Community Associations of Chalk Grassland Leafhoppers (Hemiptera: Auchenorrhyncha): Conclusions for Habitat Conservation

Due to their confinement to specific hostplants or restricted habitat types, Auchenorrhyncha have the potential to make suitable biological indicators to measure the quality of chalk grassland under different management practices for nature conservation. The Auchenorrhyncha data from a study designed to identify the factors influencing the invertebrate diversity of chalk grasslands in southern England was used to evaluate the potential use of this group of insects as biological indicators. Between 1998 and 2002 altogether 81 chalk grassland sites were sampled. Vegetation structure and composition were recorded, and Auchenorrhyncha were sampled at each site on three occasions in each of two seasons using a ‘Vortis’ suction sampler. Auchenorrhyncha assemblages were then linked to the different grassland plant communities occurring on chalk soils according to the British National Vegetation Classification (NVC). Altogether 96 Auchenorrhyncha species were recorded during the study. Using data on the frequency and dominance of species, as is commonly done for plant communities, it was possible to identify the preferential and differential species of distinct Auchenorrhyncha assemblages. Significant differences between the Auchenorrhyncha assemblages associated with the various chalk grassland plant communities of the NVC were observed down to a level of sub-communities. We conclude that data on Auchenorrhyncha assemblages can provide valuable information for the setting of conservation management priorities, where data on floristic composition alone may not be sufficient, providing additional information on aspects of vegetation structure and condition.     

Observations on North-West European limestone grassland communities: Phytosociological and ecological notes on chalk grasslands of Southern England

Summary In 1970 chalk grasslands were studied in southern England, according to the principles of the French-Swiss School. The communities described belong to the associationCirsio-Brometum Shimwell 1971, emend., allianceMesobromion erecti (Br. Bl. & Moor 1938) Oberd. 1957, orderBrometalia W. Koch (1926 n.n.) Br.-Bl. 1936, of the classFestuco-Brometea Br.-Bl. 1936, emend. Tüx. 1961. Within theCirsio-Brometum three new sub-associations are distinguished: 1) subass. nov.anthoxanthetosum odorati; 2) subass. nov.Cornetosum sanguineae; and 3) subass. nov.campanuletosum rotundifoliae.Special attention is paid to the relationship that exists between the management of these communities and the seral stages that lead to the development of serub following the decreasing influence of grazing. Ulex europaeus scrub occurring on calcareous soil was also studied. The cryptogams of the chalk grasslands, mainly Musci, were investigated in detail.Plant nomenclature follows Heukels & van Ooststroom (1970) or for taxa not mentioned by these, Clapham et al. (1968) for phanerograms and Margadant (1959) and van der Wijk et al. (1969) for bryophytes.Contribution to the Symposium on Plant species and Plant communities, held at Nijmegen, 11 12 November 1976, on the occasion of the 60th birthday of Professor Victor Westhoff.     

Can re-establishment of cattle grazing restore bryophyte diversity in abandoned mesic semi-natural grasslands?

Changes of agricultural practices have led to decline of semi-natural habitats sustained by traditional animal husbandry in many European regions. The abandonment of semi-natural pastures leads to increase of vascular plant biomass and subsequent decline of weak competitors such as bryophytes. Re-establishing traditional animal husbandry may potentially restore biodiversity but the success of such measures remains insufficiently known. In this study, we asked if re-establishing cattle grazing on previously abandoned grasslands will restore their bryophyte communities. The effect of cattle grazing on bryophyte communities of mesic semi-natural grasslands was studied in south-western Finland in a comparison of (i) continuously grazed pastures, (ii) previously abandoned pastures where grazing was re-established during 1990s, and (iii) abandoned pastures, where grazing had ceased during late 1960s to early 1980s. The average cover, species richness, species density and species diversity of bryophytes were significantly higher in the continuously grazed than in the abandoned grasslands. Ordination analyses revealed clear differences also in community structure between the management classes. Re-established grasslands were ecologically heterogeneous and situated in between the continuously grazed and abandoned grasslands in all characteristics, indicating variable effect of the restoration measure. Seventeen bryophyte species were recognized as significant indicators of the three grassland classes, four of which could be used as indicators of valuable grassland habitats. Although there was variation in the consequences of re-introduction of grazing, the results give evidence of positive effect of grazing on regaining bryophyte diversity of abandoned grasslands.     

