Vascular Plant Communities Research Articles

Concordance between vascular plant and macrofungal community composition in broadleaf deciduous forests in central Italy

Abstract: We examined the concordance between vascular plants and macrofungi (grouped into trophic groups) in Mediterranean forest habitats (central Italy). Our goal was to test how consistently plant and fungi groups classify plots in a broadleaf deciduous forest dominated by Quercus cerris. Our hypothesis was that groups of plants can be used as surrogates for the classification of macrofungal communities. The test of concordance comprised two steps: 1) the plant species data sets were subjected to cluster analysis, to obtain three classifications based on presence of all plants, presence and frequency of only woody species; 2) Multiple Response Permutation Procedures (MRPP) was used to test the performance of each plant classification applied to the fungi data sets. The sample scores along the first PCA axis was used to investigate the relationships between compositional patterns. In the concordance analysis, the classification of only woody plants provided better results than the classification obtained with herbaceous and woody plants together. Cross-tests gave the best results when the “woody plants” classification was applied to ectomycorrhizal fungi (EMF) and, to a certain extent, to humicolous saprotrophs (Sh). The ordination analysis indicated that the frequency of woody plants follows a similar spatial distribution to EMF and Sh fungal groups and is therefore expected to discriminate the same environmental gradients. Many EMF exhibit preferences for few (one or two) hosts. Significant associations were found among a greater number of EMF and woody plant species. Woody plants such as Sorbus domestica and Prunus spinosa appear to be associated with many EMF. The combination of a high frequency of Fraxinus oxycarpa and Quercus petraea seems to promote distinct assemblages of EMF and Sh fungi. Then, characteristic assemblages of fungi were found in association with certain tree and shrub combinations.

Experimental warming interacts with soil moisture to discriminate plant responses in an ombrotrophic peatland

AbstractQuestionA better understanding of the response of Sphagnum mosses and associated vascular plants to climate warming is relevant for predicting the carbon balance of peatlands in a warmer world. Open‐top chambers (OTCs) have been used to investigate the effect on soil biogeochemical processes in peatlands, but little information is available on the effects of OTCs on microclimate conditions and the associated response of the plant community. We aimed to understand how simulated warming and differences in soil moisture affect plant species cover.LocationA Sphagnum‐dominated peatlands in French Jura.MethodsWe used OTCs to measure the effect of a near‐ground temperature increase (+1.5 °C on average) on vegetation dynamics over five growing seasons (2008–2012) in a Sphagnum‐dominated peatland, in two adjacent microhabitats with different hydrological conditions – wet and dry. Microclimatic conditions and plant species abundance were monitored at peak biomass in years 1, 2, 3 and 5 and monthly during the plant growing season in year 5.ResultsThe response to warming differed between vascular plants and bryophytes, as well as among species within these groups, and also varied in relation to soil moisture. Andromeda polifolia abundance responded positively to warming, while Vaccinium oxycoccus responded negatively, and Eriophorum vaginatum showed a high resistance.ConclusionDepth of rooting of vascular plants appeared to control the response in plant abundance, while moss abundance depended on various other interacting factors, such as shading by the vascular plant community, precipitation and soil moisture.

Experimental Warming Alters Productivity and Isotopic Signatures of Tundra Mosses

In the tundra, mosses play an important functional role regulating belowground and ecosystem processes, but there is still considerable uncertainty about how tundra moss communities will respond to climate change. We examined the effects of 5 years of in situ air and soil warming on net primary productivity (NPP), carbon (C) and nitrogen (N) isotope signatures (δ13C and δ15N), and C:N in dominant Alaskan tundra mosses. Air warming increased mean air temperatures by up to 0.5°C and resulted in an 80–90% reduction in NPP in the feather moss Pleurozium and the peat moss Sphagnum. Soil warming increased permafrost thaw depth by 12–18%, upper soil water content by 23–27%, and resulted in a threefold increase in Sphagnum NPP. δ13C was positively correlated with moss NPP, and increased by 0.5–1‰ in all mosses under soil warming. C:N was reduced in Sphagnum and Pleurozium, due to increases in tissue %N in the soil warming treatment, suggesting that moss N availability could increase as temperatures increases. Higher N availability in warmer conditions, however, may be offset by unfavorable moisture conditions for moss growth. Similar to responses in tundra vascular plant communities, our results forecast interspecific differences in productivity among tundra mosses. Specifically, air warming may reduce productivity in Sphagnum and Pleurozium, but soil warming could offset this response in Sphagnum. Such responses may lead to changes in tundra moss community structure and function as temperatures increase that have the potential to alter tundra C and N cycling in a future climate.

