Xeric Grasslands Research Articles

Sensitivity of grassland plant community composition to spatial vs. temporal variation in precipitation

Climate gradients shape spatial variation in the richness and composition of plant communities. Given future predicted changes in climate means and variability, and likely regional variation in the magnitudes of these changes, it is important to determine how temporal variation in climate influences temporal variation in plant community structure. Here, we evaluated how species richness, turnover, and composition of grassland plant communities responded to interannual variation in precipitation by synthesizing long-term data from grasslands across the United States. We found that mean annual precipitation,(MAP) was a positive predictor of species richness across sites, but a positive temporal relationship between annual precipitation and richness was only evident within two sites with low MAP. We also found higher average rates of species turnover in dry sites that in turn had a high proportion of annual species, although interannual rates of species turnover were surprisingly high across all locations. Annual species were less abundant than perennial species at nearly all sites, and our analysis showed that the probability of a species being lost or gained from one year to the next increased with decreasing species abundance. Bray-Curtis dissimilarity from one year to the next, a measure of species composition change that is influenced mainly by abundant species, was insensitive to precipitation at all sites. These results suggest that the richness and turnover patterns we observed were driven primarily by rare species, which comprise the majority of the local species pools at these grassland sites. These findings are consistent with the idea that short-lived and less abundant species are more sensitive to interannual climate variability than longer-lived and more abundant species. We conclude that, among grassland ecosystems, xeric grasslands are likely to exhibit the greatest responsiveness of community composition (richness and turnover) to predicted future increases in interannual precipitation variability. Over the long-term, species composition may shift to reflect spatial patterns of mean precipitation; however, perennial-dominated systems will be buffered against rising interannual variation, while systems that have a large number of rare, annual species will show the greatest temporal variability in species composition in response to rising interannual variability in precipitation.

Holocene variability in hydrology, vegetation, fire, and eolian activity in the Nebraska Sand Hills, USA

This study combined multiple aquatic and terrestrial proxies, including diatoms, pollen, grain size, and bulk-sediment chemistry to reconstruct the history of three lake sites located in the central Sand Hills of Nebraska, USA. Long-term changes in effective moisture are evident at all sites, with significant changes occurring at ~6000, ~4000, and ~ 2000 cal. yr BP. Both aquatic and terrestrial indicators suggest that effective moisture was low between 10,000 and ~6000 cal. yr BP, and that this time interval was the driest period of the Holocene. The dominance of benthic and tychoplanktic diatom taxa indicates relatively shallow lake-level, high sand influx indicates moderately high eolian activity, and the pollen assemblage suggests xeric grasslands with abundant mud flats. About 6000 cal. yr BP, all three sites experienced an increase in effective moisture. Lake-level rise is indicated by increases in planktic and tychoplanktic diatoms relative to benthic taxa, while greater abundance of grass pollen and charcoal, and decreased eolian flux indicate stabilized dunes with dense vegetation sufficient to fuel local fires. A significant hydrologic shift recorded at all sites occurred at ~4000 cal. yr BP. This event was characterized by substantial lake-level rise, yet decreased grass cover and fire frequency, and increased eolian activity. Water-table rise may have been caused by a combination of factors including: (1) formation of dune-dams that blocked old drainage channels, (2) reduced grass cover and hence reduced evapotranspiration, and (3) changes in the frequency and duration of drought. The most likely cause(s) of the differential response of the terrestrial and aquatic systems at this time is not clear, none-the-less the late Holocene was not nearly as dry as the interval prior to 6000 cal. yr BP. The last ~2000 yr were characterized by several short-term fluctuations in lake level, including an interval of drought between 950 and 750 cal. yr BP, coincident with increased eolian activity during the latter part of the Medieval Climatic Anomaly.