Traditional Cattle Grazing in a Mosaic Alkali Landscape: Effects on Grassland Biodiversity along a Moisture Gradient

Extensively managed pastures are of crucial importance in sustaining biodiversity both in local- and landscape-level. Thus, re-introduction of traditional grazing management is a crucial issue in grassland conservation actions worldwide. Traditional grazing with robust cattle breeds in low stocking rates is considered to be especially useful to mimic natural grazing regimes, but well documented case-studies are surprisingly rare on this topic. Our goal was to evaluate the effectiveness of traditional Hungarian Grey cattle grazing as a conservation action in a mosaic alkali landscape. We asked the following questions: (i) How does cattle grazing affect species composition and diversity of the grasslands? (ii) What are the effects of grazing on short-lived and perennial noxious species? (iii) Are there distinct effects of grazing in dry-, mesophilous- and wet grassland types? Vegetation of fenced and grazed plots in a 200-ha sized habitat complex (secondary dry grasslands and pristine mesophilous- and wet alkali grasslands) was sampled from 2006–2009 in East-Hungary. We found higher diversity scores in grazed plots compared to fenced ones in mesophilous- and wet grasslands. Higher cover of noxious species was typical in fenced plots compared to their grazed counterparts in the last year in every studied grassland type. We found an increasing effect of grazing from the dry- towards the wet grassland types. The year-to-year differences also followed similar pattern: the site-dependent effects were the lowest in the dry grassland and an increasing effect was detected along the moisture gradient. We found that extensive Hungarian Grey cattle grazing is an effective tool to suppress noxious species and to create a mosaic vegetation structure, which enables to maintain high species richness in the landscape. Hungarian Grey cattle can feed in open habitats along long moisture gradient, thus in highly mosaic landscapes this breed can be the most suitable livestock type.     

Bryophytes, lichens and phanerogams in an alvar grassland: relationships at different scales and contributions to plant community pattern

The relationship between bryophytes and lichens versus phanerogams has been investigated in three stands of a limestone grassland community, along three transects of 500 10 X 10 cm plots. Ordination axes resulting from Detrended Correspondence Analysis for bryophytes and lichens versus phanerogams were correlated using Spearman rank correlation coefficient. The effect of grain (sample plot) size on relationships between species along the gradient and on the correlation between the layers formed by bryophytes and lichens (cryptogams) and phanerogams, and with environmental variables has been as well examined. Values for light, moisture, pH and nitrogen have been derived from the vegetation itself with the help of Ellenberg indicator values. The relative position of species in the ordination space is more or less the same until grain size 3 (10 x 40 cm) for cryptogams and phanerogams and until grain size 2 (10 × 20 cm) for all-species together. Therefore, it is suggested that sample plot sizes of 10 × 10 cm to 10×20 cm are appropriate as units for field experiments testing interactions between cryptogams and phanerogams. The respective layers were weakly correlated and the correlation between them increased with increase in grain size. The correlation of DCA axis 1 from the ordination of cryptogams, phanerogams and all-species with the environmental factors was weak and similar in order of magnitude. Only the environmental variables which were strongly correlated with the DCA axis 1 increased in correlation at larger grain sizes. The ordinations of cryptogams, phanerogams and all-species were correlated along DCA axis 1 with pH in all investigated stands and at almost all grain sizes. Multi-species patches have been detected by pattern analysis (PASFRAN) on DCA sample scores from ordinations of cryptogams, phanerogams and combined matrices. Multi-species patterns with sizes between 20-240 cm. composed by bryophytes and lichens and by phanerogams have been found. Complex patterns formed by cryptogams and phanerogams together, which are different in size than those in the separate layers, suggest that bryophytes + lichens and phanerogams may interact with each other.     

