Wildflower areas within revitalized agricultural matrices boost small mammal populations but not breeding Barn Owls

Agro-ecosystems have recently experienced dramatic losses of biodiversity due to more intensive production methods. In order to increase species diversity, agri-environment schemes provide subsidies to farmers who devote a fraction of their land to ecological compensation areas (ECAs). Several studies have shown that invertebrate biodiversity is actually higher in ECAs than in nearby intensively cultivated farmland. It remains poorly understood, however, to what extent ECAs also favour vertebrates, such as small mammals and their predators, which would contribute to restoring functional food chains within revitalised agricultural matrices. We studied small mammal populations among eight habitat types—including wildflower areas, a specific ECA in Switzerland—and habitat selection (radiotracking) by the Barn Owl Tyto alba, one of their principal predators. Our prediction was that habitats with higher abundances of small mammals would be more visited by foraging Barn Owls during the period of chicks’ provisioning. Small mammal abundance tended to be higher in wildflower areas than in any other habitat type. Barn Owls, however, preferred to forage in cereal fields and grassland. They avoided all types of crops other than cereals, as well as wildflower areas, which suggests that they do not select their hunting habitat primarily with respect to prey density. Instead of prey abundance, prey accessibility may play a more crucial role: wildflower areas have a dense vegetation cover, which may impede access to prey for foraging owls. The exploitation of wildflower areas by the owls might be enhanced by creating open foraging corridors within or around wildflower areas. Wildflower areas managed in that way might contribute to restore functional links in food webs within agro-ecosystems.     

Comparative breeding performance of Marsh Harriers Circus aeruginosus along a gradient of land‐use intensification and implications for population management

Assessing variation in breeding performance in relation to habitat characteristics may provide insights into predicting the consequences of land‐use change on species ecology and population dynamics. We compared four Marsh Harrier Circus aeruginosus populations subject to similar environmental conditions, but which differed in habitat composition, ranging from natural habitats to intensively cultivated areas. Using a 6‐year dataset, we characterized breeding habitat and diet in these four study sites, and analysed breeding performance in relation to this gradient of land‐use intensification. There was minimal variation in breeding performance between study years but consistent variation between study sites. Unexpectedly, Marsh Harriers breeding in intensively cultivated habitats had higher reproductive success than those breeding in more natural habitats, which, however, hosted higher breeding densities, so overall net population productivity (fledglings per unit area) was similar across sites. This resulted from combined effects of density‐dependence and different predation rates between study sites. The colonization of intensive farmland habitats may not necessarily impact negatively on population sustainability when breeding success and population density are traded against each other. However, our findings should not mask longer‐term conservation issues for populations breeding in these intensively managed areas, and further studies should assess potential long‐term negative effects of occupancy of human‐altered habitat.     

Strategies for agrobiodiversity conservation and promotion: a case from Yunnan, China

This paper deals with strategies for agrobiodiversity conservation and promotion based on studies on four plant groups (selected from 50 plant groups) occurring in the Yunnan Province of China. These plants are edible konjac (Amorphophallus), medicinal Paris, Musella lasiocarpa and wild tea (Camellia sinensis and its wild relatives), including their cultivars and wild populations. After analyzing the target plants, we conclude that the following strategies should be adopted to conserve and promote agrobiodiversity: (1) in situ conservation of agrobiodiversity, including habitat protection of wild populations, maintenance of native species and varieties in traditional agroecosystems, and relevant environmental education; (2) ex situ conservation and promotion of agrobiodiversity, including establishment of living collections and germplasm banks, and introduction of species and varieties into agroecosystems for agricultural practice; and (3) promotion and conservation of agrobiodiversity through sustainable uses, including technique development of propagation, cultivation, pest and disease control, on farm and off farm management, and other activities such as new variety breeding and scientific studies. Strategies developed here will be helpful to conserve and promote agrobiodiversity at agroecosystem, species, variety or landrace, and management system levels.     

Mosquito species diversity and abundance in relation to land use in a riceland agroecosystem in Mwea, Kenya.

