Patterns of air temperature and accumulation of snow in subalpine heathlands and grasslands on the Bogong High Plains,Victoria

On well drained sites in the subalpine tract of the Bogong High Plains, Victoria, the distribution of grassland, dominated by Poa spp., and closed heathland, dominated by Prostanthera cuneata, can be correlated with patterns of maximum and minimum air temperature, and the accumulation and persistence of snow. Both maximum and minimum temperatures are lower, and the accumulation and persistence of snow is less in grassland, the dominant community of gentle slopes and hollows, than in closed heathland, the dominant community on steeper, leeward slopes. On gentle slopes and in hollows, the development of closed heath may be limited by the accumulation of cold air, relatively low temperatures and exposure to strong winds. However, on leeward slopes where snow persists the longest (until mid-late December), the development of heath may be limited by a shortening of the growing season. The distribution of grassland and heathland, especially the limits to the distribution of the heath, may also be affected by infrequent climatic events, such as the co-incidence of unusually low temperatures during winters when snow cover is meagre.     

New palynological and tephrostratigraphical investigations of two salt lagoons on the island of Mljet, south Dalmatia, Croatia

In the sediments of both of the investigated lakes, the tephra from the Mercato-Ottaviano eruption (Vesuvius, southern Italy) (ca. 7900 B.P.) could be identified. The palynological investigations show that from ca. 9000-7200 B.P. (8000-6000 cal B.C.) deciduous oak forests predominated, with only a few representatives of Mediterranean vegetation. At the transition to the central European Atlantic Period those forests changed to an open vegetation type, dominated byJuniperus andPhillyrea. At about 5500 B.P. (4400 cal B.C.), theJuniperus-Phillyrea vegetation was replaced byQuercus ilex woodland that still occurs on the island of Mljet today and is considered to be the natural vegetation of the Dalmatian coastland. The associated vegetation of theQ. ilex forests changed several times. At the beginning of theQ. ilex period,Juniperus values were still high, but soon they decreased andErica spread. In more recent times theQ. ilex forests were partially replaced by plantations ofPinus halcpensis. Indicators of human impact are sparse throughout the pollen record. Clear evidence for human influence exists only from ca. 3100 B.P. (1300 cal B.C.) whenJuglans andPinus halepensis were introduced to the area. Later,Olea andSecale cultivation can be suggested and further spreading ofJuniperus indicates use of the land as pasture.     

Effects of fire on the vegetation of a lowland heathland in North-western Italy

This study focuses on the effect of fire on lowland heathlands at the extreme southern edge of their European distribution (Vauda Nature Reserve, NW Italy). Forty-nine plots (50 m radius) were surveyed between 1999 and 2006. Each year, fire occurrences were recorded and per cent cover of four vegetation types (grassland, heath, low shrubland, and tall shrubland) was estimated in each plot. Vascular plant species richness was also recorded in 255, 1 m² quadrats. After a fire, grassland vegetation expanded, but then declined rapidly as heath and shrubland recovered: 7 years after a fire, tall shrubland encroached on to more than 40% of the plots, and grassland declined from 50% to 20% cover. Between 1999 and 2006, Betula pendula shrubland greatly expanded, while grassland decreased over most of the Reserve, even where fire frequency was high. Tall shrubland had low plant diversity and was dominated by widespread species of lower conservation value. By contrast, early successional vegetation (grassland and low shrubland) had higher richness and more narrowly distributed species, indication that the development of tall shrubland causes significant species loss in the heathland. Italian lowland heathlands are characterized by high rates of shrubland encroachment that threatens both habitat and species diversity. Burning frequencies of once in 3–6 years seem appropriate in this habitat, but burning alone might not suffice without actions to increase herbivore grazing.     

