A European pest to control a new zealand weed: investigating the safety of heather beetle, Lochmaea suturalis (Coleoptera: Chrysomelidae) for biological control of heather, Calluna vulgaris

Heather, Calluna vulgaris (L.) Hull, is a serious invasive weed in the central North Island of New Zealand, especially in Tongariro National Park, a World Heritage Area. Heather beetle, Lochmaea suturalis (Thomson), is a foliage-feeding pest of Calluna in Europe, that was selected as the most promising biological control agent for introduction into New Zealand, because it causes high levels of damage to Calluna in Europe. Host-range tests indicated that L. suturalis poses a negligible threat to native New Zealand plants. Cultivars of Calluna grown as ornamentals are suitable food plants, but are unlikely to be severely affected because L. suturalis requires a damp understorey of moss or litter for successful oviposition and pupation, which is rarely present in gardens. However, mosses and litter occurring under Calluna stands in Tongariro National Park are suitable substrates for eggs and pupae. Lochmaea suturalis released in New Zealand has been freed of parasitoids and a microsporidian disease that attack the beetles in Europe.     

Vkgetation analysis along a successional gradient from heath to oak forest

At Hjelm Hede in Denmark where an oak shrub is invading into a heathland the successional process has been studied on poor sandy outwashed plain. The study used a transect through a successional gradient from open heath to oak shrub where vegetation, major topsoil parameters and tree characteristics were analysed. The study enables us with spatial variation of key parameters to combine numerous detailed studies from the same site into an overall picture of changing vegetation and soil parameters reflecting the succession, which has been documented previously. The data were analysed by the use of Detrended Correspondence Analysis (DCA). Along the gradient from heath to forest the thick mor layer of the heathland soil decomposed, the CM ratio decreased from 25 to 15, pH increased and ammonium became available for the plants during a time span of approximately 120 years. The vegetation on the open heath was typical Danish inland heath vegetation dominated by Calluna vulgaris, Empetrum nigrum and Deschampsiaflexuosa. Under the young oak shrub the vegetation was dominated by Deschampsia Jexuosa, Trientalis europaea , and Maianthemum bijiolium. In the oldest and most forest like parts of the shrub a vegetation dominated by Holcus mollis, Anemone nemomsa and Stellaria holostea was found. Woody chamaephytes were replaced first by hemicryptophytes and later by geophytes. The vegetation's Ellenberg values indicated an increase in nitrogen availability and a decrease in acidity and light availability through secondary succession.     

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.     

Genetic and morphological divergence among Gravel Bank Grasshoppers, <Emphasis Type="BoldItalic">Chorthippus pullus</Emphasis> (Acrididae), from contrasting environments

Gravel Bank Grasshopper (Chorthippus pullus) populations inhabit two contrasting environments, pebbly gravel banks with scarce vegetation cover in mountainous areas along the Alps and lowland grasslands dominated by Common Heather (Calluna vulgaris). Heath populations of C. pullus have been rediscovered only recently, and show a distribution scattered across Central Europe. The wings are reduced in this species; thus, it has low potential for long-distance dispersal. We used sequence data on a newly developed non-coding nuclear marker from three gravel-bank and four heath populations to test whether grasshoppers from the two environments represent distinct lineages. Gravel-bank populations were studied in southern Germany (Bavaria), heath populations in eastern Germany (Brandenburg and Saxony) and Ukraine. We compared those genetic data with an analysis of variation in a suite of morphometric traits. Finally, we combined genetic and morphometric data to reconstruct a plausible scenario for the ecological shift observed in C. pullus. Our newly developed marker did not sort populations from contrasting environments in two monophyletic lineages. Nevertheless, we found a general lack of gene flow between the gravel-bank and heath populations. There was pronounced variation among populations in morphometric traits. That variation was partially partitioned by habitat type, and populations from the same habitat tended to be more similar than those from different habitats. Our data suggest that heath populations originated through northward expansion from multiple southern European refugia, and that the gravel-bank populations represent one of these sources. Patterns of genetic and morphometric divergence suggest that gravel-bank and heath populations may be in the process of incipient speciation.     

