Butterflies and diurnal moths along road verges: Does road type affect diversity and abundance?

Roadsides form potential habitats for several grassland species adapted to regular mowing management. We studied the communities of butterflies and day-active moths in 51 sites along the verges of the three road types, i.e., highways, urban roads and rural roads. Despite different traffic densities and widths of the road and verge, the groups were rather similar with regard to soil properties, vegetation structure and mowing intensity. The species richness and total abundance of butterflies (53 species, 5964 individuals) and diurnal moths (46 species, 4626 individuals) were also rather similar in each road type, although a preference for wider verges was observed. Butterfly diversity increased (but not significantly) from the verges of narrow rural roads to wider highways. The highest numbers of meadow species were recorded along highways and the total abundance, especially of diurnal moths, decreased in accordance with the road size. High nectar abundance was the most important factor increasing the numbers of meadow butterflies along road verges, while meadow moths were mostly favoured by shelter provided by tall vegetation. Verges surrounded by cultivated fields were generally related to low numbers of both Lepidoptera groups, whereas adjacent forests increased the total number of all species and favoured several butterflies inhabiting forest edges. The adjacent environment inflicted compositional differences on the Lepidoptera fauna of the three road types. The results indicate that road verges should be considered an important reserve for species dependent on semi-natural grasslands in Finland. A growing interest in accommodating current roadside management for conserving biodiversity is likely to benefit Lepidoptera communities in the verge habitats.     

Invasive alien goldenrods negatively affect grassland bird communities in Eastern Europe

Invasive alien plants constitute a major threat to local biodiversity. Moreover, their appearance often coincides with land use change. Many endangered groups of organisms suffer from habitat loss, which is often a consequence of the invasion of alien plants. This paper examines how invasive alien goldenrods Solidago spp. affect the richness of endangered grassland bird species and numbers of breeding pairs in abandoned meadows in southern Poland. Meadows invaded by goldenrods (n = 15) had lower bird species richness and a lower number of breeding pairs than meadows in which goldenrods were absent (n = 15). Two important factors positively influencing bird species richness were meadow area and shrub density (the latter only in meadows without goldenrods). Moreover, both the index of potential food density (number of butterflies) and plant species richness were much lower in meadows invaded by goldenrods than in meadows without these plants. Urgent action aimed at preventing the invasion of alien goldenrods in abandoned meadows is needed and such measures should involve regular mowing. Our results also highlight the fact that land abandonment in Central and Eastern Europe is not necessarily as beneficial for biodiversity as it is commonly believed and it may even lead to a decrease in the populations of several bird species in the agricultural landscape.     

Wild pollinator communities are negatively affected by invasion of alien goldenrods in grassland landscapes

The increasing spread of invasive alien plants has changed biodiversity throughout the world. To date research in this area has focused on how invasive plant species affect pollinator behaviour, but there is a lack of data on the impact that alien plant species have on wild pollinator populations. Since their introduction in the 19th century, and rapid spread after the 1950s, alien goldenrods (Solidago canadensis, Solidago gigantea) have been among the most successful invasive plant species in Europe. We studied the effects of goldenrods on wild pollinator communities in SE Poland. The abundance, species richness and diversity of wild bees, hoverflies and butterflies were compared between wet meadows invaded by goldenrod (10 transects) and non-invaded controls (10 transects). Furthermore, we compared the plant diversity and average cover between the two groups of sites. Invasion of goldenrods had a very strong negative effect on wild pollinator diversity as well as abundance. Plant diversity and average cover were also negatively affected by goldenrod invasion. Wild pollinators were grouped according to their nesting and food specialization, but none were resistant to the invasion, indicating that introduced goldenrod may affect the entire wild pollinator community. Our study emphasises the urgent need to develop specific protection plans for wild pollinators in habitats threatened by foreign plants and we call for the introduction of programs to stop the invasion of goldenrod not only in Poland, but also on a continental scale.     