Problems, Approaches, and Results in Restoration of Dutch Calcareous Grassland During the Last 30 Years

This paper is based on research of the restoration of species‐rich calcareous grasslands in The Netherlands, over the last 30 years. Chalk grassland is a semi‐natural vegetation with a high density of species at a small scale. This type of vegetation was once widespread in Western Europe as common grazing land, mainly for flocks of sheep for which the main function was dung production. In some regions of Central Europe, these grasslands were also used for hay production. The dung was used to maintain arable field production at a reasonable level. In the chalk district in the southernmost part of The Netherlands some 25 sites of this vegetation, varying in area from 0.05–4.5 ha, are still present. Chalk grassland completely lost its significance for modern agricultural production after the wide application of artificial fertilizer following World War II. This grassland has a high conservation value both for plants and animal species, of which a large number of species are exclusively restricted to this biotope. When conservation activities started at a large scale in the early 1960s, three different types of restoration activities could be distinguished: (1) restoration of fertilized sites; (2) restoration of abandoned grasslands; and (3) recreation of chalk grassland on former arable fields. The main aim of the restoration attempt is to create and/or improve sustainable conditions for both plant and animal species characteristic of the chalk grassland ecosystem. In the process of restoration, several phases of different activities can be distinguished: (1) pre‐restoration phase, during which information of the land use history is collected and, based on these data, clear restoration goals are established; (2) initial restoration phase, during which effects of former, non‐conservational land use has to be undone in order to stimulate germination and establishment of target species originating from soil seed bank and species pool; (3) consolidation phase, including the introduction and continuation of a regular management system for sustainable conservation; and (4) long‐term conservation strategy, including measures to prevent disturbance from the outside and genetic erosion and extinction of locally endangered plant populations.     

Vegetation changes in semi-natural meadows with unchanged management in southern Sweden, 1965–1990

Vegetation records from 1963–66 and 1990 were compared in eight semi-permanent plots from continuously managed, semi-natural hay-meadows from five sites in southern Sweden to find out whether changes in plant communities could be detected in these grasslands over a period of ca. 25 years in spite of unchanged management. It was found that species richness, α-diversity and species frequency distribution remained fairly constant over the period, while there was considerable species turnover. However, it was also found that the total cover of vascular plants increased as well as the proportion of graminoids, both in cover and in species number, with a corresponding decrease of forbs. The number of species favoured by mowing also decreased as well as the number of typical grassland species. The detected changes are interpreted partly as effects of increased loads of atmospheric nitrogen deposition, and partly related to small changes in management intensity (changed frequency of mowing and/or aftermath grazing). It is possible that the significant land use changes in adjacent areas resulting in large landscape changes (increase of forests and woodlands) might have negatively influenced the interchange of grassland species, leading to an increase in the number of non-typical grassland species in the meadows.     

Effects of long-term grazing on the morphological and functional traits of Leymus chinensis in the semiarid grassland of Inner Mongolia, China

Livestock grazing represents a major human disturbance to grasslands throughout the world. We evaluated the effects of long-term grazing (>20 years) on a dominant perennial grass species, Leymus chinensis (Trin.) Tzvel., in the semiarid grassland of Inner Mongolia, China, in terms of its morphological and functional responses. L. chinensis, one of the most abundant species in semiarid grassland, had significantly smaller leaf area, fewer vegetative tillers and shorter shoot internodes length, but significantly greater specific leaf area for the individuals in the grazing plot than those in the exclosure (grazing-free) plot. Long-term grazing also altered the relative distribution of biomass to leaves, roots and rhizomes. The biomass, coverage and the number of species were lower in the grazing plot by 50–70% in comparison with those in the grazing-free plot. In addition, the long-term grazing substantively decreased the physiological capacities of this grass species, including significantly lower net photosynthetic rate, apparent quantum efficiency, photochemical efficiency of PSII and water use efficiency. Significantly higher stable oxygen isotope ratios (δ ¹⁸O) of the soil water in the grazing plot than those in the grazing-free plot indicated a much higher soil evaporation in the grazing plot because of less litter coverage. Seasonal patterns in the δ ¹⁸O values of the stem water of L. chinensis and three other common species in the grazing and grazing-free plots indicated that plants in the grazing and grazing-free plots might shift their water sources differently from a dry month (June) to a wet month (August). This study illustrated the importance of using different approaches to study the possible responses of grass species in arid regions to human disturbances, such as long-term grazing.     