How life history affects threat status: Requirements of two Onobrychis-feeding lycaenid butterflies, Polyommatus damon and Polyommatus thersites, in the Czech Republic

Comparisons of related species differing in conservation status may offer insights into causes of species declines. We studied egg-laying patterns and landscape occupancy of two sympatric lycaenidae butterflies inhabiting xeric grasslands, vulnerable Polyommatus thersites and critically endangered Polyommatus [Agrodiaetus] damon, both developing on sainfoin, Onobrychis spp. Females of bivoltine P. thersites oviposit on host plant leaves at a relatively low height (≈20 cm), in both spring (May–June) and summer (July–August) generations. Females of univoltine P. damon (July–September) oviposit to senescing inflorescences, in significantly higher heights (>30 cm), and the species is hence vulnerable to summer mowing or grazing. On a landscape scale, both species tended to occur at sites with diverse sward management, including temporarily unmanaged patches. In addition, P. damon occurred only in the proximity of other occupied sites. The study documents that grassland management must respect the needs of the most vulnerable species, and because these needs are seldom known, it must maintain a high diversity of conditions within individual sites.

Soil hydrology and soil properties on a partially reforested hillside in the Central Alps

  The landscape on southern exposed hillsides in the inneralpine Vinschgau Valley (Northern Italy) is shaped by many thousand years of cultivation. Phases of intensive land use and deforestation were followed by phases of natural regeneration and later by governmental programs of reforestation. The result in the present landscape is the juxtaposition of reforested woodland (RF-areas) and xeric grassland with steppe species (XG-areas) on the same hillside. The scenic and ecological contrast presents ideal conditions for comparative studies in ecology, forest and soil science. On the side of soil science especially the depth and intensity of soil development on the whole hillside have been underrated, whereas the existence of podzolised soils in the reforested area has mostly been overrated so far. One aim of this study was to investigate differences in the development of soils. A further aim was the comparative investigation of the recent hydrological and physical properties as well as the present dynamics of the hillside soils. With regard to that some results of the field and laboratory studies are presented which are contradictory to results of other studies concerning this region.  

Integrating climate change into calcareous grassland management

Summary1. Climate change is rarely taken into consideration in conservation management strategies aimed at protecting biodiversity from other threats. We examined the implications of this perspective in European calcareous grasslands, which are among the richest herbaceous systems of the continent and are therefore of high nature conservation interest. These systems are currently undergoing species loss because of the abandonment of agro‐pastoral practices. Classic ecological theory assumes that conservation management activities (such as regular mowing) and drought events should increase diversity through decreased plant competition in abandoned mesic communities. In turn, this could reduce diversity in xeric communities although positive plant interactions (facilitation) might buffer these negative effects and maintain diversity.2. We studied the effects of regular mowing and experimentally induced drought on diversity and biotic interactions between two transplanted species in mesic and xeric calcareous grasslands. The study sites in south‐western France have not been subjected to any management for the last 30 years.3. Drought did not affect mesic systems although mowing increased plant diversity through decreased competition. By contrast, mowing had no significant effect in xeric systems although drought decreased diversity. Interestingly, transplants were subject to neither competition nor facilitation in the xeric systems.4. Synthesis and applications. Regular mowing and drought events impact plant diversity of mesic and xeric calcareous grassland communities in different ways. We recommend regular mowing of mesic grasslands, even in the context of climate change. By contrast, we recommend less‐frequent mowing of xeric grasslands together with specific interventions such as assisted migration for species with poor drought tolerance. Similar studies in other ecosystems on larger spatial and temporal scales should examine the dual effects of management and climate change to identify appropriate management programmes.

Importance of marginal habitats for grassland diversity: fallows and overgrown tall‐grass steppe as key habitats of endangered ground‐beetle Carabus hungaricus