A quantitative description of the forest vegetation on an altitudinal gradient in the Mount Field National Park,Tasmania, and a discussion of its history and dynamics

The aim of this study was to describe the forest vegetation along an altitudinal transect running from 158 m to 1220 m (treeline) in the Mount Field National Park, Tasmania. Eighteen 1 ha plots were sampled along this transect, using a modified point-centred quarter method for species composition and density. Size frequency distributions were used to calculate basal areas. Estimates of relative density, frequency and basal area for each species were combined in to an importance value. The altitudinal ranges of all woody species were determined. The altitudinal temperature lapse rate was measured, and data on soil pH obtained. The initial ‘direct gradient’ analysis revealed relatively well marked discontinuities in the vegetation which were further examined by ordination and classification techniques. The latter provided a simple threefold classification into altitudinal zones. The lower zone reaches from the Park entrance (158 m) to between 600 and 670 m, and comprises tall open forest dominated by Eucalyptus regnans and/or E. obliqua and with a ‘wet sclerophyll’ understorey characterized by Olearia argophylla. The middle zone stretches from c. 670 to 940 m and comprises closed rainforest or ‘mixed’ forest (i.e. with senescent emergent eucalypts) dominated by Nothofagus cunning hamii and Atherosperma moschatum. This zone is characterized by the absence of O. argophylla and the presence of Phyllocladus aspleniifolius. The upper part of this zone constitutes an interdigitating transition to the subalpine forests, usually dominated by E. coccifera and occurring on suitable sites between c. 880 m and the timberline. The transition to subalpine forests is associated with a marked decline in basal area. Species richness (of woody plants) increases with altitude to reach a peak in the sub-alpine zone. This trend is the reverse of that normally encountered elsewhere in the world, and is mainly due to relatively high α and β diversities in the shrub stratum of this zone. The significance of fires, aspect and substrate is discussed in relation to the variations in composition within each zone. The low diversity of Nothofagus-dominated rainforest is thought to be due, in part, to the intense competitive thinning in the eucalypt re-growth phase following burning, and the subsequent ‘capture’ of the Eucalyptus niche by Nothofagus. It is speculated that, in Tasmania, the downhill migrations during the cooling phases of the Pleistocene were associated with extinctions of lowland forest taxa, while uphill migrations during warming phases were associated with speciation on the plateaux of the present subalpine zone. This hypothesis implies that the relative proportions of land area available at different altitudes, now and in the past, have determined the relative rates of speciation and extinction, and hence the altitudinal gradients of species richness.     

Comparisons of nutrient recovery and specific leaf area variation betweenCarex lasiocarpa var.occultans andCarex thunbergii var.appendiculata with reference to nutrient conditions and shading byPhragmites australis

The distribution of two sedge species was studied in two mires which differ in abiotic environments and in distribution ofPhragmites australis. Carex lasiocarpa var.occultans dominated in nutrient-poor valley mire, andCarex thunbergii var.appendiculata dominated in nutrient-rich flood plain subject to water fluctuations.Phragmites australis grew well in nutrient-rich conditions. The distribution ofC. lasiocarpa showed a strong negative correlation withP. australis coverage, whereasC. thunbergii coverage was not affected byP. australis. The leaf area per dry leaf mass (specific leaf area: SLA) ofC. thunbergii increased with shading byP. australis, but that ofC. lasiocarpa was stable. The SLA flexibility ofC. thunbergii to light interception might enable this species to invadeP. australis patches in nutrient-rich environments. The residual nutrient ratio of nitrogen and phosphorus (the ratio of the residual nutrient content at the end of the growing season to peak nutrient content) in the vegetative ramet ofC. thunbergii was 1.7 times higher than that ofC. lasiocarpa. This low residual ratio may indicate effective nutrient recovery to storage organs. The effective nutrient recovery inC. lasiocarpa might enable this species to grow even in nutrient-poor environments. However, it may be difficult forC. lasiocarpa to expand its habitat to nutrient-rich areas whereP. australis dominates as it is not shade tolerant.     