Scaling disturbance instead of richness to better understand anthropogenic impacts on biodiversity.

A primary impediment to understanding how species diversity and anthropogenic disturbance are related is that both diversity and disturbance can depend on the scales at which they are sampled. While the scale dependence of diversity estimation has received substantial attention, the scale dependence of disturbance estimation has been essentially overlooked. Here, we break from conventional examination of the diversity-disturbance relationship by holding the area over which species richness is estimated constant and instead manipulating the area over which human disturbance is measured. In the boreal forest ecoregion of Alberta, Canada, we test the dependence of species richness on disturbance scale, the scale-dependence of the intermediate disturbance hypothesis, and the consistency of these patterns in native versus exotic species and among human disturbance types. We related field observed species richness in 1 ha surveys of 372 boreal vascular plant communities to remotely sensed measures of human disturbance extent at two survey scales: local (1 ha) and landscape (18 km2). Supporting the intermediate disturbance hypothesis, species richness-disturbance relationships were quadratic at both local and landscape scales of disturbance measurement. This suggests the shape of richness-disturbance relationships is independent of the scale at which disturbance is assessed, despite that local diversity is influenced by disturbance at different scales by different mechanisms, such as direct removal of individuals (local) or indirect alteration of propagule supply (landscape). By contrast, predictions of species richness did depend on scale of disturbance measurement: with high local disturbance richness was double that under high landscape disturbance.

Inferring resilience to fragmentation-induced changes in plant communities in a semi-arid Mediterranean ecosystem.

Predicting the capacity of ecosystems to absorb impacts from disturbance events (resilience), including land-use intensification and landscape fragmentation, is challenging in the face of global change. Little is known about the impacts of fragmentation on ecosystem functioning from a multi-dimensional perspective (multiple traits). This study used 58 500-m linear transects to quantify changes in the functional composition and resilience of vascular plant communities in response to an increase in landscape fragmentation in 18 natural scrubland fragments embedded within a matrix of abandoned crop fields in Cabo de Gata-Níjar Natural Park, Almería, Spain. Changes in functional community composition were measured using functional diversity indices (functional richness and functional dispersion) that were based on 12 plant traits. Resilience was evaluated using the functional redundancy and response diversity from the perspective of plant dispersal, which is important, particularly, in fragmented landscapes. Scrubland fragmentation was measured using the Integral Index of Connectivity (IIC). The functional richness of the plant communities was higher in the most fragmented scrubland. Conversely, the functional dispersion (i.e., spread) of trait values among species in the functional trait space was lower at the most fragmented sites; consequently, the ecological tolerance of the vegetation to scrubland fragmentation decreased. Classifying the plant species into four functional groups indicated that fragmentation favoured an increase in functional redundancy in the ‘short basal annual forbs and perennial forbs’ group, most of which are species adapted to degraded soils. An assessment based on the traits associated with plant dispersal indicated that the resilience of ‘woody plants’, an important component in the Mediterranean scrubland, and habitat fragmentation were negatively correlated; however, the correlation was positive in the ‘short basal annual forbs and perennial forbs’ and the ‘grasses’ groups.

Primary succession of Bistorta vivipara (L.) Delabre (Polygonaceae) root-associated fungi mirrors plant succession in two glacial chronosequences.

Glacier chronosequences are important sites for primary succession studies and have yielded well-defined primary succession models for plants that identify environmental resistance as an important determinant of the successional trajectory. Whether plant-associated fungal communities follow those same successional trajectories and also respond to environmental resistance is an open question. In this study, 454 amplicon pyrosequencing was used to compare the root-associated fungal communities of the ectomycorrhizal (ECM) herb Bistorta vivipara along two primary succession gradients with different environmental resistance (alpine versus arctic) and different successional trajectories in the vascular plant communities (directional replacement versus directional non-replacement). At both sites, the root-associated fungal communities were dominated by ECM basidiomycetes and community composition shifted with increasing time since deglaciation. However, the fungal community's successional trajectory mirrored the pattern observed in the surrounding plant community at both sites: the alpine site displayed a directional-replacement successional trajectory, and the arctic site displayed a directional-non-replacement successional trajectory. This suggests that, like in plant communities, environmental resistance is key in determining succession patterns in root-associated fungi. The need for further replicated study, including in other host species, is emphasized.

