Limnological studies on two acid sensitive lakes in the Central Alps (lakes Paione Superiore and Paione Inferiore, Italy)

A limnological study was performed during 1991 and 1992 on lakes Paione Superiore (LPS)and Paione Inferiore (LPI), located in the Ossola Valley, Central Alps. The two lakes are characterized by very low alkalinity values (LPI <3ueq l-1); notwithstanding the relatively low atmospheric acid load, diatom remains, carbonaceous particles and pigment profiles in the sediments all indicate that the two lakes have undergone acidification since the fifties. The biological communities (phyto-zooplankton and macrobenthic fauna) are simplified, in consequence of the extreme physical and chemical conditions. The biological characteristics of the two lakes are discussed in relation to the water chemistry and the presence or absence of stocked fis

The chemical and biological response of two remote mountain lakes in the Southern Central Alps (Italy) to twenty years of changing physical and chemical climate

Two small high mountain lakes in the Alps were monitored in 1984-2003 to follow their response to changes in human impact, such as deposition of atmospheric pollutants, fish stocking and climate change. The results were compared to occasional samplings performed in the 1940s, and to the remains found in sediment cores. When monitoring started, the most acid-sensitive of them, Lake Paione Superiore, was acidified, with evident effects in its flora and fauna: benthic diatoms assemblage was shifted towards aci- dophilous species, and zooplankton lost the dominant species, Arctodiaptomus alpinus. Palaeolimnological studies outlined that lake acidification paralleled the increasing input of long-range transported industrial pollutants, traced by spherical carbonaceous parti- cles. On the contrary, the biota of Lake Paione Inferiore appeared to be mainly affected by fish stocking. In the last twenty years, de- crease in acid load from the atmosphere led to an improvement in lake water quality, with an increase in both pH and alkalinity. First signs of biological recovery were identified, such as change in diatom flora and appearance of sensitive species among benthic insects. However, climate change and episodic deposition of Saharan dust were important driving factors controlling lake water chemistry. Further monitoring to assess the effects of climate change and of the increasing load of nitrogen and other pollutants is recommended. Key word: atmospheric deposition, acidification, plankton, benthos, diatom

AKKALE CISTERN IN MERSIN-ERDEMLI: STATIC ANALYSIS AND RISK ASSESSMENT

The paper deals with the structural analysis of the ancient cistern located in archaeological site of Akkale in Erdemli (Mersin) in Turkey. The cistern, even though discovered many years ago, has been for longtime abandoned. Recent policy is oriented in reuse of the structure, as archaeological/monumental site, as well as to rehabilitate the architecture in order to preserve it. A team from University of Rome “Tor Vergata” and from University of Mersin, organized a surveying campaign for structural analysis and evaluations on existing conditions of the building, its material and structural risk assessments, since the site will be opened to visitors. Surveying activity of the geometry of the monument and limited analysis of samples collected on site provided basic and ineludible information to use in the subsequent numerical/geometric analysis. The Cistern is one of the biggest closed reservoirs of ancient Olbian region of Eastern Rough Cilicia from late Antiquity Period, realized partially buried in the soil, with a large roof supported by a double order of masonry arches. The analysis has been carried out performing standard simplified approach, but also comparing the results with more sophisticated Finite Element models. The results of the analysis are encouraging, and it seems that only limited works should be done in order to allow visiting people inside the structure. Further and periodical chemical analysis are suggested, in order to monitor the state of the material and the possible decay

Which climate change path are we following? Bad news from Scots pine

<div><p>Current expectations on future climate derive from coordinated experiments, which compile many climate models for sampling the entire uncertainty related to emission scenarios, initial conditions, and modelling process. Quantifying this uncertainty is important for taking decisions that are robust under a wide range of possible future conditions. Nevertheless, if uncertainty is too large, it can prevent from planning specific and effective measures. For this reason, reducing the spectrum of the possible scenarios to a small number of one or a few models that actually represent the climate pathway influencing natural ecosystems would substantially increase our planning capacity. Here we adopt a multidisciplinary approach based on the comparison of observed and expected spatial patterns of response to climate change in order to identify which specific models, among those included in the CMIP5, catch the real climate variation driving the response of natural ecosystems. We used dendrochronological analyses for determining the geographic pattern of recent growth trends for three European species of trees. At the same time, we modelled the climatic niche for the same species and forecasted the suitability variation expected across Europe under each different GCM. Finally, we estimated how well each GCM explains the real response of ecosystems, by comparing the expected variation with the observed growth trends. Doing this, we identified four climatic models that are coherent with the observed trends. These models are close to the highest range limit of the climatic variations expected by the ensemble of the CMIP5 models, suggesting that current predictions of climate change impacts on ecosystems could be underestimated.</p></div

Schematic idea behind the experiment.

<p>Five hypothetical range shifts are shown with the relative expected effects on local populations. Let’s suppose only one of the five hypothesized range shifts is actually occurring. In the case an appropriate set of local data on population responses being available, it is possible to identify which specific range shift is actually occurring on the basis of the spatial pattern of positive, neutral, and negative responses.</p

Agreement between observed responses by tree ring analyses and expected responses by habitat suitability models under different GCMs for <i>Pinus sylvestris</i>.

<p>Agreement between observed responses by tree ring analyses and expected responses by habitat suitability models under different GCMs for <i>Pinus sylvestris</i>.</p

Models explaining the observed responses.

<p>Each column shows results for one of the four models with the highest level of agreement between expected and observed responses. In the upper row, the current range of <i>Pinus sylvestris</i> (thin grey line) and its future climate suitability are shown (grey-yellow-green scale; 0 < HS < 1000). In the lower row, the expected variation of climate suitability is shown (grey-yellow-green scale), together with the observed responses of <i>Pinus sylvestris</i> populations: green points represent populations with positive responses, grey points represent neutral responses, and red points represent negative responses. The small histograms within lower maps show the results of the null-model tests of agreement between expected and observed responses: when the vertical red line is on the left of the black line, <i>P{A</i>_<i>sim</i> <i>> a</i>_<i>obs</i><i>}</i> > 0.05, when the red line is on the right of the black one, <i>P{A</i>_<i>sim</i> <i>> a</i>_<i>obs</i><i>}</i> < 0.05. All the maps are Albers equal-area conic projections and coordinates are metric. See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0189468#pone.0189468.s005" target="_blank">S5 Table</a> for model details.</p

Potential improvement in future suitability predictions.

<p>Difference between habitat suitability under future climatic conditions as predicted by the entire set of models and by the selected four. The colour scale is the difference between the consensus model of the entire set of 59 models and the consensus of the selected four models. The darker area within the red line indicates where the difference is significant.</p