Experimental trampling and vegetation recovery in some forest and heathland communities

Abstract. Over the past decades outdoor recreation has become progressively more important and as a result human‐induced potential damage has increased. In this study, short‐term effects – a 2‐yr period – of human trampling on some common forest and heath communities in Central Belgium were studied experimentally. Vulnerability to disturbance was compared among plant communities in terms of resistance, resilience and tolerance, which are based on cover measurements. The herb layer of the examined mesophilous forest communities appeared to be more sensitive than the heath and dry forest community, which were dominated by more resistant graminoid (Molinia caerulea, Deschampsiaflexuosa) and dwarf‐shrub species (Vaccinium myrtillus, Calluna vulgaris, Erica tetralix). The analysis showed that site structure and vegetation were already affected by low intensities of trampling, while vegetation recovery during the first year after trampling was limited in most plant communities. Recovery during the second year in vegetation cover as well as height was most pronounced in mesophilous forest communities. Occasional trampling clearly can lead to increased visual evidence of previous use and continued recreational disturbance. Therefore management plans should discourage hiking activity off paths and restrict recreation activities to the least vulnerable communities.     

Vegetation changes of a Danish mire 1957–1981

A Danish mire influenced by culture until ca. 100 years ago and since then with incipient growth of Betula pubescens , was analyzed in 1957 and 1981 with regard to height of the Betula trees and cover percentage of plant species in the field layer. In 1957, every m2 along a 110 m transect was examined; in 1981 only 56 m2 representatively selected from the transect were examined. Betula showed considerable changes with a net intake of 10 trees (23%) and a net loss of 23 trees (52%), i.e. a net loss of 13 trees (30%). The mean height of the trees has, however, increased by 80 cm and the sum of the height of the trees per m2 by 29 cm. An increased total cover was found for Em–petrum nigrum, Molinia coerulea , and Erica tetralix , and a decreased total cover for Calluna, Sphagnum magellanicum, S. nemoreum, S. rubellum, Hypnum cupressi–forme, Pleurozium schreberi , and Aulacomnium palustre. An almost unchanged total cover was found for Eriophorum vaginatum, E. angustifolium, Sphagnum recurvum, Andromeda polifolia, Drosera rotundifolia , and Oxycoccus palustris. On the basis of quantitative changes in the individual plots, a specific index of change is calculated, decreasing in the order Empetrum > Sphagnum magellanicum > S. recurvum = Molinia > Calluna > Hypnum cupressiforme > Pleurozium schreberi> Oxycoccus palustre> Sphagnum nemoreum = S. rubellum = Eriophorum vaginatum = E. angustifolium > Aulacomnium palustre > Erica> Drosera > Andromeda. Analyses from 1981 demonstrate that usually the light conditions and/or the water content and rarely the bulk density of the soil is correlated with the change in cover of the individual species. For some species it is also shown that the change is correlated with the strongly increased cover of Empetrum in particular. The changes are finally illustrated by showing the position of the species along ecological gradients in 1981.     

Biodiversity and vegetation dynamics in the coastal heathlands of western Norway

The heaths of Lygra, western Norway, were investigated, and 19 communities at the association level were distinguished. Distinct ecotypes of Ranunculus acris and Poa humilis and microspecies of Euphrasia were restricted to the grass heaths. No distinct ecotypes were found in the Calluna -dominated vegetation. It is suggested that the regular burning, which has been part of the management of the area, has activated the seed bank of the ericaceous heath, and thus maintained genetic diversity and slowed down ecotype differentiation. The grass heaths, with no combustible material, have been unaffected in this way. Permanent plots in the two dominant heath types, dry heath (Vaccinio-Callunetum) and wet heath (Ericetum tetralicis) were followed over six years and the data analysed using a modification of Jaccard's index, allowing for species abundances.     

Recovery of subalpine dwarf shrub heath after neighbour removal and fertilization

We tested if subalpine heath vegetation in northern Italy recovered after experimental perturbation of soil nutrient availability (fertilization) and species composition (removal of co-dominant dwarf shrubs). Species cover was assessed non-destructively before the start of the treatments (1995), at the end of the treatments (1999) and 4 years after the treatments ended (2003). Shrub removal had rather modest effects on heath vegetation, except for mosses which decreased significantly in removal plots. Fertilization decreased the cover of shrubs, mosses, and some graminoids but increased the cover of Festuca rubra. Fertilization converted heath to grassland, but the response of graminoid species was individualistic. Fertilization decreased vascular species richness and evenness, probably through negative effects of shading and litter accumulation on plant growth or recruitment. The vegetation had not recovered completely 4 years after the perturbations had stopped. This suggests that, in contrast to rapid responses to species removal and fertilization, recovery from these perturbations was rather slow, presumably because recovery was affected by long-term biotic interactions and species controls on ecosystem properties.     