Comparative ecology of vascular plant, bryophyte and testate amoeba communities in four Sphagnum peatlands along an altitudinal gradient in Switzerland

Monitoring tools are needed to assess changes in peatland biotic communities and ecosystem functions in response to on-going climate and other environmental changes. Although the responses of soil organisms and plants to ecological gradients and perturbations do not always correlate, peatland monitoring is mainly based on vegetation surveys. Testate amoebae, a group of protists, are important contributors to carbon and nitrogen cycling in organic soils and are useful bioindicators in peatland ecology and paleoecology. There is however little comparative data on the value of testate amoebae, vascular plants and bryophytes as bioindicators of micro-environmental gradients in peatlands.We compared the relationships of testate amoebae, bryophytes, and vascular plants with soil temperature, water table depth, micro-habitats and the carbon and nitrogen content of Sphagnum mosses in four peatlands along a 1300m altitudinal gradient in Switzerland. We used the full diversity of vascular plants and bryophyte but only a selection of ten easily identifiable testate amoeba morpho-taxa (i.e. species or species-complexes).Indirect and direct gradient ordinations, multiple factor analysis (MFA) and transfer function models for inferring water table depth showed that a selection of ten testate amoeba taxa are more powerful (% variance explained in RDA) and accurate (discrimination among habitats) indicators of local conditions (micro-habitat type, water table depth and Sphagnum C/N ratio) than the vegetation (vascular plants and bryophytes either individually or combined and considering the full diversity).Our study showed that a limited list of ten easily identifiable testate amoeba taxa have higher bioindication value than the full bryophytes and vascular plants. Furthermore, testate amoebae can be analyzed on samples collected at any season (accessibility allowing and if precise sampling sites are well marked) – a clear advantage for biomonitoring and can be used to infer past changes from the peat record at the same taxonomic resolution. This simple approach could therefore be very useful for biomonitoring of peatlands.

Covariation of soil bacteria functional diversity and vegetation diversity along an altitudinal climatic gradient in the Western Carpathians

The belowground microbiota are directly affected by vegetation via resource inputs and indirectly affected through the effects on physico-chemical soil properties. This study examines the relationship between vascular plant community diversity and the functional diversity of soil bacteria. The total vascular plant diversity of trees, shrubs and forest floor vegetation was investigated along an altitudinal climatic gradient in the Polish Carpathians. Soil (upper 10 cm) was collected in forest stands at three elevations (600, 900, and 1200 m a.s.l.) on five separate mountain slopes (treated as independent replicates). The overall microbial activity was determined by the soil respiration rate, whereas the bacterial catabolic activity and functional diversity (H′bact) was determined using Biolog® ECO plates. The vegetation diversity (H′plant) decreased with elevation. The organic matter content, water holding capacity and dissolved organic nitrogen differed significantly between elevations and were highest for stands at 1200 m a.s.l. Soil physico-chemical characteristics varied widely between sites and only showed an effect on the bacterial catabolic activity. Within microbial indices, only H′bact was correlated with elevation (p < 0.03). Both bacterial catabolic activity and functional diversity were positively correlated with H′plant (p < 0.005 and p < 0.02, respectively). Among the six chemical substrate groups on the Biolog® ECO plates, the most variable chemical substrate group utilised by soil bacteria were amines; their utilisation was highest for soil bacteria originated from 600 m a.s.l. and lowest for bacteria from 1200 m a.s.l. Our results underline the close associations between above- and belowground biological diversity in forest ecosystems, which can emerge as a result of carbon and nitrogen cycling.

Vascular plant community composition from the campos rupestres of the Itacolomi State Park, Brazil.

