Dry Grassland Communities Research Articles

Competition between alien and native species in xerothermic steno-Mediterranean grasslands: Cenchrus setaceus and Hyparrhenia hirta in Sicily and southern Italy

AbstractPerennial dry grassland communities, vital for plant biodiversity conservation in the Mediterranean, often harbor rare and endangered species. However, these habitats face threats, including the invasion of alien species. Cenchrus setaceus, a highly invasive grass, is spreading in the Mediterranean region. Historical records and observations document its establishment and invasiveness across various Italian regions. This study investigates the impact of C. setaceus on native grasslands dominated by Hyparrhenia hirta. We assessed the impact of C. setaceus invasion on plant biodiversity in Sicily and southern Italy, and we identified and characterized plant species’ composition using Ellenberg indicator values. The intention to analyze species richness, diversity, and ecological indicators is also emphasized. Starting from the use of the phytosociological method, multivariate analysis and Ellenberg indicator values to assess the impact of C. setaceus on grasslands composition were considered. There are several similarities and differences in diversity, floristic composition, and ecological traits between the two grassland types. A deep comparison with central European studies and evaluation of the impact of C. setaceus on species richness and community dynamics in Mediterranean habitats were concluded. Although C. setaceus is invading native grasslands, it does not drastically reduce species richness. The ecological implications of the invasion are explored, urging ongoing monitoring and collaborative efforts for effective conservation. The importance of interdisciplinary cooperation is highlighted to address the threat of invasive species and sustain the biodiversity of Mediterranean grasslands.

Patterns of floral resources and pollination interactions along dry grassland succession

Succession following the abandonment of traditional management practices can pose severe consequences for the conservation of semi-natural dry grassland communities. In the present study, we investigated whether the quantity of floral resources changes during succession of semi-natural dry grasslands and how this is related to pollinator richness and the number of pollination interactions at the community level. We addressed this issue by quantifying floral resources (i.e., number of flowers, nectar volume and number of pollen grains) and monitoring pollination interactions in dry grassland communities at different stages of succession, defined as the total cover of plant species of forest edges. The relationship between the quantity of floral resources and cover of plant species of forest edges was significantly hump-shaped, i.e., regardless of the type of floral resource, all peaked at intermediate values of cover of plant species of forest edges. The richness of animal-pollinated plants in bloom also showed a hump-shaped relationship with the cover of plant species of forest edges, while the richness of pollinator species and the number of pollination contacts were indirectly related to the cover of plant species of forest edges, as they were significantly associated with the number of flowers and the richness of animal-pollinated plants in bloom. Results suggest that succession of dry grasslands after abandonment may affect a crucial function in terrestrial ecosystems, namely animal-mediated pollination. Nevertheless, the conditions of early succession, which could be achieved by the presence of scattered shrubs, could ultimately be favourable for the pollination function in dry grasslands.

Resurveying inner-alpine dry grasslands after 70 years calls for integrative conservation efforts

European inner-alpine dry grasslands face substantial threats within the increasingly human-altered landscape, endangering their persistence. To understand changes in dry grassland communities, we revisited historical vegetation plots of Josias Braun-Blanquet after 70 years in Val Venosta, Italy, hosting rare steppe-like grassland vegetation. By disentangling the key environmental factors encompassing climate, land use and human management, and ecological site preferences, we aimed at explaining changes in dry grassland communities with implications for future conservation.By extending our analysis beyond conventional dissimilarity metrics and adopting a landscape-ecological perspective accounting for species-environment interactions, we assessed how environmental changes affect dissimilarity patterns among historical sites, recent non-protected sites, and recent protected sites with generalized additive modelling. Moreover, we examined ecologically significant species changes to evaluate their contribution to community variation within and between sites, discerning their consequences at the landscape scale.Our results revealed significant changes in dry grassland sites, both on non-protected and protected sites. The encroachment of shrubs was associated with a significant increase in generalist species, including various woody species on sites where grazing had ceased. Furthermore, we observed a higher abundance of nutrient-demanding species on sites next to intensive agriculture. These trends were consistent regardless of the protection status, implying that current conservation measures may be insufficient to guarantee their future persistence. To ensure the long-term conservation of typical inner-alpine dry grasslands, interdisciplinary conservation efforts are essential to address adverse environmental impacts across the entire landscape.