Diversity declines in Microstegium vimineum (Japanese stiltgrass) patches

The spread of invasive plant species and their impacts on plant communities have received international attention as global trade and global environmental change enhance the colonization and establishment of introduced species and threaten the integrity of native ecosystems. Because introduced species vary in their impact, studying the relationship between invasion and native communities is necessary to guide allocation of finite management resources. By studying adjacent pairs of invaded and uninvaded plots across an eastern United States forested landscape, we demonstrate Microstegium vimineum was associated with local declines in species richness and cover of native species. Negative impacts of M. vimineum on species richness did not emerge until August when M. vimineum cover and height were greatest, highlighting the value of following study subjects through the growing season. In contrast, native species cover was already lower in invaded plots early in the growing season. M. vimineum invasion was not the only important driver of species richness and community composition within the study region; abiotic environmental gradients, such as soil nitrate concentration and pH, across the six study sites were also important in affecting species richness and cover, but lessened in explanatory power through the growing season. We conclude that M. vimineum has effects on community structure that may have long-term consequences for biodiversity. Studies which track sites through time and consider multiple scales are required as invaders impact multiple biotic and abiotic factors operating at different spatial and temporal scales.     

Conservation in a city: Do the same principles apply to different taxa?

Factors shaping overall species richness and representation of endangered species of vascular flora and butterflies were determined in 48 nature reserves in Prague, Czech Republic. Total species richness of both groups, and the presence of endangered butterflies, reflect the present status of habitats, while that of endangered plants reflects habitat composition at the time of reserve establishment. Reserve area has a much stronger effect on the species richness of sessile plants than mobile butterflies which, especially endangered species, respond more positively to heterogeneity than to area. Both species richness and endangered species peak in reserves half covered with forest, likely because they harbor species of both woodland and non-woodland habitats, and edge specialists. Solely relying on area and disregarding habitat quality, or a failure to conserve small but high quality sites, may be counterproductive for conserving endangered plant and butterfly species. To conserve diversity of plants and butterflies current management practices, often aimed at maintaining large blocks of pre-selected plant communities, should change to include maintenance of fallows, edges and transient zones.     

Pimpinella saxifraga is maintained in road verges by mosaic management

Road verges have been proposed as refuges for vulnerable grassland species in the modern, changing landscape, but little comparative knowledge exists on how management regimes affect population dynamics of such species. We compared the effects of various management regimes on the population dynamics of Pimpinella saxifraga in road verges and pastures, using elasticities and LTRE analyses with underlying vital rates as model components in three road verges and three pastures in an agricultural landscape in W Norway. Under present management regimes, we observed slightly higher population growth rates in pastures than in road verges. The pasture populations had comparatively lower survival but higher reproduction than the road verge populations, thus demonstrating a management-induced negative correlation. Such negative correlations may reflect species’ adaptability to environment changes, thereby reducing the extinction risk. We generally observed small changes in P. saxifraga demography to management but considerable variation along environmental gradients, underlining the importance of studying multiple populations. The linear form of the road verges enabled a fine-scale mosaic application of different management regimes. Individuals growing in zones receiving survival-lowering management produced seeds that compensated the lack of seeds in zones receiving fertility-lowering management. The observation of ‘mosaic’ management that allows road verge metapopulations to complement each others life-history characteristics exemplifies the unique potential of road verge ecosystems to maintain semi-natural grassland species like P. saxifraga, as well as providing habitats for different species exhibiting various life histories.     

Species groups occupying different trophic levels respond differently to the invasion of semi-natural vegetation by Solidago canadensis

We studied the impact of the invasive plant species Solidago canadensis on the species richness of vascular plants and the abundance, species richness and diversity of butterflies, hoverflies and carabid beetles in herbaceous semi-natural habitats near Ljubljana, Slovenia. The species groups were sampled in sites dominated by S. canadensis and paired nearby sites covered by semi-natural vegetation. Plant species richness and species richness, abundance and diversity of butterfly species were lower in plots dominated by S. canadensis. Hoverfly abundance, diversity and species richness were negatively affected only in July just before the onset of flowering of S. canadensis, but tended to be positively affected in August during the height of flowering of S. canadensis. Only the abundance of carabid beetles was reduced in plots dominated by S. canadensis. The responses of the insect groups seem largely driven by the effects of Solidago on the availability of essential resources like food or larval host plants. Our results suggest that insect species that are closely related to plant species composition are more vulnerable to the effects of invasive plant species than those that are loosely or only indirectly related to plant species composition.     

