21 Mar. 2014 - CNRS France ChronoEnvironnement

 

Giornata di Studio
con CNRS Francia

Sedimentary archives to infer ecosystem response to disturbance

10.30-11.00
Michel MAGNY, and LAMA Members

North-south palaeohydrological contrasts in the central Mediterranean during the Holocene: tentative synthesis and working hypotheses

On the basis of a multi-proxy approach and a strategy combining lacustrine and marine records along a north-south transect, data collected in the Central Mediterranean within the framework of a collaborative project have led to reconstruction of high-resolution and well-dated palaeohydrological records and to assessment of their spatial and temporal coherency. Data give evidence of contrasting palaeohydrological patterns operated throughout the Holocene, both on millennial and centennial scales. Comparison between available palaeohydrological data for the whole Mediterranean suggests possible influences of forcing factors and general atmospheric circulation patterns.

11.00-11.30
Laurent MILLET

Subfossil chironomids in paleolimnology: from the inference of temperature changes to the reconstruction of lake functioning history

In lakes, chironomid larvae (Insecta Diptera) are benthic organisms that produce chitinous remains (head capsules) during their development. Past changes in communities are reconstructed after extraction and identification of head capsules preserved in the sediment. Chironomid assemblages are potentially affected by a variety of environmental conditions interacting in complex ecological processes. Inferring temperature changes from a chironomid sequence using a transfer function assumes that the chironomid assemblages respond, directly or indirectly, to temperature. We will present temperature reconstructions for the last 1500 years derived from chironomid records of three neighboring lakes in the Northern French Alps. In addition to temperature, the most commonly recognized influencing factors are trophic status, oxygen conditions and organic matter in the sediment. In the bottom of deep stratified lakes, the sensitivity of the bottom community to changes in oxygen availability derives from the differential behavioural and/or physiological adaptations of the taxa to survive under hypoxia of variable degree. As a last example, we will present the results from the multiproxy study (IPER-RETRO project) carried out at Lake Annecy (French Alps).

11.30-12.00
Simon BELLE

Current states and ecological trajectories of lakes over the last 1500 years: the study of the biological and biogeochemical responses to disturbances

The evolution of lake is determined by “natural” (climate, lake ontogeny) and “anthropic” (agricultural development, fish introduction, pollutants…) factors (Leavitt et al., 2009). Because monitoring records exist since the early XX° century for only a few lakes, paleolimnological studies are key approaches to understand the response of ecosystems to disturbance. We conducted a multi-proxy paleolimnological investigation to understand: (i) the biological response (Chironomid assemblages) and (ii) the changes in carbon cycle (in particular methanogenesis). 15 lakes, belonging to different typologies and presenting different stories in land use and occupation, have been studied from Jura Mountains to Greenland

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19 Mar. 2014 - Modenutti - Balseiro

Seminar Modenutti - Balseiro

Impact of a volcanic eruption on pelagic
communities of North-Patagonian Andean lakes

Presentano: Beatriz Modenutti and Esteban Balseiro ( CONICET - Universidad Nacional del Comahue, Bariloche, Argentina )

On 4 June 2011, an eruption in the Puyehue volcanic complex (40°35′S, 72°06′W, Chile) discharged massive amounts of ash and pumice into the surrounding landscape in Argentina (North Andean Patagonia). The ejected material affected nearby aquatic environments, producing an increase in total suspended solids. We combined field data and experimental data to determine the effect of the volcanic ashes suspended in the water column on pelagic communities. We analyze the consequences of this eruption from subcellular to ecosystem level and we found different effects on each one.

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11 Mar. 2014 - Marco Caccianiga

Seminar Caccianiga

Il limite della vegetazione arborea : struttura, dinamica e risposte alle variazioni climatiche

Presenta: Marco Caccianiga ( Dipartimento di Bioscienze, Università degli Studi di Milano )

The position of the treeline (the uppermost or northernmost limit of tree growth form) represents a well-known climatic boundary, and a powerful proxy for past and present climate variations. Growth season temperatures are widely considered the main factor affecting the position of both latitudinal and altitudinal treelines, However, the ongoing global temperature increase is not causing a global advance of treelines worldwide thus emphasizing the complexity of climate-treeline relationship; moreover, the different species composition at the treeline (driven by bioclimatic, historical or biogeographic factors) could result in different responses to climatic forcing.

The seminar will show some case studies of different altitudinal and latitudinal treelines. An interdisciplinary approach, including floristic analysis, dendrochronology, paleoecology and soil science, was used. The analysed treelines showed contrasting responses to past and present climatic fluctuations as a function of regional climate, species composition and historical events. The knowledge of the response of this important ecological boundary is of great importance for the modelling of ecosystem dynamics in a changing climate.

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04 Mar. 2014 - Paolo Colangelo

Seminar Colangelo

Biologia evolutiva e biodiversità nei piccoli mammiferi

Presenta: Paolo Colangelo ( CNR - ISE, Roma )

La classe dei mammiferi conta più di 5000 specie e fra queste i piccoli mammiferi ne rappresentano la maggioranza. I roditori da soli includono circa 2300 specie che rappresentano all'incirca il 42% della biodiversità mondiale dei mammiferi. L'elevata diversità filogenetica, morfologica ed ecologica rende i piccoli mammiferi un eccellente modello per gli studi di biologia evolutiva e negli ultimi anni l'ampia disponibilità di tecniche di indagine genetica e molecolare e lo sviluppo di nuove tecniche di indagine morfologiche hanno favorito un avanzamento delle conoscenze dei meccanismi di speciazione e dei fenomeni responsabili dell'imponente radiazione che ne hanno contraddistinto l'evoluzione. Le ricerche presentate si inquadrano nel contesto più ampio degli studi che mirano a comprendere i meccanismi di speciazione e migliorare il quadro conoscitivo della biodiversità dei piccoli mammiferi. Verranno presentati alcuni esempi di ricerche condotte utilizzando tecniche di citogenetica, filogenesi molecolare, morfometria geometrica e modellistica ecologica con il fine di incrementare le conoscenze sulla biologia evolutiva e la biogeografia di diversi gruppi di micromammiferi sia africani che europei.

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04 Feb. 2014 - Carrara-Oggioni

Seminar Carrara-Oggioni

Soluzioni EnvEurope per i dati ecologici e proposte future

Presentano: Paola Carrara e Alessandro Oggioni  ( CNR - IREA, Milano )

Durante il seminario verranno presentati i principali risultati ottenuti nel progetto Life+ EnvEurope, ponendo particolare attenzione agli aspetti riguardanti la gestione dati: strumenti creati per la descrizione dei dati ecologici, per il loro ritrovamento e per la loro pubblicazione. Saranno cosi identificate le principali peculiarità, le difficoltà incontrate, i punti deboli e le sfide future anche alla luce di nuovi progetti che vedono coinvolti l'Istituto per il Rilevamento Elettromagnetico dell'Ambiente (CNR IREA).

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