Abstract. 1. To facilitate effective conservation management of dry‐grassland diversity we studied the habitat selection of Carabus hungaricus, the globally declining, highly endangered, dry‐grassland specialist beetle listed in the EU Habitats Directive, and several co‐occurring beetles at a pannonian dry‐grassland fragment, the Pouzdrany steppe, SE Czech Republic. The beetles were sampled using 186 pitfall traps from March to November 2006. Number of C. hungaricus captures in each trap was related to vegetation and abiotic habitat characteristics; captures of all sampled beetles in each trap were related to each other.2. We found that C. hungaricus prefers relatively humid patches of tall‐grass steppe within the xeric grassland and tall‐grass ruderal vegetation nearby. During the breeding period, females preferred drier and warmer sites than males.3. Its potential competitors, i.e., Carabus spp., Calosoma spp. (Coleoptera: Carabidae), and other species of conservation interest, including Meloe spp. (Coleoptera: Meloidae), Dorcadion spp. (Coleoptera: Cerambycidae), were associated with vegetation avoided by C. hungaricus, such as short‐grass and bare‐soil patches and woody plants.4. Vegetation structure within 2.5 m affected C. hungaricus captures more than on smaller and larger scales. Carabus hungaricus enters unfavoured non‐forest habitats such as arable land, which allows it to spread into suitable habitats within agricultural landscapes. It strictly avoids closed forest; even narrow strips of forest thus likely act as migration barriers.5. The preference of C. hungaricus for overgrown steppe and fallow land highlights that habitats often considered of low conservation value are important to sustain grassland biodiversity.

Reconstruction of Neogene zonal vegetation in South China using the Integrated Plant Record (IPR) analysis

Reconstructions of past vegetation are crucial for our understanding of palaeoenvironments. However, we still lack good quantitative reconstructions for the Neogene vegetation of China. This geological time is key for the development of the modern vegetations in China because it corresponds to the establishment and evolution of the South-East Asian monsoon system. The present study uses Integrated Plant Record (IPR) vegetation analysis for the first time on the Chinese Neogene data including 71 palaeobotanical sites from five time intervals: early Early Miocene (Aquitanian, early Burdigalian), late Early to early Middle Miocene (late Burdigalian, early Langhian), late Middle Miocene (late Langhian, Serravalian), Late Miocene to earliest Pliocene (Tortonian, Messinian, early Zanclean), and Pliocene (late Zanclean, Piacenzian). Based on the ecophenological type of the nearest living relative to the fossils, IPR analysis reconstructs six types of vegetation: broad-leaved deciduous forests, mixed mesophytic forests, broad-leaved evergreen forests, subhumid sclerophyllous forests, xeric open woodlands, and xeric grasslands or steppe. The geographic distribution of reconstructed palaeovegetation shows a distinct latitudinal gradient which is congruent with the latitudinal temperature gradient recognised from previous studies. Throughout the Neogene the broad-leaved deciduous (BLD) component is greater in the more northern regions whereas the broad-leaved evergreen (BLE) component is greater in the more southern areas. During the Pliocene there was a further rise of the BLE component in the southern areas, indicating an increasingly warm and moist climate. An episodic longitudinal aridity gradient was also recorded during the Neogene: the more western areas were drier than the eastern ones in the Early Miocene; but this gradient vanished in the Late Miocene with all areas having a balanced supply of moisture. A second episode of aridification of the western regions occurred in the Pliocene.

Tetraploa aristata Berkeley & Broome (Fungi, Pleosporales), a new taxon to Poland

<em>Tetraploa aristata</em> Berkeley & Broome represents the anamorphic stage of a pleomorphic fungus with holomorph <em>Tetraplosphaeria tetraploa</em> (Scheuer) Kaz. Tanaka & K. Hiray (<em>Lophiostoma tetraploa</em> (Scheuer) Aptroot & K.D. Hyde). Until now this taxon has not been reported in Poland, where it is probably on the fringe of its distribution. Conidia of <em>Tetraploa aristata</em> were found during palynological analyses of modern surface samples and later on the decaying leaves of <em>Phleum phleoides</em> from xeric grasslands in Kraków and its vicinity. Since <em>Tetraploa aristata</em> was discovered during palynological analysis, this method might be considered to be a useful tool for investigations of contemporary microfungal mycobiota.

