Vegetation development and nitrogen dynamics of sown and spontaneous set-aside on arable land

The area of arable land devoted to ecological compensation in Switzerland has increased markedly in the last decade. We studied the influence of plant cover upon nitrogen (N) dynamics in the uppermost soil layer in experimental plots representing three types of ecological compensation area (set-aside sown with two different seed mixtures and without sowing) and a grass-clover ley. Potential losses, apparent uptake and net mineralisation of N were investigated during critical periods: during the early development of the vegetation, after a first mowing, and before and after ploughing and sowing with winter wheat.The four plant-cover types differed in species richness as well as in the proportions of forbs, grasses and legumes, and annuals and perennials. N dynamics varied with time of sampling, but differences between plant-cover types were small, and neither early mowing nor ploughing had a significant effect. We conclude that as far as N dynamics in the uppermost soil layer is concerned, both species-poor and species-rich seed mixtures and natural regeneration can be recommended for set-aside.     

Vegetation development in sown field margins and on adjacent ditch banks

The creation of temporal and newly sown field margins for 6 years is a common agri-environment scheme (AES) in the Netherlands. Conservation profits resulting from AES vary over different areas and need further studying. We examined plant species richness in such field margins and adjacent ditch banks in the province of Zeeland, where these linear elements do not experience plant biomass removal after mowing as management strategy. First, during 2 years, we inventoried field margins sown with a wildflower mixture and related the species composition and richness to the age of the margins. In a second assessment, we studied plant species richness on ditch banks protected from arable fields by these margins. Major clusters in a principal component analysis (PCA) on species composition in the field margins showed a succession from sown and ruderal annual species (year 1), to sown perennial species (year 2) and ending with a dominance by tussock forming grass species and Urtica dioica (year 5–6). Total plant species richness decreased with increasing age of the margins, and this was caused by the combination of a decline in sown species and a stable number of not-sown species. The presence of field margins during several years did not result in an increase in plant species richness on adjacent ditch banks. In both the field margins and on the ditch banks, mowing management is not followed by the removal of the cuttings. For plant conservation, the results of these field margins are disappointing, probably due to the lack of a proper management. Therefore, we recommend implementing a hay-making and opening management, to increase plant richness and to reduce noxious weeds in the margins and on the ditch banks.     

Establishment and persistence of target species in newly created calcareous grasslands on former arable fields

The effects of different restoration measures and management variants on the vegetation development of newly created calcareous grasslands were studied in southern Germany from 1993 to 2002. In 1993, fresh seed-containing hay from a nature reserve with ancient calcareous grasslands was transferred onto ex-arable fields with and without topsoil removal. Nine years after start of the restoration, the standing crop was lower and the cover of bare soil was higher on topsoil-removal sites than on sites without soil removal. Topsoil removal had a positive effect on the proportion of target species (class Festuco-Brometea), because the number and cover of productive meadow species (class Molinio-Arrhenatheretea) were reduced. Persistence of hay-transfer species and the number of newly colonizing target species were highest on topsoil-removal sites. On plots with and without soil removal, species richness and the number of target species increased quickly after hay transfer and were always higher on hay-transfer plots than on plots that had not received hay in 1993. In 2002, differences induced by hay transfer were still much more pronounced than differences between management regimes. Management by mowing, however, led to higher species richness, a greater number of target species and a lower number of ruderals in comparison to no management on restoration fields without soil removal. A detrended correspondence analysis (DCA) indicated that vegetation composition of the hay-transfer plots of the restoration fields still differed from the vegetation of ancient grasslands in the nature reserve. Vegetation of an ex-arable field in the nature reserve (last ploughed in 1959) showed an intermediate successional stage. In general our results indicate that the transfer of autochthonous hay is an efficient method for the restoration of species-rich vegetation, which allows not only quick establishment but also long-term persistence of target species.     

Survey of the bryophytes of arable land in Britain and Ireland 1: a classification of arable field assemblages

