The movements of the Kittiwake

Capsule During winter songbirds were far more abundant in game cover crops than conventional agricultural habitats.

Aims To quantify game crop use during winter by farmland songbirds when compared with conventional farmland at a regional scale.

Methods Songbirds were counted on 20 farms in eastern Scotland. The number of songbirds using game crops was compared with a sample of nearby conventional crops – with particular emphasis on set-aside and cereal stubbles.

Results Game crops supported up to 100 times as many birds per hectare, of significantly more species, than the other two habitat categories. Many of these species were those currently causing concern because of their declining populations.

Conclusion Game crops could provide opportunities for increasing food resources to songbirds whose populations may be limited by food availability and possibly arrest population declines. At present, the only measures likely to facilitate this are the government's various agri-environment schemes.     

The environmental impacts of biomass crops: use by birds of miscanthus in summer and winter in southwestern England

We compared birds in a group of established and well‐managed miscanthus (Miscanthus x giganteus) fields in Somerset and East Devon, southwestern England, with plots of short rotation coppice (SRC) willow, arable crops and grassland in two winters and one summer. Following early spring cutting, 19 miscanthus fields grew taller, initially produced greater cover and were less weedy than SRC. As stubble in May, the miscanthus contained broadly similar species at similar densities to arable and grassland comparison plots. By July, at 2‐m‐tall, miscanthus held higher densities of birds but of fewer species, most of them characteristic of woodland and scrub. SRC, previously identified as being a beneficial crop for many birds, always contained more species and individuals than miscanthus. Throughout each of two winters, 15 miscanthus plots remained unharvested and contained more wood/scrub species such as Blackbirds Turdus merula, tits, Reed Buntings Emberiza schoeniclus and Woodcock Scolopax rusticola than the comparison plots, which held more corvids and Skylarks Alauda arvensis amongst others. Similar overall mean densities of birds in the miscanthus and the comparison plots masked relatively low density variance in miscanthus and very high variance in the comparison plots. Unharvested miscanthus crops grown in place of habitat types supporting flocks of wintering birds would displace these flocks. Miscanthus plantations with open patches attracted more finches and waders in winter. The two previous studies of birds in miscanthus in the UK found more species and more individuals than we did in summer and winter. Both these studies documented high levels of weediness and patchy crop growth. In the context of this previous work our data suggest that bird use of miscanthus in summer and winter is likely to be variable, affected by region, weediness, crop structure and patchiness. While large‐scale cropping of SRC in England is likely to have a positive overall impact on a suite of common farmland and woodland birds, our data suggest that miscanthus in the southwest of England may have an approximately neutral effect. However, some open farmland specialist species may be lost when planting either crop.     

Birds in willow short-rotation coppice compared to other arable crops in central England and a review of bird census data from energy crops in the UK

We present the results of spring and winter surveys of birds using 22 willow short-rotation coppice (SRC) fields and 22 paired arable or grassland controls over a 5 year period in central and northern England. The study sites were linked to the first commercial wood-fuelled electricity plant in Yorkshire and were managed commercially. We use the findings of this study, in the context of other work on birds in energy crops, to suggest how birds may be affected by commercial cropping of SRC or energy grasses on UK farmland. For willow SRC, most existing farmland species were not completely displaced by SRC cropping. Even farmland specialists such as Skylark Alauda arvensis used cut SRC fields. Some species characteristic of scrub and wood-type habitats were attracted onto farmland by SRC. Birds were more abundant in hedgerows next to SRC than in those adjoining arable or grass. The interior of large SRC plots contained fewer birds than the edge-zone (< 50 m). In winter, the same resident species occured in SRC as the summer, plus winter migrants such as Snipe Gallinago gallinago and Fieldfare Turdus pilaris . Overall, more individuals and species were recorded in and around SRC than equivalent arable or grassland throughout the year. Yellow Wagtail Motacilla flava and certain locally occurring farmland specialists may be displaced by SRC plantations. Equivalent census data for energy grasses in the UK are not available. The impact of large regional energy crop developments on birds is not known. We do not know if species commonly recorded in these crops survive and breed well so population effects are unknown. However SRC crops are often weedy and insect rich and hence have potential as foraging habitats in summer and winter. The scope for agri-environment schemes to include energy crops is discussed.     

