impacts of non‐native species on native biota have occurred through competition, predation, herbivory, habitat alteration, disease and genetic effects (i.e. hybridization). There are potential effects on genetic biodiversity as well as species biodiversity. 4. Several high profile examples highlight the technical difficulties, and financial implications, of removing an introduced species once it is established. Few UK control or eradication programmes have been successful. 5. Control might be more feasible if ‘problem’ species could be identified at an earlier stage of establishment. However, the poor success of attempts to characterize invasive species and predict which will have negative impacts highlight the individual and unpredictable nature of invasions. The difficulties of making general predictions suggest that every proposed species introduction should be subject to rigorous ecological characterization and risk assessment prior to introduction. 6. The plethora of UK legislation and guidelines developed to reduce impacts of non‐native species only go part of the way towards ameliorating impact. Many species already established in the wild might cause future problems. Illegal releases and escapes of non‐native species may augment feral populations or establish new colonies. While regulation of imports and releases is important, further enforcement of existing legislation and action against unlicensed releases is necessary.
On the measure of sampling effort used in species accumulation curves
Authors: Moreno Claudia E. , Halffter Gonzalo 
Published: March 2003

Summary

We agree with Willott (2001) that number of individuals would be an appropriate measure of sampling effort to compare species accumulation curves among sites, but the reason is not sampling bias. It has been shown theoretically that number of individuals is an unbiased effort unit when density varies among sites, although our results with bats do not prove this.
We compared our results using nights and individuals as measures of effort in bat species accumulation curves, but did not detect changes in the estimated richness using the two measures.
We maintain our position about the utility of species accumulation curves as practical tools for inventory assessment, even for very diverse groups. To compare curves from different sites, we agree that number of individuals may be an unbiased measure of effort. But to give practical recommendations for sampling, we suggest that effort also be expressed in standard sampling units.
Long‐term indirect effects of mechanical cockle‐dredging on intertidal bivalve stocks in the Wadden Sea
Authors: Piersma Theunis , Koolhaas Anita , Dekinga Anne , Beukema Jan J. , Dekker Rob , Essink Karel 
Published: March 2003

Summary

There is world‐wide concern about the effects of bottom‐dredging on benthic communities in soft sediments. In autumn 1988, almost a third of the 50‐km2 intertidal system around the island of Griend in the western Dutch Wadden Sea was suction‐dredged for edible cockles Cerastoderma edule and this study assessed subsequent effects. An adjacent area not directly touched by this fishery and an area from which the mussel Mytilus edulis beds were removed, served as reference areas.
Sediment characteristics, together with the total stock size and settlement densities of Cerastoderma, Baltic tellin Macoma balthica and soft‐shelled clam Mya arenaria, were documented during 11 successive autumns before (August–September 1988) and after (August–September 1989–98) the suction‐dredging event in fished and unfished areas. Four other areas in the Dutch Wadden Sea, where changes in densities of juvenile bivalves from 1992 to 1998 were measured, served as additional reference locations.
Between 1988 and 1994, median sediment grain size increased while silt was lost from sediments near Griend that were dredged for cockles. The initial sediment characteristics were re‐attained by 1996.
After the removal of all Mytilus and most Cerastoderma, the abundance of Macoma declined for 8 years. From 1989 to 1998, stocks of Cerastoderma, Macoma and Mytilus did not recover to the 1988 levels, with the loss of Cerastoderma and Macoma being most pronounced in the area dredged for cockles. Declines of bivalve stocks were caused by particularly low rates of settlement in fished areas until 1996, i.e. 8 years after the dredging.
A comparison of settlement in the short (1992–94) and medium term (1996–98) after cockle‐dredging in several fished and unfished areas spread over the entire Dutch Wadden Sea, showed a significant negative effect of dredging on subsequent settlement of Cerastoderma. Macoma also declined, but not significantly.
We conclude that suction‐dredging of Cerastoderma had long‐lasting negative effects on recruitment of bivalves, particularly the target species, in sandy parts of the Wadden Sea basin. Initially, sediment reworking by suction‐dredging (especially during autumn storms) probably caused losses of fine silts. Negative feedback processes appeared to follow that prevented the accumulation of fine‐grained sediments conducive to bivalve settlement.
The importance of arable habitat for farmland birds in grassland landscapes
Authors: Robinson Robert A. , Wilson Jeremy D. , Crick Humphrey Q.P. 
Published: March 2003