Long term changes of the inner-alpine steppe vegetation: the dry grassland communities of the Vinschgau (South Tyrol, Italy) 40–50 years after the first vegetation mapping

Aims: The Vinschgau is the driest inner-alpine valley in the Eastern Alps and harbours a unique steppe vegetation. We studied these dry grassland communities and aimed to answer the following questions: Which plant communities can be found currently? Do the syntaxa described by Braun-Blanquet in the 1960s still prevail in the area? Has there been any change in species composition over the last 40–50 years?Study area: Along an approximately 40 km transect, the south-facing slopes of the Vinschgau valley (South Tyrol, Italy) from Mals to Plaus were investigated.Methods: For the classification, 92 relevés were sampled in 2019 and compared with 76 relevés from the 1960s and ´70s by means of vegetation tables and ordinations (Detrended Correspondence Analysis).Results: Based on our investigation, the majority of dry grassland communities can be classified asFestuco-Caricetum supinae. Three subassociations were defined by the dominant speciesStipa capillata,Bothriochloa ischaemumandStipa pennataagg. The comparison of new and old relevés shows an increase in species from the classSedo-Scleranthetea(e.g.Trifolium arvense,Erodium cicutarium) and the associationArtemisieto-Agropyretum. In addition, ruderal elements (e.g.Erigeron annuus,Convolvulus arvensis) have also migrated into dry grasslands. A shift in the dominance over time can be recognized as well. In particular,Festuca rupicolaand to some extent alsoStipa capillata, have increased in abundance and frequency.Conclusions: We suggest to include the investigated closed dry grasslands in the allianceFestucion valesiacae. The rank of the character species at association, alliance and order level should be re-analysed. In order to obtain a better syntaxonomic overview of western and eastern alpine dry grassland communities in relation to Eastern European dry grasslands, a comprehensive study is absolutely necessary. Furthermore, long-term vegetation dynamics and vegetation change need to be studied in more detailed future studies.Taxonomic reference: Fischer et al. (2008).Syntaxonomic references: Mucina et al. (2016) for syntaxa from alliance to class level; Braun-Blanquet (1961) for associations.Abbreviations: agg. = aggregate; cf. = confer (means ‘compare’); DCA = Detrended Correspondence Analysis; s. lat. = sensu lato; s. str. = sensu stricto

Xeric grasslands of the inner-alpine dry valleys of Austria – new insights into syntaxonomy, diversity and ecology

Aims: We studied the syntaxonomic position, biodiversity, ecological features, nature conservation value and current status of dry grasslands investigated by Josias Braun-Blanquet more than 60 years ago. Study area: Inner-alpine valleys of Austria. Methods: We sampled 67 plots of 10 m2, following the standardized EDGG methodology. We subjected our plots to an unsupervised classification with the modified TWINSPAN algorithm and interpreted the branches of the dendrogram syntaxonomically. Biodiversity, structural and ecological characteristics of the resulting vegetation units at association and order level were compared by ANOVAs. Results: All the examined grasslands belong to the class Festuco-Brometea. From ten distinguished clusters, we could assign four clusters to validly published associations, while the remaining six clusters were named tentatively. We classified them into three orders: Stipo-Festucetalia pallentis (Armerio elongatae-Potentilletum arenariae, Phleo phleoidis-Pulsatilletum nigricantis, Medicago minima-Melica ciliata community, Koelerio pyramidatae-Teucrietum montani), Festucetalia valesiacae (Sempervivum tectorum-Festuca valesiaca community); Brachypodietalia pinnati (Astragalo onobrychidis-Brometum erecti, Agrostis capillaris-Avenula adsurgens community, Anthericum ramosum-Brachypodium pinnatum community, Ranunculus bulbosus-Festuca rubra community, Carduus defloratus-Brachypodium pinnatum community). Conclusions: The ten distinguished dry grassland communities of the Austrian inner-alpine valleys differ in their ecological affinities as well as their vascular plant, bryophyte and lichen diversity. We point out their high nature conservation importance, as each of them presents a unique habitat of high value. Taxonomic reference: Names of vascular plants, bryophytes and lichens follow Fischer et al. (2008), Frahm and Frey (2004) and Nimis et al. (2018), respectively. Syntaxonomic reference: Names of orders and classes follow Mucina et al. (2016), references for associations and alliances are given in the text. Abbreviations: ANOVA = analysis of variance; DCA: detrended correspondence analyses; EDGG: Eurasian Dry Grassland Group; EIV: ecological indicator value; FL: Fließ; GR: Griffen; GU: Gulsen; KA: Kaunerberg; LA: Laudegg castle in Ladis; MA: Marin; NM: Neumarkt in der Steiermark; OM: Obermauern; PÖ: Pöls; PU: Puxer Loch; TWINSPAN = Two-way indicator species analysis; ZS: Zinizachspitze.