An experimental approach to Neolithic shifting cultivation

Archaeobotanical data from Late Neolithic lake-shore dwellings (4300-3500 cal B.C.) in the northern Pre-alpine lowlands are interpreted in different ways. The presence of permanent arable fields as well as arable fields with short fallow phases and shifting cultivation with slash-and-burn has been discussed. To test these hypotheses experimentally we have been conducting tests in a forest northeast of Stuttgart since 1994. The slightly south-exposed experimental area of approximately 4.5 ha on a loess soil is covered by mixed deciduous forest, is available for at least 20 years and has been divided into 34 plots of 30 × 30 m. Up to 2001, five plots were used for experiments. The normal procedure is clearing, burning the dry small timber (less than 10 cm in diameter) and then growing winter cereals (bread wheat) for one season. The yields were between 2000 and 4000 kg grains per ha. The harvest was more or less free from weeds. First attempts with summer crops gave much lower yields of about 1100 kg grains per ha. Continuous cereal growing on the same place in the following years resulted in minimal to zero yields, mainly due to vigorous weed growth. These weeds are not crop weeds, but forest perennials of clearings and forest fringes. Ploughing to remove the weeds is not possible, because of the presence of roots and tree-stumps, most of them still living. Weed regulation by hoeing, burning or cattle grazing remains to be tested. Protection of the crop from game and birds is by fences and nets, but protection from mice seems difficult. In the spectra from the pollen traps, clearing and burning are strongly indicated, but cereal growing only slightly. Received July 31, 2001 / Accepted April 9, 2002     

The provision of winter bird food by the English Environmental Stewardship scheme

Environmental Stewardship (ES) is the main mechanism for reversing the decline in farmland birds in England, and includes a range of options designed to provide winter foraging for seed‐eating species. We estimated granivorous songbird densities on ES options designed to provide winter food, on farms within the Entry Level (ELS) or Higher Level (HLS) strata of ES. ES Wild Bird Mixtures (WBMs) hosted higher densities and a wider range of granivores than non‐ES game covers, although in East Anglia the enhanced HLS WBM was used no more than the basic ELS WBM. In the West Midlands there were low densities of granivores on all WBMs and game covers. The widespread ELS WBM appeared to provide little food for buntings but supported finches, partially through greater weed burdens. There was a weak, non‐significant trend for Skylarks Alauda arvensis to make greater use of ELS cereal stubbles than non‐ES stubbles, possibly because of post‐harvest herbicide restrictions allowing overwinter weed growth. At the field scale, this work demonstrates that although some ES options provide winter food resources for birds, there is limited evidence for additional benefits of Higher Level vs. Entry Level Stewardship to wintering farmland songbirds.     

Dedicated biomass crops can enhance biodiversity in the arable landscape

Suggestions that novel, non‐food, dedicated biomass crops used to produce bioenergy may provide opportunities to diversify and reinstate biodiversity in intensively managed farmland have not yet been fully tested at the landscape scale. Using two of the largest, currently available landscape‐scale biodiversity data sets from arable and biomass bioenergy crops, we take a taxonomic and functional trait approach to quantify and contrast the consequences for biodiversity indicators of adopting dedicated biomass crops on land previously cultivated under annual, rotational arable cropping. The abundance and community compositions of biodiversity indicators in fields of break and cereal crops changed when planted with the dedicated biomass crops, miscanthus and short rotation coppiced (SRC) willow. Weed biomass was consistently greater in the two dedicated biomass crops than in cereals, and invertebrate abundance was similarly consistently higher than in break crops. Using canonical variates analysis, we identified distinct plant and invertebrate taxa and trait‐based communities in miscanthus and SRC willows, whereas break and cereal crops tended to form a single, composite community. Seedbanks were shown to reflect the longer term effects of crop management. Our study suggests that miscanthus and SRC willows, and the management associated with perennial cropping, would support significant amounts of biodiversity when compared with annual arable crops. We recommend the strategic planting of these perennial, dedicated biomass crops in arable farmland to increase landscape heterogeneity and enhance ecosystem function, and simultaneously work towards striking a balance between energy and food security.     