We conducted an entomological survey to determine the mosquito species diversity and abundance in relation to land use in the Mwea rice scheme, Kenya. Adult mosquitoes were collected by indoor spraying of houses and outdoors by CDC light traps in three villages representing planned (Mbuinjeru) and unplanned (Kiamachiri) rice agroecosystems and a non-irrigated agroecosystem (Murinduko). During the 12-month sampling period, a total of 98,708 mosquitoes belonging to five genera and 25 species were collected. The five most common species collected during this study were Anopheles arabiensis Patton (52.5%), Culex quinquefasciatus Say (36.7%), Anopheles pharoensis Theobald (5.2%), Anopheles coustani Laveran (1.4%), and Anopheles funestus Giles (1.3%). Anopheles arabiensis, Cx quinquefasciatus, and An. pharoensis were more abundant in rice agroecosystems than in the non-irrigated agroecosystem, and in planned than in the unplanned rice agroecosystems. In contrast, An. funestus was more abundant in the non-irrigated agroecosystem. The mosquito species diversity (H) and evenness (E(H)) in the non-irrigated agroecosystem (Shannon diversity Index, H = 1.507, EH = 0.503) was significantly higher than in the rice agroecosystems (H) = 0.968, E(H) = 0.313, unplanned; and H= 1.040, E(H) = 0.367 planned). Results of lag cross correlation analysis revealed a strong relationship between rainfall and the abundance of An. arabiensis, and C. quinquefasciatus in the non-irrigated agroecosystem but not in the rice agroecosystems. It is inferred from the data that different levels of habitat perturbations with regard to rice cultivation have different effects on mosquito diversity and abundance. This provides an understanding of how mosquito diversity is impacted by different habitat management and rice cropping strategies.     

Reproduction in an endemic bird of a semiarid island: a food-mediated process

We analyse the effects of rainfall, temperature, food availability and nest predation on the between-year variation in reproduction of the Canary Islands stonechat Saxicola dacotiae , a bird species endemic of the semiarid island of Fuerteventura (Canary Islands, Spain). We monitored the reproductive performance and output of the species across its whole distribution area during three consecutive breeding periods, also measuring rainfall, temperature and food (arthropod) availability on the ground monthly. Rainfall varied from 27.3 mm in 2000–2001 (dry year) to 124.5 mm and 125.1 mm (average years), respectively, in the 2001–2002 and 2002–2003 breeding seasons. The onset of breeding closely matched variation in the onset of the autumn-winter rains among years. Arthropod availability was strongly and positively related to rainfall one month before. Reproductive investment (number of clutches and clutch size) was correlated to arthropod availability both among years and among sites within years. Stonechat pairs bred once or did not breed at all in the dry year whereas they bred twice in the other two years. Clutch size was smaller in the dry year and larger in the second as compared with the first in the other two years. Reproductive investment largely determined reproductive output (number of fledglings) as there were no significant spatial or temporal variation in hatching success (90% on average) or nest predation (29% on average, mostly due to feral cats Felis catus ). Within- and among years variability in temperature or predation did not match variability in the onset, length or reproductive investment and output recorded throughout the study years. These results suggest that variability in annual fecundity in the Canary Islands Stonechat was mainly driven by rainfall through a food-mediated process.     

城市化过程中广州市农业生态系统服务价值的变化

根据1996、2000、2004和2008年广州市统计数据,运用市场价值法、影子价格法、造林成本法、碳税法和工业制氧法等,分别计算了广州市各农业生态系统的相关服务价值,据此对城市化进程中广州市农业生态系统服务价值进行评估.结果表明：1996-2008年,尽管农田、草地、水体生态系统的生态服务价值有所增加,但因林地生态系统服务价值减小较多（各年份林地生态系统在农业生态系统总服务价值中所占比例均在90%以上）,导致广州市农业生态系统服务价值呈减少的总趋势.各类型生态功能的服务价值所占比例在年际间变化不大,服务价值大小总体表现为：气候调节>气体调节>产品服务>废物处理>土壤形成与保护>生物多样性保护>娱乐文化>涵养水源,且气候调节和气体调节的价值之和占总价值的91%以上.广州市城市化率与农业生态系统服务总价值间呈极显著的负相关关系（R=-0.905,P<0.01）,说明城市化率的提高将导致农业生态系统服务价值的降低.在城市化发展过程中,需要考虑保留适度的农业生态系统,以此保证区域的可持续发展.     