Sphagnum subfulvum Sjörs in Ireland compared with the occurrences in Norway

Abstract

The discovery of Sphagnum subfulvum in Western Ireland is reported and the Irish specimens are described. The habitat of the species at Errisbeg, Co. Galway, is described and compared with the occurrences in Norway. It is concluded that the ecology of S. subfulvum at Errisbeg closely resembles its ecology in Norway where it is an intermediate/rich fen species, and in the ‘mud-bottomto hummock’ vegetational gradient it belongs to lawn and low hummock vegetation. The occurrence of Sphagnum subfulvum on flushed mountain slopesin West Mayo is apparently related to localised basic conditions as indicated by its association with Schoenus nigricans, Anagallis tenella, Selaginella selaginoides and Breutelia chrysocoma. Sphagnum subfulvum is reported from raised bog in Co. Roscommon. Its occurrence in ombrotrophic vegetation is somewhat unexpected but the ombrotrophic vegetation in Western Ireland includes some species which are restricted to minerotrophic vegetation elsewhere.     

Incidence of leaf mining in different vegetation types across rainfall,canopy cover and latitudinal gradients

Abstract Leaf miners are insects whose larval stages live between layers of leaf epidermis, feeding on mesophyll and lower epidermis to create mine‐like cavities. Little is known about the ecology or distribution of leaf miners in Australia. We investigated the incidence of leaf miners in relation to aridity, vegetation types, host plant taxonomy, leaf traits, canopy cover and latitude. We surveyed leaf miners at 15 sites in NSW, eastern Australia, situated along a rainfall gradient from 300 to 1700 mm per annum and a latitudinal gradient of 28°S to 33°S, within four vegetation types (mallee, heath, woodland and rainforest). Leaf mining was recorded from 36 plant species, 89% of which had no previous record of mining. The proportion of mined plant species at each site varied, but there was no significant difference between vegetation types. Leaf mining presence was positively correlated with both total leaf length and leaf thickness. No significant correlations were found between the proportion of mined species at a site and rainfall, latitude or foliar projected cover. We conclude that leaf mining is a widespread type of insect herbivory whose distribution patterns are more likely to be influenced by biotic than abiotic factors.     

The Effect of Habitat Changes on the Endangered Ground Beetle Carabus Nitens (Coleoptera: Carabidae)

Carabus nitens, one of the most endangered ground beetles in Central Europe, was investigated with pitfall traps at 30 sampling sites in 17 heath fragments of the largest German heath landscape under nature conservation (nature reserve 'Lüneburger Heide'). The preference for damp Erica heaths and dry Calluna heaths in the building phase was thereby evident. Calluna heaths in the mature and degenerate phase, with and without extensive coverage by Avenella flexuosa, are either not inhabited or are avoided. The results of ovary dissections indicate that the populations in two successive spring seasons consisted mainly of animals which had already reproduced and were therefore older than one and a half years. Allozyme electrophoreses revealed variation for three of the nine investigated enzyme loci, and large differences in the allele frequency at one of these loci indicated genetic drift and fluctuations in the size of local populations. According to these results and statements in the literature, the loss of heathland areas and habitat quality are both responsible for the decline of the species. Suitable measures for preserving the species are (1) restoration of building phases of the Calluna heaths and (2) interconnection of at least the smaller heath fragments. Finally, recommendations are given for reintroductions.     

Interaction of diffuse competition and insect herbivory in limiting brittle prickly pear cactus,Opuntia fragilis (Cactaceae)

We tested the effects of above- and belowground competition and evaluated insect herbivory on the growth of a common cactus (Opuntia fragilis) in Sandhills prairie. Our purpose was to determine the independent and joint contribution of these factors to the variation observed in cactus size and local abundance. We manipulated ambient prairie vegetation and surface water availability in a full factorial design. When Opuntia fragilis was released from competition with surrounding vegetation, it grew significantly larger in the second growing season, both in terms of number and size of new cladodes. Ramets grown within live prairie vegetation averaged no net growth. These ramets were also more frequently fed upon by the larvae of two internally feeding cactus insects. As a result, insect herbivory reinforced the competitive suppression of the cactus by grasses. Water supplementation had no significant effect, either on cactus growth or on insect herbivory. We conclude that the mechanism by which dense prairie vegetation influenced net growth of O. fragilis was both direct, through competition for nonwater resources such as light, and indirect, through its mediation of feeding by specialized insect herbivores. Furthermore, since the direct growth response to treatment did not precede the indirect effect of habitat-mediated variation in feeding by insects, our results contradict the current expectation that indirect effects require more time to be expressed than do direct effects.     