Habitat selection by Skylarks Alauda arvensis wintering in Britain in 1997/98

The results of a national survey of wintering Skylarks Alauda arvensis undertaken by the British Trust for Ornithology (BTO) between November 1997 and February 1998 are reported here. Over three visits, volunteers counted Skylarks and mapped habitats in 541 1-km squares selected from the Skylark's winter range based on BTO Winter Atlas data and a stratified random sampling approach. Four landscape strata were defined from the Institute of Terrestrial Ecology landscape classification: arable, pastoral, marginal upland and saltmarsh. The survey counts underestimated Skylark abundance, but were good measures of relative abundance across habitat types. The two best predictors of Skylark presence–absence at the landscape scale were the availability of coastal and farmland habitats. Squares with saltmarsh had the highest densities and occupancy (80% of squares). At the patch scale crop stubbles, especially weedy cereal stubbles, were used significantly more than expected by chance. Oilseed rape was positively selected whereas cereal crops were used in proportion to availability and grazed grass was avoided. Skylarks avoided fields smaller than 2.5 ha and selected fields larger than 7.5 ha. We estimate that in midwinter there may be less than 1–2 ha of weedy cereal stubble per 1-km square. We recommend the retention of over-winter stubbles for the conservation of Skylarks and other farmland birds, and research on stubble management and effects on grain availability and arable weed regeneration on Skylark use.     

Assessing the implications of the loss of set‐aside for farmland birds

Between 1988 and 2007, set‐aside, a European Commission production control measure, took an average of 10% of arable farmland in the EU out of production each year. In 2007, the set‐aside rate was set to 0% and the scheme was later abandoned altogether. By assessing associations of farmland birds with set‐aside and quantifying the extent of set‐aside loss, this study aims to assess the implications of set‐aside loss for farmland bird conservation. During the lifespan of set‐aside, a large number of studies assessed the biodiversity value of set‐aside and other agricultural crops and habitats. Where possible we considered measurable benefits of set‐aside. However, some studies did not specify the type of set‐aside and in some cases set‐aside fields were grouped with cereal stubble fields. In these cases, we took the pragmatic approach of assessing the value of generic stubble fields as a conservative minimum estimate of the value of set‐aside fields. A re‐analysis of data from 30 intensive studies demonstrates that farmland bird densities tended to be higher on set‐aside than on either cereal or oilseed rape crops. Without mitigation, these are the two crops likely to replace most set‐aside fields. We estimate that 26–52% of the farmland populations of key granivorous passerines were present on stubble fields, giving an indication of the proportion of birds likely to be present on set‐aside fields within this broader category. An extensive survey of lowland farmland during winters 1999/2000, 2000/2001 and 2002/2003, repeated in February 2008, showed a doubling of the number of 1‐km squares with no stubble and a halving of the number of squares with more than 10 ha of stubble. After set‐aside abandonment, 72% of squares had no stubble in the important late winter period, confirming that many of the former stubble fields were retained as set‐aside. A simple correlative model suggests that this could cause a small increase in the rate of decline of Skylark Alauda arvensis and Yellowhammer Emberiza citrinella populations, assuming causal links between stubble area and demography. However, even if this assumption cannot be supported, these results clearly indicate that a significant proportion of some farmland bird populations will need to find alternative breeding and foraging habitats.     

Development of an agri-environment scheme option: seed-bearing crops for farmland birds

Winter mortality, resulting from reduced food supply during a period of agricultural intensification, is thought to have driven population declines for some farmland bird species. Planting of game crops has increased over this period in order to provide food and cover for gamebirds. We investigate the potential of this managed habitat for farmland songbird conservation, using intensive single-site studies, and an extensive national survey. Game crops were used more than other farmland habitats by a wide range of bird species. Kale and quinoa were used by many species, whereas maize was used by very few. Cereals such as triticale and millet were used by many species, including several not associated with brassicas such as kale. Crop species differed in the rate of seed shedding, and therefore in the amount of seed food that they provided through the winter. Crop location influenced use by some bird species, with crops close to hedges or other cover generally being favoured. Use of nitrogen fertilizer influenced seed yield, and therefore crop value as a source of food for birds. Our results suggest that, if managed and sited correctly, a combination of two or three crop species can provide a valuable winter food resource for many nationally declining farmland bird species, but further attention needs to be given to their agronomy. This form of management is now incorporated as an option within agri-environment schemes in England, Scotland and Wales. It enables farmers to apply existing skills to conservation and is compatible with their cultural values.     