Butterflies and bumblebees in greenways and sown wildflower strips in southern Sweden

Greenways have recently been established in some intensively farmed areas of South Sweden in order to enhance recreation opportunities and biodiversity, but the effects of these green structures on biodiversity have not yet been determined. In this study, greenways and experimental sown wildflower strips were investigated for butterfly and bumblebee diversity. In total, 1,769 butterflies of 18 species and 1,216 foraging bumblebees of eight species were recorded. Sown wildflower strips proved to support much higher abundances and species numbers of butterflies and bumblebees than greenways, with 86% of all butterflies and 83% of all bumblebees being observed in the sown flower strips. However, in both types of green structure mostly common species were found. Counts of flower visits showed that Knautia, Centaurea and Cirsium were the most commonly visited plant species. The greenways studied did not seem to fulfil their function of enhancing biodiversity—at least not for butterflies and bumblebees. However, these greenways could easily be improved for common bumblebee and butterfly species by sowing wildflower strips along their margins.     

Stable isotope analysis of aquatic invertebrate communities in irrigated rice fields cultivated under different management regimes

In this study we have used stable isotope analysis to identify major food resources driving food webs in commercial rice agroecosystems and to examine the effects of agricultural management practices on the trophic structure of these food webs. Potential carbon sources and aquatic macroinvertebrate consumers were collected from large-scale rice farms in south-eastern Australia cultivated under three different crop management regimes conventional-aerial (agrochemicals applied, aerially sown), conventional-sod (agrochemicals applied, directly sown) and organic-sod (agrochemical-free, directly sown). Evidence from stable isotope analysis demonstrated the importance of food sources, such as biofilm and detritus, as the principal energy sources driving aquatic food webs in rice agroecosystems. Despite the greater diversity of potential food sources collected from the organic-sod regime across all sampling occasions, the range of food resources directly assimilated by macroinvertebrate consumers did not differ substantially across management regimes. Trophic complexity of aquatic food webs, as evidenced by the number of trophic levels identified using δ¹⁵N data, differed across management regimes at the early season sampling. Sites with low or no agrochemical applications contained more than two trophic levels, but at the site with the highest pesticide application no primary or secondary consumers were found. Our data demonstrates that the choice of agricultural management regime has a season-long influence on aquatic food webs in rice crops, and highlights the importance of conserving non-rice food resources that drive these trophic networks.     

Limited genetic exchanges between populations of an insect pest living on uncultivated and related cultivated host plants

Habitats in agroecosystems are ephemeral, and are characterized by frequent disturbances forcing pest species to successively colonize various hosts belonging either to the cultivated or to the uncultivated part of the agricultural landscape. The role of wild habitats as reservoirs or refuges for the aphid Sitobion avenae that colonize cultivated fields was assessed by investigating the genetic structure of populations collected on both cereal crops (wheat, barley and oat) and uncultivated hosts (Yorkshire fog, cocksfoot, bulbous oatgrass and tall oatgrass) in western France.Classical genetic analyses and Bayesian clustering algorithms indicate that genetic differentiation is high between populations collected on uncultivated hosts and on crops, revealing a relatively limited gene flow between the uncultivated margins and the cultivated part of the agroecosystem. A closer genetic relatedness was observed between populations living on plants belonging to the same tribe (Triticeae, Poeae and Aveneae tribes) where aphid genotypes appeared not to be specialized on a single host, but rather using a group of related plant species. Causes of this ecological differentiation and its implications for integrated pest management of S. avenae as cereals pest are discussed.     

Habitat use by three Acrocephalus warblers in an intensively used farmland area: the influence of breeding patch and its surroundings

Habitat use by the sedge warbler Acrocephalus schoenobaenus, reed warbler A. scirpaceus and marsh warbler A. palustris was studied during 1998–2000 in an intensively cultivated agricultural landscape in western Poland. The birds occupied mid-field marsh patches (0.05–9.84 ha) and drainage ditches. Using logistic regression models, habitat preferences for particular patch type, characteristics of breeding patch vegetation and surrounding crop type were investigated. All habitat measurements were done within 50-m radius circles around breeding territory centers. The most important factors that influenced species distributions were the proportions of particular habitats within patch area and the type of surrounding crops. Sedge and reed warblers preferred areas with a high proportion of reeds and meadows. Marsh warblers avoided emergents other than reeds, and favored herbaceous vegetation and bushes. Open water areas positively affected reed warbler distribution. Crop type had a significant influence on within-year territory distribution and changes in between-year occupation pattern. In general, birds preferred to settle near fields of oil seed rape, while root crops and spring cereals were avoided. Breeding patch type and structure of reedbeds had relatively little influence on the distribution of breeding territories. The results obtained show that the surrounding landscape may significantly influence habitat use of species breeding in habitat islands in farmland. Depending on their structure and food resources, crops might have different value to the birds.     

