Community assembly processes along a sub-Mediterranean elevation gradient: analyzing the interdependence of trait community weighted mean and functional diversity

Plant Ecology - Community-weighted mean (CWM) and functional diversity (FD) describe the two aspects of plant communities’ functional structure. While they have been often used separately to...     

Cellular actions of testosterone in vascular cells: Mechanism independent of aromatization to estradiol

In this work we investigated the role of testosterone on cellular processes involved in vascular disease, and whether these effects depend on its local conversion to estradiol. Cultures of rat aortic endothelial and smooth muscle cells in vitro treated with physiological concentrations of testosterone were employed. Testosterone rapidly increased endothelial nitric oxide production. To evaluate whether this non genomic action was dependent on testosterone aromatization we used an aromatase inhibitor. Anastrozole compound did not modify the fast increase in nitric oxide production elicited by testosterone. The hormonal effect was completely blocked by an androgen receptor antagonist (flutamide); meanwhile it wasn′t modified by the presence of an estrogen receptor antagonist (ICI182780).The possibility of intracellular estradiol synthesis was ruled out when no differences were found in estradiol measurements performed in culture incubation medium from control and testosterone treated cells. The 5α-reductase inhibitor finasteride partially suppressed the enhancement in nitric oxide production, suggesting that the effect of testosterone was partially due to dihydrotestosterone conversion. Testosterone stimulated muscle cell proliferation independent of local conversion to estradiol. When cellular events that play key roles in vascular disease development were analyzed, testosterone prevented monocyte adhesion to endothelial cells induced by a proinflammatory stimulus (bacterial lipopolysaccharides), and prompted muscle cell migration in presence of a cell motility inducer. In summary, testosterone modulates vascular behavior through its direct action on vascular cells independent of aromatization to estradiol. The cellular actions exhibited by the steroid varied whether cells were under basal or inflammatory conditions.     

Recovering mountain Mediterranean grasslands for breeding birds: ecology and population status shape species responses to management

The Mediterranean basin is considered one of the most important biodiversity hotspots. This extraordinary richness originates mainly from thousands of years of human activities that deeply modified the landscape. Safeguarding the so-called cultural landscapes plays a key role in biodiversity conservation. In this paper we present the results of our monitoring of the effects of the life project “Preservation of mountain grasslands of the Tuscan Apennines”, mainly characterized by shrub-cutting actions, on bird populations in the Pratomagno pasture, one of the two areas where the project was implemented, a SPA in eastern Tuscany. The monitoring plan covers a period of 5 years. We tested the effects of shrub clearing on a series of bird community parameters, such as abundance and richness of common species and of some ecological guilds. We also tested the timing of the response to the interventions (immediate or drawn out over time). Our results show a dramatic decrease of birds associated with shrubland, while there were no important increases in grassland species, with the sole exception of Woodlark. Regardless of their positive or negative effects, our results show different response times for individual species or groups of species. Moreover, species with a bad regional conservation status increased less than those with a good one. Broadly speaking, these results suggest that the efficacy of such projects depends on a careful preliminary assessment of a number of aspects, encompassing the nature of the interventions themselves and the characteristics of the target sites, but also the type of response of target species and the conservation status of target populations.     

The Quercus cerris woods of the alliance Carpinion orientalis Horvat 1958 in Italy

Abstract

A phytosociological study of the alliance Carpinion orientalis in the hilly and subcoastal areas of the Italian peninsula is presented. These woods are included in the suballiances Laburno-Ostryenion and Lauro-Quercenion; the distinction between these two suballiances is not always easy also because of the conservation status of these forest ecosystems. The hilly and subcoastal Turkey oak woods of the alliance Carpinion orientalis are mainly distributed on the Adriatic side of the Italian peninsula, where they are found on neutro-basic substrata to which these coenoses are linked. The Turkey oak woods of the alliance Teucrio siculi-Quercion cerridis are strongly linked to the acidic substrata typical of the Tyrrhenian side, but are sporadically found on the Adriatic side within small enclaves with more acidic substrata. A numerical analysis allowed us to rearrange the lower hierarchical levels of the associations of Turkey oak woods of the alliance Carpinion orientalis. In particular, the association Lonicero xylostei-Quercetum cerridis is included in the alliance Carpinion orientalis, and the new subassociation festucetosum exaltatae is proposed. The subassociation rosetosum arvensis is proposed for the association Daphno laureolae-Quercetum cerridis, and the new subassociation cytisophylletosum sessilifolii of the association Aceri obtusati-Quercetum cerridis is described.     

Analysis of the Colosseum's floristic changes during the last four centuries

ABSTRACT

Different floristic lists of the Colosseum have been carried out starting from the XVII century (Panaroli, 1643; Sebastiani, 1815; Deakin, 1855; Fiorini Mazzanti, 1874; Anzalone, 1951; and recently Celesti Grapow et al., 2001). The comparison among these investigations reveals the rich plant colonisation, due to the great variety of habitats present in the monument and to its state of abandon. The maximum peak of 418 species can be referred in Deakin's list, and the minimum are the current 242 species, mainly distributed in the hypogeans. The total amount of colonising species in time was 684 vascular plants. The species listed for the monument in all the studies are 135, and all the common ones are 192. These are mainly herbaceous plants of ruderal habitats, widely distributed in more or less nitrophylous pastures or pioneer on rocks and walls. 426 species were enumerated before the XX century and later disappeared from the places. 117 species no longer belong to the Roman flora, and 24 species are no longer listed in the regional flora. These were mainly herbaceous and woody species typical of dynamically developed stages, belonging to forest and border line communities. Typical species of very disturbed habitats are also frequent. 66 species were collected only in more recent times. These belong to the synanthropic flora, though less nitrophylous compared with the previous, or are cultivated plants capable of becoming spontaneous under favourable conditions. The comparison among the different floras indicates not only the change in use of the monument, but also that climatic and microclimatic changes occurred in the last centuries. The relative biological and chorological spectra confirm the progressive warming and average reduction of humidity of the site.     

