bluuebunny/crossref_metadata_2025_split huggingface dataset:
Breeding skylarks Alauda arvensis on Environmentally Sensitive Area arable reversion grass in southern England: survey‐based and experimental determination of density
Authors: Wakeham‐Dawson Andrew , Szoszkiewicz Krzysztof , Stern Karen , Aebischer Nicholas J. 
Published: December 2010

1. In the South Downs and South Wessex Downs (southern England), designated an Environmentally Sensitive Area (ESA) in 1987 and 1993, respectively, farmers may undertake to conserve existing areas of downland turf (chalk grassland rich in plants and invertebrates) and to create new areas of grassland out of previously cultivated land (arable reversion), in exchange for annual payments. These areas are subject to strict management prescriptions. 2. Singing skylarks were surveyed on 40 km2 of downland turf, arable reversion, non‐ESA grass and arable land between 1994 and 1996 (April–July) in the two ESAs. The emphasis was on two types of arable reversion: permanent grassland sown with agricultural grass species, and chalk downland sown with traditional chalk grass species. 3. The surveys showed that singing skylark density was greater on chalk downland arable reversion than on permanent grassland reversion, in swards above 15 cm in height and in fields without boundary scrub. In general, permanent grassland reversion did not support more skylarks than winter wheat or grass not entered in the ESA schemes; highest densities were in undersown spring barley. Singing skylark density decreased after mowing in May–June in the South Wessex Downs ESA. 4. In 1995 and 1996, a fully randomized experiment was carried out on 12 fields (each c. 5 ha) at Plumpton, Sussex, to verify the survey findings. Six fields were grazed to maintain a sward below 10 cm in height (short‐grazed), and the others grazed to maintain a sward between 15 and 25 cm (long‐grazed) during the skylark breeding season (April–July). 5. On average, singing skylarks were six times as abundant, and non‐singing ones twice as abundant, in experimental long‐grazed fields as in short‐grazed fields. The total number and number of taxa of chick‐food invertebrates were about twice as large on average, and the number of grass seed heads recorded in July was two to 15 times as great, in long‐grazed as in short‐grazed fields. 6. Grazing‐exclusion cages within a randomized block experiment at New Erringham, Sussex, were sampled for invertebrates in mid‐May 1995 & 1996. Ungrazed cages (sward up to 40 cm tall) supported over five times as many invertebrates and over three times as many invertebrate taxa as grazed areas (sward <2 cm tall). 7. These results contributed to revised management prescriptions for the South Downs (1997) and South Wessex Downs (1998) ESAs. Prescriptions to encourage taller swards and to prevent mowing during the nesting season in the South Wessex Downs, and removal of the 10‐cm limit on sward height, allowance of fertilizer on some arable reversion grassland, and an arable tier encouraging undersown spring cereals and overwinter stubbles in the South Downs, will benefit grassland birds.
Acidifying peat as an aid to the reconstruction of lowland heath on arable soil: lysimeter experiments
Authors: Davy A. J. , Dunsford S. J. , Free A. J. 
Published: December 2010

1. Soil acidification is prerequisite for the reconstruction of lowland heath communities dominated by Calluna vulgaris on land that has been cultivated intensively. Naturally occurring sulphidic peat from a coastal basin deposit was investigated as a potential soil modifier. Its total S and Fe contents confirmed the presence of pyrite (FeS2). 2. In a lysimeter experiment, the surface pH of peat dropped rapidly from 6·5 to 2·5 as pyrite oxidized to produce sulphuric acid. It increased only slightly in the following 5 years. The pH of leachate from the lysimeters dropped to c. 2·0, rising to c. 3·0 over 5 years. Large pulses of soluble iron and sulphate were released from the lysimeters, peaking in the first winter; the Fe discharge fell to background levels after 2 years but SO42− concentrations were still elevated after 5 years. Calluna vulgaris seeds were not able to germinate and survive on the raw peat, even with irrigation. Some seedlings became established on the control agricultural soil but succumbed rapidly to competition from arable weeds. 3. In a second experiment, we amended the surface 15 cm of agricultural soil with peat and compared its properties with bracken litter. The peat sample acidified less, but both peat and bracken incorporation resulted in surface acidification. Neither acidity nor Fe was released in leachates, although the expected pulse of SO42− was discharged from treatments involving peat. Calluna vulgaris seedlings established well on peat mixtures and responded to initial weed control and irrigation treatments. However, after 1 year, competition from Trifolium repens, Agrostis gigantea and Agrostis capillaris had extinguished the C. vulgaris populations, except on the bracken litter mixture where some seedlings persisted for a further 2 years. Weed roots had grown through all the surface layers and exploited the underlying arable soil. 4. The weed seed bank is a major obstacle to heathland reconstruction on arable soil. Pyritic peat has potential as a soil amendment to lower pH and fertility and improve water retention, but it would be needed in greater proportions and to greater depths than used here in order to reduce weed competitiveness. Its use would release large amounts of mobile sulphate into the soil, potentially an issue for groundwater protection; the evidence suggests that the soluble iron and acidity released would not penetrate to a great depth in the profile.
Modelling the incidence of virus yellows in sugar beet in the UK in relation to numbers of migrating Myzus persicae
Authors: Werker A. R. , Dewar A. M. , Harrington R. 
Published: December 2010