Demography of Sulfur Cinquefoil (Potentilla recta) in a Northern Rocky Mountain Grassland

AbstractSulfur cinquefoil is native to Eurasia and has invaded meadows and grasslands of North America. It occurs in intermountain valleys of the Rocky Mountains, including a nature reserve in northwest Montana that supports a mosaic of mesic fescue and xeric needlegrass grassland communities. We did tests to determine germination requirements, followed the fate of mapped sulfur cinquefoil from 1998 to 2005 to determine vital rates, and used a matrix modeling framework to analyze population-level dynamics. Sulfur cinquefoil plants were highly fecund; large plants produced > 10,000 seeds that require light for germination. The survivorship curve of the 1999 cohort suggested low juvenile but high adult survival. Simulations indicated that a 10% decline in survival would decrease population size more than a 10% decline in recruitment. Annual recruitment, growth of nonreproductive plants, survival, and flowering frequency of sulfur cinquefoil were all higher in the three needlegrass sample plots compared with the one fescue plot, and projected equilibrium sulfur cinquefoil populations were approximately 12 times larger in needlegrass than fescue grasslands. Our results suggest that biological control agents that negatively affect survival, such as root borers, might be more effective at controlling established sulfur cinquefoil populations than those that diminish seed production. Our results also suggest that sulfur cinquefoil might have more potential to become dominant in xeric grasslands and demonstrate the need for doing multiple demographic studies over a variety of habitats because the same species will respond differently in different habitats.

Phylogeny of the leafhopper subfamily Deltocephalinae (Hemiptera: Cicadellidae) based on molecular and morphological data with a revised family-group classification

Deltocephalinae, a highly diverse and economically important subfamily of leafhoppers, contains over 6200 species and 36 tribes distributed worldwide in habitats ranging from xeric grasslands and shrublands to tropical rainforests. Recent morphological and molecular phylogenetic analyses of Cicadellidae and a morphology-based analysis of Deltocephalinae and related subfamilies indicated that several previously recognized cicadellid subfamilies are closely related to or derived from within Deltocephalinae, but these analyses did not provide a comprehensive or well-supported hypothesis of the phylogeny of Deltocephalinae s.l. due to either low taxon sampling or low branch support. Here, taxon sampling was increased to include members of most family-group taxa of Deltocephalinae and molecular data (∼2800 bp 28S rDNA and ∼350 bp histone H3) were added to improve the phylogenetic estimate. Five putative outgroup taxa were included, and parsimony and Bayesian analyses of the combined molecular and morphological (119 characters) data and maximum likelihood analyses of the 28S data showed strong support for the monophyly of Deltocephalinae as defined here. Branches near the base of the tree and towards the tips were longer and better supported than many of the shorter internal branches. Similar to a previous morphological phylogenetic analysis of Deltocephalinae, all of the grass- and sedge-specializing tribes were recovered in one common clade, with a few apparent reversals to nongrass feeding. Although support for this clade was low and requires further testing, the results suggest that grass/sedge specialization is a phylogenetically conservative trait within Deltocephalinae. The history of the classification of Deltocephalinae and related subfamilies is reviewed, and based on the results of the phylogenetic analyses presented here, a revised family-group taxonomic classification is proposed. In addition to subfamilies that were recently included in Deltocephalinae, the following are considered junior synonyms of Deltocephalinae: Acostemminae syn.n., Arrugadinae syn.n., Drakensbergeninae syn.n., Mukariinae syn.n. and Stegelytrinae syn.n. The morphological characters supporting this interpretation of Deltocephalinae are provided and discussed, and a description of the subfamily is provided. A new tribe, Faltalini tribe n. (11 genera, 31 species) is described, and Magnentiini placement n. and Paraphrodini placement n. are transferred to Deltocephalinae from Nioniinae and Aphrodinae, respectively. New placements of genera include: Twiningia Ball and Eusama Oman (Athysanini: Platymetopiina), placement n.; Cerrillus Oman (Athysanini), placement n.; Scaphotettix Matsumura and Agrica Strand (Mukariini), placement n.; Loralia Evans and Phlogotettix Ribaut (Deltocephalinae, unplaced to tribe), placement n. The recognition of Scaphoideini Oman 1943 as a nomen nudum results in the following placements: Acunasus DeLong, Cantura Oman, Danbara Oman, Osbornellus Ball, Prescottia Ball, Scaphodhara Viraktamath & Mohan, Scaphoideus Uhler, Scaphoidophyes Kirkaldy, Sincholata DeLong, Sobara Oman and Soleatus DeLong (Deltocephalinae, unplaced to tribe), placement n.