Alpine and subalpine snow patch vegetation on the Bogong High Plains,SE Australia

Abstract. Snow patch vegetation in Australia is rare, being restricted to the relatively small area of alpine and subalpine country in the highlands of southeastern Australia. Snow patch vegetation occurs on steeper, sheltered southeastern slopes, where snow persists until well into the growing season (December/January). We surveyed the vegetation of 33 snow patch sites in the alpine and subalpine tracts of the Bogong High Plains, within the Alpine National Park, in Victoria. The vegetation was dominated by herbs and graminoids, with few shrubs and mosses. Major structural assemblages identified included closed herb‐fields dominated by Celmisia spp, and grasslands dominated by Poa fawcettiae or Poa costiniana. These assemblages occurred on mineral soils. Open herb‐fields dominated by Caltha introloba and several sedge species occurred on rocky and stony substrata. Vegetation‐environment relationships were explored by ordination and vector fitting. There was significant variation in the floristic composition of snow patch vegetation as a function of duration of snow cover, altitude, slope and site rockiness. Alpine sites were floristically distinct from subalpine sites, with a greater cover of Celmisia spp. and a lesser cover of low shrubs in the former. There was floristic variation within some snow patches as a function of slope position (upper, middle or lower slope) but this was not consistent across sites. The current condition of snow patch vegetation on the Bogong High Plains is degraded, with bare ground exceeding 20% cover at most sites. Snow patch vegetation is utilized preferentially by domestic cattle, which graze parts of the Bogong High Plains in summer. Such grazing is a potential threat to this rare vegetation type.     

Phytosociological and palynological studies of alpine steppe communities on the northern Tibetan Plateau,Qinghai Province,China

The dry cold climate in the highland of the eastern Kunlun Mountains in Qinghai Province, north‐western part of China supports the establishment of alpine grassland, consisting of Poaceae and Cyperaceae species and dwarf shrub communities dominated by Potentilla and Krascheninnikovia shrubs. The phytosociological vegetation studies carried out around Lake Heihai (36°00′N/93°26′E, 4446 m a.s.l.) reveals a complex pattern of high mountainous vegetation, including three major vegetation communities. A Polygonum sibiricum community occupies wet and slightly saline sites close to the Heihai lake shoreline and Kobresia robusta and Poa pachyantha communities are characteristic for the drier slopes. These communities differ in ecological conditions, exposure and several characteristic species that form local subunits. Main ecological factors influencing plant growth are moisture coming from glacial melt water and the composition and texture of the surface sediments. The atmospheric circulation (i.e. monsoonal wind system) and the different amount of insolation of the southern and northern slopes are of minor importance for the establishment of the different communities. The reflection of the vegetation composition in the modern pollen rain is generally poor, since the pollen spectrum is highly influenced by the local appearance of taxa. Though the vegetation unit of a alpine steppe can be detected. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Vegetation changes around the last glacial maximum and effects of the Aira-Tn ash,at the Itai-Teragatani site,central Japan

On the basis of fossil pollen, plant macrofossils and fossil wood, vegetation existing around the Itai-Teragatani Site between 26000 and 20000 yr ago was reconstructed. On the upland, there were mixed forests of conifers and deciduous broad-leaved trees throughout the studied period. The forests consisted mainly ofPinus subgen.Haploxylon andQuercus subgen.Lepidobalanus, together withTsuga, Cryptomeria andUlmus-Zelkova. In the wetland, there were stands ofBetula andAlnus in grassland consisting of Cyperaceae, Gramineae,Lysichiton, Thalictrum, Sangusiorba, Umbelliferae and Compositae. The vegetation changed three times during the studied period. The first change, which occurred prior to the fall of the Aira-Tn ash, was characterized by an increase inAbies, Pinus subgen.Haploxylon and hygrophytes, and a decrease inCryptomeria andAlnus. This is considered to reflect a cooler climate, and expansion of grassland. The second change was caused by the fall of the Aira-Tn ash, which caused serious damage to the vegetation. Many taxa, except forAlnus, Cyperaceae andLysichiton, decreased or vanished after the ash fall. The third change was the process of recovery after the damage. The regenerated forests differed from those before the ash fall. With the regeneration conifers andArtemisia increased. This seemed to reflect the changes in climate and ground conditions caused by the accumulation of the ash.     

