The identification of the seeds and fruits of common Scottish aquatic herbs

Background: There have been few quantitative observations of the attributes of native animal paths and no studies of their variation between vegetation types. These paths may be important in extending the local ranges of plant species.

Aims: To determine the incidence, cover and characteristics of native animal paths in different vegetation types, their relationships with other variables and the influence of paths on plant species distributions.

Methods: Randomly located line transects, and paired quadrats on and adjacent to paths, were used to record path and environmental attributes at 10 sites in each of 10 vegetation types. The relationships between path cover, number, width and depth and potential predictor variables were determined by using Pearsons product moment correlation.

Results: The mean cover of paths in plant communities varied between 6.5% and 12.6%. Path cover, number, width and depth varied between vegetation types. Penetration resistance, bare ground, scat density and plant species richness had higher values in path quadrats than in controls. Within particular vegetation types, several plant species were restricted to paths.

Conclusions: Animal trampling is an important influence on vegetation structure and the distribution of plant species in the study area.     

Vegetation pattern of mountains in West Greenland – a baseline for long-term surveillance of global warming impacts

Background: Steep environmental gradients, coupled with predicted high temperature rises in the Arctic make arctic mountain vegetation highly suitable for surveillance of changes related to global warming. However, guidelines and baselines for such a purpose are widely lacking since arctic mountain vegetation has been little explored.

Aims: We explore options for long-term surveillance on the basis of a detailed analysis of extant plant community patterns and their underlying environmental conditions in the mountainous inland of West Greenland.

Methods: Distribution, abundance and site conditions of vegetation types were analysed, using 664 vegetation samples and detailed vegetation maps in four altitudinal belts.

Results: Most plant communities had a restricted elevation distribution and were confined to special habitats predominantly defined by mesotopography and soil moisture.

Conclusions: Based on the strong linkage to habitat conditions, horizontal and vertical changes of species distribution and vegetation pattern are excellent indicators for inferring underlying environmental changes on three different scales. The recommendations given concerning climate sensitive species and plant communities, ecotones for setting up observation sites as well as stratification of analysis by habitats can be the basis for establishing long-term surveillance programmes on arctic mountain vegetation.     

Floristic diversity and the richness of locally endangered plant species of semi-natural grasslands under different management practices,southern Kyushu,Japan

Background: The rapid decline of semi-natural grasslands in Japan threatens many relic and endemic plant species. There is insufficient knowledge on how the impacts of land-use changes and management of grasslands have been affecting grassland ecosystems and what conservation measures may be taken to conserve as much of the existing plant diversity as possible.

Aim: We assessed the existing management regimes for their suitability for conserving Red Data Book (RDB) species.

Methods: We conducted our study in four districts of Kushima, Kyushu, south-west Japan, with different land-use histories. We compared species richness, plant density and abundance in six grassland types: regularly burnt, regularly mown, paddy levee, roadside, landslip and wetland communities in a total of 289 1 m x 1 m quadrats, recorded in172 grassland patches. Species richness plant density and abundance were analysed with special reference to RDB species under different land use history.

Results: Species richness of grasslands did not differ across different land use histories, yet our analysis showed that the reduced area of grasslands markedly affected the density of RDB species. Grassland types differed in their ability to support RDB species: regularly burnt grasslands were the richest in RDB species and poorest in alien species, followed by regularly mown grasslands, paddy levees, landslip, wetland and roadside communities.

Conclusions: Traditional management regimes, such as regular burning or mowing of grasslands have the best potential for conserving RDB species, and thus should be part of conservation management practices of semi-natural grasslands.     

On Cannabis indica,Indian hemp

Background: The South Aegean Volcanic Arc (SAVA), one of the most notable geological structures of the Mediterranean Sea, is floristically well known. Nevertheless, the factors that contribute to shaping the plant species richness of the SAVA remain unclear.

Aims: To investigate the factors that affect plant species richness and identify plant diversity hotspots in the SAVA and other central Aegean islands.

Methods: We used stepwise multiple regression to test the relationship between a number of environmental factors and plant species richness in the SAVA, as well as the residuals from the species–area linear regressions of native, Greek and Cycladian endemic taxa as indicators of relative species richness.