Biodiversity of semi‐arid Mediterranean grasslands: Impact of grazing and afforestation

Question: What is the impact of grazing and/or afforestation on grassland diversity, species composition and cover parameters? Location: Semi‐arid Mediterranean grasslands of Jordan. Methods: Vegetation, litter, bare soil and rock cover were compared among four management types – free grazing and protected from grazing with three levels of tree cover. Species composition, plant cover, species richness and evenness were used to evaluate differences in vegetation among management types. Species composition differences among management types were also investigated. Results: Semi‐arid Mediterranean grasslands harbour appreciable levels of plant biodiversity. Grazing did not affect plant diversity, indicating the high resilience against and adaptation to grazing; however,grazing affected species composition and cover parameters. Afforestation seems to protect soil through higher litter cover but its impact on plant biodiversity was negative and markedly affected species composition. Conclusions: Neither protection from grazing or massive afforestation alone are sufficient for conserving biodiversity in this system. A management model is suggested where the landscape should be maintained as a mosaic of four management types: complete protection from grazing, grazing rotation, planting sparse trees in eroded areas and revegetating degraded areas using native, herbaceous and grazing tolerant species.     

Changes in vegetation states in grazed and ungrazed Mackenzie Basin grasslands, New Zealand, 1990-2000

Changes in vegetation from 1990 to 2000 were examined at 10 high country localities, representing four grassland types: fescue tussock (Festuca novae-zelandiae), snow tussock (Chionochloa rigida), red tussock (C. rubra), and silver tussock (Poa cita). At each locality, three treatments were established: ambient sheep+rabbit grazing, rabbit grazing only, and no grazing. The mutivariate methods of classification and ordination were used on individual-quadrat cover data to define vegetation states and to examine transitions between them over time. Vegetation states in quadrats already dominated by Hieracium pilosella(> 50% cover) in 1990 showed little change in species composition regardless of grassland type and grazing treatment. In fescue tussock grassland, H. pilosellaincreased regardless of grazing treatment in states with low initial H. pilosellacover (< 5%), while the cover of Carex colensoi, Aira caryophyllea and Rumex acetosella decreased. In the single silver tussock locality, Poa citadecreased markedly in the ungrazed treatment as adventive species such as Dactylis glomerataand Echium vulgare increased. However, Poa citaalso decreased, probably due to drought, in the grazed treatment. Snow tussock and red tussock grassland states were more stable than those in short tussock grasslands, but there was also a general trend towards increasing H. pilosellacover in intertussock vegetation regardless of treatment. However, at one snow tussock locality, transitions from H. piloselladominated to C. rigida-dominated states occurred in ungrazed quadrats, while the reverse occurred in grazed vegetation. Implications for the management of tussock grasslands for conservation are discussed.     

Differential Indirect Effects of Excluding Livestock and Rabbits from Chalk Heath on the Associated Leafhopper (Hemiptera: Auchenorrhyncha) Fauna

Preliminary results are presented of sampling the leafhopper assemblages on a field experiment designed to examine the differential effects of rabbits and livestock (mainly sheep) on the vegetation of chalk heath in southern England. Experimental plots that excluded livestock either allowed entry by rabbits or excluded them. Results were compared with those from plots grazed by both livestock and rabbits. After 7 years, exclusion of grazing herbivores had resulted in predictable increases in vegetation height, but no major changes were detected in the species composition of the vegetation. As expected, ungrazed plots had higher species richness and greater abundances of several individual leafhopper species. However, plots grazed only by rabbits had a leafhopper assemblage that was distinct from either ungrazed or mixed grazing plots. It is suggested that rabbit grazing may have subtle effects on grassland invertebrate assemblages that are not necessarily predictable from an examination of the species composition of the vegetation. Chalk heath vegetation contains an unusual mixture of calcicole and calcifuge plant species, but the leafhopper assemblage included a restricted number of calcareous grassland specialist species and only one species strongly associated with acidic grasslands; most leafhoppers recorded were generalist grassland species.     