Landscape level processes driving carabid crop assemblage in dynamic farmlands

Landscape heterogeneity has been shown to be a major factor in the maintenance of biodiversity and associated services in agricultural landscapes. Farmlands are mosaics of fields with various crop types and farming practices. Crop phenology creates asynchrony between fields sown and harvested in different periods (winter vs. spring crops). The present study was conducted to examine the influence of such spatio-temporal heterogeneity on biodiversity, with the hypothesis that it would lead to spatio-temporal redistribution (shifting) of species. Species richness and activity-density of carabid beetles in winter cereal (winter) and maize (spring) crops were compared across 20 landscapes distributed along a double gradient of relative area and spatial configuration of winter and spring crops. Maize fields were sampled in spring and late summer for comparison over time. The response of carabid species richness to landscape heterogeneity was weak in spring, but maize field richness benefited from adjacencies with woody habitat, in late summer. In spring, increased length of interfaces between winter and spring crops lowered carabid activity-density in winter cereal fields, suggesting that maize fields acted as sinks. Interfaces between woody habitats and crops increased activity-density in both crop types. We found no evidence of spatio-temporal complementation, but different species benefited from winter cereals and maize in spring and late summer, increasing overall diversity. These findings confirm the role of adjacencies between woody and cultivated habitats in the conservation of abundant carabid assemblage in winter cereals and maize. We conclude that between-field population movement occurs, and advocate for better consideration of farmland heterogeneity in future research.     

Farmland bird invertebrate food provision in arable crops

Invertebrates are an essential food source for most farmland birds yet their relative abundance and biomass in the most commonly grown arable crops are poorly understood. Dvac suction sampling was used to determine the abundance, biomass and community composition of those invertebrate groups considered important in the diet of farmland birds for the commonest arable crops. Approximately 40 fields were sampled at the edge and mid‐field over 2 years in three different locations in England. In cereals, the fauna was primarily comprised of Araneae (10%), Coleoptera (30%) and Hemiptera (58%), whereas the oilseed rape fauna was dominated by Coleoptera (65%) and peas and potatoes by Hemiptera (89%). Beans contained a high proportion of Coleoptera (39%) and Hemiptera (49%). Aphididae were the most abundant family (20–86% of total), although in oilseed rape and beans, Chrysomelidae, Curculionidae and Nitidulidae formed ca 20% of the fauna. Aphids only formed a small proportion (7%) of the total biomass, except in peas (32%). Instead, Araneae, Carabidae, Heteroptera, Homoptera and Tipulidae formed much larger and more equal proportions. The highest abundance and biomass of invertebrates were recorded in cereals and least in potatoes. The Grey Partridge chick‐food index in all crops was only a half or less of the level required to ensure that chick survival is sufficient to maintain numbers of this red‐listed species. The total number of invertebrates, their biomass, diversity and the Grey Partridge chick‐food index were higher at the crop edge compared to mid‐field. Conservation measures are needed to help reverse the long‐term declines of invertebrates on farmland, which should include developing further invertebrate‐rich, agri‐environment scheme options and management techniques to encourage invertebrates considered important as bird food within arable crops.     

Non-inversion tillage and farmland birds: a review with special reference to the UK and Europe

This paper reviews the current knowledge of the effects of non-inversion tillage (NIT) on farmland birds and their food resources. NIT is a method of establishing a crop without using a mouldboard plough and is becoming increasingly popular in the UK. NIT generally disturbs the soil to shallower depths than conventional tillage and is therefore expected to have beneficial effects on biodiversity on arable land as compared with mouldboard ploughing. The diets of farmland birds change throughout the year, and many species take invertebrates over the breeding season. Seeds are also important for many species of farmland birds throughout the year and especially over the winter months. The effects of NIT on these farmland bird food resources, in particular ground beetles (Coleoptera: Carabidae), spiders (Arachnida: Araneae), earthworms (Annelida) and seeds (arable weeds and cereal crops) are reviewed.     