Results: The area was confirmed to be the most powerful single explanatory variable of island species richness, while geodiversity, maximum elevation and mean annual precipitation explained a large proportion of variance for almost all the species richness measures. Anafi, Amorgos and Folegandros were found to be endemic plant diversity hotspots.

Conclusions: We have demonstrated that geodiversity is an important factor in shaping plant species diversity in the Cyclades, while mean annual precipitation, human population density and maximum elevation were significant predictors of the Greek endemics present in the Cyclades. Finally, Anafi was found to be a plant diversity hotspot in the South Aegean Sea.     

Linear landscape elements in an Austrian viticultural landscape have limited effects on spatial patterns of plant genetic diversity

Background: The Wachau region along the river Danube in eastern Austria represents one of central Europe's hotspots of plant and animal species diversity. One of the typical landscape elements is vineyards, mostly established as linear elements on terraces along the slopes, with a characteristic and species-rich flora and fauna on terrace slopes lying between the cultivated terraces.

Aims: We addressed the question of how the genetic variation of four plant species of open grassland vegetation types is distributed. We asked if levels and distribution of genetic diversity of the plant species Aster amellus, Gentianella aspera, Pulsatilla grandis, and Stachys recta were correlated with geographic distances along the terrace slopes.

Methods: The dominant inherited molecular marker system random amplified polymorphic DNA (RAPD ) was used to estimate and compare the distribution of genetic diversity of the four selected species.

Results: We found only low levels of correlation of the distribution of genetic variation with linear geographic patterns and obtained indirect evidence for high levels of gene flow between adjacent terrace slopes.

Conclusions: We found that genetic diversity parameters of the four target species did not mirror the pattern of linear landscape elements, indicating that gene flow acts efficiently against the linear distribution of genetic variation.     

The effects of micro-habitats and grazing intensity on the vegetation of burial mounds in the Kazakh steppes

Background: Burial mounds (kurgans) of Eurasian steppes are man-made habitat islands that have the potential to harbour rich plant diversity due to micro-habitats associated with their topography.

Aims: We assessed whether kurgan micro-habitats harboured different species pools and functional groups from those found on the surrounding steppes. In addition, we asked if these mounds were affected by different grazing intensities from those on the surrounding vegetation.

Methods: We surveyed kurgan micro-habitats (northern and southern slopes, surrounding ditch) and adjacent steppe plains in non-grazed, moderately grazed and heavily grazed sites in northern Kazakhstan. We analysed differences in species composition of four habitats under three grazing regimes using Generalised Linear Mixed Models, PCA ordination and indicator species analysis.

Results: Kurgan micro-habitats had diverse vegetation and supported the co-existence of plant species with different environmental needs. We identified 16 steppe specialists confined to kurgan micro-habitats. Steppe vegetation was well-adapted to extensive grazing, although heavy grazing supported ruderals and a decline in steppe specialists. There was a significant interaction between grazing intensity and habitat type: heavy grazing supported ruderals and suppressed steppe specialists especially on the slopes.

Conclusions: We highlighted that kurgans play an important role as maintaining high plant diversity locally in extensive steppe plains in Central-Asia by increasing environmental heterogeneity and supporting specialist species confined to these micro-habitats.     

Positive effects of an extremely hot summer on propagule rain in upper alpine to subnival habitats of the Central Eastern Alps

Background: Propagule production and dispersal largely determine the distribution and potential migration ability of alpine plant species. Variation in reproductive success caused by year-to-year variation in climate may critically influence these processes.

Aims: To obtain estimates for the propagule rain in high-alpine plant communities and detect potential dispersal events from lower elevations.

Methods: The magnitude and composition of the propagule rain was studied in different plant communities along an elevation gradient from the upper alpine to subnival zone. Propagules were trapped at eight elevations from 2760 to 3070 m a.s.l. for three years from July to September 2003–2005. Vascular plant species and their cover were recorded in an area with a radius of 10 m surrounding the traps.

