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1.
Syntaxonomy and biogeography of dry grasslands on calcareous substrates in the central and southern Balkans
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Vlado Matevski Andraž Čarni Renata Ćušterevska Mitko Kostadinovski Ladislav Mucina 《应用植被学》2018,21(3):488-513
Questions
Which major syntaxa of dry grasslands supported by carbonate bedrock occur in the central and southern Balkans? What is their position along major ecological gradients and in the context of phytogeographic patterns of the region?Location
Central and southern Balkans, including western Bulgaria, northern Greece, Kosovo, Macedonia (FYROM) and Serbia.Methods
We compiled a matrix of 660 relevés of dry grasslands over lime‐rich bedrock, previously classified in the Festuco‐Brometea. We applied clustering techniques to classify separately synoptic and relevé data, and applied NMDS with passive projection of indicator values, climatic data and biogeographic geo‐elements onto ordination diagrams to assist interpretation of the syntaxonomic patterns. We constructed elevation distribution profiles for alliances and classes of grasslands of several grassland classes from a broader study area to elucidate the relationship of the elevational sorting of the syntaxa in relation to latitude.Results
The analysis revealed six major vegetation types, classified into four orders: (1) Stipo pulcherrimae‐Festucetalia pallentis, incl. (sub)montane rocky steppic grasslands of the Saturejion montanae of central Balkans, and the Koelerio‐Festucion dalmaticae – submontane rocky grasslands of southern Serbia and Kosovo; (2) Astragalo onobrychidis‐Potentilletalia represented by the Saturejo‐Thymion (low‐elevation steppic grasslands of southern Balkans); (3) Festucetalia valesiacae represented by grasslands on deep soil and low elevation of northern Greece, and finally (4) high‐elevation rocky grasslands of southern Balkans, classified as a new alliance – Diantho haematocalycis‐Festucion hirtovaginatae, that might belong to a new, yet undescribed, syntaxonomic order. Ordination suggests that the major differentiation of the high‐rank syntaxa follows north–south geographic and low–high elevation gradients.Conclusions
Because of the transitional biogeographic position of the studied region, as well as considerable large elevation span across latitudes, the diversity of vegetation types is high. The indication a putative new dry grassland order, the mid‐high altitudes of the southern Balkans points to a need to re‐assess the Balkan vegetation occupying the community niche between the low‐elevation dry grasslands (Festuco‐Brometea) and those typical of high elevations (Elyno‐Seslerietea and Daphno‐Festucetea), seeking parallels to patterns described from the western Alps, Pyrenees, and Apennines. This syntaxonomic unit is poised to expand the concept of the Festuco hystricis‐Ononidetea striatae to the Balkans.2.
3.
Marcelo Cabido Sebastián R. Zeballos Marcelo Zak María L. Carranza Melisa A. Giorgis Juan J. Cantero Alicia T. R. Acosta 《应用植被学》2018,21(2):298-311
Question
What are the composition and spatial patterns of native woody plant communities in the southern Great Chaco and Espinal?Location
Córdoba Province, central Argentina, an area of ca. 161,000 km2.Methods
We collected 351 geo‐referenced relevés representative of the geographic, topographic and ecological variation of the Chaco and Espinal woody vegetation in central Argentina. The relevés were classified into vegetation types using the hierarchical ISOPAM method. Forest and shrubland types were described on the basis of diagnostic species occurrences and their distribution in relation to environmental factors. A map of the actual vegetation derived from remote‐sensed images (Landsat) and field data was used to describe the current distribution and abundance of the different vegetation types.Results
The classification of the 351 plots × 837 species matrix revealed two major clusters comprising seven woody vegetation types corresponding to Chaco lowland and mountain forests and shrublands, Espinal forests and edaphic vegetation. The most important gradients in woody vegetation types are related to elevation, temperature and rainfall variables.Conclusions
Subtropical seasonally dry woody plant communities from the southern extreme of the Great Chaco and Espinal forests were described for the first time based on complete floristic data. Our results show that lowland Chaco native forests, as well as replacement communities, are still present in its southern distribution range and are well distinguishable from other vegetation types such as the Espinal and mountain forests. Overall, extensive Espinal forests have almost disappeared while Chaco vegetation is highly fragmented and degraded.4.