Simple to sample: Vascular plants as surrogate group in a nature reserve

Summary One of the basic tools to quantify biodiversity is based on the use of surrogate species. Such groups of species are easily assessed and may reflect the diversity of other important and less easily detectable taxa (cross-taxon surrogacy). Among these key groups of species, the vascular plant flora has great potential in determining diversity of other groups, since in terrestrial ecosystems it constitutes the bulk of total biomass and provides the physical structure for other organisms. The cross-taxon congruence of species diversity (species richness and species composition) among vascular plants, bryophytes, lichens, fungi, oligochaetes, butterflies and birds was investigated with special attention to testing the potential role of vegetation as surrogate for the other studied taxa. The 271 ha Nature Reserve “Bosco di S. Agnese” (Tuscany, Italy) characterised by evergreen Mediterranean woodlands, scrublands, garigues, xeric grasslands and cultivations was used as study area. A multi-scale sampling design, based on a restricted random selection of plots, was used to get information about vascular plants, bryophytes, lichens, fungi, oligochaetes, butterflies and birds. The congruence in species richness and composition among the different taxa was tested by Spearman rank correlation coefficient. Most of the pair-wise comparisons showed weak and statistically not significant correlations for both species richness and compositional data, indicating a limited cross-taxon congruence. Species richness of vascular plants was significantly correlated only to that of birds and butterflies. Compositional patterns were congruent only between vascular plants and butterflies. The results of this study indicated that neither vascular plants nor any other taxonomic group is a valid surrogate in this nature reserve.

Migration Bottlenecks, Climate, and the Conservation of Pleistocene Relicts in Central Asia

Land bridges once assured transcontinental connectivity, but climate-induced habitat loss resulted in the extinc- tion of numerous North American large mammals. Using GPS technology on the formerly widespread but now endan- gered saiga in Mongolia, we identified a fine-scaled 5-km wide critical corridor, whose protection is critical for maintain- ing migration and meta-population structure. The world's great overland migrations are disappearing, truncating fundamental processes that have contributed to ecosystem functioning for millennia. With more people reli- ant on lands that were once remote, intact habitats are now replaced by livestock, fences, and people (1). Nevertheless, expansive grasslands and deserts in China, Mongolia, Ka- zakhstan, and Russia still sustain extraordinary movements between winter and summer ranges, including those of chiru (Pantholops hodgsonii), white-(Procapra gutturosa) and black-tailed (Gazella subgutturosa) gazelles, khulan (Equus hemionus), saiga (Saiga tatarica), and Bactrian camels (Camelus bactrianus) (2 - 4). The latter three species - all recognized as endangered by the IUCN - along with mam- moths, Panthera lions, and wild horses (Equus spp.) once moved between Asia and North America using the Bering Land Bridge. That conduit for inter-continental movement collapsed during the Late Pleistocene when climate changed, ocean levels rose, and the arid Mammoth Steppe of Beringea disappeared (5). Although saiga, camels, and wild horses were dependent upon these cold-adapted xeric grasslands, such remnant Pleistocene habitats and their associated fauna currently persist in situ only in Central Asia (5). While the Being Land Bridge once enabled connectivity across broad landscapes, today's conservation challenges are appropriately more linked to the maintenance of connectivity among population subunits, protecting corridors at a fine scale, and understanding the direct impacts of humans under an umbrella of climate change. Long-term conservation of fragmented populations requires maintenance of meta- population structure. With the above little-known relicts re- stricted to Central Asia, a critical challenge has been the ac- quisition of knowledge, not only about migration routes, if any, but the protection of land(s) critical to sustaining movements among disjunct population segments (6).