Social and ecological trade offs in combating land degradation: the case of invasion by a woody shrub (Euryops Floribundus) at Macubeni,South Africa

Woody plant invasions, either of alien or indigenous species, are deemed to result in loss of ecosystem goods and services in many areas throughout the world, resulting in significant degradation and economic costs. Invasion of Euryops floribundus, a species indigenous to South Africa, is perceived to have reduced the grazing available for domestic livestock. Consequently, a programme of manual eradication has been implemented to improve the grazing resource and provide jobs for poverty alleviation. However, there is potential for a conflict of interest as our study shows that almost all households rely on Euryops for fuel and at times fencing material, whereas only a minority of households own livestock. Moreover, comparison of invaded and non‐invaded sites indicated that the invaded sites harbour greater plant species richness and higher grass culm density per unit area of grass cover, as well as higher forb and litter cover. While invaded sites had lower grass cover, overall plant cover was no different between invaded and non‐invaded sites. Multivariate analysis indicated no obvious differentiation in community composition between invaded and non‐invaded areas, suggesting stronger drivers of community composition other than Euryops invasion presumed to be facilitated by the effects of high livestock densities. Overall, our study suggests that the clearing operation may well benefit from a better understanding of the social needs, perceptions of degradation by the various stakeholders and ecological dynamics of the area, especially local reliance on the resources, and the dynamics of the invasion, particularly its extent, rate of spread and susceptibility for re‐invasion in the cleared areas. Copyright © 2008 John Wiley & Sons, Ltd.     

Tree invasion in naturally treeless environments: Impacts of quinine (Cinchona pubescens) trees on native vegetation in Galápagos

Impacts of plant invasions are largely scale-dependent and responses to the same exotic species may vary among communities. Since impacts caused by individual trees could anticipate consequences of a closed canopy of an invader, we studied the response of Galápagos native plants to quinine (Cinchona pubescens) trees in two vegetation zones. Quinine has invaded >11,000 ha of Santa Cruz Island, including the Miconia- and Fern-Sedge-Zones. We analysed species composition and abundance along transects radiating from the trunks of individual quinine trees. Species richness and percentage cover decreased significantly with proximity to individual trees, and these effects were more pronounced in the Fern-Sedge Zone than in the Miconia Zone. Cover of endemic and native herb species and grass species significantly declined by 57–88% in the Fern-Sedge Zone. This was not the case in the Miconia Zone, but here the dominant endemic Miconia robinsoniana decreased by 41%. Quinine is a major driver of plant community change in both vegetation zones. The greater susceptibility of species in the Fern-Sedge Zone was ascribed to the presence of a new growth form: quinine trees in a formerly treeless environment. Species of the Miconia Zone appeared to be better pre-adapted to higher shade levels created by the Miconia shrubs. Our results emphasize the need for future control of quinine to preserve the diversity of the native Galápagos flora.     

What is the impact of Impatiens glandulifera on species diversity of invaded riparian vegetation?

Effect of invasion by Impatiens glandulifera (Balsaminaceae) on the community characteristics and species composition of invaded riparian communities was studied at six rivers in the Czech Republic. Two approaches were used: space for time substitution approach, i.e., comparing invaded and uninvaded sites under the same habitat conditions, and removal of the invader from experimental plots. Differences in the number of species, Shannon diversity index H′ and evennes J were compared between invaded and uninvaded plots. Uninvaded plots of the comparative study harboured by 0.23 more species per 16 m², and had higher value of H′ and J, calculated with species covers as importance values; however only the difference in J was marginally significant (p = 0.04). Other effects were not significant, indicating that once I. glandulifera is removed, communities recover without any consequences for species diversity. Multivariate analysis did not reveal any effect of invasion on the species composition in terms of species presence but their cover hierarchies changed after the invasion, as I. glandulifera became dominant at the expense of tall native nitrophilous dominants. It is concluded that I. glandulifera exerts negligible effect on the characteristics of invaded riparian communities, hence it does not represent threat to the plant diversity of invaded areas. This makes it very different from other Central European invasive aliens of a similar performance.     