Diversity and floristic patterns of mediterranean grasslands: the relative influence of environmental and land management factors

Managed grasslands are normally ecosystems with high species diversity. They are associated with traditional extensive livestock grazing. Land-use changes, in particular gradual abandonment or grazing intensification, lead to major changes in floristic patterns of these grasslands, some included in priority habitats of the EU Habitats Directive. In order to analyse these patterns of change, Mediterranean grasslands of eastern areas of mainland Portugal were studied aiming to: (1) establish ecological gradients underlying their floristic patterns; (2) examine the relative importance of both environmental and land-use factors on their floristic composition; (3) assess how floristic composition and species richness are affected by land-use factors. Vegetation sampling was carried out from 2008 to 2009 following phytosociological procedures. Canonical Correspondence Analysis was applied. Variation partitioning was used to assess the relative influence of land-use variables. Richness, legumes cover, endemic species and bryophytes cover were compared in four land-management regimes: unmanaged; extensive grazing by sheep; extensive grazing by cattle and sheep; frequent soil tillage. Significant differences were found in floristic and diversity patterns, revealing the importance of grazing as a management tool for maintaining or improving floristic diversity. From our findings slight extensive grazing can contribute to both maintenance of species diversity and to the increase in legumes cover and thus to palatability and economic value of studied grasslands. Interactions between herbivores and grasslands, considering also their influences on soil properties, have an important role in the equilibrium states which promote biodiversity and conservation of the services of these ecosystems.     

The significance of habitat continuity and current management on the compositional and functional diversity of grasslands in the uplands of Lower Saxony,Germany

There is a growing concern that land use intensification is having negative effects on semi-natural grasslands and that it leads to a general loss of biodiversity among all types of formerly extensively managed grasslands of poor to medium nutrient richness. Since the 1950s, many Central European uplands have been subject to an increase in grassland cover as a result of changes in land use practices. Using such a landscape in Lower Saxony, Germany, as a model region, we assessed environmental factors that control grassland diversity, including plant community composition, species richness and pollination trait composition. In 2007, 189 vegetation sampling sites were randomly distributed among grasslands covering some 394 ha within a 2500 ha study area. Plant communities were classified using TWINSPAN and the effects of environmental factors (soil, topography, current management and habitat continuity) were analysed by canonical correspondence analysis and regression analysis reducing for the effects of spatial autocorrelation by using principal coordinates of neighbour matrices.We found a wide range of six species-poor (<15 plant spp.) to extremely species-rich (>27 spp.) grassland types under mesic to dry site conditions, including sown, Cynosurion, Arrhenatherion and semi-natural grasslands. Grassland community composition was best explained by soil factors and species richness and pollination type composition by combined effects of current management and habitat continuity. During the 1950/60s, the extent of grassland area within the studied landscape rapidly increased to more than double its previous extent, and in 2007, grasslands comprised 16%. Natura 2000 grassland types comprised 1% of the surveyed site and medium-rich, high-nature-value grasslands a further 5%. While the number of wind-pollinated plant species was equal among all grassland types, there was a parallel decline in insect-pollinated plants and overall median species richness in the grassland communities along a gradient of increasing land use intensity (mowing, nutrient supply). Moreover, insect-pollinated plants occurring in intensively managed grasslands were found to additionally have the ability for self-pollination. Species-rich grasslands – including semi-natural grasslands and a semi-improved, species-rich Arrhenatherion community – occurred exclusively on old sites (with >100 years of habitat continuity) that had been used for traditional sheep grazing (environmental contracting). Medium-rich Arrhenatherion grasslands were established primarily on less productive, formerly arable fields (<30 years). We conclude that conservation efforts should focus on extant species-rich grassland types and should aim to implement traditional land use practices such as sheep grazing. Additional restoration efforts should focus on establishing new grasslands on less productive sites in the proximate surroundings of species-rich grasslands to facilitate seed dispersal, but nitrogen deposition should be buffered where appropriate. These measures would enhance the interaction between nature reserves and agricultural grasslands and thus improve the ecological quality of grasslands at the landscape scale.     