Complex vegetation responses to soil disturbances in mountain grassland

We studied vegetation responses to disturbances originated by ants and voles in subalpine grasslands in the Eastern Pyrenees. We compared the effects of these small-scale disturbances with those of a large-scale disturbance caused by ploughing. We wanted to know if these soil disturbances promoted species richness through the existence of a specific guild of plants colonizing these areas, and if this guild was the same for all soil disturbances, independently of their extent. In general, grassland vegetation seemed to recover relatively quickly from soil-displacement disturbances, and the effects could be scaled up in time and space in terms of species richness and composition. Vole mound composition was similar to that in the surrounding grassland, suggesting that mounds were rapidly colonized by the neighbouring vegetation. Vegetation composition differed between the grassland and the ant mounds. Grasses and erect dicots coped well with repeated disturbance, while rosette-forming species and sedges were very sensitive to it. Landscape processes could be important to understanding recolonization. Species from xeric grasslands were found in mesic grasslands when disturbed by ploughing and on the tops of active ant mounds. Furrows in mesic grasslands recovered well, but decades after disturbance showed long persistence of some xeric species and increased species richness compared to terraces, while xeric grasslands showed decreased richness. This suggests that, because of those disturbances, within-habitat diversity was increased, although landscape diversity was not. However, specific disturbances showed idiosyncratic effects, which could enhance the species richness globally. In ant-affected areas, the grassland itself showed the highest plant species richness, partially associated to the presence of some species with elaiosomes not, or only rarely, found in adjacent grasslands without ant mounds. Therefore, soil disturbances occurring at different spatial scales contributed to complexity in vegetation patterns in addition to abiotic factors and grazing.

The Integrated Plant Record: An Essential Tool For Reconstructing Neogene Zonal Vegetation In Europe

A semi-quantitative evaluation method has been developed to map integrated fossil plant records (leaf, fruit, and pollen assemblages) in terms of zonal vegetation. It incorporates taxonomy, physiognomy, and autecological features of the fossil plants. To derive vegetation types, the final stage of this method involves a quantitative evaluation. The maps presented here are based on 198 organ assemblages from 173 localities and stratigraphic levels of the Miocene–early Pliocene across Europe. They cover three time intervals: (1) 4–7 Ma (Messinian–middle Zanclean; late Miocene–early Pliocene); (2) 8.5– 12 Ma (latest Serravallian–middle Tortonian); and (3) 14–17 Ma (late Burdigalian–late Langhian). We also look at the interval 13–14 Ma (late Langhian–early Serravallian). They not only show vegetation types but offer more detailed information on the composition of these associations (proportions of major components). The major zonal vegetation types recognized here are broad-leaved deciduous forests, mixed mesophytic forests, broad-leaved evergreen forests, subhumid sclerophyllous forests, open woodlands, and xeric grasslands. Between 14 Ma and 17 Ma, broad-leaved evergreen forests were widespread, and subhumid sclerophyllous forests were more strongly represented in western parts of Central Europe than in eastern parts. In the interval 8.5–12 Ma, broad-leaved deciduous forests largely replaced the evergreen forests, although these were still present in some refugia (e.g., the Lower Rhine embayment and northern Balkan peninsula), and first records of xeric grasslands are found along the northern margin of the Black Sea. The more discontinuous record available from 4 Ma to 7 Ma indicates that broad-leaved evergreen forests still occurred in northern parts of the Mediterranean (northern Italy, Balkan peninsula), while open woodlands increasingly appeared in central and southern parts of Italy and Greece.

Revisiting urban refuges: Changes of butterfly and burnet fauna in Prague reserves over three decades

We studied changes in the composition of butterfly and burnet fauna in 25 reserves of xeric grasslands within the city Prague, Czech Republic, based on a recent repetition of a survey conducted three decades ago. The past and recent survey detected 91 and 84 species, 12 species were lost and four were gained between the surveys. There was no significant change in mean numbers of species per reserve or in mean species incidences, even if the categories of the habitat association, mobility and body size were analysed separately. Contrary to these comparisons, ordination analyses indicated a significant shift in species composition in individual reserves. Species of short-sward xeric grasslands tended to be associated with the past survey, whereas species of taller grasslands and xeric scrub were associated with recent survey. These shifts were more prominent in large reserves with high proportion of natural (as opposed to urban) perimeter, connected with other reserves, having diverse topography and high plant and biotope richness. We interpret this by gradual successional changes which affect the reserves despite conservation management. Despite these changes, butterfly losses were lower than in comparable surveys recently conducted elsewhere in Central Europe, partly because major losses occurred long before the 1980s survey and partly owing to a high heterogeneity of the urban landscape surrounding the reserves.