Campos rupestres are rare and endangered ecosystems that accommodate a species-rich flora with a high degree of endemism. Here, we make available a dataset from phytosociological surveys carried out in the Itacolomi State Park, Minas Gerais, southeastern Brazil. All species in a total of 30 plots of 10 x 10 m from two study sites were sampled. Their cardinality, a combination of cover and abundance, was estimated. Altogether, we registered occurrences from 161 different taxa from 114 genera and 47 families. The families with the most species were Poaceae and Asteraceae, followed by Cyperaceae. Abiotic descriptions, including soil properties such as type, acidity, nutrient or aluminum availability, cation exchange capacity, and saturation of bases, as well as the percentage of rocky outcrops and the mean inclination for each plot, are given. This dataset provides unique insights into the campo rupestre vegetation, its specific environment and the distribution of its diversity.

Limited impacts of extensive human land use on dominance, specialization, and biotic homogenization in boreal plant communities.

BackgroundNiche theory predicts that human disturbance should influence the assembly of communities, favouring functionally homogeneous communities dominated by few but widespread generalists. The decline and loss of specialists leaves communities with species that are functionally more similar. Evenness of species occupancy declines, such that species become either widespread of rare. These patterns have often been observed, but it is unclear if they are a general result of human disturbance or specific to communities that are rich in species, in complex, spatially heterogeneous environments where the problem has often been investigated. We therefore tested whether human disturbance impacts dominance/evenness of species occupancy in communities, specialism/generalism of species, and functional biotic homogenization in the spatially relatively homogeneous, species poor boreal forest region of Alberta, Canada. We investigated 371 boreal vascular plant communities varying 0 – 100% in proportion of human land use.ResultsRank species occupancy curves revealed high species dominance regardless of disturbance: within any disturbance class a few species occupied nearly every site and most species were found in a low proportion of sites. However, species were more widespread and displayed more even occupancy in intermediately disturbed communities than among communities of either low or high disturbance. We defined specialists and generalists based on turnover in co-occupants and thereby assessed impacts of human disturbance on specialization of species and community homogenization. Generalists were not disproportionately found at higher disturbance sites, and did not occupy more sites. Communities with greater human disturbance were not more functionally homogeneous; they did not harbor communities with more generalists.ConclusionsWe unexpectedly did not observe strong linkages between species specialism/generalism and disturbance, nor between community homogenization and disturbance. These results contrast previous findings in more species rich, complex or spatially heterogeneous systems and ecological models. We suggest that broad occupancy-based intercommunity patterns are insensitive to human land use extent in boreal vascular plants, perhaps because of ubiquity of generalists, low species richness, and history of natural disturbance. The poor sensitivity of these metrics to disturbance presents challenges for monitoring and managing impacts to biodiversity in this region.

RARE SPECIES OF VASCULAR PLANTS AND PLANT COMMUNITIES IN THE RICH FEN BETWEEN KANDALAKSHA AND KOLVITSA (MURMANSK REGION)

Rare and protected vascular plants and plant communities were investigated in the rich fen near the Luvenga Settlement (Kandalaksha District). A brief description of the vegetation cover in the rich fen is presented. According to the field geobotanical materials and literature sources vegetation association Trichophoro-Schoenetum ferruginei Gors 1964 and alliance Caricion davallianae Klika 1934, new for the Murmansk Region, were described. The characteristic of species composition, structure, ecology and distribution in the region were given. Schoenus-communities from the Murmansk Region were compared with mire communities of the Western Europe and Fennoscandia. During the field floristic survey in the rich fen near the Luvenga Settlement the records of Schoenus ferrugineus were confirmed, moreover, four protected species were found: Carex echinata Murr., Platanthera bifolia (L.) Rich., Hammarbya paludosa (L.) O. Kuntze, Dactylorhiza incarnata (L.) Soo. It was recommended to create new protected areas (natural monuments) in the rich fens encompassing hard-water eutrophic biocenoses and rare species near the Luvenga Settlement and the town of Apatity.

Does cattle movement between forest pastures and fertilized grasslands affect the bryophyte and vascular plant communities in vulnerable forest pasture biotopes?