Corrado Marcenò Riccardo Guarino Javier Loidi Mercedes Herrera Maike Isermann Ilona Knollová Lubomír Tichý Rossen T. Tzonev Alicia Teresa Rosario Acosta Úna FitzPatrick Dmytro Iakushenko John A. M. Janssen Borja Jiménez‐Alfaro Zygmunt Kącki Iva Keizer‐Sedláková Vitaliy Kolomiychuk John S. Rodwell Joop H. J. Schaminée Urban Šilc Milan Chytrý 《应用植被学》2018,21(3):533-559
5.
Pavol Eliáš Jr Desislava Sopotlieva Daniel Dítě Petra Hájková Iva Apostolova Dušan Senko Zuzana Melečková Michal Hájek 《应用植被学》2013,16(3):521-537
Question
How does the plant species composition of Pontic–Pannonian salt‐rich habitats vary on a large geographical scale? Do the floristic differences between Pannonia and the Balkans correspond to the current phytosociological classification?Location
Pannonia (Hungary, Slovakia, Austria, Czech Republic, Croatia, Serbia, Romania) and the Balkans (Bulgaria, Macedonia, Greece).Methods
Two thousand four hundred and thirty‐seven relevés from halophytic and sub‐halophytic habitats were classified using a modified TWINSPAN. The crispness of classification was checked. DCA and CCA with climate data as explanatory variables were applied.Results
The classification was best interpreted at the level of 15 clusters. The vegetation changed along the salinity gradient from sub‐halophytic grasslands (including Trifolion resupinati alliance of the Molinio‐Arrhenatheretalia class and Beckmannion eruciformis and Festucion pseudovinae p. p. alliances of the Festuco‐Puccinellietea class) and reed beds (Bolboschoenion maritimi p. p. alliance; the Phragmito‐Magnocaricetea class), through steppe and wet inland halophytic vegetation (Festucion pseudovinae p. p., Puccinellion limosae, Pucinellion convolutae, Bolboschoenion maritimi p. p. and Juncion gerardii of the Festuco‐Puccinellietea class) towards the extreme halophytic vegetation of the Thero‐Salicornietea, Crypsietea and Juncetea maritimi classes. This gradient was longer in the Balkan region, where it spanned from the sub‐mediterranean salt‐rich grasslands to the extremely halophytic vegetation at the Black Sea coast. The second most important gradient coincided with the water regime. Some vegetation types appeared to be confined to either the Pannonian or the Balkan region (especially within dry sub‐halophytic and steppe halophytic grasslands), while others were distributed across the entire study area. The above‐mentioned pattern did not always correspond with current classification systems.Conclusions
Variation in salt‐rich vegetation predominantly follows the salinity and water regime gradients. Geographical variation, generally coinciding with climatic and historical effects, is also important, especially in drier salt‐rich habitats. Our large‐scale analysis of the floristic variation of salt‐rich habitats might be useful for the unification of classification systems that differ substantially between the countries involved. In addition, the analysis may be useful for adjustment of a classification system in the poorly explored Balkan region, where particular vegetation types were identified with, or delimited from, Central European vegetation types without detailed comparative analysis until now.6.
S. Del Vecchio E. Fantinato J.A.M. Janssen F. Bioret A. Acosta I. Prisco R. Tzonev C. Marcenò J. Rodwell G. Buffa 《应用植被学》2018,21(2):312-321
Question
Coastal environments have often been described as azonal. While this characteristic is clear for the foredune system, it seems less evident for more inland fixed dunes, which host habitats of major conservation concern, whose features seem to be more related to local climatic conditions. We hypothesized that, unlike other coastal habitats, dune perennial grasslands differ floristically and structurally across their European range and that patterns of variation are linked to the corresponding climate.Location
European coasts (Atlantic Ocean, Baltic, Mediterranean, Black Sea).Methods
We used a large data set of phytosociological relevés, representative of coastal grasslands throughout their European range. The role of climatic variables (temperature, precipitation and continentality) in determining the variability in species composition and vegetation structure (by means of life forms) was investigated through CCA, DCA and GLM. The degree of concentration of species occurrences within groups was calculated through the Phi coefficient.Results
Through multivariate analyses we identified seven major types of coastal grassland, corresponding to different geographic areas. The groups significantly differed in their climatic envelope, as well as in their species composition and community structure.Conclusion
Our results confirm the hypothesis that coastal dune perennial grasslands are subjected to local climate, which exerts significant effects on both floristic composition and community structure. As a consequence, coastal grasslands are particularly prone to the effect of possible climate change, which may alter species composition and distribution, and lead to shifts in the distribution of native plant communities.7.
