170 research outputs found
Intraspecific functional differences of subalpine plant species growing in low-altitude microrefugia and high-altitude habitats
No full textMountain ice holes are microrefugia at low altitudes characterized by colder temperatures compared to the surrounding areas. Ice holes harbor extra-zonal plant communities composed of plant species that generally grow at higher altitudes in subalpine habitats. Understanding how subalpine species adjust their functional traits to extra-zonal environmental conditions in ice holes can improve our knowledge of plants’ ability to cope with environmental changes. We compared the intraspecific trait variability of four species growing in ice holes and in subalpine areas in the south-eastern Alps of Italy. Plant functional traits presented different patterns of variation between the two habitats. Leaf area, leaf nitrogen and phosphorus content and stomatal traits (stomatal density and stomatal length) differed consistently between habitats in all species. Conversely, specific leaf area and leaf dry matter content varied differently between habitats depending on species. The four species developed differing strategies for adapting leaf functional traits to the peculiar environment of ice holes. Two species, Vaccinium myrtillus and Rhododendron ferrugineum, took advantage of extra-zonal location by developing a more competitive ecological strategy. Conversely, Vaccinium vitis-idaea and Homogyne alpina adopted a more conservative strategy by optimizing adaptation of leaf traits to cold temperature. Our study represents a first attempt to understand the role of marginal populations within the total functional variation of a species. We highlighted the importance of protecting ice holes as important reservoirs of functional diversity for subalpine plant species
Hierarchical bayesian models of social inference for probing persecutory delusional ideation
No full textWhile persecutory delusions (PDs) have been linked to fallacies of reasoning and social inference, computational characterizations of delusional tendencies are rare. Here, we examined 151 individuals from the general population on opposite ends of the PD spectrum (Paranoia Checklist [PCL]). Participants made trial-wise predictions in a probabilistic lottery, guided by advice from a more informed human and a nonsocial cue. Additionally, 2 frames differentially emphasized causes of invalid advice: (a) the adviser’s possible intentions (dispositional frame) or (b) the rules of the game (situational frame). We applied computational modeling to examine possible reasons for group differences in behavior. Comparing different models, we found that a hierarchical Bayesian model (hierarchical Gaussian filter) explained participants’ responses better than other learning models. Model parameters determining participants’ belief updates about the adviser’s fidelity and the contribution of prior beliefs about fidelity to trial-wise decisions, respectively, showed significant Group × Frame interactions: High PCL scorers held more rigid beliefs about the adviser’s fidelity across both experimental frames and relied less on advice in situational frames than low scorers. These results suggest that PD tendencies are associated with rigid beliefs and prevent adaptive use of social information in “safe” contexts. This supports previous proposals of a link between PD and aberrant social inference. (PsycInfo Database Record (c) 2021 APA, all rights reserved
Plant diversity and annual layer counting based on pollen analyses of an Adamello glacier ice core
No full textTrait-based assembly rules across climatic gradients of European grasslands
No full textBackground & Aims: Trait-based studies of species assembly reveal mechanisms of species coexistence. Are these mechanisms similar within European grasslands? Are these mechanisms influenced by site-specific disturbance history?
We investigated fine-scale patterns of trait-based community assembly in European grasslands across continental gradients within the framework of the BiodivERsA project SIGNAL. The gradient extends from the mesic grasslands in France and Germany (P: 1200 to 750 mm/year; T: 8 to 7°C respectively), to intermediate ones in Italy and Bulgaria (P: 880 to 560 mm/year; T: 12,1 to 10,2°C respectively), to the xeric ones in Turkey and Hungary (P: 715 to 550 mm/year; T: 16,7 to 10,5°C respectively).
The sites also differ in management, disturbance history, geology and edaphic factors. They represent common types of grasslands of the respective study country.
Methods: Fine-scale patterns of species combinations (rooting individuals) were sampled in 2.80 m x 0.40 m blocks, subdivided into 448 microquadrats of 25 cm2 (5 cm x 5 cm). For representing within site heterogeneity, six blocks were sampled at each site. Three important plant traits (specific leaf area, plant height and seed mass) were assessed (from literature and direct measurements) for all recorded vascular herbaceous species. Based on these traits, the functional diversity (Rao index) was calculated for each microquadrats and compared to a null model. We used Schamp’s methods (Schamp 2008) for randomization (keeping the abundances of species and the local species richness as in the field and assigning traits at random to each species combinations). Deviation of functional diversity from random expectation was interpreted as trait divergence or trait convergence.
Main Results & Interpretations: Several occurrences of trait-based assembly rules could be detected across countries. The strongest deviations from randomness in terms of seed mass were found in the Turkish grassland (driest one). In Bulgaria, Hungary, France and Germany, by contrast, a convergence of seed mass was seen. Strong convergence of plant heights appeared in Germany and France, in tall mesic grasslands, while this trait showed random patterns in dry grasslands. The Turkish grassland showed convergence for SLA. Similar tendency occurred at the German and the Italian sites while France and Bulgaria mostly showed random patterns. Based on our first results, we conclude that assembly rules can be contrasting and context dependent (cf. Wellstein et al. 2014) at different grassland sites and climatic differences are often masked by local factors (e.g. by disturbance regime or soil heterogeneity). For example Italian grasslands showed both convergence and divergence of seed mass even at nearby blocks indicating heterogeneous environmental conditions and complex site history
Differences in gene expression of drought-stress candidate genes across natural populations of Quercus pubescens Willd. in Italy. IUFRO 2012 Genetics of Fagaceae and Nothofagaceae. Poster abstracts. Bordeaux.