Summary

Over the last 25 years, populations of seed‐eating birds have declined severely over most of western Europe. Local extinctions have occurred in grassland‐dominated areas in western Britain, which may be influenced by loss in habitat diversity and a decline in the amount of arable cultivation.
We used the large‐scale British Breeding Bird Survey of 1998 to investigate the importance of arable habitat within grassland landscapes for 11 common seed‐eating birds and four similar sized insectivores. Generalized linear models were used to model the number of birds recorded in agricultural habitat within survey squares as a function of the amount of arable habitat present.
Numbers of grey partridge Perdix perdix, skylark Alauda arvensis, tree sparrow Passer montanus, corn Miliaria calandra and reed buntings Emberiza schoeniclus, yellowhammer Emberiza citrinella and whitethroat Sylvia communis increased with the amount of arable habitat present in a survey square; the numbers of house sparrow Passer domesticus, four finch species, dunnock Prunella modularis, robin Erithacus rubecula and blackcap Sylvia atricapilla did not.
The positive association between numbers of some species and arable habitat within 1‐km squares was strongest where arable habitat was rare in the surrounding area, and weakest or even reversed when arable habitat was common. These results demonstrate the scale‐dependence of bird–habitat associations in agricultural landscapes, only demonstrable where data are available at fine grain over large geographical areas.
These results support the hypothesis that range contractions (i.e. local extinctions) of some granivorous species have occurred because of contraction in arable cultivation. The loss of arable habitat where it is scarce may be causing declines in some areas, even though intensification of arable management is thought to be the main cause of declines elsewhere. Agri‐environment schemes may need to vary between regions, for example to encourage arable cultivation in pastoral areas.
Optimal application strategies for entomopathogenic nematodes: integrating theoretical and empirical approaches
Authors: Fenton A. , Gwynn R. L. , Gupta A. , Norman R. , Fairbairn J. P. , Hudson P. J. 
Published: March 2003

Summary

The nematode Steinernema feltiae has been developed commercially as a biocontrol agent and is successful in controlling sciarid flies in mushroom houses. We used a simple model developed in parallel with a series of field trials, to optimize the application strategy of the nematode.
The first field trial provided life‐history parameter estimates for both the sciarid flies and the nematodes and showed there to be substantial levels of nematode recycling, leading to high levels of control. Crucially, the field trial showed that by splitting the application into two, and applying half the nematodes at day 0 and half at day 7, the overall number of nematodes (dose) could be substantially reduced from currently recommended levels without sacrificing control success.
The model confirmed that there should be a benefit in splitting the dose, if the second application is timed to coincide with the peak in numbers of highly susceptible sciarid larvae. Importantly, the model provided insight into the dynamics of the sciarid larvae, even though the original data set only recorded adult fly numbers.
Using a split dose, optimally timed, the model suggested that total doses could be reduced by up to 75% and still achieve control comparable to that found with currently recommended dosages. The timing of the second application of nematodes was crucial in determining the level of control.
The model predictions were validated against a second independent field trial with considerably lower fly densities. Even under these different conditions, the predictions were accurate, indicating the robustness of the modelling approach.
To date models have rarely provided genuine practical advice to applied agriculturists and biocontrol practitioners. This study shows how a simple model developed in parallel with replicated field trials leads to a better understanding of the biological processes underlying successful control, resulting in improvements in recommended application strategies.
Impact of the rosette crown weevil Trichosirocalus briesei on the growth and reproduction of Onopordum thistles
Authors: Briese D. T. , Thomann T. , Vitou J. 
Published: March 2003