Does alpine grazing reduce blazing? A landscape test of a widely‐held hypothesis

Abstract ‘Alpine grazing reduces blazing’ is a widely and strongly held view concerning the effects of livestock grazing on fuels, and therefore fire behaviour and impact, in Australia's high country landscapes. As a test of this hypothesis, we examined the patterns of burning across the alpine (treeless) landscapes of the Bogong High Plains in Victoria, following the extensive fires of January 2003. Data were collected from multiple transects, each 3–5 km long, with survey points located randomly at either 50, 200 or 500 m intervals. The transects traversed the major regions of the Bogong High Plains, both grazed and ungrazed. At each point, we recorded whether the point was burnt or unburnt, the vegetation type (closed‐heath, open‐heath, grassland or herbfield), the estimated prefire shrub cover, slope, aspect, and a GPS location. At burnt heathland sites, we recorded the minimum twig diameter (an a posteriori measure of fire severity) in a sample of common shrubs. In total, there were 108 km of transect lines, 419 survey points and 4050 twig measurements, with sample points equally distributed across grazed and ungrazed country. The occurrence of fire (i.e. burnt or unburnt) in grazed and ungrazed areas was analysed by logistic regression; the variation in twig diameters by anova . Approximately half of all points were burnt. There was no statistically significant difference between grazed and ungrazed areas in the proportion of points burnt. Fire occurrence was determined primarily by vegetation type, with the proportion burnt being 0.87 for closed‐heath, 0.59 for open‐heath, and 0.13 for grassland and all snow‐patch herbfield points unburnt. In both closed‐heath and open‐heath, grazing did not significantly lower the severity of fire, as measured by the diameter of burnt twigs. We interpret the lack of a grazing effect in terms of shrub dynamics (little or no grazing effect on long‐term cover of taller shrubs), diet and behaviour of cattle (herbs and dwarf shrubs eaten; tall shrubs not eaten and closed‐heath vegetation generally avoided), and fuel flammability (shrubs more flammable than grass). Whatever effects livestock grazing may have on vegetation cover, and therefore fuels in alpine landscapes, they are likely to be highly localized, with such effects unlikely to translate into landscape‐scale reduction of fire occurrence or severity. The use of livestock grazing in Australian alpine environments as a fire abatement practice is not justified on scientific grounds.     

The role of a native tussock grass (Paspalum quadrifarium Lam.) in structuring plant communities in the Flooding Pampa grasslands, Argentina

The patches of Paspalum quadrifarium-dominated grasslands found atpresent could be remnants of the vegetation that defined the Pampas landscape inthe past. The mere presence of such physical structures should lead to systemsin which many other species are dependent upon both the autogenic creation ofsurface area for living space and the autogenic and allogenic modulation ofresources controlled by these structures. We carried out amensurative–comparative study in naturally occurring sites dominated byP. quadrifarium that occupy different positions within thelandscape in the Flooding Pampa. We found different species assemblages in thesestructurally homogeneous stands, related to the edaphic and topographicgradients. The comparison with sites from similar positions in the landscapewhere this native tussock-grass was absent showed that the dominance ofP. quadrifarium is a minor determinant of floristicdifferences, which are mainly controlled by abiotic factors. We assigned thesedominated grassland stands to previously delimited vegetation units for theFlooding Pampa grasslands and we compared them with the vegetation unitsassigned, in terms of composite properties of the community that may beindicators of ecosystem processes, such as biological invasions andproductivity. Our results show that this native tussock grass is associated withhigher floristic richness, higher representation of perennials and grasses andlower presence of alien plants. This homogeneous pattern of variation across thevegetation units would suggest that, despite the absence of dramatic changes incommunity composition, the dominance of this tussock grass plays an importantrole in structuring species diversity patterns.     