Limited by the host: Host age hampers establishment of holoparasite Cuscuta epithymum

A good understanding of the relationship between plant establishment and the ecosystem of which they are part of is needed to conserve rare plant species. Introduction experiments offer a direct test of recruitment limitation, but generally only the seed germination and seedling phases are monitored. Thus the relative importance of different establishment stages in the process of recruitment is not considered. This is particularly true for parasitic plants where empirical data are generally missing. During two consecutive growing seasons we examined the effect of heathland management applications, degree of heathland succession (pioneer, building and mature phase) and seed-density on the recruitment and establishment of the endangered holoparasite Cuscuta epithymum. In general, recruitment after two growing seasons was low with 4.79% of the sown seeds that successfully emerged to the seedling stage and a final establishment of 89 flowering adults (i.e. <1.5% of the sown seeds). Although a higher seed-density resulted in a higher number of seedlings, seed-density did not significantly affected relative germination percentages. The management type and subsequent heath succession had no significant effect on seedling emergence; whereas, seedling attachment to the host, establishment and growth to full-grown size were hampered in older heath vegetation (i.e. high, dense, and mature canopy). Establishment was most successful in turf-cut pioneer heathland, characterised by a relatively open and low vegetation of young Calluna vulgaris. The age of C. vulgaris, C. epithymum's main host, proved to be the most limiting factor. These results emphasise the importance of site quality (i.e. successional phase of its host) on recruitment success of C. epithymum, which is directly affected by the management applied to the vegetation. Lack of any heathland management will thus seriously restrict establishment of the endangered parasite.     

Is Calluna vulgaris a suitable bio-monitor of management-mediated nutrient pools in heathland ecosystems?

In the face of ongoing atmospheric nutrient loads the employment of management measures to remove nutrients from heathland ecosystems has increased in importance. The present study is the first to analyse whether Calluna vulgaris is a suitable bio-monitor of management-mediated nutrient pools in heathland ecosystems. If Calluna vulgaris proves to be an appropriate indicator, its bio-indicative usage may prove to be a helpful tool for an assessment of management success in heathland ecosystems. In the Lüneburger Heide nature reserve (NW Germany) we analysed the impacts of grazing, mowing, prescribed burning, choppering and sod-cutting on the nutritional status of Calluna vulgaris by measuring nutrient contents (N, P, Ca, Mg, K) of current year's shoots 1 and 5 years after application of management measures. Results were related to management-induced nutrient flows and nutrient pools at the focal heath sites. Our results indicate that the less the physical environment of a heath site was affected by management measures the better the nutrient contents of current year's shoots of Calluna vulgaris mirrored changes in nutrient pools. For low-intensity measures (i.e. grazing, mowing, prescribed burning), shoot nutrient contents were a suitable indicator for changes in nutrient pools, particularly for nutrients with conservative cycles such as P. At grazed and mown sites high output rates of P caused by these measures were well reflected by decreased shoot P content. At burned sites, Calluna vulgaris proved to be a good indicator of changes in nutrient pools of the organic layer, mainly attributable to the deposition of nutrients with ash. In contrast, at sites subjected to high-intensity measures, shoot nutrient contents did not reflect management-mediated shifts in nutrient pools, despite the high nutrient losses caused by choppering and sod-cutting. At these sites, shoot nutrient contents mirrored only the effects of altered mineralisation rates attributable to changes in the physical environment following high-intensity measures. As plant growth and competition in heathlands is considered to be controlled by N or P, shoot N:P ratios are recommended as a tool to indicate whether plant growth tends to be limited by N, by P or by N and P. This, in turn, allows for an assessment of long-term effects of both atmospheric nutrient loads and management-mediated shifts in N and P pools at a focal heath site.     

Fertiliser Response of soils and vegetation on ultrabasic terraces on the isle of rum between 1965 and 1996

Summary

In 1965, an experiment was begun on the Isle of Rum, in the Inner Hebrides of Scotland. The experiment aimed to determine the limiting effect of soil nutrient deficiency on the re-colonisation of vegetation on the sparsely vegetated slopes of the island's ultrabasic mountain ridges. A fertilisation regime was implemented between 1965 and 1968. In 1996, sampling of a newly established ‘untreated’ plot revealed that, on untreated areas, the soils and vegetation had remained largely unchanged since 1965. Resampling of the fertilised plot however, demonstrated the development of a more organic rich surface soil with a significantly reduced soil acidity and increased soil cation, extractable phosphorus and total nitrogen contents. Most of these changes could be directly attributed to the fertiliser applications. On the fertilised plot, vegetation cover had increased from 5–10% in 1965 to 100% in 1996 and a shift from patchy herb-rich Calluna heath to closed speciesrich Festuca-Agrostis grassland had taken place. A range of acidophile species and bare soil bryophytes had been lost, having been replaced predominantly by grasses and mosses. The importance of nutrient availability as the principal limiting factor on vegetation cover in the study area has been uneqivocally established.     