Collagen-induced platelet shape change is not affected by positive feedback pathway inhibitors and cAMP-elevating agents

Shape change is the earliest response of platelets to stimuli; it is mainly dependent upon Ca(2+)/calmodulin interaction subsequent to Ca(2+) mobilization and is mediated by myosin light chain kinase (MLCK) activation. It has been recently suggested that collagen itself is not able to elicit platelet shape change in the absence of ADP and thromboxane A(2) costimulation but is capable of inducing MLCK activation. Since we hypothesize that the morphological changes of the few platelets that adhere to collagen might not be revealed by turbidimetry, the aim of this study was to assess platelet shape change using transmission electron microscopy, in the absence of the amplificatory feedback pathways of ADP and thromboxane A(2). Our results demonstrated that only the platelets in contact with insoluble collagen fibers underwent a typical shape change, whereas those further away remained quiescent. Moreover, since cAMP enhances Ca(2+) mobilization in response to collagen, in the present study, we also investigated whether cAMP is involved in the inhibition of collagen-induced platelet shape change and MLC phosphorylation. Platelets were thus treated with iloprost (28 nm) prior to stimulation. Electron microscopy studies demonstrated that iloprost did not modify collagen-induced shape change, whereas immunoblotting studies showed a slight inhibition of MLC phosphorylation in the presence of enhanced cAMP levels. We can thus conclude that collagen is able to cause platelet shape change through activation of Ca(2+)/calmodulin-dependent MLCK, without the involvement of amplificatory pathways. Enhanced cytosolic cAMP levels do not inhibit collagen-induced platelet shape change but exert a weak inhibitory action on MLCK.     

Multifaceted Analysis of Patch-Level Plant Diversity in Response to Landscape Spatial Pattern and History on Mediterranean Dunes

Landscape structure is known to critically affect biodiversity. However, although the multi-facetted character of biodiversity is widely recognized, few studies have linked landscape spatial pattern and history simultaneously to multiple facets (taxonomic, functional, and phylogenetic) and spatial components (α, β, and γ) of plant diversity. We set out to reveal whether landscape parameters have specific effects on the separate diversity facets and components of plant diversity at a patch scale on coastal dune landscapes of Central Italy. For each landscape patch, we computed a set of patch-based metrics relying on multi-temporal land-cover maps. Based on a database of plant community plots, on functional traits from field measurements and on a dated phylogenetic tree, we calculated taxonomic (TD), functional (FD), and phylogenetic diversity (PD) within each patch at α, β, and γ level. Diversity measures were then related to the landscape metrics via linear mixed-effect models. Landscape pattern and transformations affected TD only moderately in coastal dune ecosystems. We found much stronger and contrasted effects on FD and PD. FD increased in patches surrounded by human-dominated habitats; PD was higher in fragmented patches, particularly in the Mediterranean macchia. Moreover, landscape pattern affected differently the single communities, the turnover among communities and the pool of species within the patch (α, β, and γ components). Our results call for the combined inclusion of FD and PD and their partitions into ecological analyses, being TD too crude to capture the comprehensive and contrasted response of plant diversity to landscape spatial pattern.     

Tree-ring growth of silver fir (Abies alba Mill.) in two stands under different silvicultural systems in central Italy

A preliminary analysis was made of growth trends in two silver fir forests in the Apennines in central Italy. The forests are closely located but were managed differently in the past. The aim was to verify the climatic variation over time, the influence of extreme events on radial growth and the role of silvicultural systems in defining growth response. The two forests have distinct structures due to differing past silvicultural management. The Camaldoli Forest, containing one-storeyed, evenaged, pure silver fir stands, was essentially managed in the past for wood production and featured high plantation density, low to moderate thinning, and clear cutting every 80–100 years. The La Verna Forest includes multi-layered, unevenaged stands that are mixed in with beech and other broadleaves. Increment cores were collected from aged dominant and healthy trees in the two forests. Climatic data were taken from the Camaldoli station and covers the period 1885–1994. All the analysed dendroecological parameters displayed similar patterns and indicated suitable site conditions for the silver fir. Silvicultural systems played an important role in defining growth pattern and rate. In the evenaged system there were higher growth rates and a greater number of pointer years, whereas there were lower growth rates and long, homogeneous development stages in the semi-natural conditions of La Verna. A rising growth trend recorded in the last three decades in both series could be explained by the consistent extension of the growing season due to a significant increase of mean spring and autumn temperatures. No correlation was found with precipitation while significant correlations were found between tree ring growth and February, April and August temperatures. Preliminary results indicated that the silvicultural system does not bias, but just enhances the ability of the species to record the effects of disturbing factors.