Effects of some carbon and nitrogen sources on spore germination,production of biomass and antifungal metabolites by species of Trichoderma and Gliocladium virens antagonistic to Sclerotium cepivorum

Conidia of Trichoderma pseudokoningii (IMI 322662) and T. viride (IMI 322659) were incubated in 1% bacteriological peptone at 25° C for 20 h and more than 95% of the spores germinated. In the same medium, only 35% of the conidia of Gliocladium virens (G20) and T. viride (IMI 322663) germinated but when 1% glucose was added, germination was increased to 70%. In the presence of glucose as a carbon source, maximal biomass production of G. virens (G20) after seven days at 25°C was obtained with either potassium nitrate or L‐alanine as the nitrogen source, whereas the Trichoderma isolates needed an organic nitrogen source. With L‐alanine as a nitrogen source, glucose, galactose and sucrose were readily utilized for biomass production by all fungal isolates. Maltose utilization by G. virens (G20) and T. pseudokoningii was incomplete after 21 days incubation, whereas glucose utilization was complete by this time. G. virens, T. pseudokoningii and T. viride (IMI 322663) produced antifungal metabolites which were effective at reducing radial growth of Rhizoctonia solani, Botrytis cinerea as well as S. cepivorum. The metabolites produced by G. virens were very active against all three pathogens but the metabolites produced by T. pseudokoningii and T. viride (IMI 322663) were less active. T. viride (IMI 322659) was a very poor antifungal metabolite producer.     

Effects of salinity and waterlogging on the vegetation of Lake Toolibin,Western Australia

Increased rates of tree senescence and mortality in and adjacent to an ephemeral lake in the Western Australian wheatbelt have been attributed to increased levels of soil salinity and inundation following agricultural clearing. Winter lake salinities approximate freshwater lake values, but during periods when the lake is dry, capillary rise of groundwater is thought to increase surface soil salinity. An undescribed species of Melaleuca and Casuarina obesa dominated the seasonally inundated regions of the lake bed. Aeolian deposits of higher elevation were dominated by Eucalyptus loxophleba, Allocasuarina huegeliana or species of Banksia. Woodland of E. oleosa var. longicornis and E. salmonophloia occurred predominantly on upland fluviatile deposits of sand and sandy clays. Measurements of soil salinity and the calculation of percentage inundation from tree elevations and observations of tree vigour and xylem pressure potential response indicated that tree deaths in Melaleuca sp. and C. obesa were due to increased levels of salinity. Deaths and low vigours in E. rudis were attributed to both increasing salinities and prolonged inundation. We believe control of ground water levels should be a major consideration in the preservation of this ephemeral lake and the water fowl populations it supports.     

Palynological investigations on vegetation and climate change in the Late Quaternary of Lake Rukche area,Gorkha Himal,Central Nepal

Palynological data and pedological investigations including stable isotopes and lignin biomarkers (Glaser et al. in press) from a 4 m core of Lake Rukche (3500 m a.s.l.) enhance our palaeoecological knowledge of the time since the LGM in the Gorkha Himal, Central Nepal. Even before 15000 B.P. forest types became established which prove the existence in Central Nepal of a temperate-humid climate with a considerable amount of winter and spring precipitation from westerly disturbances. Lignin input and pollen data point to a patchy vegetation cover around Lake Rukche with meadow-steppes dominated by Poaceae. Around 15000 B.P. Quercus and Pinus roxburghii dominated the lower altitudes while the vegetation around Lake Rukche was more steppe-like (Chenopodiaceae, Artemisia). Subsequently the climate became warmer and drier as winter and spring precipitation decreased while summer rain remained low. Later on more resource-demanding forests became established under improved temperature and precipitation conditions (Engelhardia). Around Lake Rukche coniferous forests (Abies, Picea) occurred beside meadow-steppes. The transition from the Pleistocene to the Holocene is not recorded. In the Holocene alpine Kobresia-meadows stabilised the soil surface causing sand accumulation to end. During the mid-Holocene (7800–2750 B.P.) humid oak forests with demanding elements (Ilex, Coriaria, Myrsine and Engelhardia) dominated the vegetation cover. A charcoal layer and a marked emergence of fire-induced communities with Pinus roxburghii, Poaceae, Ericaceae and Pteridium are proofs of a first strong anthropogenic change in vegetation which coincided with the climatic deterioration at the onset of the Subatlantic. Since 900 B.P. grazing pressure and the frequency of fires increased, resulting in a replacement of Betula utilis-forests by meadows and woods of Juniperus and Rhododendron. While previous anthropogenic influence increased the biodiversity by promoting replacement communities, recent developments have led to a decrease in biodiversity through loss of natural vegetation communities.     