Spatial configuration and landscape context of wildflower areas determine their benefits to pollinator α- and β-diversity

Wildflower areas have become a staple tool within agro-environmental schemes (AES) to counteract pollinator declines. While their role in providing food resources to resident flower-visiting insects is unambiguous, the conservation effectiveness in a landscape context is less clear. Particularly, how multiple vs. single wildflower area utilization differs between simple and complex landscapes is understudied. We examined colonisation and community dynamics of wild bees and hoverflies in 33 newly established wildflower areas across a gradient of landscape complexity (amount of semi-natural habitat) and connectivity (presence of additional wildflower areas) for seven weeks during three consecutive years (one year during and two after establishment). We recorded more than 25% of the wild bee and hoverfly species of Hesse in an area of approx. 10 ha, substantiating the general benefit of wildflower areas to pollinators. While alpha-diversity increased with landscape complexity in isolated wildflower areas, the opposite pattern was observed for connected areas. The low alpha-diversity in complex landscapes indicated a dilution effect between connected sites. The inverse relationship between alpha and beta diversity among wildflower areas within landscapes suggests interspecific trade-offs between local resource conditions and landscape context. Accordingly, the establishment of multiple wildflower areas within AES is advisable to increase connectivity of suitable habitats in simple landscapes. Moreover, adjusting local conditions (plant diversity) to landscape context likely optimizes conservation effectiveness in modern agroecosystems.     

Diversity and trophic structure of insects associated with grains of three maize landraces in San Agustín Loxicha,Oaxaca, Mexico

Diversity and trophic structure of grain insect communities were examined in Olotillo, Nal‐Tel and Comiteco maize landraces cultivated within a milpa agroecosystem by Zapotec ethnic groups in Mexico. Higher insect diversity was expected in Olotillo, whose cultivation comprises a wide variety of agroecosystems, and low insect abundance in Nal‐Tel with small grains and thick testa. Forty Olotillo cobs were collected at low, medium and high elevations, and 40 each of Nal‐Tel at low elevation and Comiteco at high elevation. Cobs were monitored for 30 days under controlled laboratory conditions until all insects emerged. Thickness of testa of 400 grains from each landrace was measured. Community composition and trophic structure were described and standard diversity indices were estimated. A total of 9,708 insects, corresponding to five orders, 24 families and 36 species, were recorded, with six species not previously reported in this region. Insect guilds were composed of 70% phytophages, 22% parasitoids and 8% predators. Species richness was S = 27, 16 and 8 in Olotillo, Comiteco and Nal‐Tel, respectively. Nal‐Tel and Olotillo had the highest diversity index values (H′ = 1.32 and 1.2, respectively) and no significant differences; Comiteco had the lowest value (H′ = 0.65) and differed significantly from the other landraces. Comiteco and Olotillo, which have large grains and thin testa, showed higher insect abundance than Nal‐Tel, which has small grains and thick testa and showed lower abundance. Results support our hypotheses and highlight the role of traditional crop management in insect agrobiodiversity maintenance and conservation.     

Reproductive characteristics of free-livingCalomys venustus (Rodentia, Muridae)

Calomys venustus showed a cyclic seasonal pattern of reproductive activity characterized by a period of repose and a variable length of the period of sexual activity between August—September to May—June. The study was done from 1983 to 1999. During this time the population density increased from October—November to the end of autumn and sharply decreased in winter. Three peaks in rate of pregnancy were recognized in the breeding period: spring, summer and late summer. The average litter size was different among the three peaks in rate of pregnancy. The reproductive pattern had a peak at the beginning of the spring produced by overwintering animals, and another peak in summer-autumn caused by the reproductive activity of young born in the same period in which they breed. The spring cohort exhibited the greatest breeding contribution suggesting that this cohort is principally responsible for the yearly peak in abundance.     