Phytosociology of Atractylis cancellata and Micromeria microphylla communities in southern Italy with insights on the xerothermic steno-Mediterranean grasslands high-rank syntaxa

In the present paper a phytosociological study on the dry grassland communities identified in the western sector of the Murgia Plateau (Murgia delle Gravine) and in the Lucanian badlands territory is presented. Forty vegetation releves were carried out using the Braun-Blanquet phytosociological approach. Two new associations characterized by a therophytic dominance, namely Lysimachio foeminae-Atractylidetum cancellatae and Campanulo erini-Micromerietum microphyllae, are described and discussed from a syntaxonomic and biogeographic viewpoint. In addition, new phytosociological data concerning the Petrosedum ochroleucum communities developed on limestone outcrops, the perennial Hyparrhenia hirta steppe-like grasslands of the low-altitude areas of the Murgia hills and the small-size Brachypodium distachyum therophytic communities are presented.

Trait means or variance-What determines plant species' local and regional occurrence in fragmented dry grasslands?

One of the few laws in ecology is that communities consist of few common and many rare taxa. Functional traits may help to identify the underlying mechanisms of this community pattern, since they correlate with different niche dimensions. However, comprehensive studies are missing that investigate the effects of species mean traits (niche position) and intraspecific trait variability (ITV, niche width) on species abundance. In this study, we investigated fragmented dry grasslands to reveal trait‐occurrence relationships in plants at local and regional scales. We predicted that (a) at the local scale, species occurrence is highest for species with intermediate traits, (b) at the regional scale, habitat specialists have a lower species occurrence than generalists, and thus, traits associated with stress‐tolerance have a negative effect on species occurrence, and (c) ITV increases species occurrence irrespective of the scale. We measured three plant functional traits (SLA = specific leaf area, LDMC = leaf dry matter content, plant height) at 21 local dry grassland communities (10 m × 10 m) and analyzed the effect of these traits and their variation on species occurrence. At the local scale, mean LDMC had a positive effect on species occurrence, indicating that stress‐tolerant species are the most abundant rather than species with intermediate traits (hypothesis 1). We found limited support for lower specialist occurrence at the regional scale (hypothesis 2). Further, ITV of LDMC and plant height had a positive effect on local occurrence supporting hypothesis 3. In contrast, at the regional scale, plants with a higher ITV of plant height were less frequent. We found no evidence that the consideration of phylogenetic relationships in our analyses influenced our findings. In conclusion, both species mean traits (in particular LDMC) and ITV were differently related to species occurrence with respect to spatial scale. Therefore, our study underlines the strong scale‐dependency of trait‐abundance relationships.