Coastal heathland succession influences butterfly community composition and threatens endangered butterfly species

Succession has a strong influence on species diversity and composition of semi-natural open terrestrial ecosystems. While several studies examined the effects of succession on butterflies in grassland and forest ecosystems, the response of heathland butterflies to succession had not been investigated so far. To address this issue we sampled butterfly abundance and environmental parameters on the Baltic island of Hiddensee (NE Germany) along a gradient of coastal heathland succession from grey dunes to birch forest. Our results provide evidence that succession of coastal heathland has a strong influence on butterfly diversity, abundance, and species composition. Thereby grass and tree encroachment present the main threats for heathland butterflies. Diversity and abundance of butterflies were highest in shrub-encroached heath directly followed by early stages of coastal heathland succession (dwarf-shrub heath, grey dune). Both observed threatened species (Hipparchia semele, Plebeius argus) were negatively affected by succession: abundance decreased with increasing vegetation density (both species) and grass cover (P. argus); consequently, the two later successional stages (shrub, birch forest) were not occupied. Our findings highlight the importance of the preservation of early stages of coastal heathland succession for endangered butterfly species. For coastal heathland management we therefore suggest to maintain early successional stages by sheep grazing, mowing or, in case of high nutrient contents, intensive techniques such as sod-cutting or choppering. To a lower extend shrub-encroached sites should also be present, which might be beneficial for overall species richness.     

Resource partitioning by small mammals in lowland heath communities of south-eastern Australia

Habitat selection by seven species of small mammals was investigated in three areas of heathland in Victoria. A total of 12 120 trapnights over 22 months was used to assess preference for different vegetation groups formed by clustering trap sites on (a) floristic and (b) structural criteria. Rattus lutreolus proved to have both floristic and structural requirements. Seasonal changes in distribution in relation to rainfall appeared to be dependent on soil type. Greatest movement occurred on sandy podzol soils. Pseudomys shortridgei selected the most diverse vegetation types. Rattus fuscipes preferred wet, structurally complex vegetation. Mus musculus appeared to fill the niche of Antechinus minimus and partially replace A. stuartii and A. flavipes when Antechinus spp. were absent. M. musculus seems to commonly fill three niches in these heathlands: fossorial insectivore, scansorial insectivore and immediate post-fire omnivore. A small mammal community structure of five major food niches may be common to both heathland and forest communities of south-eastern Australia.     

The heath-savannah problem: the effect of fertilizer on sand-heath vegetation of North Stradbroke Island,Queensland

A balanced fertilizer treatment - equivalent to that optimal for pasture development on the infertile sandy soils of the Coastal Lowlands of south-eastern Queensland - was applied to a heathland stand on North Stradbroke Island in 1968, 3 years after the vegetation had been razed by bushfire. The fertilized and control plots were examined in detail in 1968 (before application of fertilizer), in 1969 and in 1976. Eight years after fertilizer treatment the heath species have declined in density and/or biomass. The native grass, Themeda australis, responded to fertilizer and is expanding into gaps as the heath species die. A few composites and grasses are invading the fertilized plots.     

The lichen generaCatapyrenium andPlacidiopsis in Greenland

Seven species ofCatapyrenium and one ofPlacidiopsis are reported from Greenland. Five taxa, viz.Catapyrenium michelii, C. norvegicum, C. squamulosum, C. waltheri andPlacidiopsis pseudocinerea are new to the area. Taxonomy, distribution and ecology are briefly discussed. A key to species and distribution maps are presented.Catapyrenium norvegicum is described as new.     