Results: A five- to 10-fold higher propagule rain was observed in 2003, a year with an exceptionally hot summer, compared to 2004 and 2005. Propagule and species numbers varied highly among years and community types. Few propagules of non-local origin were recorded in any year.

Conclusions: Extremely hot summers are likely to greatly magnify the propagule rain size of species in alpine habitats. Such ‘mast years’ may contribute to enhanced and accelerated vegetation changes in alpine habitats in the absence of limiting factors.     

Limited effect of hare grazing and short-term climatic variations on the most common alpine vegetation community in the Snowy Mountains,Australia

Background: In the alpine zone of the Snowy Mountains, grazing by mammals is limited. However, introduced European hare numbers have increased since the 1970s.

Aims: To estimate the density of hares and hence grazing pressure among years. To assess the response of biomass, vegetation height and composition to a cessation of hare grazing.

Methods: We used indices of hare abundance based on spotlighting and counts of hare pellets on a transect. The effect of hare grazing on tall alpine herbfield was assessed by using 15 paired exclosure and control quadrats for six years.

Results: The indices of hare abundance suggested densities similar to those in upland areas of Britain. Grazing did not affect the composition, cover of herbs or graminoids or, for 2010, vegetation height or biomass. Variation in vegetation and hare numbers among years was not correlated with climatic variables. Observations of selective grazing suggested that impacts on vegetation may be localised and restricted to certain species. Prior analyses of hare pellets indicated that hares might spread seed of native and exotic species.

Conclusions: Hares are having no general effect on tall alpine herbfield but may affect certain plant species via selective grazing or by spread of viable seed.     

The relationship between soil water storage capacity and plant species diversity in high alpine vegetation

Background: In those alpine regions where growing season precipitation is decreasing due to climate change, the capacity of soils to retain water may become an important factor for the persistence of plant species. However, the importance of soil water storage capacity (WSC) for plant species diversity has not been studied so far.

Aims: We aim to evaluate the relevance of WSC for species diversity of alpine plant communities in relation to temperature and length of growing season.

Methods: Species diversity was determined in 150 plots from a broad range of alpine vegetation types in the calcareous western part of the central Swiss Alps. WSC of soil cores sampled in every plot was determined, as well as rooting zone temperature and snowmelt date. Linear mixed models were used to assess the relationship between environmental data and species diversity.

Results: Species diversity was most strongly and positively related to WSC, followed by mean daily minimum temperature (T_min) of the growing season. Species diversity was significantly related to date of snowmelt only in sites with high WSC and/or T_min.

Conclusions: WSC represents an integrative measure for habitat quality and accounts for differences in species diversity within the study region. In order to understand and predict responses of plant species to climate change in high mountain regions, it may be crucial to also take changes in plant water supply into account.     

Transactions of the Botanical Society of Edinburgh

Background: Due to the dry continental climate, the mountains of eastern Ladakh are unglaciated up to 6200–6400 m, with relatively large areas of developed soils between 5600 and 6000 m covered by sparse subnival vegetation. However, there are no studies on the composition of plant assemblages from such extreme elevations, their microclimates, vertical distributions and adaptive strategies.

Aims: The subnival vegetation was described and the relationship between microclimate, species distribution and species functional traits was analysed.

Methods: In total, 481 vegetation samples from 91 permanent plots, a floristic database of Ladakh and extensive microclimate measurements were used. Measurements of 15 functional traits were made and their relationship with species distribution between 4600 and 6150 m was tested.

Results: The subnival zone was characterised by extreme diurnal temperature fluctuations, a short growing season (between 88 and 153 days) and low soil temperature during the growing season (between 2.9 °C and 5.9 °C). It hosted 67 species, mainly hemicryptophytes, and ranged from ca. 5600 m to the highest known occurrence of vascular plants in the region (6150 m). The most common plant families were Brassicaceae, Asteraceae, Poaceae, Fabaceae and Cyperaceae. Subnival specialists with narrow elevational ranges represented 42% of the flora; these species were shorter, had relatively higher water content and water-use efficiency and contained more nutrients and soluble carbohydrates than species with a wider elevational range.