Dry grasslands on sedimentary outcrops of the Dniester canyon (Ukraine)

The main aim of this article is to characterize vegetation data of dry grassland communities on sedimentary outcrops of the Dniester Canyon (Ukraine) ecologically and to provide their syntaxonomy. For this purpose, we collected 155 releves, and included published data from Ukrainian and Moldovian literary sources. We used cluster analysis, including the nomenclatural types of previously described relevant associations from the study area and adjacent territories. As a result, we recognized two associations of the order Alysso-Sedetalia and six of the order Stipo pulcherrimae-Festucetalia pallentis. Two associations of pioneer communities with therophytes and succulents were transferred from the endemic alliance Sempervivo ruthenici-Schivereckion of the class Asplenietea trichomanis to the widely spread alliance Alysso-Sedion of the class Sedo-Scleranthetea. Five associations of petrophytic steppes were transferred from different alliances within the classes Festuco-Brometea (Genisto tetragonae-Seselion peucedanifoliae, Festucion valesiacae) and Sedo-Scleranthetea (Alysso-Sedion) to the alliance Galio campanulati-Poion versicoloris within the class Festuco-Brometea. We also described the new association Cephalario uralensis-Agropyretum cristati. Furthermore, we tested for ecological differences between these associations using ecological scales of the Ukrainian flora and measured soil parameters. We conclude that the relief, geological structure, soils, and climate parameters determine the distribution and diversity of the communities as well as their particular floristic features.

Weather fluctuations drive short‐term dynamics and long‐term stability in plant communities: A 25‐year study in a Central European dry grassland

AbstractQuestionInfrequent events of extreme drought or extreme temperatures may considerably affect the structure and functioning of vegetation. Here we investigate how fluctuations in precipitation and temperature shape year‐to‐year dynamics and plant species composition in a dry grassland community, and how this variation affects plants with different life histories.LocationDry grassland (Festucion valesiacae) in the Pavlov Hills, SE Czech Republic.MethodsLong‐term trends in vegetation change in the grassland studied were assessed by the ordination of plot records from vegetation surveys performed between 1930 and 2019. In addition, year‐to‐year changes in vegetation were studied in seven permanent plots of 16 m2 surveyed annually from 1993 to 2018. Variation in species composition and abundances was related to temperature and precipitation in the preceeding two springs, summers, autumns and winters using ordinations and mixed‐effect linear models.ResultsThere were no remarkable directional changes in the grassland community over the period 1930–2019. However, during the last 25 years, the community exhibited pronounced year‐to‐year fluctuations, which depended on weather conditions in the previous two years. Species with different life histories (e.g. perennials vs. annuals) and different ecology (e.g. ruderal vs. dry‐grassland species) responded differently to specific weather patterns. Perennials were sustained by wet summers, annuals benefitted from wet springs and autumns and moderately warm and wet winters, and covers of ruderals of mixed life histories increased after dry summers.ConclusionsPlant species composition in a Central European dry grassland shows remarkable year‐to‐year dynamics in response to weather patterns over the previous two years. These community changes are non‐directional and contribute to the stability of this grassland, which has not changed considerably over the past 90 years. However, increasing frequency of drought events because of ongoing climate change can result in a directional change with an expansion of ruderal species.

Climatic drivers of dry grassland phylogenetic diversity in the Republic of Macedonia

Abstract Climatic gradients can be used to predict the extent to which climate drives biodiversity and to which biodiversity may be affected by global climate changes. Climate and evolutionary history are linked by the ecological adaptations of species and the history of Earth’s climate. If so, phylogenetic diversity may be a good metric to estimate biodiversity. We aimed to test whether the phylogenetic diversity of Macedonian dry grasslands was related to climatic variables. We sampled 575 plots, identifying the species and building a phylogenetic tree for them. We calculated two metrics of phylogenetic diversity and regressed them against climatic variables. We also tested whether there were nodes in the tree responsible for the main observed spatial patterns of phylogenetic diversity. We found a strong signature of evolutionary history in species sorting across a gradient driven by climate in Macedonian dry grasslands. First, the amount of evolutionary history decreased towards drier and more seasonal climates, suggesting a phylogenetic niche conservatism. Second, there was an air temperature filter and a temperature seasonality filter, acting in opposite directions and leading to phylogenetic clustering. Third, there were few nodes in the phylogenetic tree with high degrees of allopatry, associated with clades that differed not only in their geographic distribution, but also in their climatic preferences. Macedonian dry grassland communities developed over centuries of traditional land use but are threatened nowadays by human activities. The use of phylogenetic approaches may lead to more effective conservation policies and help us preserve this highly diverse vegetation.