The intensification of agriculture has led to a dramatic decrease in traditional forest pastures in Northern Europe. Furthermore, the remaining forest pastures have often lost their typical characteristics due to eutrophication and forestry practices. We investigated whether the common management practice of fencing forest pastures within the same enclosures as fertilized grassland pastures leads to eutrophication and the consequent decline of bryophyte and vascular plant diversity in Finnish forest pastures, given that when cattle can freely roam between the fertilized grassland pastures and unfertilized forest pastures, nutrients are transported to the forest pastures in the feces and urine of the grazing animals. We found that grazing led to higher electrical conductivity and potassium (K) levels in the forest pastures (n=18) compared to the background levels in adjacent non-grazed forests (n=18). Vascular plant species richness and diversity (Shannon’s entropy) were higher and community structures different in the forest pastures compared to the adjacent forests. Highest species richness was observed in the forest pastures that were unconnected to fertilized grasslands (n=7). Connection here refers to the situation where cattle can access both forest pasture and adjacent fertilized grassland simultaneously. Furthermore, many species indicative of valuable semi-natural pasture biotopes were found only in these traditionally managed forest pastures. In contrast, bryophyte species richness did not differ between the forests and the two types of forest pastures. Moreover, bryophyte communities largely overlapped between the forests and the forest pastures. Our results indicate that even if the forest pastures connected to the fertilized grasslands sustain plant communities that are characteristic of unfertilized semi-natural forest pastures, the conservational quality and diversity of vascular plant communities in particular may be reduced in comparison to the forest pastures without grassland connection. This decline can, at least partially, be caused by the transport of nutrients to the forest pastures and, hence, we recommend that forest pastures are not connected with fertilized grasslands.

Elevational gradients of terricolous lichen species richness in the Western Himalaya

Elevation confers limitations on distribution of organisms through correlated variations in temperature, moisture, radiations and precipitation. The elevation gradients of terricolous lichen species richness in Garhwal, western Himalaya were assessed using generalized additive models, in order to compare distribution patterns of different growth-forms, photobiont types, and dominant families. A total of 148 terricolous lichen species belonging to 42 genera and 19 families were recorded. The total species richness showed unimodal relationship with elevation, where the highest species richness was observed at mid elevations (3,200 m). The species richness of lichens with green algae (chlorolichens) and of lichens with cyanobacteria (cyanolichens) also exhibited significant unimodal elevational patterns with cyanolichens peaked at somewhat lower (2,800–2,900 m) elevation than chlorolichens (3,200 m). Growth forms showed statistically significant relationship of species richness to elevation, with crustose and squamulose lichens reaching their maxima at higher elevation than foliose, fruticose and dimorphic terricolous lichens. Unimodal pattern of species richness was also followed by six dominant families, with these families reaching maximum richness at different elevations. Elevational variation in topography, climate, and competition from vascular plant communities, together with the tolerance of specific growth forms to zoo-anthropogenic pressures, shape the distribution of terricolous lichens in the Garhwal Himalaya.

Direct and Indirect Drivers of Moss Community Structure, Function, and Associated Microfauna Across a Successional Gradient

Relative to vascular plants, little is known about what factors control bryophyte communities or how they respond to successional and environmental changes. Bryophytes are abundant in boreal forests, thus changes in moss community composition and functional traits (for example, moisture and nutrient content; rates of photosynthesis and respiration) may have important consequences for ecosystem processes and microfaunal communities. Through synthesis of previous work and new analyses integrating new and published data from a long-term successional gradient in the boreal forest of northern Sweden, we provide a comprehensive view of the biotic factors (for example, vascular plant productivity, species composition, and diversity) and abiotic factors (for example, soil fertility and light transmission) that impact the moss community. Our results show that different aspects of the moss community (that is, composition, functional traits, moss-driven processes, and associated invertebrate fauna) respond to different sets of environmental variables, and that these are not always the same variables as those that influence the vascular plant community. Measures of moss community composition and functional traits were primarily influenced by vascular plant community composition and productivity. This suggests that successional shifts in abiotic variables, such as soil nutrient levels, indirectly affect the moss community via their influence on vascular plant community characteristics, whereas direct abiotic effects are less important. Among the moss-driven processes, moss litter decomposition and moss productivity were mainly influenced by biotic variables (notably the community characteristics of both vascular plants and mosses), whereas moss functional traits (primarily specific leaf area and tissue nutrient concentrations) also were important in explaining moss di-nitrogen-fixation rates. In contrast, both abiotic and biotic variables were important drivers of moss microfaunal community structure. Taken together, our results show which abiotic and biotic factors impact mosses and their associated organisms, and thus highlight that multiple interacting factors need to be considered to understand how moss communities, associated food webs, and the ecosystem processes they influence will respond to environmental change.