Determinants of bryophyte species composition and diversity on the Great Alvar of Öland,Sweden

Factors driving the species richness and distribution of bryophytes are poorly studied and not well understood, particularly in grasslands. We analysed the occurrence of bryophyte species and variation in species richness across 674 plots (0.5?m?×?0.5?m) in alvar vegetation (grassland on limestone pavement with thin or no soil) on Öland (Sweden) in relation to substrate characteristics and chemistry, inundation frequency, grazing pressure and geographical variables. We found 148 taxa, including 11 nationally red-listed ones. Species richness per plot was significantly associated with substrate type, positively associated with pH and grazing intensity, but negatively associated with soil depth. However, richness of species typical of, or restricted to, alvar habitats responded differently to richness of species more common in other habitats. Typical alvar species were favoured by high pH, shallow soil and low phosphate availability, while generalists preferred relatively low pH, higher phosphate availability and organic or mull soil types. Distance from the alvar margin had only weak effects. Concerning the effects on individual species and community composition, inundation frequency and pH were found to have the largest effects, although other factors (substrate type, soil depth, bare soil, bare stone, phosphate availability and grazing pressure) were more important for some individual species, stressing the importance of microsite variability and variability in management for regional species richness. From a conservation perspective, it is concluded that grazing is generally positive whilst factors increasing phosphate availability may disadvantage the typical alvar species, and proximity to the alvar margin is not a major problem.     

Carabid beetle (Coleoptera: Carabidae) richness and functional traits in relation to differently managed grasslands in the Alps

Species richness, composition, and functional traits of carabid beetle assemblages (Coleoptera: Carabidae) were studied in relation to different grassland management. Carabid beetles were sampled during the summers 2008 and 2009 by 165 traps located in 11 sites in the central-eastern Italian Alps. Using mixed effect models to account for potential spatial bias, we found that mown grasslands had significantly more species, a lower proportion of wingless species and a lower proportion of species with long larval development than grazed and natural grasslands. Within grazed and mown grasslands, neither cattle density nor number of cuts had any significant effect neither on species richness nor on any of the traits. The influence of grassland management can be summarised as follows: (1) grazing does not change community structure and functional traits compared to natural grasslands; (2) mowing negatively affects the carabid beetle assemblages; (3) the intensity of grazing and of cutting may not affect the structure of species assemblages of ground beetles. Our results support the hypothesis that agroecosystem practices in alpine grasslands influence carabid beetle communities. Specifically, the species with traits typical of undisturbed habitats (low dispersal abilities and long larval development) are more sensitive to perturbations (e.g. cutting). Our suggestion for agricultural and environmental planning and for conservation schemes is that the preservation of natural grasslands (e.g. forest gaps) and the implementation of grazing should be promoted during the planning of agroecosystem mosaics.     

Long‐term effects of the abandonment of grazing on steppe‐like grasslands

Question: What are the consequences of grazing abandonment on the Stipa lessingiana dominated steppe‐like grasslands? What is the relative importance of management and environmental factors in causing variation in species composition and abundance in the continuously grazed and abandoned grassland stands? Location: Transylvanian Lowland, Romania. Methods: Repeated vegetation mapping of a grassland stand, where grazing was abandoned 35 years ago; re‐sampling six grassland stands surveyed 29–57 years ago. For revealing long‐term changes in species composition and rank abundance PCoA ordination was applied. The relative importance of management and environmental factors in structuring vegetation were explored by CCA ordination. Diversity, evenness and the relative number and abundance of red‐listed species were compared between managed and abandoned stands. Results: Our results pointed out that grasslands which were formerly grazed and dominated by S. lessingiana, in the long‐term absence of grazing, have been transformed into a S. pulcherrima dominated type. Management, probably by creating bare surfaces and preventing litter accumulation, had the strongest effect on the species composition and abundance in the grasslands. Abandoned grassland stands had lower diversity and evenness compared to continuously grazed stands. While at the same time, the relative number of threatened, rare species did not differ between managed and abandoned sites. Conclusion: Maintaining extensively grazed, as well as un‐managed, Stipa dominated grasslands would be important in order to create various habitat conditions for plant species, especially threatened and rare species, and promote diversity on the landscape scale.     