Summary

Several European thistle species of the genus Onopordum have become naturalized in Australia and are considered serious pasture weeds, leading to a project aimed at their biological control.
The population structure of a potential control agent, the crown weevil Trichosirocalus briesei, a newly described member of the Trichosirocalus horridus species group, was studied under natural conditions on its Onopordum spp. host‐plants in northern Spain.
Trichosirocalus briesei was found to be the most abundant of three species of crown‐feeding insect utilizing these plants. Adults of this univoltine weevil began to lay eggs in mid‐autumn and larval population sizes increased over winter until pupation in early spring.
The spatial distribution of the immobile larvae was not random, indicating that females were selective in their oviposition behaviour. Field data suggested that plants in dense patches were attacked less frequently, and larger rosettes were preferred for egg‐laying.
A preliminary cage experiment indicated that feeding by T. briesei could damage Onopordum spp. thistles. A second experiment using plants in individual cages showed a clear relationship between the density of the weevils and the reduction in several growth parameters and seed production. At the highest densities, larval feeding could kill Onopordum rosettes before they produced flowering stems.
These results indicated that T. briesei has the potential to contribute to the biological control of Onopordum spp. thistles in Australia. Following host‐specificity testing, the weevil was released in 1997.
Effect of PCP and sigma ligands on both noradrenaline‐ and electrically‐induced contractions and on [3H]‐noradrenaline uptake in rat vas deferens
Authors: Pubill D. , Canudas A. M. , Sureda F. X. , Camins A. , Pallas M. , Escubedo E. , Camarasa J. 
Published: March 2003

1 Electrically induced contractions of the epididymal portion of rat vas deferens were potentiated in concentration‐dependent manner (0.1–30 μm) by different sigma and PCP receptor ligands (PCP, TCP, (+)‐MK‐801, dextromethorphan and (+)‐3‐PPP); dextrorphan did it in a minor extent. 2 Sigma and PCP receptor ligands also potentiated the effect of noradrenaline, inducing a reduction of the noradrenaline EC50 value in the rat vas deferens. The rank order of potencies was: PCP > TCP > (+)‐3‐PPP > (+)‐MK‐801 > dextrorphan > > > dextrometorphan. 3 In contrast, haloperidol (1 μm), a sigma receptor ligand, inhibited both the neurogenic and noradrenaline‐induced responses in this tissue. 4 The effect of PCP and sigma receptor ligands on noradrenaline uptake was evaluated. All compounds tested, including haloperidol, inhibited the tritiated noradrenaline incorporation to the tissue. IC50 values were in the micromolar range, between 1.09 μm for dextrophan and 18 μm for dextrometorphan. 5 It is concluded that a direct interaction with the noradrenaline uptake system is involved in the potentiating effect of some sigma and PCP receptor ligands in the epididymal portion of rat vas deferens.
Cholinergic influence on the sensitivity of cough reflex in awake guinea‐pigs
Authors: Jia Y. X. , Sekizawa K. , Sasaki H. 
Published: March 2003

1 We studied the effects of an intraperitoneal (i.p.) administration of atropine on bronchomotor tone induced by carbachol aerosols in anaesthetized and ventilated guinea‐pigs and on the sensitivity of cough reflex to capsaicin aerosols in awake guinea‐pigs. 2 The intraperitoneal administration of atropine (10−−8–10−−6 m kg−−1) reduced carbachol (8 mgml−−1; 1 min)‐induced increases in pulmonary insufflation pressure and a complete inhibition was achieved at a dose of 10−−6 m kg−−1 in anaesthetized guinea‐pigs. 3 In awake guinea pigs, capsaicin aerosols (10−−5–10−−3 m) caused dose‐dependent increases in the number of coughs. Atropine (10−−7–10−−6 m kg−−1 i.p.) shifted the dose–response curves to capsaicin to the right in a dose‐dependent fashion. Carbachol aerosols, at the maximal concentration (2 mg ml−−1) that did not cause bronchoconstriction, shifted them to the left compared with the control. 4 Atropine (10−−6 m kg−−1 i.p.) significantly increased the provocative concentration of capsaicin that caused five coughs (P < 0.01) and carbachol aerosols (2 mg ml−−1) significantly decreased it (P < 0.01). 5 We conclude that cholinergically mediated airway tone regulates cough sensitivity in awake guinea pigs.
The offset of β‐adrenoceptor antagonism of the responses of the rat right ventricle to isoprenaline
Authors: Doggrell S. A. , Henderson C. J. 
Published: March 2003