Aims
To delineate boundaries of vegetation belts, characterize these belts by indicator species, plant functional types and plant distribution types, and explore options for climate change monitoring.Location
Three research sites in the continental inland of West Greenland.Methods
Based on spatially constrained clustering of 147 vegetation relevés and 145 transect plots of plant communities, boundaries of altitudinal vegetation belts were assessed. Indicators for altitudinal sections were identified from 664 vegetation relevés among vascular plants, bryophytes, lichens and plant functional types using indicator species analysis. The performance of different plant groups along the altitudinal gradient was visualized with response curves.Results
Boundaries of altitudinal vegetation belts were detected at 400, 800 and 1175 m a.s.l. on north‐facing slopes and at 450, 900 and 1250 m a.s.l. on south‐facing slopes. The resulting four vegetation belts were well defined by 99 indicator species and nine indicator plant functional types. Species, plant functional types and vascular plant distribution types showed clear sequences along the altitudinal gradient, which partly resemble their distribution along the latitudinal gradient.Conclusions
As an easily observable expansion of shrubs and a decline of mosses and lichens is expected, the boundary at 400/450 m a.s.l. is particularly promising for climate change monitoring. The anticipated replacement of numerous cryophilous by thermophilous indicator species, as well as an obvious shift of plant functional types suggest several monitoring options at 800/900 m a.s.l. The summit areas above 1175/1250 m a.s.l., having a discontinuous plant cover, are considered to be especially vulnerable to fast invasion by species of lower altitudes such as woody plants and sedges. Due to steep gradients and short migration distances in mountains, it can be assumed that these anticipated changes in the study area will be stronger and faster than the already observed changes along the latitudinal gradient in lowland areas of the Arctic.8.
Jaime Fagúndez 《植被学杂志》2018,29(4):765-774
Questions
What is the general pattern of species co‐occurrence in managed heathlands? Is the pattern consistent among functional groups? Is it ruled by species competition, or by contrasting environments at a fine scale? Does grazing pressure and herbivore species condition species interactions?Location
Erica mackayana wet heaths, Galicia, NW Iberian Peninsula.Methods
A null model approach was used to compare species co‐occurrence with generated random matrices from 54 10‐m transects. The C‐score was obtained from the multispecies presence/absence matrix for each transect of shrubs and graminoids recorded at 25‐cm intervals. Differences in canopy height were recorded to assess the importance of the environment compared to inter‐specific competition. Results were linked to different levels of grazing pressure and herbivore species.Results
Species segregation was the main pattern for all species, but mainly among graminoid species compared to shrubs. Graminoids showed an even proportion of segregated pairs explained by different canopy heights and competition. These differences were mainly species environmental requirements of canopy height. Levels of grazing pressure enhanced species segregation in graminoids but had no effect on shrubs or the total species set.Conclusions
Competition and canopy height affect the E. mackayana heathland composition, but differently for functional groups. A heterogeneous vegetation profile with shrub mats and open gaps created by light grazing promotes species co‐existence within mats and competition in gaps. I suggest this is an optimum structure for the habitat to be targeted through management.9.