The resilience of pollination interactions: importance of temporal phases

The loss of species that engage in close ecological interactions, such as pollination, has been shown to lead to secondary extinctions, ultimately threatening the overall ecosystem stability and functioning. Pollination studies are currently flourishing at all possible levels of interaction organization (i.e., species, guild, group and network), and different methodological protocols aimed to define the resilience of pollination interactions have been proposed. However, the temporal dimension of the resilience of pollination interactions has been often overlooked. In the light of these considerations, we addressed the following questions: does a temporal approach help to reveal critical moments during the flowering season, when pollination interactions are less resilient to perturbations? Do pollination interactions evaluated at species, guild, group and network level show different patterns when assessed through time? We monitored contacts between plant and pollinator species in dry grassland communities every 15 days during the overall community flowering season (12 surveys). For each survey, we built a quantitative plant–pollinator interaction matrix and we calculated two sets of metrics characterizing, respectively, the diversity and the distribution of interactions across hierarchical levels. To describe the diversity of interactions, we calculated partner diversity (PD) at the species level, vulnerability/generality (V/G) at the guild level, and interaction diversity and evenness at the network level. The distribution of interactions was characterized by calculating selectiveness at the species and the network level, and modularity at the group level. We assessed the temporal variation of PD, V/G at the level of plants and pollinators, and species selectiveness, by means of Linear Mixed Models (LMMs). To investigate the temporal variation of indexes calculated at group and network level, we applied simple linear and quadratic regressions after checking for temporal autocorrelation in residuals. When taking into account the temporal dimension of interactions, the diversity of interactions showed different patterns at different levels of organization. At the species level, no relationship was disclosed between PD and time, when assessing the temporal trend of V/G separately for the guild of plants and pollinators we observed an asymmetric structure of interactions. Pollination interactions showed to be asymmetric throughout the flowering season; however, evenness of interactions and network selectiveness showed significant positive relationships with time, revealing a poorer network of interactions during the end of the flowering season. The temporal analysis of pollination interactions revealed a stronger risk of secondary extinctions at the end of the flowering season, due to a lower degree of redundancy and thus of resilience of the overall network of interactions.

Roles of Arbuscular Mycorrhizal Fungi and Soil Abiotic Conditions in the Establishment of a Dry Grassland Community.

BackgroundThe importance of soil biota in the composition of mature plant communities is commonly acknowledged. In contrast, the role of soil biota in the early establishment of new plant communities and their relative importance for soil abiotic conditions are still poorly understood.Aims and MethodsThe aim of this study was to understand the effects of soil origin and soil fungal communities on the composition of a newly established dry grassland plant community. We used soil from two different origins (dry grassland and abandoned field) with different pH and nutrient and mineral content. Grassland microcosms were established by sowing seeds of 54 species of dry grassland plants into the studied soils. To suppress soil fungi, half of the pots were regularly treated with fungicide. In this way, we studied the independent and combined effects of soil origin and soil community on the establishment of dry grassland communities.Key ResultsThe effect of suppressing the soil fungal community on the richness and composition of the plant communities was much stronger than the effect of soil origin. Contrary to our expectations, the effects of these two factors were largely additive, indicating the same degree of importance of soil fungal communities in the establishment of species-rich plant communities in the soils from both origins. The negative effect of suppressing soil fungi on species richness, however, occurred later in the soil from the abandoned field than in the soil from the grassland. This result likely occurred because the negative effects of the suppression of fungi in the field soil were caused mainly by changes in plant community composition and increased competition. In contrast, in the grassland soil, the absence of soil fungi was limiting for plants already at the early stages of their establishment, i.e., in the phases of germination and early recruitment. While fungicide affects not only arbuscular mycorrhizal fungi but also other biota, our data indicate that changes in the AMF communities are the most likely drivers of the observed changes. The effects of other soil biota, however, cannot be fully excluded.ConclusionsThese results suggest that the availability of soil fungi may not be the most important limiting factor for the establishment of grassland species in abandoned fields if we manage to reduce the intensity of competition at these sites e.g., by mowing or grazing.