Plant and spider communities benefit differently from the presence of planted hedgerows in highway verges

Road verges should play a crucial role as a refuge for native flora and fauna in human dominated landscapes. However, the influence of construction choices, such as plantation of woody species, on the biodiversity supported by roadsides has received little attention, although the presence of hedgerows in roadsides is likely to enhance their role as a refuge, notably for woodland species. Using standardised methods, we assessed the impact of planted hedgerows on two taxonomic groups (plants and spiders) inhabiting highway verges within an intensive agricultural landscape. We examined community richness, taxonomic and functional composition in sites with and without planted hedgerows. At the site level, the response of plant and spider communities to the presence of planted hedgerows differed markedly: hedgerows were associated with significantly higher plant richness (higher α-diversity), but similar spider richness. Plant communities in sites without hedgerows appeared as a subset of communities in sites with hedgerows, whereas spider communities in non-planted sites were complementary to that of planted sites (increased β-diversity). The presence of planted hedgerows was also associated with increased taxonomic and functional trait diversity at the landscape level (γ-diversity), through an increased β-diversity in both plants and spiders. Our results thus suggest that a mosaic of planted hedgerows and grassland habitats is crucial for the maintenance of biodiversity at a landscape scale. By providing information for road practitioners and policy makers regarding their potential impact on biodiversity, these results have important direct implications for the management of road networks.     

Composition and abundance of birds in Andean alder (Alnus acuminata) patches with past and present harvest in Bolivia

We compared species richness and abundance of birds between five patches under selective Alnus exploitation and five patches that have not been harvested for at least 10 years prior to our study, during the early dry season (April-July 2001), in Cotapata National Park. Using “point counts” we recorded birds and their distribution in two (<1.5 m and >1.5 m) forest layers. Simultaneously we evaluated the floristic structure (size [dbh] distribution, basal area, tree density, tree height, and vegetation cover) and composition (diversity) on three transects placed within each Alnus patch. Both bird diversity and vegetation cover were significantly higher in not presently used patches but only for the higher layer of the forest, whereas plant diversity was higher in presently used patches. Lack of differences between the two types of Alnus patches in any of the vegetation parameters measured in the lower layer was coupled with an indistinct avifauna. Small changes in habitat characteristics following a perturbation like selective logging have the potential to affect richness and abundance of birds, at least within the habitats directly affected by the perturbation.     

A river runs through it: Land-use and the composition of vegetation along a riparian corridor in the Cape Floristic Region, South Africa

Riparian zones are important for the many ecosystem services they supply. In settled areas, the vegetation of such zones is shaped by human land-use; this often creates conditions under which alien plant species thrive. Alien plants have been shown to induce large-scale changes in riparian habitats, and they pose a major threat to the continued provision of key ecosystem services. We used direct gradient analysis to assess correlations between land-use and the composition of vegetation along a riparian river corridor in the highly transformed landscape surrounding Stellenbosch in South Africa’s Western Cape Province. Vegetation plots were sampled along the entire length of the river from headwaters to estuary (ca. 40 km). Plant community composition was analyzed in relation to land-use data collected in the field, and additional land-use variables computed from digital land-cover data. Patterns of plant community structure were found to be directly related to land-use, with measures of cover, richness, and diversity differing significantly among land-use types. Portions of the riparian zone adjacent to agricultural land had the greatest level of alien plant cover, while areas bordered by urban land maintained the highest alien species richness. Areas adjacent to grazing and natural lands showed intermediate and low levels of invasion, respectively. Several native species were found to persist in areas with high abundance and diversity of invasive alien plants, suggesting that they will be valuable focal species for future restoration attempts. Due to the level of human-mediated change in many areas of the riparian zone, restoration to historic conditions over most of the river is not considered feasible. These areas should be recognized as examples of novel ecosystems, and management efforts should focus on restoring or creating desirable ecosystem functions, rather than on achieving assemblages comprising only native species.     