Propagule pressure and land cover changes as main drivers of red and roe deer expansion in mainland Portugal
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João Carvalho Pelayo Acevedo João P. V. Santos Tânia Barros Emmanuel Serrano Carlos Fonseca 《Diversity & distributions》2018,24(4):551-564
Aim
The management of the rapid expansion of wild ungulate populations is a challenging task and a societal priority. Using a progressive database of red (Cervus elaphus) and roe (Capreolus capreolus) deer colonization over the last three decades, we estimate the range expansion rates and the underlying mechanisms involved in the expansion patterns of red and roe deer populations at the south‐western edge of its European distribution.Location
Mainland Portugal.Methods
We compiled and grouped historical red and roe deer distribution data in three time periods (1981–1990, 1991–2000 and 2001–2010). We used generalized linear mixed models to evaluate how biotic and abiotic drivers determine the expansion patterns of red and roe deer.Results
We reported a significant expansion of red and roe deer populations during the last three decades. The significant interaction between propagule pressure and land cover suggests that the effects of propagule pressure vary along environmental gradients. We found that the influence of livestock on red and roe deer expansion is idiosyncratic. Contrary to red deer, roe deer expansion was also influenced by climatic conditions. We did not detect any significant effect of human factors on the red and roe deer expansion.Main conclusions
The synergistic effects between variables should be taken into account when studying the patterns of species expansion. Our study emphasize that policy makers should consider the spatial, temporal, ecological and societal nuances of species expansion in order to prioritize management measures and to allocate management budgets. Although concerted strategies to curtail species spread should mitigate red and roe deer economic and ecological impacts, these effects can be neutralized by a continuous rural exodus and the consequent forest and shrub encroachment.10.
Higher spring temperatures increase food scarcity and limit the current and future distributions of crossbills
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Eduardo T. Mezquida Jens‐Christian Svenning Ron W. Summers Craig W. Benkman 《Diversity & distributions》2018,24(4):473-484
Aim
Understanding how climate affects species distributions remains a major challenge, with the relative importance of direct physiological effects versus biotic interactions still poorly understood. We focus on three species of resource specialists (crossbill Loxia finches) to assess the role of climate in determining the seasonal availability of their food, the importance of climate and the occurrence of their food plants for explaining their current distributions, and to predict changes in their distributions under future climate change scenarios.Location
Europe.Methods
We used datasets on the timing of seed fall in European Scots pine Pinus sylvestris forests (where different crossbill species occur) to estimate seed fall phenology and climate data to determine its influence on spatial and temporal variation in the timing of seed fall to provide a link between climate and seed scarcity for crossbills. We used large‐scale datasets on crossbill distribution, cover of the conifers relied on by the three crossbill species and climate variables associated with timing of seed fall, to assess their relative importance for predicting crossbill distributions. We used species distribution modelling to predict changes in their distributions under climate change projections for 2070.Results
We found that seed fall occurred 1.5–2 months earlier in southern Europe than in Sweden and Scotland and was associated with variation in spring maximum temperatures and precipitation. These climate variables and area covered with conifers relied on by the crossbills explained much of their observed distributions. Projections under global change scenarios revealed reductions in potential crossbill distributions, especially for parrot crossbills.Main conclusions
Ranges of resource specialists are directly influenced by the presence of their food plants, with climate conditions further affecting resource availability and the window of food scarcity indirectly. Future distributions will be determined by tree responses to changing climatic conditions and the impact of climate on seed fall phenology.11.
Thomas Mang Franz Essl Dietmar Moser Ingrid Kleinbauer Stefan Dullinger 《Diversity & distributions》2018,24(5):652-665
Aim
We develop a novel modelling framework for analysing the spatio‐temporal spread of biological invasions. The framework integrates different invasion drivers and disentangles their roles in determining observed invasion patterns by fitting models to historical distribution data. As a case study application, we analyse the spread of common ragweed (Ambrosia artemisiifolia).Location
Central Europe.Methods
A lattice system represents actual landscapes with environmental heterogeneity. Modelling covers the spatio‐temporal invasion sequence in this grid and integrates the effects of environmental conditions on local invasion suitability, the role of invaded cells and spatially implicit “background” introductions as propagule sources, within‐cell invasion level bulk‐up and multiple dispersal means. A modular framework design facilitates flexible numerical representation of the modelled invasion processes and customization of the model complexity. We used the framework to build and contrast increasingly complex models, and fitted them using a Bayesian inference approach with parameters estimated by Markov chain Monte Carlo (MCMC).Results
All modelled invasion drivers codetermined the A. artemisiifolia invasion pattern. Inferences about individual drivers depended on which processes were modelled concurrently, and hence changed both quantitatively and qualitatively between models. Among others, the roles of environmental variables were assessed substantially differently subject to whether models included explicit source‐recipient cell relationships, spatio‐temporal variability in source cell strength and human‐mediated dispersal means. The largest fit improvements were found by integrating filtering effects of the environment and spatio‐temporal availability of propagule sources.Main conclusions
Our modelling framework provides a straightforward means to build integrated invasion models and address hypotheses about the roles and mutual relationships of different putative invasion drivers. Its statistical nature and generic design make it suitable for studying many observed invasions. For efficient invasion modelling, it is important to represent changes in spatio‐temporal propagule supply by explicitly tracking the species’ colonization sequence and establishment of new populations.12.