Conclusions: The subnival vegetation of eastern Ladakh is dominated by generalist species with wide vertical ranges and not by high-elevation specialists. These findings, in view of the vast unglaciated areas available for range extension, suggest a relatively high resilience of the subnival flora to climate change in this region.     

Giant stem rosettes have strong facilitation effects on alpine plant communities in the tropical Andes

ABSTRACT

Background: Giant rosettes constitute one of the most distinctive growth-forms in tropical alpine ecosystems. However, their interactions with other plant species remain unexplored in high Andean páramos.

Aims: Quantify the effect of a dominant rosette (Coespeletia timotensis) on soil and microclimatic conditions and relate the impacts to plant community structure.

Methods: We analysed topsoil temperatures, soil organic matter (SOM) and plant species cover in areas adjacent to C. timotensis and paired areas outside, at three sites (4250–4360 m a.s.l.) in La Culata National Park, Venezuela. Species richness, total vegetation cover and percent cover of each species near and away from the rosettes were compared.

Results: Topsoil temperature amplitudes were lower and SOM greater near C. timotensis stems, compared to areas away from them. C. timotensis had a consistent positive effect on species richness, vegetation cover and the cover of many abundant species (including cushions and herbs).

Conclusions: The facilitation effects of C. timotensis on abiotic conditions and community structure indicate they play a key role as nurse plants, pointing to giant rosettes as foundation species for the maintenance of plant diversity in the alpine tropics.     

Segregation,nestedness and homogenisation in plant communities dominated by native and alien species

ABSTRACT

Background: Highly modified landscapes offer the opportunity to assess how environmental factors influence the integration of alien plant species into native vegetation communities and determine the vulnerability of different communities to invasion.

Aims: To examine the importance of biotic and abiotic drivers in determining whether alien plant species segregate spatially from native plant communities or become integrated and lead to biotic homogenisation.

Methods: Ordination and classification of a floristic survey of over 1200 systematically located 6 m × 6 m plots were used to examine how plant community segregation, nestedness and homogenisation varied in relation to climate, environmental and human-related factors across Banks Peninsula, New Zealand.

Results: The analyses of community structure indicated that native and alien plant communities were spatially and ecologically segregated due to different responses primarily to an anthropogenic impact gradient and secondly to environmental factors along an elevation gradient. Human-land use appeared most strongly linked to the distribution of alien species and was associated with increased vegetation homogenisation. However, despite spatial segregation of alien and native plant communities, biotic homogenisation not only occurred in highly managed grasslands but also in relatively less managed shrublands and forest.

Conclusions: The role played by anthropogenic factors in shaping alien and native plant species community structure should not be ignored and, even along a marked environmental gradient, if the recipient sites have a long history of human-related disturbance, biotic homogenisation is often strong.     

Litter and its interaction with standing vegetation affect seedling recruitment in Tibetan alpine grasslands

Background: Seedling recruitment is widely recognised to be important in the maintenance of diversity and coexistence of species. It is not clear how local abiotic factors mediated by litter and biotic interactions influence plant species recruitment in alpine grasslands.

Aims: To determine how litter and standing vegetation affected seedling recruitment in plant communities in Tibetan alpine grasslands.

Methods: Seedling recruitment was quantified in response to experimental treatments: (1) removal of standing vegetation and litter; (2) removal of standing vegetation with litter intact; (3) intact standing vegetation and removal of litter and (4) control: intact standing vegetation and litter.

Results: Litter removal increased seedling numbers, while standing vegetation removal had no effect. An interaction between litter and standing vegetation removal marginally increased seedling number. Species richness of seedlings was not related to either litter removal or standing vegetation removal. Species composition of seedling differed significantly between removal of both litter and standing vegetation and control.

Conclusions: Litter and its interaction with standing vegetation has an important role in affecting plant species recruitment in this alpine plant community. In contrast, biotic interactions, such as competition or facilitation from standing vegetation, appear to have only minor effects on recruitment.     

Grassland plant species occurring in extensively managed road verges are filtered by urban environments

Background: Urbanisation filters species in communities depending on their adaptability to conditions in built-up areas, especially in semi-natural habitats. Roadside vegetation is widespread along urban-rural gradients and is therefore a good place to study landscape-scale factors influencing plant community composition.