Transition from heathland to grassland initiated by the heather beetle

This paper discusses the transition from heather-dominated vegetation to one dominated by grass. The dominating species involved are Calluna vulgaris and Deschampsia flexuosa. The study covered three years, 1980–82, and was done at the Hoorneboeg heathland in the Netherlands. Several factors account for this transition: damage caused by the chrysomelid heather beetle Lochmaea suturalis Thomson, soil type, and interaction between beetle damage and Deschampsia when already present underneath or in the immediate vicinity of a Calluna canopy. There was a time-lag between beetle damage and grass establishment or expansion. In fact, this transition concerns a type of vegetation succession and can be treated as such. This succession therefore involves several causative factors external to the system Calluna-Deschampsia. The successional process is conceived as a stochastic one defined by transition probabilities which depend on a time component, a space component and a logistic response component. All these components are discussed in this paper, but the discussion of yet another component, the crowding of Deschampsia itself, will be treated separately.     

The effect of herbivore density on host plant mediated interactions between two insects

Recent work suggests that foliar- and root-feeding insects can interact in a novel plus-minus fashion. However, the effects of herbivores may be different at different densities. This paper describes two laboratory experiments investigating the effect of increasing insect density on plant performance and the host-plant mediated interaction between a leaf-mining fly and root-feeding chafer larvae. Above- and below-ground insect herbivory decreased plant performance. The effects of the root feeder were, for some parameters, different between the two densities of chafer larvae. Leaf mining significantly decreased the performance of the chafer larvae, while root herbivory was found to increase the pupal weight (related to fecundity) of the leaf miner. The effects of root herbivory suggest that the relationships between herbivore density and plant performance may be curved as the greater chafer density had no significant increased effect on the plants or foliar-feeding insects.     

Vegetation transition following drainage in a high‐latitude hyper‐oceanic ecosystem

Questions: How does draining affect the composition of vegetation? Are certain functional groups favoured? Can soil parameters explain these differences? Location: Central Faroe Islands, treeless islands in the northern boreal vegetation zone. Since 1987, an area of 21 km² at 100–200 m a.s.l. was drained in order to provide water for hydro‐electric production. Method: Vegetation and soil of a drained area and a control, undrained neighbouring area of approximately the same size were sampled in 2007. Six sites were sampled in each area. The vegetation was classified with cluster analysis. Results: Four plant communities were defined in the area: Calluna vulgaris–Empetrum nigrum–Vaccinium myrtillus heath, Scirpus cespitosus–Eriophorum angustifolium blanket mire, Carex bigelowii–Racomitrium lanuginosum moss‐heath, Narthecium ossifragum–Carex panacea mire. Heath was more extensively distributed within, and was the dominant community of the drained area, whereas moss‐heath was more extensive in the undrained area. Blanket mire and mire had approximately the same distribution in both areas. For the blanket mire, species composition indicated drier conditions in the drained than in the undrained area. The drained area had higher frequencies of woody species and lichens, grasses had finer roots and available soil phosphate was considerably higher, whereas the undrained area had higher frequencies of grasses and sedges. Conclusion: The dominant plant communities were different in the two areas, which indicated that the blanket mire was drying in the drained area. Higher concentration of soil phosphate in the drained area also indicated increased decomposition of organic soils owing to desiccation.     

Direct evidence of heathland management in the early Bronze Age (14th century <Emphasis Type="SmallCaps">b</Emphasis>.<Emphasis Type="SmallCaps">c</Emphasis>.) from the grave-mound Skelhøj in western Denmark

Plant macrofossil analysis of soil samples from the grave-mound Skelhøj, western Jutland in Denmark, showed that heather sods had been used as building material. The original vegetation horizon, which was still preserved within the sods allowed the reconstruction of the original vegetation cover of the Bronze Age landscape. It was therefore possible to determine the land-use systems of the Bronze Age societies there during the 14th century b.c. The sods derived from a dry to medium-dry heathland community previously used as pasture. Many grasses and herbs indicate that it was not a very well developed (or old) heathland that was used for the building material of the mound, but a newly re-established heath cover above an older one that had been burnt some years before the sod-cutting activities took place. Charred finds of roots, twig fragments, flowers and seeds of Calluna vulgaris L. (heather) dominated the plant spectrum. Cuscuta epithymum L. (dodder) was found in 31% of the sod samples. This parasitic plant is known for successfully spreading on burnt heather plants that have started to re-develop with new shoots.