Breeding ecology of Yellow Wagtails Motacilla flava in an arable landscape dominated by autumn-sown crops

Capsule Yellow Wagtails successfully raised two consecutive broods in landscapes dominated by autumn-sown crops and did not require spring crops or fallow plots for later nesting.

Aims To assess whether arable landscapes dominated by winter cropping provide habitats that allow Yellow Wagtails to raise two successful broods. To assess the utility of spring cultivated agri-environment fallow plots as a nesting and foraging habitat for Yellow Wagtails.

Methods Nesting success and foraging behaviour of Yellow Wagtails was monitored on lowland arable farmland dominated by winter cropping during two successive breeding seasons.

Results Yellow Wagtails successfully raised first and second broods mainly in winter cereals, with later nests being more successful. Some nests were initiated in bean fields where egg-stage failure rates were high, probably as a consequence of depredation. Fallow plots were not used for nesting but, along with other areas of sparse vegetation, were regularly used for foraging.

Conclusions Yellow Wagtails breeding at relatively low densities achieved high rates of reproductive success in a landscape dominated by winter cereals and with few spring-sown crops. This study suggests that spring-sown crops may not be necessary for Yellow Wagtails to rear two successful broods each summer within arable landscapes.     

Winter field use and habitat selection by Eurasian Golden Plovers Pluvialis apricaria and Northern Lapwings Vanellus vanellus on arable farmland

Eurasian Golden Plovers Pluvialis apricaria and Northern Lapwings Vanellus vanellus winter in large numbers on Britain's farmland. Previous studies in mixed farming areas showed pronounced preferences for permanent pasture, but increasing numbers of plovers winter in eastern Britain where arable farmland dominates. We show that an area of intensive arable farmland supported significant numbers of both species from October to February in the absence of large areas of pasture. Habitat use varied seasonally as the habitats present changed. Throughout winter, use of cereal crops matched their availability: plovers selected harrow in early winter, sugar beet stubbles in midwinter and other crops in late winter. Pastures were rarely used at any time of the year. Flocks occupied only a fraction of the available fields, concentrating most in large fields with open boundaries and where manure had been applied. Daytime feeding was more likely during cold days after nights with a new moon, short duration of moonlight or low-intensity moonlight. These results show that plovers are currently able to utilize intensive arable farmland but future changes in management, such as cessation of manure applications and reductions in sugar beet cropping, could have detrimental effects.     

Interaction of local and landscape features in the conservation of Hungarian arable weed diversity

Question: How do local and landscape management contribute to weed diversity in Hungarian winter cereal fields? Location: Central Hungary. Methods: Vascular plants were sampled in 18 winter cereal fields along an intensification gradient according to nitrogen fertilization, in the first cereal rows (edge) and in the interior part of the fields. Weed species were divided into groups according to their residence time in Central Europe (native species, archaeophytes, neophytes) and nitrogen preference (low to medium, LMNP, and high, HNP species). The percentage of semi‐natural habitats was calculated in the 500 m radius circle. Effects of fertilizer use, transect position and semi‐natural habitats were estimated by general linear mixed models. Results: We recorded 149 weed species. Fertilizer had a negative impact on the species richness of archaeophytes and LMNP species, and on the cover of native weeds. There was greater species richness and weed cover at the edge of the fields than in the centre. A higher percentage of seminatural habitats around the arable fields resulted in greater total species richness, especially of archaeophytes and LMNP species. We found an interaction between the percentage of semi‐natural habitats and transect position for species richness of archaeophytes and LMNP species. Conclusions: Reduced use of fertilizers and a high percentage of semi‐natural habitats would support native and archaeophyte weed diversity even in winter cereal fields, while large amounts of fertilizer may promote invasion of neophytes. However, the beneficial effect of the semi‐natural habitats and greater species pool on the arable flora may prevail only in the crop edges.     