Abstract

Knowledge of the distribution of arable bryophytes lags behind that of bryophytes of many other habitats, and we have almost no information on their occurrence in relation to crop type and agricultural management regime. A survey of arable fields in Britain and Ireland carried out by members of the British Bryological Society in 2001–05 was designed to provide such baseline data. We surveyed a stratified random sample of 200 fields in the main areas of arable agriculture and a further 620 fields in these areas and in areas where arable fields are less frequent. The species present in each field were listed and their frequency within the field assessed. Data on the crop, the cover of vascular plants, bryophytes, trash and bare soil, and the pH and texture of the soil were recorded for each field. Six species assemblages are described on the basis of a classification of the species recorded in each field and their frequency values. The Tortula truncata–Anthoceros and Dicranella staphylina–Riccia glauca assemblages are the most species-rich and are concentrated on acidic soils in northern and western Britain and in Ireland. By contrast, the Barbula unguiculata–Bryum klinggraeffii and Phascum cuspidatum–Microbryum davallianum assemblages are mainly found on calcareous soils in southern and eastern England. The Bryum dichotomum–Marchantia polymorpha assemblage is characterised by widespread, weedy generalist species and is concentrated in East Anglia. The final assemblage, Brachythecium rutabulum–Fissidens taxifolius, characteristically occurs in late-successional fields and was scattered throughout the area sampled. A comparison of the results from Kent with those of a survey of Kentish fields (using a different methodology) by A.G. Side in 1973–74 suggests that the Bryum dichotomum–Marchantia polymorpha assemblage may possibly have replaced the Dicranella staphylina–Riccia glauca assemblage on acidic soils in the last 30 years. The considerable geographical variation within the arable flora of Britain and Ireland revealed by the survey should be taken into account when assessing the meagre evidence for historic changes in the arable bryophyte flora.     

The effects of arable field margin management on the abundance and species richness of Araneae (spiders)

The effects of ten different management regimes on the abundance and species richness of Araneae on pre-existing and newly expanded zones of field margins surrounding arable fields are compared in a large-scale experiment conducted between 1987 and 1991. Most of the management regimes involved varying the Liming and frequency with which the field margins were cut. There was no evidence of consistent temporal trends in the abundance and species richness of Araneae on either the existing or expanded zones of the field margins during the first four years of the experiment. However, lowest numbers were recorded before expansion of the margins in 1987, and highest numbers in the final sample, in 1991. Araneae remained less abundant, and less species rich, on the newly expanded than on the existing zones of the field margins four years after they were set-aside'. Culling reduced both abundance and species richness. Regimes which included culling in mid-summer had a greater impact which persisted for longer than did those involving cutting in spring and autumn. Removal of cut material was associated with lower species richness than leaving it in situ. Sowing the margins with a wild flower seed mixture was associated with increased abundance and species richness of Araneae. Annual spraying with a broad-spectrum, non-persistent herbicide reduced the abundance of Araneae but the effect was not detectable until several months after the application of the spray. Both the species richness and abundance of Araneae were positively correlated with a measure of vegetation height made on the field margins in September, on both the pre-existing and newly expanded zones of the margins. The extent to which management practices which benefit Araneae are compatible with both the management requirements for various other taxa. and the overriding constraint of effective pernicious weed control on field margins, is discussed.     

Microbial community succession and bacterial diversity in soils during 77,000 years of ecosystem development

The origins of the biological complexity and the factors that regulate the development of community composition, diversity and richness in soil remain largely unknown. To gain a better understanding of how bacterial communities change during soil ecosystem development, their composition and diversity in soils that developed over c. 77 000 years of intermittent aeolian deposition were studied. 16S rRNA gene clone libraries and fatty acid methyl ester (FAME) analyses were used to assess the diversity and composition of the communities. The bacterial community composition changed with soil age, and the overall diversity, richness and evenness of the communities increased as the soil habitat matured. When analysed using a multivariate Bray-Curtis ordination technique, the distribution of ribotypes showed an orderly pattern of bacterial community development that was clearly associated with soil and ecosystem development. Similarly, changes in the composition of the FAMEs across the chronosequence were associated with biomarkers for fungi, actinomycetes and Gram-positive bacteria. The development of the soil ecosystem promoted the development of distinctive microbial communities that were reminiscent of successional processes often evoked to describe change during the development of plant communities in terrestrial ecosystems.     

耕地和林地土壤动物群落组成和多样性的差异——中国区域的整合分析

采用Meta分析对中国区域耕地和林地的土壤动物数量、组成和多样性差异进行定量研究。整合分析结果表明,在中国区域耕地比林地有显著低的土壤动物个体密度(-55.74%)、类群数(-27.56%)和Shannon-Wiener多样性指数(-24.51%),其中个体密度的响应与类群数和Shannon-Wiener多样性的响应存在显著差异。年均温高于20℃地区耕地和林地间土壤动物数量、类群数和多样性的响应绝对值显著低于年均温小于20℃地区,且耕地与林地间无差异;年降水量400—800mm地区耕地和林地间土壤动物多样性的响应绝对值最大,其次在年降水量大于800mm地区,最小值在年降水量小于400mm地区(耕地与林地无差异)。耕地中水田土壤动物Shannon-Wiener多样性与林地无差异;经济林土壤动物Shannon-Wiener多样性与耕地间无差异。在不同土壤动物尺寸的亚组中,大型土壤动物数量、类群数和多样性的响应绝对值大于小型土壤动物的响应绝对值,且类群数差异显著。耕地中蜱螨类(Acarina)数量显著低于林地(-64.11%),而耕地的弹尾目(Collembola)数量与林地无差异;膜翅目(...     