Nest defence in the meadow pipit <Emphasis Type="Italic">Anthus pratensis</Emphasis>: the influence of renesting potential

The reproductive value hypothesis predicts that the level of nest defence is determined by the expected chance of offspring to survive until reproduction, and by the reproductive potential of the parents. Rates of survival from one breeding season to the next are low in small passerines, and their residual reproductive potential strongly declines as the current breeding season terminates. Therefore, we can expect that parents which have only one breeding attempt per season should defend their nests more intensively than parents with a possibility to renest. We studied nest defence in populations of meadow pipit (Anthus pratensis) breeding in Norway and the Czech Republic, differing in renesting potential. To simulate the threat from a predator, we placed a stuffed stoat (Mustela erminea) first 5 m and then 1 m away from a nest with nestlings. Parents increased or kept nest defence constant when the stoat approached their nests in Norway and, during a breeding season shortened by severe weather, in the Czech Republic (when renesting potential was limited). Parents decreased nest defence when the stoat approached the nest during “normal” breeding seasons in the Czech Republic (when renesting was common). These findings give support to the reproductive value hypothesis.     

Use of agroecosystem matrix habitats by mammalian carnivores (Carnivora): a global‐scale analysis

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Effects of changes in farming of subalpine meadows on a grassland bird, the whinchat ( Saxicola rubetra)

The increasing intensity of farming of meadows is supposed to be the major cause for strong declines of many meadow breeding birds. The whinchat, Saxicola rubetra, a Palaearctic migratory bird, is an indicator species of open grassland farmed at a low intensity. Originally widespread throughout Switzerland, it is now restricted to mountain and subalpine grassland. We document the changes in meadow cultivation in subalpine farmland from 1988 to 2002, and the breeding performance and density of the whinchat. We explored the impact of habitat degradation on the population dynamics of this meadow bird. The cultivation of hay meadows changed markedly within the 15 years: the onset of mowing was shifted forward by about 20 days, and farmers applied new techniques such as silage and irrigation. This shift was more pronounced in the favourable farmland in the valley bottom (Pradellas) than on the slopes (Vnà). The percentage of successful whinchat broods, ranging from 5% to 78% in different years, strongly depended on mowing date on both sites. In spite of earlier mowing, birds did not change their time schedule of breeding. Breeding success in Pradellas was too low to compensate for mortality (sink population), but because of immigration the number of breeding pairs did not decrease untill 2000. Population size may therefore be a misleading indicator of local population viability. Based on the breeding schedule of whinchats at different altitudes, we recommend mowing dates in agreement with the reproductive cycle of ground nesting meadow birds.     

Feeding behaviour and diet composition of Marsh Harriers Circus aeruginosus in agricultural landscapes

Capsule Diet composition and feeding behaviour of breeding birds differed between areas of high and low agricultural intensification.

Aims To analyze diet composition and feeding behaviour of Marsh Harriers Circus aeruginosus in agricultural landscapes with different degrees of agricultural intensification.

Methods Diet composition and feeding behaviour was assessed by focal observations at nests during breeding seasons in 2001–03 in two agricultural areas within the eastern Ebro Basin (on the northern Iberian Peninsula) which differed in their degree of agricultural intensification: a traditional non-irrigated and non-intensively managed farmland area; and an irrigated and intensively managed farmland area.

Results Marsh Harriers in the intensively managed area took higher percentages of small mammals than harriers in the traditional area managed at low-intensity, where they also had a more diverse diet. Male delivery rates increased throughout the breeding season in the intensively managed area. On the contrary, no significant trend in delivery rates was observed in the traditional area, where harriers turned to larger prey late in the season.

Conclusion Marsh Harriers probably took advantage of different prey types in intensively managed and traditional farmland according to prey availability. Differences in diet composition seem to be related to different foraging strategies adopted by harriers in traditional and intensively managed farmlands. In the traditionally managed farmlands, harriers responded to increases in the energy requirements of the brood over the course of the breeding season by taking larger prey, whereas in the intensively managed farmlands harriers increased feeding rates.     