Resolving conflicts between butterfly host resource abundance and genet population size estimates for a vegetatively spreading, threatened grassland legume

Population size estimates are an integral part of rare plant conservation, but common abundance measurements such as cover and ramet number may not accurately index genet population size for vegetatively spreading species. Population monitoring of Kincaid’s lupine (threatened species) populations occurs through genet-anonymous leaf cover and raceme counts despite extensive, non-adventitious rhizome growth. While the current monitoring scheme provides important resource abundance measurements for the endangered Fender’s blue butterfly, whose larvae feed on Kincaid’s lupine leaves, the methods are not appropriate for estimating lupine genet number. Major axis regression revealed well supported statistical relationships between cover, raceme, and plantlet (a measurement of modular plant growth) density within six study patches (n = 3 populations) of Kincaid’s lupine (R² > 0.90) and when all patch data were combined (R² > 0.91). Genet population size estimates from genotype only data with ACE (an estimator used to infer species richness) were similar to estimates derived from a combination of plantlet density and genet to plantlet ratios (genotype derived) in small, more thoroughly genotyped lupine patches. However, genet number estimates from ACE were 3–5-fold greater in less intensely genotyped patches. Genet-anonymous plant abundance measurements, such as cover, can be used to estimate genet number in populations of vegetatively spreading plants provided they are calibrated with a unit of modular plant growth. Calibration of vegetative measurements, consistency of between population relationships, and closer scrutiny of highly supported statistical models may be necessary to develop more pertinent monitoring methods for rare, vegetatively spreading plants.     

The Effects of Expansive Shrubs on Plant Species Richness and Soils in Semi‐arid Communal Lands,South Africa

Expansion by expansive species can have severe ecological, social and economic impacts through the reduction of ecosystem goods and services and species richness. However, expansion by expansive species may also offer benefits to ecosystems and humans, through the supply of ecosystem goods and services (such as firewood, fodder and fruits), as well as potentially offering refugia in heavily used landscapes. Here, we examine the effects of four expansive dwarf shrub species (Aspalathus subtingens , Dicerothamnus rhinocerotis , Pteronia incana and Oedera genistifolia ) on plant species richness (at the point scale), vegetation cover, soil properties and whether the expansive species offer refugia to other species. Plant species richness, cover and soil properties were recorded in 1‐m² quadrats located within a mosaic of expanded and non‐expanded patches for the four expansive shrub species. Plant species richness was significantly higher in the non‐expanded areas compared to the expanded ones for all four expansive species. Some of the expansive shrubs provided refugia to certain plant species and limited the frequency of other species. With regard to species composition, there was little separation of expanded and non‐expanded samples within sites, indicating that the site factors were stronger determinants of plant species richness and composition than expansion. Therefore, it is more likely that the reduction in species richness in expanded sites is caused by multiple drivers, including vegetation attributes cover, litter cover and soil nutrients (organic C, Zn and P) and soil compaction. Copyright © 2017 John Wiley & Sons, Ltd.     

Recent declines in northern tall-grass prairies and effects of patch structure on community persistence

Tall-grass prairies are a critically endangered ecosystem in North America. Our objectives were to evaluate potential roles of prairie patch structure (defined in terms of prairie patch area, matrix type, and edge effects) in explaining changes in number, size, and quality of northern tall-grass prairies over time. In 2006, we evaluated changes in remnant tall-grass prairies at the most northern extent of the tall-grass prairie range, by resurveying plant communities in 65 remnant patches in Manitoba, Canada, that were previously surveyed in 1987 or 1988. In 2007 and 2008 we conducted more detailed surveys of vegetation structure and composition at 580, 0.2 × 0.5 m quadrats distributed within 24 remnant patches of northern tall-grass prairie. Our findings suggest remnant northern tall-grass prairies continue to suffer from serious threats: 37% of the patches surveyed in 1987 or 1988 had changed to other habitat types by 2006; patches smaller than 21 ha tended to decrease in size, while larger patches increased in size; and most patches, particularly smaller ones, declined in quality. Both native and alien species responded more strongly to distance to edge than to patch size or matrix type. Edge effects may explain why prairie quality is lower and more likely to decline in smaller remnants. Richness of native plants was negatively correlated with cover and richness of alien species, suggesting that alien species may displace native species. Few existing northern tall-grass prairies are likely to be self-sustaining, and immediate active management is required to prevent further loss of remnant northern tall-grass prairies.     