Bringing Color into the Picture: Using Digital Repeat Photography to Investigate Phenology Controls of the Carbon Dioxide Exchange in a Boreal Mire

Mire vegetation phenology is closely linked to the ecosystem carbon cycle but rarely monitored and quantified with high temporal resolution. In this study, we use digital repeat photography to explore phenology as a control of the carbon dioxide (CO2) exchange measured by eddy covariance (EC) in a minerogenic boreal mire in northern Sweden over 2 years (2011–2012). Strong correlations and seasonal hysteresis effects were observed between the green chromatic coordinate (g cc) derived from the digital image archive and leaf area index, day length, and growing degree-day sum (GDDS). Differences in GDDS between the 2 years were the main control on the between-year variations in the spring patterns of g cc. Periods with lower water table level coincided with an increase of the red chromatic coordinate. The onset and magnitudes of EC-derived photosynthetic CO2 uptake (that is, gross ecosystem production, GEP) and net ecosystem CO2 exchange (NEE) during the spring green-up of vascular plants were more closely related to those of g cc than to those of air temperature and photosynthetically active radiation. In contrast, abiotic variables controlled GEP during the summer period when vascular plant canopy cover was fully developed. Stepwise regression analysis suggested that g cc contributed substantially in explaining variations in GEP during spring and autumn. Over both growing seasons, g cc was well correlated with GEP (r 2 = 0.68), NEE (r 2 = 0.58), and ecosystem respiration (r 2 = 0.50). Overall, we show that digital repeat photography provides an inexpensive and effective method for the continuous quantification of the phenological patterns of the vascular plant community in mire ecosystems. Our results suggest that vegetation phenology is an important control of the mire CO2 exchange and should be considered in both experimental and modeling studies to better account for the separate effects of phenology and abiotic drivers on mire carbon dynamics.

Both local and landscape factors determine plant and Orthoptera diversity in the semi-natural grasslands of Transylvania, Romania

Semi-natural grassland supports a large proportion of biodiversity and ecosystem services in Europe, however, it is continuing to be destroyed or degraded. In addition to the clear role of local management in these processes, there is increasing evidence for wider landscape-scale effects on species richness and community composition of plants and animals. Most of this evidence comes from studies in highly altered western European landscapes with only fragments of remaining semi-natural grassland. In contrast, Eastern European countries such as Romania still contain large areas of semi-natural grassland, but this habitat is threatened by agricultural intensification and homogenization. We analyzed vascular plant and Orthoptera communities from species-rich pastures in Southern Transylvania, Romania, against a range of local and landscape factors. Species richness of plants had a highly significant positive relationship with landscape heterogeneity. Orthoptera species richness and abundance were negatively correlated with plant species richness, and increased with proportion of grassland in the landscape and local vegetation height. The results suggest that large and species-rich grassland communities can be significantly affected by both local and landscape scale land use changes, but effects can vary within and between taxonomic groups. Conservation measures such as agri-environment schemes should therefore seek to address landscape scale processes better, promoting a range of low-intensity land use practices in order to support a variety of landscape types.

Is there a density compensation effect in plant communities in extreme habitats?

The occurrence of a density compensation effect (DCE) has been estimated in north Caucasian areas of extreme habitats occupied by communities of vascular plants, mosses, and lichens. The species densities have been estimated according to their frequency. The correlation between species number and frequency in the studied areas has failed to confirm the assumption that extreme environmental conditions alone is responsibile for the DCE, at least locally.

Long-term resilience of above- and below ground ecosystem components among contrasting ecosystems.

