Calcicolous Grassland Research Articles

Nomenclature of Italian Syntaxa of the Classes Festuco hystricis-Ononidetea striatae and Rumici-Astragaletea siculi

This paper aims at revising the nomenclature of the Italian syntaxa belonging to the Festuco hystricis-Ononidetea striatae and Rumici-Astragaletea siculi classes according to the 'EuroVegChecklist' at the ranks of class, order and alliance. The correct syntaxon names, authors’ citations, nomenclatural types and eventual causes of invalidity and illegitimacy are identified and reported. Two classes (Cerastio-Carlinetea nebrodensis, Festuco hystricis-Ononidetea striatae), two orders (Erysimo-Jurineetalia bocconei, Euphorbietalia myrsinitae) and three alliances (Cerastio-Astragalion nebrodensis, Armerio denticulatae-Stipion etruscae, Sideritidion italicae), treated as valid syntaxa in the EuroVegChecklist, turned out to be invalidly published. The new class Helianthemo cani-Seslerietea nitidae is here described to replace the Festuco hystricis-Ononidetea striatae. The Erysimo bonanniani-Jurineetalia bocconei is validated to contain the new alliance Alysso nebrodensis-Koelerion splendentis and the validated Cerastio tomentosi-Astragalion nebrodensis. Since the Koelerio brutiae-Astragalion calabrici turned out to be a superfluous name, to represent the silicicolous pulvinate scrub of the Sila Mountains the Plantaginenion serpentinae is raised to the rank of alliance. The order Festuco-Seslerietalia nitidae, previously deemed as invalid, is proven to be validly published, and it is the earliest available name for the supra- and oromediterranean xeric calcicolous grasslands of the Italian Peninsula. Three mutations of names are provided, and the Astragaletum calabrici is lectotypified.

Grassland habitat restoration: lessons learnt from long term monitoring of Swanworth Quarry, UK, 1997-2014.

Habitat restoration projects are often conducted when prior use or extraction of natural resources results in land degradation. The success of restoration programmes, however, is variable, and studies that provide evidence of long term outcomes are valuable for evaluation purposes. This study focused on the restoration of vegetation within a limestone quarry in Dorset, UK between 1997 and 2014. Using a randomised block design, the effect of seed mix and seed rate on the development of community assemblage was investigated in comparison to a nearby target calcareous grassland site. We hypothesised that seed mix composition and sowing rate would influence both the trajectory of the grassland assemblage and final community composition. We found that species composition (in relation to both richness and community assemblage) was strongly influenced by time and to some extent by seed rate and seed mix. However, no treatments achieved strong resemblance to the calcareous grassland target vegetation; rather they resembled mesotrophic communities. We conclude that (as with previous studies) there is no “quick fix” for the establishment of a grassland community; long-term monitoring provides useful information on the trajectory of community development; sowing gets you something (in our case mesotrophic grassland), but, it may not be the target vegetation (e.g., calcicolous grassland) you want that is difficult to establish and regenerate; it is important to sow a diverse mix as subsequent recruitment opportunities are probably limited; post-establishment management should be explored further and carefully considered as part of a restoration project.

Just how important are structural elements as habitat components? Indications from a declining lycaenid butterfly with priority conservation status

Recently, it has been suggested that habitats for insect herbivores have been too narrowly defined, often on the basis of larval hostplants; in particular, non-consumable resources (called utilities; structural elements) have been ignored. Here, the importance of utility resources for roosting and mate location has been examined in the silver-studded blue butterfly Plebejus argus (L.) (Lycaenidae) on the Great Ormes Head, North Wales, UK. The methods included using dedicated surveys and correspondence analysis applied to behavioural observations in relation to vegetation structure on a transect through a key patch for this metapopulation model species. A substantial and significant bias in roosting (97%) and mating (75%) is found to occur outside hostplant areas on shrubs and rank bunched grasses and forbs. Population density is higher in shrubby areas and shrubs are increasingly occupied during the afternoons and night, during the late flight season and in cloudy, cool and windy weather. These findings suggest that shrubs are a valuable habitat component for this butterfly, at least at this coastal location, and important for their conservation. As scrub growth is inimical to calcicolous grassland, population status will depend on a fine balance between shrub and hostplant cover dependent on grazing and browsing by the indigenous goat, sheep and rabbit populations as well as on controlled cutting and burning. Opportunities exist for increasing population size and distribution on the headland but this will need to be managed carefully. There are also implications for metapopulation dynamics studies; the status of shrubs neighbouring host plant areas switches from that of barriers to resources and refuges.