Fifty years vegetation development of a xerothermic calcareous grassland in Central Europe after heavy disturbance

Fifty years ago on the south-facing slope of a limestone hill 4 km NE of Göttingen (Germany) a small plot of 4 m² size was chosen in a xerothermic calcareous grassland (Mesobromion alliance) for investigation. The formerly grazed slope was abandoned a few years prior to the study, but in 1987 intermittent grazing started again. The mean annual temperature in Göttingen (1953–2003) was 8.8 °C on the average; the annual mean increased by 1.1 °C during the study period. Mean annual precipitation amounted to 642 mm (393–1093 mm). The mean monthly precipitation during summer (April–August) varied in the range between 29 and 101 mm. In the years 1953–2003 the presence of species was recorded annually in 400 subplots (100 cm² each). In part of this time also the amount of bare soil within the plot was recorded, and standing crop and the nitrogen contents in leaves of Bromus erectus were measured in the immediate surrounding of the plot.In fall 1953 the vegetation was removed completely in half of the plot, in the other half the two dominant grasses Bromus erectus and Brachypodium pinnatum were left. The differences between the two halves vanished already after 2 years (starting phase 1953–1955). Thus, only results concerning the plot as a whole are reported here. During the investigation three periods could be distinguished. After the starting phase in period I (1955–1986) total presence, presence of the most important species, species richness, number of endangered species, diversity and evenness increased. In this way the grassland regenerated after the heavy disturbance, and a dense, species-rich vegetation formed. Only a few species showed maximum values already within the first 10 years and faded out later.Period II (1987–1997) spanned 10 years of grazing. During this time total presence, presence of many important species, species richness, number of endangered species, diversity and evenness decreased, whereas areas with bare soil increased. Only two species showed maximum values during this phase, and just one new species invaded (Lolium perenne). During this period a more open type of grassland was formed. Period III (1998–2003) spanned 5 years without grazing and only one grazing year (2002). Here, a partial regeneration of a more closed grassland took place with traits similar to period I.Several phenomena occurred continuously through all three periods. Bromus erectus always was the dominating species. Nevertheless, proportions of graminoids (in % total presence) were lowered, and the proportion of herbs increased. The ratio Bromus erectus/Brachypodium pinnatum was determined mainly by Brachypodium. Seedlings of woody plants were always present, but in most cases survived only one summer. Shrubs did not settle inside the plot, although small bushes developed in the immediate surrounding. In summary the 50-year process can be described as a slow recovery of a calcareous grassland after very heavy disturbance, modified by intermittent grazing, without formation of shrub vegetation.     

Distribution and abundance of small insects and arachnids in relation to structural heterogeneity of grazed, indigenous grasslands

1. The species composition and spatial distribution of small insects (Hemiptera, Coleoptera, Lepidoptera) and arachnids (Araneae, Opiliones, and Pseudoscorpiones) were investigated in three indigenous, upland grasslands identified as the National Vegetation Classification Festuca–Agrostis–Galium typical subcommunity (code U4a), Festuca–Agrostis–Galium, Vaccinium–Deschampsia subcommunity (code U4e), and Nardus stricta species-poor sub-community (code U5a), on which grazing management was manipulated experimentally. 2. Two hypotheses were tested that predicted arthropod diversity in upland grasslands. The habitat heterogeneity hypothesis predicts that the species number and abundance of arthropods will have an asymptotic relationship with increasing numbers of plant species and greater structural heterogeneity in the vegetation. The symbiosis between patches hypothesis states that the species number and abundance of arthropods will express a unimodal relationship with the grain size of sward patches created by grazing. The sward patches must be large enough to be apparent to, and support populations of, arthropods, but small enough that interspersed tussocks provide shelter from weather and a deterrent to disturbance by grazers. 3. The hypotheses were tested by sampling arthropods from the geometrical patterns represented by the individual tussocks and intermediate sward components of three indigenous grasslands produced by different grazing treatments. Paired samples of arthropods were taken by motorized suction sampler, the first of the pair from the grazed sward and the second, the accumulated samples from the surrounding triad of tussocks (U4a and U5a grasslands) or hummocks (U4e grassland). The paired samples were taken from six randomly-selected locations across both replicates of each of the grazing treatments. 4. Arthropod species composition and abundance were compared between the paired sward and tussock samples and in turn with measures of the vertical and horizontal components of vegetation structure, i.e. the variance in vegetation height per unit area and the area covered by tussock compared with sward. 5. There were consistently more species and a greater abundance of arthropods associated with tussocks than with swards and the average species number and abundance for the combined pair of samples declined with increased grazing pressure. The relationship between vertical and horizontal components of vegetation structure and the species number and abundance of selected arthropods was asymptotic as opposed to unimodal, supporting the habitat heterogeneity hypothesis, rather than the symbiosis between patches hypothesis. 6. Small and relatively sedentary insects and arachnids are more sensitive to grazing intensity and species of grazer in these upland, indigenous grasslands than are larger Coleoptera and Araneae, which respond less directly to varied grazing management. The overall linear reduction of small herbivorous and predatory arthropods with increased grazing intensity was buffered in grasslands with substantial tussock patches.     