Robert Puschendorf Lauren Hodgson Ross A. Alford Lee F. Skerratt Jeremy VanDerWal 《Diversity & distributions》2013,19(10):1313-1321
Aim
Accurately documenting and predicting declines and shifts in species’ distributions is fundamental for implementing effective conservation strategies and directing future research; species distribution models (SDM) have become a powerful tool for such work. Nevertheless, much of the data used to create these models are opportunistic and often violate some of their basic assumptions. We use amphibian declines and extinctions linked to the fungus Batrachochytrium dendrobatidis (Bd) to examine how sampling biases in data collection can affect what we know of this disease and its effect on amphibians in the wild.Location
Queensland, Australia.Methods
We developed a distribution model for Bd incorporating known locality records for Bd and a subset of climatic variables that should correctly characterize its distribution. We tested this (original) model with additional surveys, recorded new Bd observations in novel environments and reran the distribution model. We then investigated the difference between the original and new models, and used frog abundance and infection status data from two of these new localities to look at the susceptibility of the torrent frog Litoria nannotis to chytridiomycosis.Results
While largely correct, the original SDM underestimated the distribution of Bd; sampling in ‘unsuitable’ drier environments discovered abundant populations of susceptible frogs with pathogen prevalences of up to 100%. The validation surveys further uncovered a new population of the frog Litoria lorica coexisting with the pathogen; this species was previously believed to be an extinct rain forest endemic.Main conclusion
Our results indicate that SDMs constructed using opportunistically collected data can be biased if species are not at equilibrium with their environment or because environmental gradients have not been adequately sampled. For disease ecology, the better estimations of pathogen distribution may lead to the discovery of new populations persisting at the edge of their range, which has important implications for the conservation of species threatened by chytridiomycosis.13.
Liba Pejchar Travis Gallo Mevin B. Hooten Gretchen C. Daily 《Diversity & distributions》2018,24(6):811-819
Aim
Ecological restoration is critical for recovering biodiversity and ecosystem services, yet designing interventions to achieve particular outcomes remains fraught with challenges. In the extensive regions where non‐native species are firmly established, it is unlikely that historical conditions can be fully reinstated. To what degree, and how rapidly, can human‐dominated areas be shifted via restoration into regimes that benefit target species, communities or processes?Location
We explore this question in a >20‐year‐old reforestation effort underway at Hakalau Forest National Wildlife Refuge in montane Hawaii. This large‐scale planting of Acacia koa trees is designed to secure populations of globally threatened bird species by transitioning the site rapidly from pasture to native forest.Methods
We surveyed all forest birds in multiple corridors of young planted trees, remnant corridors of mature trees along gulches and at sites within mature forest. Using a Bayesian hierarchical approach, we identified which factors (distance from forest, habitat type and surrounding tree cover) had the most important influence on native and exotic bird abundance in the reforestation area.Results
We found that 90% of native and exotic bird species responded quickly, occupying corridors of native trees approximately a decade after planting. However, native and exotic forest birds responded to markedly different characteristics of the reforested area. Native bird abundance was strongly predicted by proximity to mature forest and remnant corridors; conversely, exotic bird abundance was best predicted by overall tree cover throughout the area reforested.Main conclusions
Our results demonstrate that large‐scale tree planting in corridors adjacent to mature forest can catalyse rapid recovery (both increased abundance and expanded distribution) of forest birds and that it is possible to design reforestation to benefit native species in novel ecosystems.14.