The extent of semi‐natural grassland communities in lowland England and Wales: a review of conservation surveys 1978–96

The extent of semi‐natural grassland has diminished considerably across lowland landscapes of England and Wales during the second half of the twentieth century. Locating, describing and evaluating the dwindling cover has been a major challenge for conservationists. A concentrated vegetation survey effort at grassland sites has been mounted within different parts of Britain since the late 1970s. Plant community recognition has benefited considerably from the development of the contemporary National Vegetation Classification, and its widespread adoption permits national inventory of comparable vegetation data.Findings of a range of surveys (ninety‐eight in total), undertaken between 1978 and 1996 in England and Wales covering different forms of unimproved lowland grassland, are collated and reviewed. Vegetation data were abstracted from internally published survey reports. Calcicolous and neutral grasslands have been covered more thoroughly than acidic and wet or marshy grasslands. Cover data are summarized at community level. Overall estimates from survey results indicate that there are some 27 500–40 000 ha of calcicolous grassland, 7500–15 000 ha of unimproved neutral pasture and hay meadow, 8000–15 000 ha of acidic grassland and 9000–17 500 ha of wet grassland in lowland England and Wales; these represent only 1–2% of the cover of permanent lowland grassland. Some communities have additional representation in heathlands, mires and upland environments.Although they require further refinement, the cover data for individual communities provide a context for assessing priorities in site‐based and agri‐environment conservation programmes. It is concluded that, as well as arresting further depletion, it will be necessary to restore and expand lowland grassland habitats to counteract the negative impacts of fragmentation and isolation of various community types, such as the Centaureo–Cynosuretum, which is widely but thinly distributed. Habitat rehabilitation schemes also need to assimilate local patterns of community diversity characteristic of both wet and dry grasslands. It is suggested that reversal of the recent successional trends that followed relaxation of grazing at certain sites might produce a more appropriate balance in the relative cover of coarse tall grasslands and fine short turf. Vegetation surveys provide a source of spatial data for identifying local aggregations of semi‐natural grassland remnants.

The responses of Briza media and Koeleria macrantha to drought and re‐watering

1. To test whether differences in response to drought can help to explain the differing distributions of Briza media and Koeleria macrantha, changes in their leaf growth and water relations during soil drying were measured. After droughting, plants were re‐watered and recovery recorded. 2. Leaf growth of the two species showed a similar sensitivity to drought with respect to duration of soil drying and soil moisture content. 3. In both species tiller base relative water content (RWC) was maintained at similar levels to controls until soil moisture content had fallen to less than 9%. This may aid survival in habitats subject to periodic droughting by preventing damage to the meristems. 4. Briza media did not respond to re‐watering. However, plants of K. macrantha re‐grew after periods of over 20 days of drought, when tiller base RWCs had fallen as low as 13%. This ability to resurrect may explain the occurrence of K. macrantha in xeric calcicolous grasslands subject to episodes of severe droughting, from which B. media is absent.

The seedbanks of the Breckland heaths and heath grasslands, eastern England, and their relationship to the vegetation and the effects of management

The vegetation and the associated germinable seedbank of a range of heath and grass heath communities in Breckland, eastern England, were compared. The composition of vegetation and seedbank were similar for heather‐dominated communities due to the predominance of Calluna vulgaris. Recent rotovation of previously heather‐dominated communities invaded by Deschampsia flexuosa reduced the number of emerging C. vulgaris seedlings by more than 80%. The composition of seedbanks of calcicolous grasslands differed considerably from the vegetation, with a significant contribution from many ruderal species not present in the vegetation and an absence of important species such as Pilosella officinarum. Acidic grasslands were intermediate between calcicolous grasslands and heather‐dominated heathlands, with seedbanks characterized by high densities of Rumex acetosella and a number of ruderal species that were absent or rare in the vegetation. The composition of the seedbank of more mesotrophic grasslands suggests that the imposition of some form of disturbance may recreate more open grasslands typical of Breckland.

The UK status and suspected metapopulation structure of a threatened European butterfly, the marsh fritillary Eurodryas aurinia

Results are presented of a partial quantitative survey of Eurodryas aurinia colonies in 1983 and a full review of all UK colonies in 1990. Since records began, the butterfly has declined from 663 10-km grid squares to 253 squares in 1990: a reduction of 62%. A total of 432 separate colonies were identified in 1990 (228 in England, 111 in Wales, 58 in N. Ireland, and 35 in Scotland), confirming that the UK is a major European stronghold of the species. However, the current loss rate of colonies in Britain is estimated to be at least 11.5% per decade and is almost as high on protected as on unprotected sites. The butterfly usually breeds in damp, acidophilous grassland but spread onto calcicolous grassland during the present century, probably due to a general relaxation in grazing pressure combined with a switch from sheep to cattle grazing. Almost half the colonies surveyed in 1983 occupied very small habitat patches (<2 ha) and only one-sixth occupied patches larger than 10 ha (max = 40 ha). The species is sedentary and colonial, but 149 single adults were reported from non-breeding habitats in 1971–1990 and at least nine sites were colonised. Certain habitats appear to be transient or are intrinsically sub-optimal and patch occupancy is often short, leading to a constant state of flux in the butterfly's distribution. The suspected metapopulation structure of E. aurinia and its implications for conservation are discussed.