Does flowering synchrony contribute to the sustainment of dry grassland biodiversity?

Phenological relationships among entomophilous species for pollination may play an important role in structuring natural plant communities.The main aim of this work was to test whether in dry grassland communities there is a non-random flowering pattern and if the pattern influences the species richness, and the richness of subordinate and common species.Field sampling was carried out in temperate dry grasslands in NE Italy. Species composition and the flowering phenology were monitored in 45 2m×2m plots randomly placed over dry grasslands.To quantify the degree to which insect-pollinated species overlap in their flowering time we developed a “co-flowering index” (CF-index). The significance of the observed flowering pattern was tested using a null model.A positive correlation was found between the synchronic flowering and the number of subordinate species. Subordinate species showed shorter flowering length than the common species and a mostly specialized pollination system.Our findings suggest that flowering synchrony might be a key characteristic which may contribute to shape dry grassland composition by favouring the long lasting maintenance of rare species populations within the community.The comprehension of such functional relationships between species of different trophic levels is of great importance for the conservation of dry grasslands and the maintenance of the ecosystem services that pollination provides.

Variation in dry grassland communities along a heavy metals gradient.

The aim of this study was to investigate the variation in plant communities growing on metal-enriched sites created by historical Zn–Pb mining. The study sites were 65 small heaps of waste rock covered by grassland vegetation and scattered mostly over agricultural land of southern Poland. The sites were described in terms of plant coverage, species richness and composition, and the composition of plant traits. They were classified using phytosociological methods and detrended correspondence analysis. Identified plant communities were compared for vegetation parameters and habitat properties (soil characteristics, distance from the forest) by analysis of variance. The variation in plant community parameters was explained by multiple regression, in which the predictors were properties of the habitat selected on the basis of factor analysis. Grasslands that developed at low and high concentrations of heavy metals in soil were similar to some extent: they were composed on average of 17–20 species (per 4 m2), and their total coverage exceeded 90 %. The species composition changed substantially with increasing contamination with heavy metals; metal-sensitive species withdrew, while the metal-tolerant became more abundant. Other important predictors of community structure were: proximity to the forest (responsible for the encroachment of competitive forest species and ruderals), and the thickness of the surface soil (shallow soil favored the formation of the heavy metal grassland). The heavy metal grassland was closely related to the dry calcareous grasslands. The former was an earlier succession stage of the latter at low contamination with heavy metals.

Ecological Features of Spontaneous Vascular Flora of Serpentine Post-Mining Sites in Lower Silesia

Abstract The aim of this study was to determine the ecological characteristics of vascular plants colonizing serpentine mining waste dumps and quarries in Lower Silesia. The investigated flora was analyzed with regard to species composition, geographical-historical status, life forms, as well as selected ecological factors, such as light and trophic preferences, soil moisture and reaction, value of resistance to increased heavy metals content in the soil, seed dispersal modes and occurrence of mycorrhiza. There were 113 species of vascular plants, belonging to 28 families, found on seven sites in the study. The most numerous families were Asteraceae, Poaceae, Fabaceae and Caryophyllaceae. Only 13% of all plants recorded occurred on at least five of the study sites. The most numerous were species related to dry grassland communities, particularly of the Festuco-Brometea class, which included taxa endangered in the region of Lower Silesia: Avenula pratensis, Salvia pratensis, Festuca valesiaca. Apophytes dominated in the flora of the investigated communities. Hemicryptophytes were the most numerous group and therophytes were also abundant. The serpentine mining waste dumps and querries hosted heliophilous species which prefer mesic or dry habitats moderately poor in nutrients, featuring neutral soil reaction. On two study sites 30% of the flora composition consisted of species that tolerate an increased content of heavy metals in the soil. Anemochoric species were the most numerous with regard to types of seed dispersal. Species with an arbuscular type of mycorrhiza were definitely dominant in the flora of all the study sites, however, the number of nonmycorrhizal species was also relatively high. It was suggested that both the specific characteristics of the habitats from serpentine mining and the vegetation of adjacent areas had a major impact on the flora composition of the communities in the investigated sites.