Indirect effects of sea ice loss on summer‐fall habitat and behaviour for sympatric populations of an Arctic marine predator
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Donna D. W. Hauser Kristin L. Laidre Harry L. Stern Robert S. Suydam Pierre R. Richard 《Diversity & distributions》2018,24(6):791-799
Aim
Climate change is fundamentally altering habitats, with complex consequences for species across the globe. The Arctic has warmed 2–3 times faster than the global average, and unprecedented sea ice loss can have multiple outcomes for ice‐associated marine predators. Our goal was to assess impacts of sea ice loss on population‐specific habitat and behaviour of a migratory Arctic cetacean.Location
Arctic Ocean.Methods
Using satellite telemetry data collected during summer‐fall from sympatric beluga whale (Delphinapterus leucas) populations (“Chukchi” and “Beaufort” belugas), we applied generalized estimating equations to evaluate shifts in sea ice habitat associations and diving behaviour during two periods: 1993–2002 (“early”) and 2004–2012 (“late”). We used resource selection functions to assess changes in sea ice selection as well as predict trends in habitat selection and “optimal” habitat, based on satellite‐derived sea ice data from 1990 to 2014.Results
Sea ice cover declined substantially between periods, and Chukchi belugas specifically used significantly lower sea ice concentrations during the late than early period. Use of bathymetric features did not change between periods for either population. Population‐specific sea ice selection, predicted habitat and the amount of optimal habitat also generally did not change during 1990–2014. Chukchi belugas tracked during 2007–2012 made significantly more long‐duration and deeper dives than those tracked during 1998–2002.Main conclusions
Taken together, our results suggest bathymetric parameters are consistent predictors of summer‐fall beluga habitat rather than selection for specific sea ice conditions during recent sea ice loss. Beluga whales were able to mediate habitat change despite their sea ice associations. However, trends towards prolonged and deeper diving possibly indicate shifting foraging opportunities associated with ecological changes that occur in concert with sea ice loss. Our results highlight that responses by some Arctic marine wildlife can be indirect and variable among populations, which could be included in predictions for the future.15.
It's a long way to the top: Plant species diversity in the transition from managed to old‐growth forests
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Sabina Burrascano Francesco Ripullone Liliana Bernardo Marco Borghetti Emanuela Carli Michele Colangelo Carmen Gangale Domenico Gargano Tiziana Gentilesca Giuseppe Luzzi Nicodemo Passalacqua Luca Pelle Anna Rita Rivelli Francesco Maria Sabatini Aldo Schettino Antonino Siclari Dimitar Uzunov Carlo Blasi 《植被学杂志》2018,29(1):98-109
Questions
Do vascular plant species richness and beta‐diversity differ between managed and structurally complex unmanaged stands? To what extent do species richness and beta‐diversity relate to forest structural attributes and heterogeneity?Location
Five national parks in central and southern Italy.Methods
We sampled vascular plant species composition and forest structural attributes in eight unmanaged temperate mesic forest stands dominated or co‐dominated by beech, and in eight comparison stands managed as high forests with similar environmental features. We compared plant species richness, composition and beta‐diversity across pairs of stands (unmanaged vs managed) using GLMM s. Beta‐diversity was quantified both at the scale of each pair of stands using plot‐to‐plot dissimilarity matrices (species turnover), and across the whole data set, considering the distance in the multivariate species space of individual plots from their centroid within the same stand (compositional heterogeneity). We modelled the relationship between species diversity (richness and beta‐diversity) and forest structural heterogeneity and individual structural variables using GLMM s and multiple regression on distance matrices.Results
Species composition differed significantly between managed and unmanaged stands, but not richness and beta‐diversity. We found weak evidence that plant species richness increased with increasing levels of structural heterogeneity and canopy diversification. At the scale of individual stands, species turnover was explained by different variables in distinct stands, with variables related to deadwood quantity and quality being selected most often. We did not find support for the hypothesis that compositional heterogeneity varies as a function of forest structural characteristics at the scale of the whole data set.Conclusions
Structurally complex unmanaged stands have a distinct herb layer species composition from that of mature stands in similar environmental conditions. Nevertheless, we did not find significantly higher levels of vascular plant species richness and beta‐diversity in unmanaged stands. Beta‐diversity was related to patterns of deadwood accumulation, while for species richness the evidence that it increases with increasing levels of canopy diversification was weak. These results suggest that emulating natural disturbance, and favouring deadwood accumulation and canopy diversification may benefit some, but not all, facets of plant species diversity in Apennine beech forests.16.