Aim: Our study aimed to assess how plant species distributions vary between urban and rural landscape contexts and to identify biological traits favoured in urban areas.

Methods: Presence/absence data for 63 indigenous common species were collected in 296 road verge patches distributed along the urban–rural gradient in three French cities. We investigated the effects of landscape composition on species assemblages and related individual species responses to urbanisation to functional traits associated with dispersal and persistence capacity.

Results: Many grassland species were negatively affected by increasing proportion of built-up areas in the landscape. Insect-pollination and high seed production appeared to be key traits favoured in grassland communities in urban areas, whereas dispersal modes were less related to plant distribution.

Conclusions: This study has demonstrated that urban filters affect common species of widespread, managed road verges. Better knowledge of the flora of these herbaceous roadsides may contribute to the conservation of common biodiversity within other grassland habitats found in urban areas.     

Vegetation,microclimate and soils associated with the latest-lying snowpatches in Australia

Background : The Snowy Mountains contain Australia's longest-lasting snowpatches. Because of climate change, their longevity has declined, with the loss of some specialist vegetation in the underlying snowbeds.

Aims: To characterise the current status of the vegetation associated with the longest-lasting snowpatches in Australia and its association with abiotic factors.

Methods: We assessed plant composition, soil depth, moisture and nutrients and subsurface temperatures in five zones of increasing vegetation height and cover in snowbeds.

Results: The zone beneath the middle of snowpatches was characterised by little vegetation cover and lower species richness, later emergence from snow, skeletal soils, and lower mean soil temperatures than zones further downslope where soils increased in depth and nutrient levels. Vegetation beneath these snowpatches no longer occurs in distinct communities. Plants have not simply migrated upslope, instead, areas that have deep soil that used to have snowpatch specialist species are being colonised upslope by grasses and downslope by tall alpine herbfield species that prefer bare ground.

Conclusions: Reduced longevity of Australia's longest-lasting snowpatches has led to the loss of distinct snowpatch plant communities. With limited soils beneath the centre of current snowpatches, and a lack of other suitable sites there is no location for these plant communities to migrate to.     

A population approach to vegetation structure

Abstract

A synthesis is presented of some research results on the structure and dynamics of populations with respect to the phytocoenosis structure. The first aspects to be considered are concerned with the dynamism, distribution and reproductive strategy of Anemone nemorosa: the vegetation structure either favors or inhibits the various reproductive strategies, thereby influencing the distribution pattern of the species. The second area of the present study is the demography and quantitative structure of Cytisus sessilifolius populations with respect to the problematic of secondary successions: the first results obtained open up interesting prospectives on the relationship between the vegetation dynamics and the frutescent populations structure.     

Long-term vegetation stability in northern Europe as assessed by changes in species co-occurrences

Background: The effect of the anticipated climate change on the stability of vegetation and the factors underlying this stability are not well understood.

Aims: Our objective was to quantify long-term vegetation changes in a range of habitats in northern Europe by exploring species co-occurrences and their links to diversity and productivity gradients.

Methods: We re-sampled vegetation in 16 arctic, mountain and mire sites 20 to 90 years after the original inventories. A site-specific change in species assemblages (stability) was quantified using species co-occurrences. Using a randomisation test we tested whether the changes observed were significantly greater than those expected by chance. Relationships between patterns in vegetation stability and time between surveys, numbers of plots, or species diversity and proxies for productivity, were tested using regression analysis.

Results: At most sites the changes in species co-occurrences of vascular plants and bryophytes were greater than those expected by chance. The changes observed were found to be unrelated to gradients in productivity or diversity.

Conclusions: Changes in species co-occurrences are not strongly linked to diversity or productivity gradients in vegetation, suggesting that other gradients or site-specific factors (e.g. land use or species interactions) may be more important in controlling recent compositional shifts in vegetation in northern Europe.     