1 The aim of the study was to test the hypothesis that the offset of action of β‐adrenoceptor antagonists on the heart is related to their lipophilicity, with low and highly lipophilic drugs having a rapid and slow offset, respectively. The effects of β‐blockers with low (atenolol), moderate (celiprolol), high (propranolol) and very high (bopindolol) lipophilicity on the contractile responses of the rat right ventricle to isoprenaline were determined. 2 Atenolol at 10−−6 and 10−−5 m, celiprolol at 10−−7, 10−−6 and 10−−5 m, propranolol at 10−−8, 10−−7 and 10−−6 m and bopindolol at 2 × 10−−9 and 10−−8 m caused parallel rightward shifts of the isoprenaline response curves with no effect on maximum responses. The Schild plots for atenolol, celiprolol and propranolol had slopes that were not significantly different from 1, which is indicative of competitive reversible antagonism. The pKB values were 7.33, 7.78, and 8.79 for atenolol, celiprolol, and propranolol, respectively. The Schild plot for bopindolol had a slope that was significantly greater than 1. 3 Our hypothesis is supported as the effects of propranolol and bopindolol were more slowly offset than those of atenolol and celiprolol. Thus, the concentration‐ratio of 141 in the presence of atenolol at 10−−5 m was reduced to 4 after the first wash, whereas the ratio of 100 in the presence of propranolol at 10−−7 m was only reduced to 45 after a similar wash. The ratio of 54 with celiprolol at 10−−6 m was reduced to 5, whereas the ratio of 70 with bopindolol at 10−−8 m was only reduced to 28 by the first wash. 4 The effects of bopindolol were very slowly or not reversible over two washes in the absence or presence of atenolol at 10−−6 m. It is suggested that bopindolol is a very slowly reversible β‐blocker, and that this contributes to its slow offset of action.
Blood pressure control in kidney transplant recipients: influence of immunosuppression
Authors: Gerhardt U. , Riedasch M. , Hohage H. 
Published: March 2003

1 Disturbances of the blood pressure regulation, probably due to dysfunction of the autonomic nervous system, are well known complications in chronic renal failure. Haemodialysis and transplantation have been reported to ameliorate nerve dysfunction. 2 In this study, the function of the blood pressure control was investigated in kidney transplant recipients after longtime haemodialysis treated with ciclosporine A and tacrolimus and compared to healthy individuals. To investigate the influence of immunosuppression, the measurements were performed twice, at low and high whole blood concentrations of ciclosporine and tacrolimus. Besides ciclosporine, tacrolimus, azathioprine and prednisolone no other drugs were used in the group of kidney transplant recipients. 3 Kidney transplant recipients (KTR) treated with ciclosporine showed reduced blood pressure and heart rate responses to the cardiovascular stress tests (head‐up tilt and cold pressure test) under basal conditions. Two hours after ciclosporine application, the differences in the responses to cardiovascular stress tests between KTR and controls were significantly more pronounced. 4 Patients with tacrolimus immunosuppression showed a similar blood pressure and heart rate response under basal conditions. Two hours after drug application, the blood pressure response following orthostatism and heart rate response to the cold pressure test were significantly higher in tacrolimus treated patients. 5 Our results indicate, that kidney transplant recipients still express an altered function of the blood pressure control. Furthermore, ciclosporine A and tacrolimus seem to contribute to dysfunction of the blood pressure regulation by their own. Tacrolimus immunosuppression does not seem to offer advantages concerning the function of the blood pressure control as compared to ciclosporine A.