1. The incidence of virus yellows diseases in sugar beet crops in eastern England during 1965–96 was analysed in relation to numbers of migrating Myzus persicae, the principal vector. 2. A non‐linear model was fitted to the data incorporating dual routes of infection: primary infection, arising from winged immigrant aphids carrying the virus, and secondary infection, arising from local dispersion of their wingless offspring transferring the virus from infected to uninfected plants. 3. The model was fitted to the data assuming that (i) the epidemic commenced when the first migrating aphid was recorded, (ii) the rate of primary infection was dependent on the total number of aphids migrating up to the end of June, and (iii) the rate of secondary infection was dependent on the proportion of diseased plants in the crop. 4. A good description of virus yellows incidence in August depended on allowing the rate parameters for primary and secondary infection to decrease sigmoidally over the years during 1965–96. The shape of this function depicted a major change in the epidemiology of virus yellows since 1974–76. Amongst several contributory factors, this change coincided with the introduction and subsequent wide use of systemic granular pesticides. 5. Good fits also depended on allowing the rates of disease progress to decay with time to accommodate effects of increasing host resistance with plant age to feeding aphids. This meant that early epidemics rose faster than late epidemics, which is consistent with general observations. 6. Given that the changes in the epidemiology of virus yellows over the years are associated with improvements in pest management practices, the model presents a useful extension to disease forecasting by providing predictions of disease risk in the absence of pesticides. Such predictions indicate that during the last decade up to five severe epidemics would have been likely.
Spatial and temporal patterns of heather use by sheep and red deer within natural heather/grass mosaics
Authors: Hester A. J. , Baillie G. J. 
Published: December 2010

1. Fragmentation of heather and conversion to grass under heavy grazing is a widespread phenomenon. In the British uplands it is attributed in particular to the effects of sheep and red deer, but little is known about the processes by which fragmentation occurs under grazing by these different herbivores. This has hindered the prediction of herbivore impacts and thus the design of appropriate management schemes for the protection of heather‐dominated vegetation. In this paper we report the results of an experiment examining the patterns of impact by sheep and red deer grazing separately or together within an area of fragmenting heather in north‐east Scotland during 1991–95. 2. Heather utilization by both species declined rapidly with distance from grass, with both herbivores grazing similar amounts of heather, except in autumn where heather utilization by deer was greater than that by sheep. 3. Differential patterns of grass patch use by sheep and red deer resulted in greater heather utilization around larger grass patches by red deer, but no consistent differences in edge‐heather utilization by sheep. Both species grazed less edge‐heather downhill of grass patches than uphill or across the slope. Thus, we hypothesize that on sloping ground grazing impacts will be greatest uphill from grass for both herbivores, but their patterns of impact around different grass patches will diverge when a range of grass patch sizes is present. 4. Patterns of impact as a result of trampling damage differed from those due to grazing, with damage concentrated at downhill edges of patches and paths, with corresponding increases in cover of species such as Vaccinium myrtillus where the heather had declined. 5. We suggest that on sloping ground at lower herbivore densities, trampling may have more important impacts on the heather than grazing, but as herbivore densities increase the relative importance of grazing will increase, thus changing the patterns of impact on the vegetation. 6. The implications of these differences in herbivore impacts are discussed in relation to the management of heather‐dominated vegetation under grazing by sheep or red deer and the limitations of approaches based on stocking rates alone.
Management of permanent set‐aside on arable land in Sweden
Authors: Hansson Margareta , Fogelfors Håkan 
Published: December 2010