A study of the abundance and patchiness of cicada nymphs (Homoptera: Tibicinidae) in a New Zealand subalpine shrub-grassland

Abstract

Cicada emergence skins in a subalpine shrub grassland have been sampled during 1969–75 to determine the abundance and spatial distributions of nymphs feeding on plant roots. A guild of six cicada species is primarily associated with two forms of vegetation: shrubs (Dracophyllum and Cassinia) and tall tussock (Chionochloa). Skin locations were mapped relative to dominant vegetation species, litter zones, and soil and rock pavements over a range of aspects, altitudes, and vegetation types, and sampling methods were scaled at four levels: the locality, plot, quadrat, and individual plant. There were significant differences in skin counts over four years, and different measures of mean skin densities are given for the four sampling scales. The two primary vegetation types had cumulative 1969–72 mean densities of 5.2 ± 4.0 and 12.9 ± 10.0 skins/quadrat (2.3 m²) , and the 1969–72 mean productivities of the upper 25% of quadrats (adjusted for percent ground cover) were, respectively, 5.5 and 35.5 skins/m². These productivities are believed to be conservative estimates of the maturing nymph numbers per individual host plant over the span of one cicada generation. Over a 17-year span, such productivities lie within the upper range of mean densities recorded for 17-year periodical cicadas in the United States. As the dominant subalpine vegetation species are very slow-growing,it is suggested that high densities of nymphs feeding on root sap may affect plant vitality, although 1971/1987 comparisons of vitality in 52 Chionochloa tussocks could not positively demonstrate a correlation across all data. Skin dispersion analyses indicated significant levels of patchiness, in agreement with other nymphal studies and with known cicada oviposition behaviour. No single dispersion model fitted the data comprehensively, and it is suggested that a gradual shifting of the centres of cicada aggregation may occur over a cumulative period of several generations.     

Committee for the study of the Scottish Flora

Background: Damage to alpine plant communities is likely to occur when hikers and pack animals trample vegetation. Currently, there is limited research that quantifies and compares impacts from these activities.

Aims: A manipulative experimental protocol was used to assess damage to alpine meadows by pack animals and hikers in the Aconcagua Provincial Park, Andes, Argentina.

Methods: Vegetation height, overall cover, cover of dominant species and species richness were measured immediately after, and 2 weeks after different numbers of passes (0, 25, 100 and 300) by hikers or pack animals in an experiment, using a randomised block design.

Results: Pack animals had two to three times the impact of hiking on the meadows, with greater reductions in plant height, the cover of one of the dominant sedges and declines in overall vegetation cover after 300 passes. Impacts of pack animals were also apparent at lower levels of use than for hikers. These differences occurred despite the meadow community having relatively high resistance to trampling due to the traits of one of the dominant sedges (Carex gayana).

Conclusions: Pack animals caused more damage than hikers to the alpine meadow, but the scale of the difference in short-term impacts depends on the characteristics of the plant community, the amount of use and the vegetation parameters measured. Use of the meadows by hikers and pack animals should be minimised as these meadows are scarce, and have high conservation values.     

Changes in plant taxonomic and functional diversity patterns following treeline advances in the South Urals

Background: Treeline ecotones represent environmental boundaries that fluctuate in space and time and thus induce changes in plant taxonomic and functional diversity.

Aims: To study changes through time in taxonomic and functional plant diversity patterns along the treeline ecotone.

Methods: In 2002, vegetation was sampled along a gradient from upper montane forest to the treeline–alpine transition in the South Ural Mountains, Russia. In 2014, vegetation was resampled and plant functional traits were collected. We studied spatial and temporal changes in plant species composition, functional composition and functional diversity.

Results: Species composition and diversity changed along the elevational gradient. The functional composition in height, leaf area, specific leaf area and leaf nitrogen content decreased with elevation, whereas functional composition of leaf carbon content increased. We found a temporal shift towards shorter plants with smaller leaves in treeline sites. Functional richness varied in several traits along the elevational gradient, while functional dispersion showed a trend towards increased functional dispersion in height, specific leaf area and leaf nitrogen in the treeline–tundra transition.

Conclusions: Tree encroachment across the treeline ecotone has resulted in a shift in plant species relative abundances and functional diversity, possibly affecting plant community assembly patterns.