Spoločenstvá suchozemských mäkkýšov severnej časti Devínskej Kobyly (Malé Karpaty) [Land snail assemblages of the north part of the Devínska Kobyla hill (Malé Karpaty Mts., SW Slovakia)

Present paper is focused on two topics. First topic is focused on evaluation of mollusc assemblages of northern part of the Devínska Kobyla hill (Malé Karpaty Mts.). The second topic was evaluation of all published data on molluscs of this area. The research was conducted during vegetation period of the year 1978. From 9 types of biotopes altogether 47 quantitative samples were sampled. The assemblages were evaluated on the base of constancy and dominance of the species. Altogether 7913 mollusc specimens were obtained from the samples. Composition and status of the forest mollusc assemblages in northern part of the Devínska Kobyla was shown to be determined by the substratum, age of forest stand and the degree of the biotopes disturbance. The species richest assemblage was detected within old grown forest (biotope 7) and calcareous substratum. The species poorest were assemblages found within clear-cut and young stand (biotopes 5, 8). Species rich community was found also in old growth forest with quartzite substratum, however a number of steppe species is absent within this biotope. The molluscan communities of open habitats were observed only in the northern part of the Devínska Kobyla foothill area. They occur mainly within xeric degraded grassland biotopes (vacant pastures, deforested fields). Within other non-limestone substratum biotopes only species poor coenoses composed of single or e few of species occurred (biotopes 2 and 6). The exception was the natural xeric grassland biotopes, which were typical biotopes for rich community of steppe molluscs (biotope 9). Extremely rich were limestone rocks, which are in addition partially covered by forest. The rich forest land snail community together with a number of xeric species was found here (biotope 3). In second part mollusc species composition of northern and southern part of the Devínska Kobyla massive and the Devínske Hradné Bralo hill are compared. Altogether 65 mollusc species (51 species in north part, 44 species in south part, 37 species in the Devín Castle hill) were found in whole area until nowadays. 10 mollusc species were found only in the southern part of the Devínska Kobyla massive (Bythinella austriaca, Chondrula tridens, Zebrina detrita, Vitrea subrimata, Nesovitrea hammonis, Limax cinereoniger, Limax maximus, Arion fuscus, Pisidium casertanum a P. personatum), 5 species were found only in northern part of the Massive (Platyla polita, Pyramidula pusilla, Vertigo pusilla, Vitrea crystallina, Monachoides vicinus) and 4 species were only found in the Devínske Hradné Bralo hill (Pupilla sterri, Balea perversa, Trichia striolata danubialis, Fruticicola fruticum). During our research 3 species new not published from this area were found (Platyla polita, Nesovitrea hammonis and Limax maximus).

Patterns of functional clonal traits and clonal growth modes in contrasting grasslands in the central Apennines, Italy

Abstract. Aim: Patterns of plant functional traits related to clonality (clonal growth modes; CGM) in plant communities were studied and hypotheses on the importance of the selected traits in plant communities supported by soils differing in moisture and nutrient status were tested.Material and Methods: Selected plant functional traits, such as the position of the mother‐daughter plants connections, length of spacers, frequency of multiplication, persistency of ramets connections, presence of storage organs and bud protection were studied in two contrasting plant communities (xeric and mesic abandoned pastures) typical of central Apennines, Italy.Results and Discussion: Clonality was shown to be of great importance in both mesic and xeric grasslands. The major differences between the two communities were due to the dominant CGMs: turf graminoids (having effective protection of growth meristems in dense tussocks) dominated xeric grasslands, while rhizomatous graminoids (typical of competitive resource‐rich environments) dominated mesic grasslands. Below‐ground CGOs (clonal growth organs), shorter spacers, higher multiplication potential, permanent ramet connection, large bud bank and increased importance of bud protection were found to be of importance in water stressed xeric grassland. Contrary to our expectations, the mesic (less stressed) grasslands have the higher number of clonal plants possessing storage organs.