1. Set‐aside fields have been an important element of the European agricultural landscape since the introduction of the set‐aside scheme by the European Community. However, countries in the European Community differ in their rules for managing set‐aside owing to different priorities. 2. In Sweden, a major goal is to reduce the total use of agricultural pesticides, consequently their use is prohibited in set‐aside. The options for weed control are therefore cutting and/or the use of a cover crop. 3. In this study, we describe the course of succession following the abandonment of farmland managed in different ways. The floristic composition was followed over a 10‐year period. Temporal trends in community development are described. 4. The experiment began in 1975 on farmland at six localities, distributed from southern to northern Sweden. The management treatments involving the application of fertilizers and cutting were applied to plots sown with a cover crop and to plots in which the succession started from bare ground. 5. We found that competitive interactions between species largely determined the successional course in our study. The competitive success of species was related to the management practices applied but there were also interactions between management and site conditions. 6. We propose that natural succession can be recommended on poor sites in combination with cutting, mainly to prevent the invasion of woody species. On fertile sites a cover crop should be used to suppress perennial weeds, and cutting is recommended mainly to increase species diversity.
Development of Sphagnum fallax diaspores on bare peat with implications for the restoration of cut‐over bogs
Authors: Buttler A. , Grosvernier P. , Matthey Y. 
Published: December 2010

1. The growth of Sphagnum fallax was studied in a glasshouse experiment. Capitulum diaspores of S. fallax were cultivated on five different types of bare peat core, representing a gradient of increasing disturbance. Increases in length and weight were measured. Three microclimates were simulated by protecting the bare peat with a shading mesh and a plastic cover in combination with two water levels. 2. Significant differences in the growth of S. fallax were observed in relation to microclimate changes. Protection techniques such as shading mesh and perforated plastic film allowed a better development of the diaspores compared to bare peat. A plastic cover caused the best growth and compensated for a low water table level. 3. Peat properties are critical when diaspores grow in direct contact with decomposed peat. The porosity, and especially its vertical pattern in the peat profile, proved to be an important factor. A particular combination of microclimate conditions at the surface of the bare peat, and physical properties of the upper peat layers, may favour the growth of S. fallax diaspores even where there is a low water Table 4
. Restoration of Sphagnum species on cut‐over bogs needs to consider both the microclimate conditions at the surface of the bare peat and the peat properties themselves. These factors are important for the diaspores, particularly in periods of climatic and hydrological stress. In such situations, commensalism with some vascular plants may be a useful trigger for Sphagnum growth.
Satellite imagery as a tool for monitoring species diversity: an assessment
Authors: Nagendra Harini , Gadgil Madhav 
Published: December 2010

1. A landscape of 5 × 5·5 km in the Karnataka region of the Western Ghats of India was mapped into seven landscape element types, using field identification of types as well as supervised and unsupervised classification of satellite imagery. 2. Plant communities distributed in these landscape element types were surveyed in the field using 246 quadrats of 10 × 10 m, in order to assess whether these types could be distinguished in terms of species composition. All angiosperms excluding grasses, which could not be identified accurately in the field, were recorded for this purpose. 3. Landscape element types identified in the field harboured significantly distinctive sets of species of flowering plants, and were also by and large distinctive in terms of their species richness. 4. Landscape element types could be identified accurately on the basis of supervised classification: the types thus demarcated harboured distinctive sets of flowering plants. 5. Landscape element types coupled to satellite imagery could then be used to organize a programme of monitoring biodiversity. 6. Unsupervised classification of satellite imagery did not permit classification of landscape element types with a high enough level of accuracy. In consequence, the demarcated landscape element types did not harbour significantly distinctive sets of species of flowering plants. Unsupervised classification is therefore not appropriate in a programme of monitoring biodiversity.
Moisture controls on Sphagnum growth and CO2 exchange on a cutover bog
Authors: McNeil P. , Waddington J. M. 
Published: December 2010

Summary 1. Abandoned cutover peatlands are persistent sources of atmospheric CO2. Net ecosystem CO2 exchange and Sphagnum net primary production of an abandoned block‐cut bog were measured in the field and in the laboratory using gas exchange techniques to determine the processes controlling CO2 exchange in these ecosystems. 2. Sphagnum net primary production was offset by peat respiration, resulting in the peatland becoming a net source of CO2 during the summer months. 3. Sphagnum photosynthesis was greatest at wet sites. In addition, sites with vascular plant cover photosynthesized at approximately twice the rate of sites where vascular plants were removed. 4. Laboratory results indicate that drying and wetting cycles negatively affect Sphagnum net primary production and net ecosystem CO2 exchange. Sphagnum and peat respiration increased 4–14‐fold upon rewetting, whereas Sphagnum photosynthesis did not recover until 20 days of saturation. 5. Synthesis and applications. This research emphasizes the importance of stable moisture availability for the growth of Sphagnum and the eventual development of a new acrotelm on the cutover bog surface. Restoration techniques must therefore include companion species and a constant moisture supply above the minimum threshold for Sphagnum mosses.
Stochastic models of foot and mouth disease in feral pigs in the Australian semi‐arid rangelands
Authors: Dexter N. 
Published: December 2010