Interspecific interference for nest sites betweenLeptothorax congruus andMonomorium intrudens

Summary Interference competition for nest sites was studied in ant communities dominated byLeptothorax congruus in the suburbs of Tokyo, central Japan. At the two study plots located in a deciduous wood and in grassland,L. congruus constructed nests in dead branches or stems of dead grasses. Approximately 50% of the nests were physically broken within a year, suggesting that they were very fragile. Of totals of 67 and 91 nests ofL. congruus marked at the two sites, 12 (17.5%) and 53 (58.2%) nests, respectively, were replaced by other ant species (Monomorium intrudens,Crematogaster brunnea teranishii,Camponotus itoi andLasius sp.) which were common in both habitats. Field observation suggested that, among these ants,M. intrudens was a major competitor usurping the nests ofL. congruus by aggressive invasion.     

The age of Calluna stands moderates post‐fire regeneration rate and trends in northern Calluna heathlands

Questions: Does stand age influence the direction and rate of post‐fire successional dynamics in coastal Calluna heaths and can old degraded heath vegetation be restored through reintroduction of fire? Location: Coastal heaths in the Tarva archipelago, central Norway. Methods: We investigated revegetation dynamics after experimental fires set in young (8 years since last fire) and old (>50 years since last fire) grazed heath stands. A repeated measures design was used, with floristic data recorded in permanent plots in the post‐fire successions (n=12) over a 7‐year period. The data were analysed using multivariate ordination techniques (PCA, RDA and PRC) and mixed effects models. Results: The age of Calluna stands strongly influenced post‐fire succession, different trends due to age explained 10.4% of variation in floristic data. Young heath showed faster succession towards pre‐fire community composition than old heath, and this could partially be explained by succession‐related factors: young heath had lower cover of mosses and lichens in the pre‐burned vegetation, and lower cover of litter early in succession. Young heath had a less pronounced overall community response to fire than old heath. Vegetative regeneration of C. vulgaris was absent in both old and young heath, but Calluna still re‐established as the dominant species within 5–7 years in both young and old stands. Regeneration dynamics were also affected by habitat conditions, different trends due to habitat explained 6% of variation. Conclusions: Our study demonstrates that old stands do develop characteristic heathland vegetation and structure after fire, and while potential invasives into the system such as trees and rhizomatous species are present, they do not impair Calluna regeneration or vegetation development towards the target heathland community composition and structure. Further, as our young stands are only in their second fire rotation after restoration, we suggest that characteristic dynamics of managed heathlands can re‐establish relatively rapidly, even in severely degenerated sites (>50 years since last fire). Site‐specific factors also need to be considered. We conclude that there is restoration potential in old heaths, despite slow dynamics in the first rotation.     

Heathland dynamics in biotically disturbed areas: on the role of some features enhancing heath success

It is well accepted that intense anthropogenic activities threaten European heathland communities. The negative impact of high intensities of livestock grazing on heath survival has been demonstrated in many studies, however, it does not seem a straightforward consequence in some cases: in the southern Pyrenees, the existence of large heathland patches in intensively grazed areas suggests that other factors interact and affect heath success. In order to gain insight into the factors affecting heath success, this paper analyses the pattern of occurrence of ericaceous shrubs—particularly Erica vagans—and their effects on soils when compared to herbaceous vegetation, under a complex biotic disturbance regime. Survey plots were established in grassland and heathland communities disturbed by both livestock and by burrowing animals on soils with different levels of basic resources. Relative cover of the species on and off molehills was studied. In heathland plots, ericaceous shrubs were more common on old molehills than off them. This pattern was strongest in the poorest soils. Below established heath shrubs, independently of the initial properties of the soils, some basic resources were more available than in intershrub areas. In grazed ecosystems, where continuous trampling and removal of biomass occurs, the heath canopy provides a site for accumulation of litter and insects, which contribute to the build up of a resource-rich layer. We conclude that successful establishment on ubiquitous molehills and suitable, localised changes in the soil under shrubs are some of the factors that explain the success of ericaceous shrubs in complex biotically disturbed areas.