Patterns of functional clonal traits and clonal growth modes in contrasting grasslands in the central Apennines, Italy

Abstract Aim: Patterns of plant functional traits related to clonality (clonal growth modes; CGM) in plant communities were studied and hypotheses on the importance of the selected traits in plant communities supported by soils differing in moisture and nutrient status were tested. Material and Methods: Selected plant functional traits, such as the position of the mother-daughter plants connections, length of spacers, frequency of multiplication, persistency of ramets connections, presence of storage organs and bud protection were studied in two contrasting plant communities (xeric and mesic abandoned pastures) typical of central Apennines, Italy. Results and Discussion: Clonality was shown to be of great importance in both mesic and xeric grasslands. The major differences between the two communities were due to the dominant CGMs: turf graminoids (having effective protection of growth meristems in dense tussocks) dominated xeric grasslands, while rhizomatous graminoids (typical of competitive resource-ric...

Having your wildlife and eating it too: an analysis of hunting sustainability across tropical ecosystems

AbstractUnsustainable hunting of wildlife or bushmeat for human consumption across the tropics threatens both wildlife populations and the livelihoods of people who depend on these resources. The probability that hunting can be sustainable depends in part on ecological conditions that affect the ‘supply’ of and ‘demand’ for wildlife resources. In this study, supply is estimated across a number of tropical ecosystem types by calculating the theoretical ‘maximum sustainable offtake’ in kg/km2 for harvestable wildlife. Demand is estimated from observed harvests in kg/km2. We examine how supply and demand vary across relatively undisturbed ecosystems, indexed by annual rainfall. Supply is potentially highest in dry forests and wetter savannah grasslands and decreases in moist forests and more xeric grasslands. Demand tends to exceed supply in moist forests and xeric grasslands. Analogous to this ecological variation along the rainfall gradient is the gradient created by the conversion of tropical forests by humans. We hypothesise that the wild meat supply is greater in secondary forests and forest–farm–fallow mosaics than in undisturbed forests and test this with available data. We conclude that the probability that hunting will be sustainable varies with ecosystem type and degree of human disturbance and should influence where land is zoned for protected areas and where for wildlife harvests.

Role of topography and soils in grassland structuring at the landscape and community scales

Abstract The relative importance of abiotic factors in community assembly is debated and thought to be dependent on the scale. I investigated the relative role of topography and soils as structuring agents at the landscape and the community scales in 126 subalpine calcareous grasslands in the Pyrenees, in terms of species composition and abundance. I wished to know: (1) the role of abiotic factors in the organization of plant communities across the landscape; (2) how much of the variation in community distribution was accounted for by abiotic factors; and (3) how well their role applied to the distribution of dominant species at the landscape and the community scales. The hypothesis was: abiotic factors play an important role in community distribution in the landscape, but species interactions are more important within communities. Multivariate methods generated four communities, organized in two contrasting groups along the main vegetation axis, which explained 13% of the variation: mesic grasslands ( Nardus stricta and Festuca nigrescens communities) and xeric grasslands ( Carex humilis and Festuca gautieri communities). Mesic communities were more acidic and fertile than xeric communities. Changes in the abiotic environment, accounting for up to 80% of the variation in the vegetation, were smooth, while the transition between xeric and mesic grasslands was sharp in terms of species composition. The distribution in the landscape of the first main species from each community was closely related to abiotic factors, which modeled poorly the abundance of the main species at smaller scales. At the within-community scale, the explanatory power of biotic relationships was community dependent, producing the most significant models for plants highly dominant within their communities, such as N. stricta and F. gautieri . Contrary to current hypothesis, there was a shift from mainly positive relationships among dominant species in fertile mesic communities to mainly negative in infertile xeric ones.