Pathways of assessing agroecosystem health and agroecosystem management

Intrusive agriculture development, searching for higher profitability, has inflicted permanent damage to agroecosystems. Rapid deterioration of structure and functional properties in agroecosystems has intensified the need for research on agroecosystem health and agroecosystem management. This paper describes the concept of agroecosystem health which plays an important conceptual role in evaluating agroecosystem and agricultural research. Firstly, the development of agroecosystem health research is reviewed, and agroecosystem health from various dimensions is provided. Then, the methods and general criterias of agroecosystem health assessment are outlined, and a model for evaluating agroecosystem health is established. Finally, pathways of agroecosystem management from a holistic dimension are proposed to promote agroecosystem health and provide a scientific basis for making science-based policy decisions and formulating new plans in agricultural development.     

Traditional agroecosystems as conservatories and incubators of cultivated plant varietal diversity: the case of fig (<Emphasis Type="Italic">Ficus carica</Emphasis>L.) in Morocco

Background

Traditional agroecosystems are known to host both large crop species diversity and high within crop genetic diversity. In a context of global change, this diversity may be needed to feed the world. Are these agroecosystems museums (i.e. large core collections) or cradles of diversity? We investigated this question for a clonally propagated plant, fig (Ficus carica), within its native range, in Morocco, but as far away as possible from supposed centers of domestication.

Results

Fig varieties were locally numerous. They were found to be mainly highly local and corresponded to clones propagated vegetatively. Nevertheless these clones were often sufficiently old to have accumulated somatic mutations for selected traits (fig skin color) and at neutral loci (microsatellite markers). Further the pattern of spatial genetic structure was similar to the pattern expected in natural population for a mutation/drift/migration model at equilibrium, with homogeneous levels of local genetic diversity throughout Moroccan traditional agroecosystems.

Conclusions

We conclude that traditional agroecosystems constitue active incubators of varietal diversity even for clonally propagated crop species, and even when varieties correspond to clones that are often old. As only female fig is cultivated, wild fig and cultivated fig probably constitute a single evolutionary unit within these traditional agroecosystems. Core collections, however useful, are museums and hence cannot serve the same functions as traditional agroecosystems.

     

Effects of the Conversion of Native Vegetation to Farmlands on Soil Microarthropod Biodiversity and Ecosystem Functioning in a Desert Oasis

Increased demand for food due to the rapidly growing human population has led to extensive conversion of native steppes at the margins of oases in arid lands of northwest China into intensively managed farmlands. However, the consequences of this land-use change for soil microarthropod biodiversity and ecosystem functioning remain unknown. Here we assessed how conversion of a native steppe to irrigated farmlands of different ages affects the abundance and composition of soil microarthropods and how changes in soil microarthropod biodiversity could scale up to influence soil carbon and nitrogen stocks. We sampled microarthropod communities over two growing seasons from native steppes and cultivated soils of a 27-year-old irrigated farmland and a 90-year-old irrigated farmland, both of which were converted from the native steppe. Topsoil properties and bulk and labile pools of carbon and nitrogen, including soil organic carbon, dissolved organic carbon (DOC), microbial biomass carbon (MBC), total nitrogen (TN), inorganic nitrogen (IN), and microbial biomass nitrogen (MBN), were also measured. The conversion of native steppe to either of the two farmlands significantly increased the abundance and taxa richness of three taxonomic groups (mites, collembolans, and others) and four trophic groups (herbivores, predators, detritivores, and fungivores); this effect was greater in the 90-year-old farmland for the abundance of all taxonomic and trophic groups except for herbivores and was similar between the two farmlands for the richness of all taxonomic and trophic groups. Taxonomic and trophic composition of the microarthropod community showed strong shifts in response to conversion of native steppe to either of the two farmlands. Compositional changes were largely mediated by changes in soil environments. Changes in soil carbon and nitrogen stocks due to conversion of native steppe to farmlands followed similar patterns to soil microarthropod biodiversity, but the greater storage of DOC, MBC, TN, IN, and MBN occurred in the 90-year-old farmland. Our results suggest that soil microarthropod communities are affected positively by native steppe conversion to farmland and farmland age, and that increased microarthropod biodiversity significantly improved the ability of soils to retain carbon and nitrogen.