Vegetation of the Rozkoŝ reservoir near Ĉeská Skalice (East Bohemia) 1. The vegetation development during the first five years after its filling

The vegetation of the new Rozko? reservoir near ?eská Skalice, East Bohemia, Czechoslovakia, was studied in the period of filling and during the following five years. It was rather unstable and showed pronounced dynamics particularly in hydrophytes. The trends of vegetation development seem to be common for most new shallow reservoirs in Central Europe and the northern part of East Europe. A number of submerged macrophytes grew at unusual depths and their production was very high in newly filled reservoirs. The survival of trees and herbs and their reaction to long-term flooding (adventitious root formation) are discussed in the paper as well as the vegetation development of both permanently and periodically emerged shores.     

The field of vector biology: A perspective on the first 100 years

The time surrounding Ross' epic studies on the role mosquitoes play in the life cycle of Plasmodium was marked by a series of discoveries that truly defined the beginning of the field of vector biology, as outlined here by Bruce Christensen and Michael Ferdig.     

Intraorganic venous bed of the stomach cardia in children during the first 3 years of life

The intraorganic venous bed of the gastric cardial part has been studied in 27 organs, obtained from children corpses of both sex beginning from birth up to three years of life. They died from causes that were not connected with gastric or vascular system pathology. The results of the investigation prove the presence of mucous, submucous, muscular and serous-subserous venous plexuses in the wall of the gastric cardial part in children of the first three years of life. Every membrane of the stomach wall has its specific structure of the venous link in the microcirculatory bed. In the stomach mucous membrane already in a newborn there are complexly built microcirculatory pathways. Age changes are mostly expressed in the venous link of the gastric mucous membrane; this is probably connected with functional activity of the given layer of the organ. The largest venous vessels are situated in the gastric submucous base. By the end of the newborn period and, especially fully, during the successive age periods immune protection of the gastric wall is formed as an accumulation of lymphoid tissue to an antigenic effect of food. In these age groups certain structural mechanisms of blood outflow from the gastric wall appear.     

Ten years primary succession on a newly created landfill at a lagoon of the Mediterranean Sea (Lake Burullus RAMSAR site)

This study was carried out on the transported bed soil dredged from the outlet of Lake Burullus to the Mediterranean Sea and deposited nearby, forming by this way new land that underwent a primary plant succession. The multi-methodological approach comprised floristic inventories, vegetation sampling and soil composition analyses of the study site in order to detect the crucial parameters controlling the plant resettlement on recently deposited soil as related to time, local micro-topography and substrate characteristics. Floristic composition was assessed for the first 10 years of primary succession (2001–2010) on 18 stands of the area, distributed on basement, slope stands and plateau of the landfill, respectively. Vegetation surveys were the basis of multivariate analyses of the vegetation and soil data using TWINSPAN, DCA and CCA. Relationships between the edaphic gradients, floristic composition and species diversity were assessed.     

Afforestation effects on vegetation structure and diversity of grasslands in southern Brazil: The first years

We evaluated the effects of afforestation on the composition and structure of southern Brazilian subtropical grasslands directly beneath tree plantations, in pastures, and in permanent protection areas near watercourses. Cover of plants was registered in 120 plots of 1 m² in grasslands located at two distances from small watercourses in pasture and eucalypt plantation areas within a livestock ranching landscape. Livestock density is reduced in plantation areas. Species composition beneath tree plantations was significantly different from both pasture and nearby permanent protection areas. Permanent protection areas near plantations were also compositionally different from pastures. Eucalypt plantation was the environment type where ruderals were most abundant. Growth form cover distribution in pasture areas showed a consistent pattern, with graminous herbs being the most common growth form followed by prostrate herbs, prostrate subshrubs, and standing subshrubs. In plantation areas, the dominance of the graminoid herb growth form increased markedly, as well as standing herbs. These increases occurred mainly at the expense of prostrate herbs and subshrubs, which were significantly reduced. Plot-level species density was significantly affected by distance from watercourse and, more importantly, was significantly influenced by the interaction between management regime and distance to watercourse. It was reduced in eucalypt plantations relative to permanent protected areas. Current management of eucalypt plantations in southern Brazil produce unsuitable conditions for grassland species to thrive within plantations. Livestock densities <1.0 animal unit ha^?1 in eucalypt plantations undermines the ability of surrounding permanent protection areas to act as ecological networks for biodiversity conservation.     