Decline of dry grassland specialists in Mediterranean high‐mountain communities influenced by recent climate warming

AbstractQuestionsWhat changes have occurred in Mediterranean high‐mountain communities during the last 50 yr? Do these changes reflect upward shifts and decline in dry grassland specialists due to climate warming?LocationUpper belt (1900–2400 m a.s.l.) in Sierra de Guadarrama, Spain.MethodsWe re‐surveyed dry grassland communities in 50 summits that were previously sampled between the 1960s and 1980s. New plots were placed in the same localities and the same conditions as the original surveys. Changes at the species level were evaluated by comparing, between the two survey periods, species frequencies and optimal altitude estimated by local distribution models done with Maxent. Changes at the community level were assessed by comparing species richness and composition of the two surveys in relation to altitude, plot size and time between surveys. We evaluated observed changes in the whole data set and species groups by structuring the species into dry grassland specialists, other alpine species and generalists occurring at wider altitudinal ranges.ResultsThere was a general decline in the frequency of dry grassland specialists, an increase in frequency of generalists and no clear trends in the other species. Upward shifts were mainly detected in generalists, with significant increases in frequency. At the community level, we found a general increase in species richness that was mainly determined by the increase in generalists; coupled with a decline in number of dry grassland specialists. The structure of the communities evidenced changes between the historical surveys and the re‐survey, which were mainly correlated with the number of years and the increasing dominance of generalists.ConclusionsIn contrast with trends observed in other Mediterranean high‐mountain communities, our study reports a general increase in species richness, although this effect is concurrent with a decline in dry grassland specialists. The observed trends support on‐going replacement of endemic species by low‐altitude species, and associated changes in community assemblages. Despite the limitations of re‐visitation studies for assessing climate‐driven changes, our results highlight the necessity of developing more studies for assessing the effects of drought in Mediterranean high‐mountain communities.

The Effect of AMF Suppression on Plant Species Composition in a Nutrient-Poor Dry Grassland

Arbuscular mycorrhizal fungi (AMF) are expected to be one of the key drivers determining the diversity of natural plant communities, especially in nutrient-poor and dry habitats. Several previous studies have explored the importance of AMF for the composition of plant communities in various types of habitats. Surprisingly, studies of the role of AMF in nutrient-poor dry grassland communities dominated by less mycotrophic plant species are still relatively rare. We present the results of a 3-year study in which a plant community in a species-rich dry grassland was subjected to the fungicide carbendazim to suppress AMF colonization. We tested the effect of the fungicide on the following parameters: the plant species composition; the number of plant species; the cover of the rare, highly mycorrhiza-dependent species Aster amellus; the cover of the dominant, less mycorrhiza-dependent species Brachypodium pinnatum; and the cover of graminoids and perennial forbs. In addition, we examined the mycorrhizal inoculation potential of the soil. We found that the suppression of AMF with fungicide resulted in substantial changes in plant species composition and significant decrease in species richness, the cover of A. amellus and the cover of perennial forbs. In contrast the species increasing their cover after fungicide application were graminoids—the C3 grasses B. pinnatum and Bromus erectus and the sedge Carex flacca. These species appear to be less mycorrhiza dependent. Moreover, due to their clonal growth and efficient nutrient usage, they are, most likely, better competitors than perennial forbs under fungicide application. Our results thus suggest that AMF are an essential part of the soil communities supporting a high diversity of plant species in species-rich dry grasslands in nutrient-poor habitats. The AMF are especially important for the maintenance of the populations of perennial forbs, many of which are rare and endangered in the area.