Impact of an invasive plant (Elymus athericus) on the conservation value of tidal salt marshes in western France and implications for management: Responses of spider populations

As a result of Elymus athericus (Poaceae) invasion in the last 10 years, a major change in vegetation cover has occurred in salt marshes of the Mont Saint-Michel bay (France). Such invasions are known to modify biodiversity and consequently ecosystem proprieties and functions as well as the conservation value of invaded areas. In this study, we especially focus (1) on the impact of the invasive species on the conservation value of the invaded ecosystems and (2) on the impact of mowing in the invaded parts of salt marshes. Among the various biological models, spiders were selected for the present study because they are an abundant, diversified, taxonomic group of generalist predators. Furthermore, data are available on this group since 1984, allowing a comparison of species distribution ranges in salt marshes before and after the E. athericus invasion. This diachronic approach showed that the invasion of salt marshes promoted the progression of non-coastal species, web-building spiders and cursorial spiders, but did not interfere with resident species distributions, finally resulting in higher spider densities and species richness in the entire area.The species composition, functional groups, abundances and densities of spider assemblages were also compared using complementary sampling techniques (i.e., pitfall traps, collecting by hand and quadrat technique) between natural and invaded stations in 2002 for synchronic approach. One main result is that some halophilic species decreased in abundances and densities in invaded plots, which is thought to alter the marine character of salt marsh arthropod assemblages. Lastly, mowing, by reducing non-coastal species and enhancing halophilic ones, tends to reduce the negative effects of Elymus on salt marsh conservation value. The relation between the treatments tested (invasive species and mowing) and the spider assemblages by changes in environmental variables confirms the high value of this group as bioindicators.     

Urban domestic gardens (IX): Composition and richness of the vascular plant flora, and implications for native biodiversity

Garden floras interact with native biodiversity by providing resources for wildlife and by acting as a source of non-native species. Understanding the composition and richness of garden floras will help evaluate the relationships between these floras and the wider environment. The composition and richness of vascular plant floras were measured in a stratified sample of 61 urban, domestic gardens in Sheffield, UK, based on complete garden inventories. The entire garden flora contained 1166 species, of which 30% were native and 70% alien. Across gardens, aliens showed lower occupancy than natives, comprising 79% of the species recorded only once. The garden flora contained 146 plant families, which included 72% of the native, naturalised or recurrent casual families recorded in the wild in Britain and Ireland. Gardens contained on average 45% natives, irrespective of garden size. Garden area explained 30% of the variation in species richness within individual gardens. Doubling garden size led to an increase in species richness of 25%. The garden flora comprised 10% annuals, 63% biennial/perennials, 18% shrubs and 8% trees; shrubs were disproportionately composed of alien species. The floras of urban domestic gardens probably form the greatest source of potentially invasive alien plants. However, the plants found in domestic gardens have closer affinities with the uncultivated flora than is often perceived, and their role for wildlife in gardens deserves reassessment. Declines in garden size that result from recommendations on the density of new housing are unlikely to have major consequences for plant richness in gardens.     

Linear hotspots? The floral and butterfly diversity of green lanes

In this study we compared the vascular flora and butterfly fauna of green lanes, single hedged tracks and grass verges. Green lanes supported a significantly more diverse flora with >30% more species in a 200 m transect than other linear features. Indicator values confirmed the lower light and higher moisture levels expected in green lanes, but in this study did not confirm lower nitrogen levels or greater stress tolerator incidence. Significantly more butterfly species were recorded in the green lanes and butterfly abundance was more than double that along the other linear features. Greater numbers of butterfly species were associated with greater numbers of floral species and green lanes also supported more butterfly larval foodplants. Given the value of butterflies as indicator species reflecting both the quality of habitat in the countryside and changes in the environment these results combine to emphasise the biodiversity value of green lanes in addition to their historical and aesthetic value.