While several studies have explored how short-term ecological responses to disturbance vary among ecosystems, experimental studies of how contrasting ecosystems recover from disturbance in the longer term are few. We performed a simple long-term experiment on each of 30 contrasting forested islands in northern Sweden that vary in size; as size decreases, time since fire increases, soil fertility and ecosystem productivity declines, and plant species diversity increases. We predicted that resilience of understory plant community properties would be greatest on the larger, more productive islands, and that this would be paralleled by greater resilience of soil biotic and abiotic properties. For each island, we applied three disturbance treatments of increasing intensity to the forest understory once in 1998, i.e., light trimming, heavy trimming, and burning; a fourth treatment was an undisturbed control. We measured recovery of the understory vascular plant community annually over the following 14 years, and at that time also assessed recovery of mosses and several belowground variables. Consistent with our predictions, vascular plant whole-community variables (total cover, species richness, diversity [Shannon's H'], and community composition) recovered significantly more slowly on the smaller (least fertile) than the larger islands, but this difference was not substantial, and only noticeable in the most severely disturbed treatment. When an index of resilience was used, we were unable to detect effects of island size on the recovery of any property. We found that mosses and one shrub species (Empetrum hermaphroditum) recovered particularly slowly, and the higher abundance of this shrub on small islands was sufficient to explain any slower recovery of whole-ecosystem variables on those islands. Further, several belowground variables had not fully recovered from the most intense disturbance after 14 yr, and counter to our predictions, the degree of their recovery was never influenced by island size. While several studies have shown large variation among plant communities in their short-term response (notably resistance) to environmental perturbations, our results reveal that when perturbations are applied equally to highly contrasting ecosystems, differences in resilience among them in the longer term can be relatively minor, regardless of the severity of disturbance.

Potential of Short Rotation Coppice plantations to reinforce functional biodiversity in agricultural landscapes

We compared communities of vascular plants and arthropods in ten Short Rotation Coppice (SRC)–maize pairs, to (1) quantify the difference in diversity and composition between these two alternative land-use types and (2) to assess the potential of SRC plantations to increase functional biodiversity values in agricultural landscapes. In each SRC plantation and maize field, the vegetation was surveyed and arthropods were sampled by applying pitfall and pan trapping. The composition of the vegetation and of the epigeic and vegetation inhabiting arthropod communities strongly differed between the crop types. This differentiation was mainly due to true species turnover and only to a lesser extent to the occurrence of nested subsets. On average, the total cover of the vegetation was 10 times higher in the SRC plantations and taxonomic and trait diversity were also consistently higher in SRC. Arthropod activity densities were significantly higher, sometimes almost double, in SRC plantations. Significantly higher effective species numbers in SRC were only retrieved for Hymenoptera and Coleoptera. Regarding functional groups, the activity densities of omnivores, detritivores, mycophages, phytophages and parasitoids were significantly higher in SRC. While activity densities of predators were not different among the crop types, their effective species number was higher in SRC, indicating a more evenly distributed and diverse predator community. To conclude, we have shown that SRC can significantly increase vegetation and arthropod abundance and/or diversity in agricultural landscapes when replacing annual biomass crops, such as maize.

Grazing effects on biological soil crusts and their interaction with shrubs and grasses in an arid rangeland

AbstractQuestionBiological soil crust (BSC) communities can be used in the identification and monitoring of degradation. A key question is how landscape‐scale livestock disturbance and other local‐scale factors influence BSC communities. We hypothesize that at the landscape scale, increased grazing pressure would lead to decreasing cover of BSC, but at the local scale biotic interactions between BSC and vascular plants would modulate the influence of grazing on BSC.MethodsSpatially explicit sampling of vegetation composition and cover was conducted using point‐sampling methods in digital images along two disturbance gradients in the central Monte Desert in Argentina.ResultsThe grazing gradient is the major determinant of changes in the structure of plant communities at the landscape scale. Approximately 1500 to 2000 m from a watering point, there is a threshold in vegetation structure associated with a nonlinear trend of the BSC, herb, grass and shrub cover. Bivariate spatial patterns show attraction between BSC and shrubs in the vicinity of settlements, and repulsion between BSC and both grasses and litter in less disturbed sites.ConclusionGrazing affects BSC directly through trampling and indirectly by altering vascular plant communities that interact with the BSC communities. Both these effects vary according to the spatial scale being considered. The results evidence that understanding of livestock impact in structuring arid ecosystems requires an integrated analysis of BSC and vascular plant communities at different spatial scales.