Summer bird abundance and distribution on set-aside fields on intensive arable farms in England

The abundance and distribution of breeding birds were compared on paired fields comprising one set-aside field and one crop field, on 11 intensive arable farms in eastern and western England. A single observer made four visits to all set-aside and crop fields between April and July and recorded all birds seen during standardised counts and transects.
Rotational and non-rotational set-aside supported higher densities and more species of birds than fields of wheat, brassicas, root crops and seed rye. These differences in density, between set-aside and crops, were evident across a suit of species including waders, gamebirds, pigeons and passerines and were particularly marked on rotational set-aside. The majority of species recorded in fields away from boundaries would have been feeding rather than nesting there and higher bird densities on set-aside compared with adjacent arable crops probably reflects greater food abundance in the former.
The study is the first to demonstrate a clear habitat preference for set-aside by a wide range of bird species throughout the breeding season and it allows a number of recommendations to be made concerning the development of cost-effective agri-environment measures. The fact that the majority of birds utilised the outer 5 m, or in some cases 20 m, margin of the field suggests that many of the benefits of whole field set-aside may be derived from marginal strips. A slight, but not significant preference for rotational over non-rotational set-aside suggest such margins should be managed to maintain a patchy, relatively diverse sward of arable plants. A key feature of set-aside is the scale at which it has been incorporated into the arable landscape. Agri-enviromental schemes will only provide similar national benefits if they are implemented on a wide scale in such as way as to promote high uptake by farmers.     

Winter habitat associations of seed-eating passerines on Scottish farmland

CapsuleExtensive surveys highlighted the importance of weedy fodder brassicas, stubbles and open farmland landscapes to declining birds.

Aims To determine habitat associations of seed-eating passerines on Scottish farmland in winter, and recommend appropriate conservation measures.

Methods Transect surveys were carried out on farmland in 100 1-km squares, containing 2885 fields, across Scotland. Birds, crops, field boundary features and weeds were recorded on three visits. Bird–habitat associations were examined using logistic regression models.

Results Seed-eating passerines were highly concentrated: 100 fields (1.4% of the area surveyed) held half the total count. The highest field densities of birds were recorded in fodder brassica crops and stubbles, averaging 12 and 3.3 birds/ha respectively. In fodder crops, weedier fields held many more birds. Multiple regression analysis emphasized the importance of fodder crops, stubbles and farmyards and suggested that declining bird species preferred more open landscapes. Several bird species were associated with fields containing very weedy patches, and/or weeds of the family Chenopodiaceae. These features were commonest in fodder brassicas. Many of the crop types found to be important as bird habitats in winter have declined in area in Scotland; the availability of seed food in such habitats may also have diminished. Such changes may partly explain recent population declines.

Conclusions Agri-environment measures for seed-eating passerines should support the widespread provision of small areas of seed-rich wintering habitats, such as weedy fodder brassicas and stubbles, especially in open (0–10% woodland and scrub) landscapes in areas with mild winters.     

Effects of different cultivation types on native and alien weed species richness and diversity in Moravia (Czech Republic)

Changes in weed species richness and beta-diversity are partly attributable to different types and intensity of disturbance and partly to broad-scale variation in environmental conditions. We compiled a data set of 434 vegetation plots of weed vegetation in root crop and cereal fields in Moravia (eastern Czech Republic) to compare the effects of environmental conditions and different disturbance regimes on species richness and beta-diversity. To detect changes in species richness, we related the variation in species richness to individual environmental conditions. To assess differences in beta-diversity between the vegetation of cereal and root crop fields, we used Whittaker's measure of beta-diversity. The relative importance of each environmental variable for the variation in species composition was evaluated using canonical correspondence analysis. All analyses were done for all vascular plant species and separately for native species, archaeophytes and neophytes. A comparison of weed vegetation of root crops and cereals showed a distinct dichotomy between these two types of weed vegetation. There was no significant difference in total species richness and native species richness; however, cereal fields were richer in archaeophytes and root crop fields were richer in neophytes. The beta-diversity of weed vegetation was higher in root crops. Environmental factors explained a significant part of the variability in richness of both natives and aliens. The richness of native species increased and beta-diversity decreased with increasing precipitation. The opposite relationship was found for archaeophytes, in both cereals and root crops. These results confirmed the importance of climatic factors and management practices for changes in weed species composition. They also showed a distinct pattern of species richness and beta-diversity of native and alien weed species.     