How to fit the distribution of apex scavengers into land‐abandonment scenarios? The Cinereous vulture in the Mediterranean biome
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Isabel García‐Barón Ainara Cortés‐Avizanda Peter H. Verburg Tiago A. Marques Rubén Moreno‐Opo Henrique M. Pereira José A. Donázar 《Diversity & distributions》2018,24(7):1018-1031
Aim
Farmland abandonment or “ecological rewilding” shapes species distribution and ecological process ultimately affecting the biodiversity and functionality of ecosystems. Land abandonment predictions based on alternative future socioeconomic scenarios allow foretell the future of biota in Europe. From here, we predict how these forecasts may affect large‐scale distribution of the Cinereous vulture (Aegypius monachus), an apex scavenger closely linked to Mediterranean agro‐grazing systems.Location
Iberian Peninsula.Methods
Firstly, we modelled nest‐site and foraging habitat selection in relation to variables quantifying physiography, trophic resources and human disturbance. Secondly, we evaluate to what extent land abandonment may affect the life traits of the species and finally we determined how potential future distribution of the species would vary according to asymmetric socioeconomic land‐abandonment predictions for year 2040.Results
Cinereous vultures selected breeding areas with steep slopes and low human presence whereas foraging areas are characterized by high abundance of European rabbits (Oryctolagus cuniculus) and wild ungulates. Liberalization of the Common Agricultural Policy (CAP) could potentially transform positively 66% of the current nesting habitat, favouring the recovery of mature forest. Contrarily, land abandonment would negatively affect the 63% of the current foraging habitat reducing the availability of preferred food resources (wild European rabbit). On the other hand, the maintenance of the CAP would determine lower frequencies (24%–22%) of nesting and foraging habitat change.Main conclusions
Land abandonment may result into opposite effects on the focal species because of the increase in nesting habitats and wild ungulates populations and, on the other hand, lower availability of open areas with poorer densities of European rabbits. Land‐abandonment models’ scenarios are still coarse‐grained; the apparition of new human uses in natural areas may take place at small‐sized and medium‐sized scales, ultimately adding complexity to the prediction on the future of biota and ecosystems.17.
Exploring invasibility with species distribution modeling: How does fire promote cheatgrass (Bromus tectorum) invasion within lower montane forests?
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Aim
Cheatgrass (Bromus tectorum) is notorious for creating positive feedbacks that facilitate vegetation type conversion within sagebrush steppe ecosystems in the western United States. Similar dynamics may exist in adjacent lower montane forest. However, fire‐forest‐cheatgrass dynamics have not been examined. We used species distribution modeling to answer three questions about fire and invasibility in lower montane forests: (Q1) Does fire create more suitable habitat for cheatgrass? (Q2) If so, which site attributes are altered to increase site suitability? (Q3) Does fire increase connectivity among suitable habitat and enhance spread?Location
Shoshone National Forest, Wyoming, USA.Methods
We measured cheatgrass presence–absence in 93 plots within Interior Douglas‐fir (Pseudotsuga menziesii var. glauca) forests. Random Forests predicted cheatgrass distribution with and without fire using nine site attributes: elevation, slope, aspect, solar radiation, annual precipitation, maximum temperature in July, minimum temperature in January, forest canopy cover and distance to nearest trail or road. Additionally, invasion pathways and spread were mapped using Circuitscape.Results
Cheatgrass distribution was controlled by topographic and climate variables in the absence of fire. In particular, cheatgrass was most likely to occur at low elevation along dry, south‐ and east‐facing slopes. High‐severity fire increased potential cheatgrass distribution when forest canopy cover was reduced to below 30%. This process created new invasion pathways, which enhanced cheatgrass spread when modelled in Circuitscape.Main conclusions
Our study showed that in the absence of fire, drier south‐ and east‐facing slopes at low elevation are most susceptible to cheatgrass invasion. However, high‐severity fire increased the total area susceptible to invasion—allowing cheatgrass to expand into previously unsuitable sites within lower montane forests in the western United States. These results are important for present day management and reflect that integrating responses to disturbance in species distribution models can be critical for making predictions about dynamically changing systems.18.