A review of butterfly conservation in central southern Britain: II. Site management and habitat selection of key species

Management for conservation, habitat selection and use of agricultural land is examined on 308 sites in fragmented habitats in southern Britain for 29 key butterfly species. About 32% of calcicolous grassland sites were unmanaged and 21% were only partly managed either for agriculture or conservation. Corresponding figures for neutral-acidophilous grasslands were 42% and 10%. Although there have been short-term gains for some species preferring longer turf, the habitats on such sites are steadily deteriorating with serious implications for butterflies as well as the characteristic plant and animal communities they support. On managed sites, little obvious preference was found between sheep and cattle grazing for most species, but the latter was prevalent on sites with Eurodryas aurinia and Cupido minimus. Although most key species prefer slopes with a southerly aspect in the study area, E. aurinia seems to prefer westerly and Hamearis lucina northerly aspects. Two-thirds of the woodlands covered had been extensively replanted, mostly with alien conifer species but were still valuable, particularly for species requiring clearings in woods. Such species have been greatly reduced by recent changes in forest practice (notably the cessation of coppicing) and are expected to decline further in the future because of the transient nature of their current habitats. Possible solutions are discussed including the need for a conservation strategy for butterflies and appropriate management of fragmented habitats.

Plant Species Coexistence: The Role of Historical, Evolutionary and Ecological Factors

None of seven existing theories seeking to explain the coexistence of plant species, could singly explain the pattern of species richness found e.g. in calcicolous grasslands. A more general explanation of species coexistence utilizes an idealized concept, the null community, defined as an undisturbed community within stable zonal vegetation including the whole pool of potential species. The number of potential species will then be dependent mainly on evolutionary factors (speciation, species traits). The majority of «real» communities have a smaller species pool for historical reasons―migration has not taken place (...)

Community Organisation in Leaf Hoppers

Auchenorrhynchan (leafhopper) faunas were monitored by vacuum sampling in each treatment of a controlled sheep grazing experiment on ex-arable land on limestone and in two nearby older calcicolous grasslands. The effects of foodplant architecture and species composition on leafhopper abundances and species composition (leafhopper «assemblies») were investigated by comparing the fauna with matched vegetation samples. The variability of assemblies over time was examined within three years of study and by comparison with older (1964-5) leafhopper studies of the same areas

The nature and rate of development of calcareous grassland in Southern Britain

The nature of the plant succession from disturbed land to species-rich ancient calcicolous grassland communities was investigated by a survey of formerly disturbed sites adjacent to ancient grassland in southern Britain. The results are compared with previous studies documenting the nature of ex-arable grasslands. This succession takes from decades to centuries to stabilise. Any apparent conservation value of recently abandoned sites is shown to derive from species which are consistently characteristic of early-mid succession. The course of succession depends on site conditions and the availability of adjacent colonisation sources. Even on skeletal soils, management such as grazing is essential; otherwise, succession proceeds towards species-poor coarse grasslands or scrub. The implications for habitat restoration and creative conservation are outlined.

Insect Herbivory: Effects on Early Old Field Succession Demonstrated by Chemical Exclusion Methods

Insecticide (Malathion-60) was applied to replicated plots in a calcicolous grassland establishing naturally on a field abandoned from cereal cultivation five years ago. Comparison with matched control plots showed that both the direction and rate of plant succession over a two-year period were influenced by natural levels of insect herbivory. The insecticide had no independent effect on plant growth.

The use of sheep grazing to recreate species-rich grassland from abandoned arable land

This paper reports the first two years' results of an investigation into the use of sheep grazing to restore species-rich calcicolous grasslands. Five different sheep-grazing treatments were applied to separate parts of a 10 ha arable field last cultivated in 1981. The field has shallow soils over Jurassic corallian limestone. Three treatments were applied in a replicated experimental design. These were ungrazed controls, a short period of grazing in spring and a similar short period in autumn. The other two treatments, more realistic for conservation management, were impractical for a formal design: one area was grazed continuously from April to November with a short break during the summer; the other was grazed continuously from August to early November. Grazing treatments were started in 1985. By the end of 1986, 43 of the 75 vascular plant species restricted to patches of old calcicolous grassland within 2 km of the site had colonised the field. Most of these species could have spread from adjacent patches of old grassland, but six came from further away. Grazing treatment did not affect the change of species arriving, but their establishment was better in the grazed areas. Colonisation proceeded downhill, against the prevailing wind. Species richness, diversity, and the abundance of individual plant species in the sward were increased by grazing treatments. In general, the effects of ‘realistic’ grazing treatments were predictable from the effects of simpler treatments in the formally designed experimental area. By the end of 1986, the area grazed in both spring and autumn had reached a state similar to the ex-arable chalk grasslands described by Cornish (1954). Although the species composition was not yet comparable to a mature calcicolous grassland, many of the component species had already arrived (including one national rarity) and were increasing, in contrast to the control areas.