Divergence of mycorrhizal fungal communities in crop production systems

Mycorrhizal fungi are present in all arable soils and colonize nearly all crops and weed pests of crops. They may be involved as mutualists or pathogens of crops in well known but poorly understood phenomena such as crop rotation and green manure effects on soil productivity. Crop change effects on mycorrhizal fungal community parameters were evaluated in three field experiments. In Experiment 1, soybean (Glycine max (L.) Merr. cv. Douglas) was grown continuously or rotated with corn (Zea mays L.), milo (Sorghum bicolor (L.) Moench), or fescue (Festuca arundinacea Schreb cv. Johnstone) for two years, then soybean was grown on all plots. Continuous soybean plots were dominated byGigaspora spp., while rotated crops were dominated byGlomus spp. Differences in communities and community indices of continuous soybean and rotated plots were reduced after growing soybeans on rotated plots. In Experiment 2, a fescue sod was plowed and pearl millet (Pennisetum americanum Leeke) or crabgrass (Digitaria sanguinalis (L.) Scop.) grown. Both hosts resulted in great changes in populations of individual species, decreases in community dominance, and increases in community diversity and equitability. Crabgrass also resulted in reduced species richness. In Experiment 3, tobacco (Nicotiana tabacum L.) or fescue was planted on adjacent tracts of land with a long-term history of either fescue (30 yr) or sorghum-sudangrass (Sorghum bicolor (L.) Moench. ×S. sudanense (Piper) Staph.) (3 yr). The long-term cropping history had major effects on the mycorrhizal fungal communities which were related to the expression of mycorrhizal stunt disease of tobacco. Changes occurred in these communities in response to either current-season crop. These experiments suggest that crop rotation causes large changes in mycorrhizal fungal communities, that these changes may be involved in the rotation effect on soil productivity, and that design of cropping systems should take mycorrhizal fungal communities into consideration.     

Large-scale patterns of summer and winter bird distribution in relation to farmland type in England and Wales

Over the last 30 yr, the loss of traditional crop rotations and the polarisation of pastoral and arable farming have led to a marked reduction in mixed agriculture in Britain at both the individual farm and the landscape scale. We assess the potential impact of this change on lowland farmland birds by examining the extent to which distributions (as shown by national atlases of summer and winter birds) of different species are associated with arable, pastoral or mixed‐farming landscape types. Relatively few species appeared as either widespread generalists, equally associated across the three broad farmland types, or specialists associated only with one landscape type. Most were associated with two farmland types but distributions showed seasonal differences. During the breeding season there was an approximate ratio of 2:2:1 of species associated with arable, mixed and pastoral landscapes. However, in winter, most species were at highest abundance in mixed farming landscapes. This coincided with a reduction in the number of species associated with pastoral landscapes relative to the breeding season, whereas the number of species associated with arable landscapes remained relatively stable. These patterns are likely to be related to foraging requirements; granivorous birds tended to be associated with arable habitats, which tend to be more seed‐rich, and invertebrate‐feeding species tended to be associated with mixed or pastoral ones, which may be more invertebrate‐rich. The relative importance of mixed landscapes in winter was attributed to seasonal changes in the distribution of some invertebrate feeders, particularly small insectivores (pipits, chats and wagtails), and some of those species considered to be widespread in summer. The results have two important implications for future research. First, most research on farmland birds has, to date, focused on species associated with arable farming during the breeding season. More research is required on species associated with agricultural grasslands, reflecting its importance for farmland birds in Britain, and on the winter ecology of farmland birds in general. These results also emphasise the importance of mixed habitats for farmland birds, particularly in winter, and suggest that further changes in agricultural practices causing reduction in habitat diversity will be detrimental for the farmland bird community. However, widespread benefits may be derived from small scale measures that increase habitat diversity within farmland, for example field margin management options within agri‐environment schemes and support for traditional farming practices in some Environmentally Sensitive Areas.