No full textUnderstanding plant species acclimation and adaptation to climatic changes is one of the
most interesting challenges at the interface of ecology, physiology and genetics. In this
context, the investigation of functional genetic diversity related to stress tolerance of natural
populations in a contrasting climatic context is a promising approach. Plant responses to
drought stress are complex, involving a number of genes which contribute to drought
adaptation.
Here we use 30 candidate genes involved in drought-stress response in Q. robur (Brendel,
Kremer, Le Provost, pers. com.). These candidate genes are involved in processes such as
transpiration regulation, stomatal development, stomatal light response, cuticle biosynthesis,
and water use efficiency. We tested for differential gene expression in natural populations of
Quercus pubescens Willd. at mesic and xeric sites in Central and Southern Italy. For this
purpose, RNA was extracted from leaf material of 100 individuals. We aimed to identify
markers for climatic acclimation and adaptation of natural populations.
Results of SIMPER analysis for dissimilarity revealed that four out of 30 candidate genes
appear as main factors which differentiate the samples. In detail, significant differences in
gene expression were most obvious between the most mesic (central Italy) compared to the
most xeric (S Italy) site.
It will be a challenge for future research to tackle if these markers reappear in the droughtstress
response in other tree species or plants in general
Variability of clonal growth of European grass species in climate change experiments.
No full textWe investigate the impact of climate change phenomena such as drought and warming on the clonal growth of European key grass species (Alopecurus pratensis, Arrhenatherum elatius, Festuca pratensis, and Holcus lanatus
Effects of extreme weather events on Apennines grasslands productivity.
No full textExtreme weather events are expected to increase in frequency and magnitude due to climate change especially on Mediterranean chains, but their effect on ecosystem services and vegetation processes are widely unknown. Prediction of future impacts has become critical to conservation planning and management, particularly in protected areas.
Our research has been carried out in the Torricchio Nature Reserve (Central Apennines, Italy), 317 ha under strict protection since 1970, owned and managed by the University of Camerino.
Two contrasting grassland ecosystems under different environmental conditions (North and South facing slopes) were selected to simulate extreme events. The magnitude of a given recurrence interval (1000 year) were estimated by the application of extreme value distributions on climate data series covering 50 years.
In both slopes, the weather manipulations consisted of extreme drought (D), additional rainfall (R) and ambient conditions for control (C). The experiment covered 2 years (2011 and 2012). Once a year, at the end of the treatment period, the above-ground biomass was collected.
No significant differences between treatments were found in the productivity of the stony terrain of the S facing slope, while significant results were detected between the climatic extremes (D vs R) in the N facing slope with dense plant cover. In any case, the experimental treatments of the S facing slope, show a high level of biomass variability, demonstrating the importance of the fine-scale environmental heterogeneity.
The effects of climatic alteration on productivity of montane grasslands, underlines the crucial importance of future research on the outcome of climate change in these systems
Survival in nunatak and peripheral glacial refugia of three alpine plant species is partly predicted by altitudinal segregation
No full textMountain biota survived the Quaternary cold stages most probably in peripheral refugia and/or ice-free peaks within ice-sheets (nunataks). While survival in peripheral refugia has been broadly demonstrated, evidence for nunatak refugia is still scarce. We generated RADseq data from three mountain plant species occurring at different elevations in the southeastern European Alps to investigate the role of different glacial refugia during the Last Glacial Maximum (LGM). We tested the following hypotheses. (i) The deep Piave Valley forms the deepest genetic split in the species distributed across it, delimiting two peripheral refugia. (ii) The montane to alpine species Campanula morettiana and Primula tyrolensis survived the LGM in peripheral refugia, while high-alpine to subnival Saxifraga facchinii likely survived in several nunatak refugia. (iii) The lower elevation species suffered a strong population decline during the LGM. By contrast, the higher elevation species shows long-term stability of population sizes due to survival on permanently ice-free peaks and small population sizes at present. We found peripheral refugia on both sides of the Piave Valley, which acted as a major genetic barrier. Demographic modelling confirmed nunatak survival not only for S. facchinii but also for montane to alpine C. morettiana. Altitudinal segregation influenced the species' demographic fluctuations, with the lower elevation species showing a significant population increase at the end of the LGM, and the higher elevation species either showing decrease towards the present or stable population sizes with a short bottleneck. Our results highlight the role of nunatak survival and species ecology in the demographic history of mountain species
Climate change response of vegetation across climatic zones in Italy
No full textItaly represents a good model region for assessing vegetation responses to changing climate across a broad climatic range, from Mediterranean warm-dry climate to alpine cold-humid climate. We reviewed results of studies analysing the response of natural vegetation to climate change in Italy, published until July 2016 in peer-reviewed journals. Evidence provided by these studies shows that climate warming is expected overall to enhance plant growth in Italy, but the magnitude of growth stimulation will probably vary among climatic zones, with stronger effects in the cold regions of the alpine climatic zone. Drought, induced by reduced precipitation and/or increased evapotranspiration, can override the positive effects of higher temperatures on plant growth, not only in the Mediterranean warm-dry climatic zone but also in the less dry sub-Mediterranean climatic zone and even in the temperate one. Our review highlighted 2 major research gaps to which future research should be directed. First, there is poor knowledge of how species composition will change in response to changing climate and how this will affect ecosystem functioning in Mediterranean to temperate ecosystems. Second, there is poor knowledge of possible interactions between climate-induced vegetation changes and dynamic processes related to land-use changes
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