Activity time budget patterns of sheep and goats co-grazing on semi-natural species-rich dry grassland

Activity time budget patterns and grazing response to sward and environmental conditions were investigated for paddocks of sheep and goats co-grazing for conservation purposes on a semi-natural species-rich dry grassland community endangered by shrub and tall perennial plant encroachment in a protected nature reserve in South Moravia (Czech Republic). Grazing was conducted by a rotational stocking system for 14 weeks in late grazing season in 2008 with 60 dry ewes and 20 goats. Twelve ewes and four goats were observed; grazing, ruminating, idling and other activities (salt licking, social interactions, walking), along with topographical position in the paddock were recorded at 5-minute intervals within 14 hours of daylight. Sheep and goats did not differ in their principal activity time budgets, such as the average total daylight time spent grazing (sheep: 8.57 h, goats: 8.59 h), ruminating (sheep: 1.42 h, goats: 1.44 h), or idling (sheep: 3.23 h, goats: 3.18 h), the duration of bouts of each activity, or the number of bouts of grazing and ruminating. There was no pattern in activity time budgets indicating dynamics in progressing season, nor was there a response to daily average temperature or to paddock size. Sheep and goats showed similar responses to groundcover of particular plant functional types. The animals showed a positive trend in response of total daylight grazing time to grass available biomass and a negative response of total daylight grazing time to herbaceous biomass for both sheep and goats. The total daylight grazing time was independent of availability of woody plants. Goats devoted more time (1.51 h) to other activities than sheep (1.34 h), especially to social interactions and salt licking. On the other hand, sheep spent proportionally more time walking. Both sheep and goats showed similar patterns in spatial use of paddocks on hill slopes, spending the most time in the middle part and the least time in the lower part of paddocks. 

The impacts of biologically induced micro-environments on biodiversity in a dry Mediterranean grassland

Background: Many dryland plant communities are characterised by scattered shrubby vegetation. In such dry ecosystems, individual shrubs modify the local micro-environment and affect the surrounding plant community. Aims: The present study was conducted in a dry Mediterranean grassland community, with scattered shrubs, to determine the impacts of biologically induced micro-environments on the surrounding plant community. Methods: The plant community was sampled at four distances in four micro-environments, defined by cardinal compass directions (north, south, east and west) to assess vegetation composition near individual shrubs and at increasing distances from them. To quantify the impact of shrubs on surrounding species composition, we used a rarefaction approach in addition to alpha and beta diversity and cover parameters. Also, the productivity–diversity relationship was investigated. Results: We found significant micro-environment differences in non-shrub communities in terms of vegetation, bare ground and litter cover, above-ground biomass, species richness and Shannon diversity index. The diversity–productivity relationship was best fit by unimodal and linear models. Rarefaction analysis accumulated more species in the west aspect than in the other aspects. Beta diversity values for consecutive distances were significantly higher than the farthest distances. Conclusions: These findings suggest that shrubs create micro-environments and influence plant community characteristics according to distance and aspect, and therefore add to the complexity and biodiversity of the system; by creating diverse microhabitats they contribute to enhanced plant diversity.

Seed density significantly affects species richness and composition in experimental plant communities.

Studies on the importance of seed arrival for community richness and composition have not considered the number of seeds arriving and its effect on species richness and composition of natural communities is thus unknown. A series of experimental dry grassland communities were established. All communities were composed of the same 44 species in exactly the same proportions on two substrates using three different seed densities.The results showed that seed density had an effect on species richness only at the beginning of the experiment. In contrast, the effects on species composition persisted across the entire study period. The results do not support the prediction that due to higher competition for light in nutrient-rich soil, species richness will be the highest in the treatment with the lowest seed density. However, the prevalence of small plants in the lowest seed density supported the expectation that low seed density guarantees low competition under high soil nutrients. In the nutrient-poor soil, species richness was the highest at the medium seed density, indicating that species richness reflects the balance between competition and limitations caused by the availability of propagules or their ability to establish themselves. This medium seed density treatment also contained the smallest plants.The results demonstrate that future seed addition experiments need to consider the amount of seed added so that it reflects the amount of seed that is naturally found in the field. Differences in seed density, mimicking different intensity of the seed rain may also explain differences in the composition of natural communities that cannot be attributed to habitat conditions. The results also have important implications for studies regarding the consequences of habitat fragmentation suggesting that increasing fragmentation may change species compositions not only due to different dispersal abilities but also due to differential response of plants to overall seed density.