SOST,an LNGFR target,inhibits the osteogenic differentiation of rat ectomesenchymal stem cells
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Gang Li Junyu Liu Manzhu Zhao Yingying Wang Kun Yang Chang Liu Yong Xiao Xiujie Wen Luchuan Liu 《Cell proliferation》2018,51(2)
Objectives
The aim of this study was to investigate whether sclerostin (SOST) regulates the osteogenic differentiation of rat ectomesenchymal stem cells (EMSCs) and whether SOST and low‐affinity nerve growth factor receptor (LNGFR) regulate the osteogenic differentiation of EMSCs.Materials and methods
EMSCs were isolated from embryonic facial processes from an embryonic 12.5‐day (E12.5d) pregnant Sprague‐Dawley rat. LNGFR+ EMSCs and LNGFR? EMSCs were obtained by fluorescence‐activated cell sorting and were subsequently induced to undergo osteogenic differentiation in vitro. SOST/LNGFR small‐interfering RNAs and SOST/LNGFR overexpression plasmids were used to transfect EMSCs.Results
LNGFR+ EMSCs displayed a higher osteogenic capacity and lower SOST levels compared with LNGFR? EMSCs. SOST silencing enhanced the osteogenic differentiation of LNGFR? EMSCs, while SOST overexpression attenuated the osteogenic differentiation of LNGFR+ EMSCs. Moreover, LNGFR was present upstream of SOST and strengthened the osteogenic differentiation of EMSCs by decreasing SOST.Conclusions
SOST alleviated the osteogenic differentiation of EMSCs, and LNGFR enhanced the osteogenic differentiation of EMSCs by decreasing SOST, suggesting that the LNGFR/SOST pathway may be a novel target for promoting dental tissue regeneration and engineering.19.
Alexandra G. Lodge Timothy J. S. Whitfeld Alexander M. Roth Peter B. Reich 《植被学杂志》2018,29(4):746-755
Questions
Predicting which newly arrived species will establish and become invasive is a problem that has long vexed researchers. In a study of cold temperate oak forest stands, we examined two contrasting hypotheses regarding plant functional traits to explain the success of certain non‐native species. Under the “join the locals” hypothesis, successful invaders are expected to share traits with resident species because they employ successful growth strategies under light‐limited understorey conditions. Instead, under the “try harder” hypothesis, successful invaders are expected to have traits different from native species in order to take advantage of unused niche space.Location
Minnesota, USA.Methods
We examined these two theories using 109 native and 11 non‐native plants in 68 oak forest stands. We focused on traits related to plant establishment and growth, including specific leaf area (SLA), leaf carbon‐to‐nitrogen ratio (C:N), wood density, plant maximum height, mycorrhizal type, seed mass and growth form. We compared traits of native and non‐native species using ordinations in multidimensional trait space and compared community‐weighted mean (CWM) trait values across sites.Results
We found few differences between trait spaces occupied by native and non‐native species. Non‐native species occupied smaller areas of trait space than natives, yet were within that of the native species, indicating similar growth strategies. We observed a higher proportion of non‐native species in sites with higher native woody species CWM SLA and lower CWM C:N. Higher woody CWM SLA was observed in sites with higher soil pH, while lower CWM C:N was found in sites with higher light levels.Conclusions
Non‐native plants in this system have functional traits similar to natives and are therefore “joining the locals.” However, non‐native plants may possess traits toward the acquisitive end of the native plant trait range, as evidenced by higher non‐native plant abundance in high‐resource environments.20.
David G. Chapple Kimberly A. Miller Fred Kraus Michael B. Thompson 《Diversity & distributions》2013,19(2):134-146