Effects of restoration with cattle grazing on plant species composition and richness of semi-natural grasslands

Restoration of semi-natural grasslands by cattle grazing is among the most practical options for reversing the decline of northern European floristic diversity, but no studies on this subject are available. In this work the success of restoration of abandoned, privately owned mesic semi-natural grasslands by farmers receiving support from the EU agri-environmental support scheme was studied in southwestern Finland. Three kinds of grasslands were compared: old (continuously cattle grazed), new (cattle grazing restarted 3–8 years ago) and abandoned pastures (grazing terminated >10 years ago). Plant species composition of the three pasture types was floristically different in multivariate analyses (non-metric multidimensional scaling). Total species richness, richness of grassland plants, indicator plants and rare plants were highest in old and lowest in abandoned pastures in all studied spatial scales (0.25–0.8 ha, 1 and 0.01 m²). The results were congruent with different scales and species list definitions, suggesting that species density scale (1 m²) can be used as a partial surrogate for large scale species richness. Species richness of new pastures was 20% higher on 0.25–0.8 ha, 40–50% higher on 1 m² and 30% higher on the 0.01 m² scale compared to abandoned grasslands. Rare species showed insignificant response to resumed grazing. Despite problems in management quality, this study showed promising results of restoration of abandoned grasslands by cattle grazing on private farms. However, populations of several rare grassland plants may not recover with present cattle grazing regimes. Management regulations in the agri-environmental support scheme need to be defined more precisely for successful restoration.     

放牧对短花针茅荒漠草原植物多样性的影响

放牧干扰对草原植物多样性影响机制是放牧生态学研究的核心问题。以内蒙古锡林郭勒盟苏尼特右旗的短花针茅荒漠草原的长期放牧控制实验为平台,系统研究了放牧调控下植物多样性随组织尺度转换的影响,为荒漠草原植物多样性尺度推绎提供理论基础。结果显示:1)现存草地物种数未放牧最高,适度放牧次之,重度放牧最低,差异体现在多年生杂类草和一年生草本2个功能群上,且各功能群的权重基本不受放牧强度影响;2)群落尺度,放牧强度没有显著影响丰富度指数,未放牧小区的植物Simpson生态优势度指数、Shannon-Wiener物种多样性指数与Pielou均匀度指数大于适度放牧小区,显著大于重度放牧小区(P0.05);功能群尺度,多年生禾草与一年生草本的多样性指数对放牧无显著响应,多年生杂类草的多样性指数未放牧小区最高,适度放牧小区次之。3)Godron群落稳定性指数显示,适度放牧的小区稳定性高于未放牧小区和重度放牧小区。研究表明,放牧强度的上升使短花针茅荒漠草原不同组织尺度植物多样性降低,但群落稳定性结果显示适度放牧的草地表现出了更高的稳定性,植物多样性与稳定性的权衡将是合理制定区域科学放牧强度的重要途径。