The effects of management on vegetation trajectories during the early‐stage restoration of previously arable land after hay transfer

The restoration of floodplain grasslands has benefited from many studies of the underlying mechanisms. Among the operational tools that resulted, hay transfer is now used increasingly to alleviate the effects of limited seed dispersal and recruitment. To improve this method, we still need to understand how it can affect restoration trajectories, and particularly their direction and magnitude during the early stages of restoration. Based on concepts from the field of community ecology theory, we investigated the effects of early‐stage management through grazing or mowing on restoration trajectories after soil harrowing and hay transfer. We established a randomized block design experiment and quantified several community‐related metrics to formalize restoration trajectories for 3 years after hay transfer on a previously arable alluvial island in southwestern France. Whatever the management treatment, the species richness and evenness were significantly higher in hay‐inoculated than in control plots. This effect was linked to the recruitment of species originating not only from the reference grassland through hay transfer, but also from the seed bank, a well‐known effect of soil harrowing. Although generally oriented toward the reference grassland, the origin, direction, and magnitude of the trajectory of hay‐inoculated plots all depended on the management applied. Sheep grazing applied at the same time as hay transfer enhanced the recruitment of reference species as from the first experimental year, because it controlled aboveground competition and maintained the window of opportunity open for a sufficiently longer period of time. Our findings show that the type of management applied simultaneously to hay transfer influences the origin of a grassland trajectory, while its direction and magnitude are dependent on the management applied in subsequent years. Grazing immediately after hay transfer may be appropriate to accelerate the recruitment of species from the reference grassland.     

Links between global taxonomic diversity,ecological diversity and the expansion of vertebrates on land

Tetrapod biodiversity today is great; over the past 400 Myr since vertebrates moved onto land, global tetrapod diversity has risen exponentially, punctuated by losses during major extinctions. There are links between the total global diversity of tetrapods and the diversity of their ecological roles, yet no one fully understands the interplay of these two aspects of biodiversity and a numerical analysis of this relationship has not so far been undertaken. Here we show that the global taxonomic and ecological diversity of tetrapods are closely linked. Throughout geological time, patterns of global diversity of tetrapod families show 97 per cent correlation with ecological modes. Global taxonomic and ecological diversity of this group correlates closely with the dominant classes of tetrapods (amphibians in the Palaeozoic, reptiles in the Mesozoic, birds and mammals in the Cenozoic). These groups have driven ecological diversity by expansion and contraction of occupied ecospace, rather than by direct competition within existing ecospace and each group has used ecospace at a greater rate than their predecessors.     

The influence of seed addition and cutting regime on the success of grassland restoration on former arable land

Questions: Can seed addition enhance the success of establishing species‐rich grassland on former arable land? Are sowing date and cutting regime important in determining success? Location: Aberdeen and Elgin, northeast Scotland, United Kingdom. Methods: A field experiment was conducted at two sites to assess the effect of seed addition, sowing date and cutting regime on the vegetation developing on former arable land, the aim being to compare the success of different treatments at producing a species‐rich grassland. Results: Sowing a seed mix resulted in the establishment of vegetation very distinct from the species‐poor vegetation dominated by perennial grasses which otherwise developed, though establishment success of the sown grassland species was highly variable between sites. Where establishment of the sown species was poor, sowing date had no significant effect on species composition, whereas the cutting regime was very important. Cutting the vegetation significantly increased both the number and abundance of sown species compared with the uncut control. Conversely, where establishment had been good, the cutting regime in the first year had little effect on species composition. Cutting the vegetation at least twice a year appeared to be the most effective management over the length of the experiment. Conclusions: Sowing a seed mixture significantly reduced the abundance and number of naturally colonising species, effectively controlling problem weed species such as Senecio jacobaea and Cirsium vulgare, highlighting the agronomic value of sowing seed mixtures on fallow farmland. The sowing of a seed mix on former arable land has demonstrated that it is feasible to create vegetation similar in character to that of species‐rich grasslands.     

A longitudinal assessment of behavioral development in wild capuchins: Personality is not established in the first 3 years

Animal personality is defined as consistent individual differences across time and situations, but little is known about how or when those differences are established during development. Likewise, several studies described the personality structure of adult capuchin monkeys, without assessing the ontogeny of these personality traits. We analyzed the behavioral repertoire of 12 wild infants (9 males, 3 females) yellow-breasted capuchin monkeys (Sapajus xanthosternos), in Una Biological Reserve (Bahia, Brazil). Each infant was observed and filmed weekly from birth until 36 months, through daily focal sampling. We analyzed the behavior of each individual in 10 developmental points. By means of component reduction (principal component analysis), we obtained four behavioral traits: Sociability, Anxiety, Openness, and Activity. We investigated whether there were developmental effects on those traits by fitting regression models for the effect of time on behavioral traits, controlling for monkey identity, sex, and cohort. Sociability (decreasing) and Anxiety (increasing) changed significantly along development. By means of repeatability analysis, we did not find intra-individual consistency across time in those traits, so we cannot discriminate stable personality traits in early ontogeny. Our results show that the personality structure of capuchin monkeys is not established during early development, in agreement with the literature on human personality.