SummaryFoot and mouth disease (FMD) is one of the world's most important livestock diseases and pigsSus scrofaare highly susceptible. In countries with significant feral pig populations, such as Australia, the possibility that FMD may become established in these populations is a cause of considerable concern.Current models of FMD in feral pigs in Australia are based on deterministic population and behavioural parameters. However, the population dynamics of feral pigs in the semi‐arid regions of Australia vary stochastically, in concert with the biomass of rainfall‐driven pasture.This study explored how stochastic variation in the population dynamics of feral pigs in semi‐arid rangelands affected the probability of persistence of an FMD epizootic, and its impact on the density of feral pigs. A stochastic model of feral pig population dynamics, with death rate linked to vegetation and rainfall, was linked to a deterministic model of FMD in feral pigs.Unlike the fully deterministic model, the stochastic model predicted inevitable extinction of the disease. When the transmission coefficient for FMD (β) was set at the mean value of 9 km2pig−1 day−1, the mean persistence time of the epizootic (in 1000 simulations) was 3338 days, with a maximum persistence time of 8439 days.On average the FMD epizootic reduced the population density of feral pigs, compared with the density of uninfected pig populations, by between 54% and 43% for transmission coefficients (β) equal to the estimated likely mean and minimum values (9·0 km2pig−1 day−1and 2·5 km2pig−1 day−1), respectively. This compares with a suppression of 27% in density for the equivalent deterministic model.Further stochasticity was introduced to the linked population and disease model by making the transmission coefficient β stochastic with values based on radio‐telemetry of a population of feral pigs in the semi‐arid rangelands over an 18‐month period.The addition of a stochastically varying β lowered the mean persistence time of the simulated epizootic to 1037 days in 1000 simulations and reduced the maximum persistence time to 3907 days. Pig density was reduced by 45% compared with uninfected populations.Synthesis and applications.These simulations suggest that any control programme to suppress a FMD outbreak in feral pigs in the semi‐arid rangelands of Australia should take account of prevailing environmental conditions when aiming to reduce feral pig populations beneath a threshold density (NT) below which the disease cannot persist. As theNTis higher than for the equivalent deterministic model, the disease may be easier to control than such models suggest.
Long‐term dynamics of Chernobyl 137Cs in freshwater fish: quantifying the effect of body size and trophic level
Authors: Sundbom Marcus , Meili Markus , Andersson Evert , Östlund Mikael , Broberg Anders 
Published: December 2010

Summary 1. Freshwater fish are a potentially important link in the transfer of radionuclides from polluted ecosystems to people. A pulsed contamination event such as the Chernobyl fallout in 1986 is a challenge to the prediction of radioactivity in biota, because activity concentrations of radionuclides can change dynamically among populations during an initial equilibration phase. This was demonstrated from time‐series of 137caesium (Cs) in fish from three Swedish lakes (1986–2000, eight species, > 7600 individuals). In addition, we used these data to test hypotheses about the influence of fish size and trophic level on the temporal patterns of 137Cs. 2. In order to facilitate comparisons, a pulse‐response model was developed to extract key parameters from field data: the timing (tmax) and level (Csmax) of the peak concentrations, the near steady‐state level (Csbase) and the long‐term decline rate (λ). 3. Peak concentrations in different fish were attained 56–806 days after the fallout. This delay (tmax) increased with body size and trophic level. Csmax increased with fish size but was highest at intermediate trophic levels. Csbase increased by a factor of 1·8 per trophic level, but was not influenced by size across species. The 137Cs‐size relationship within species, however, shifted from negative to positive during the first 2 years. 4. The apparent ecological half‐life (T1/2) for 137Cs increased after tmax and initially differed among fish and lakes. About 10 years after the fallout T1/2 was no longer significantly different among fish or lakes, suggesting that steady‐state among 137Cs levels in fish had been reached. The mean T1/2 during 1996–2000 was 46 years, implying that the future recovery from present 137Cs levels (more than 10‐fold higher than pre‐Chernobyl levels) will be dominated by the physical decay of 137Cs (30 years). 5. The influence of fish size and trophic level on 137Cs dynamics has been consistent among the three lakes. The duration of the 137Cs pulse in fish appeared to be regulated by fish ecophysiology, whereas the amplitude also appeared to be regulated by lake characteristics. 6. Synthesis and applications. These data have implications for the predictive modelling of pulsed contaminants in lake ecosystems and show that (i) complex temporal concentration trends in fish can be adequately modelled by a combination of simple first‐order equations; (ii) a one‐component decline function is insufficient to describe the observed increase in ecological half‐life over time; (iii) fish weight and trophic level can and should be treated as independent variables because their influence differs and changes over time. For management purposes, a pulse‐response model for fish can be scaled to different systems by using established relationships to account for differences in fallout and catchment biogeochemistry.