1,721,192 research outputs found
Large perialpine lakes: a multiproxy paleolimnological laboratory for the advance of ecosystem science
No full textThe Perialpine lakes are important component of the Alpine landscape. Due to their piedmont location in
the most densely populated and productive region of the Alps, they play a crucial socio-economic role as
resource for drinking water, irrigation, industry, tourism, hydroelectric production, and biodiversity
conservation. For the same reasons, they are exposed to multiple human pressure, and, as their catchment
extend to the glacial Alpine range, they are particularly sensitive to the effects of the global warming.
Limnological surveys during the last few decades outlined coherent responses by large and small
Perialpine lakes to the massive nutrient enrichment during the 1950s-1970s, while recent trajectories are
rather heterogeneous in relation to local management policies, lake morphology, and superimposed
effects of climate change. Recent paleolimnological studies confirmed the strong coherence of the lakes’
evolution at a secular perspective, and could relate some individual evolutionary trends to the
combination of lake morphology and hydrology, and to the consequently different lake sensitivity to
climate variability.
The ongoing studies pinpoint how the investigation of different abiotic and biotic proxies preserved in
sediments of Perialpine lakes can complement limnological surveys in reconstructing the past lake
ecological evolution from several lines of evidence. In addition, the multiproxy paleoecological approach
is crucial for predicting lake sensitivity to present, and especially future human impacts. This is
particularly important when defining trophic and ecological reference conditions for setting management
policies, since inappropriate conservation/restoration targets might prove unachievable within the current
context of global change.
This presentation will show results of recent sediment investigations on large and small Perialpine lakes,
moving from a local to a general Alpine perspective, and showing the potential of the multisite and
multiproxy paleolimnological approach for the advance of aquatic science
Complexity in Low-Carbon Transitions: Uncertainty and Policy Implications
No full textWe explore the uncertain dimension induced by the complexity of energy systems, analyzing whether and under which conditions low-carbon transitions can effectively take place. By accounting for social and environmental considerations, heterogeneous single utility-maximizing agents optimally decide whether to adopt a green technology which reduces carbon emissions, allowing eventually for a green energy transition. We characterize the determinants of the success of such a transition, emphasizing that even if the favorable conditions are met the low-carbon transition may not result in long run environmental improvements due to the path-dependency and metastability phenomena which characterize the complexity arising from agents’ interactions. Public policy may solve these issues by increasing the incentive for single individuals to adopt, ensuring thus the achievement of a permanent low-carbon state. By extending the analysis to a spatial network characterized by multiplexity due to the social and environmental interconnections, we show that spatial interactions negatively affect agents’ adoption incentive and reduce the effectiveness of public policy by interacting in a complex way with path-dependency and metastability. In particular, spatial interactions may require a larger subsidy to support a permanent low-carbon transition, thus neglecting their effects on agents’ behavior and environmental outcomes may compromise our chances to achieve a greener future
Vaccine-Preventable Diseases and Individual Behavior: Deterministic vs Stochastic Outcomes
No full textIl valore aggiunto della limnologia comparata: un confronto tra laghi delle Terre Alte
Full text linkAssodato che il cambiamento climatico è in corso, molte sono ancora le incertezze sulla conseguente risposta da parte degli ecosistemi, in particolare di quelli acquatici. Come emerso sia dall’analisi delle serie storiche di dati, sia da indagini paleolimnologiche, questi ambienti, a differenza di quelli terrestri, presentano dei meccanismi di riposta più complessi, spesso non lineari, o no riconducibili ad una semplice relazione causa-effetto.
Sono qui discussi esempi o casi di studio che evidenziano come le comunità biologiche che vivono in ambienti acquatici abbiamo strutture peculiari e come queste caratteristiche siano rispondano agli impatti climatici.
Per valutare in modo appropriato quale sarà l’evoluzione di questi ecosistemi nel prossimo futuro è necessario aumentare la conoscenza di questi ambienti su scala sia spaziale sia temporale, in modo da poter discriminare il contributo di fattori locali o globali, antropici o naturali. In questo contesto gli ambienti acquatici delle Terra Alte possono dare un contributo significativo alla comprensione degli impatti del clima sugli ecosistemi acquatici
Phytoplankton and anthropogenic changes in pelagic environments
No full text“Phytoplankton” is a loosely defined functional term, indicating a group of organisms distributed into several taxonomic groups ranging from oxygenic photosynthetic bacteria to a number of eukaryotic classes included in protists. The range of specializations and adaptations of phytoplankton to a wide variety of environmental conditions is astounding. This demonstrates the susceptibility of highly different populations to react rapidly to environmental changes generated by natural stressors and anthropogenic impacts. The aim of this work is to critically review the state of the art of knowledge about the impact of anthropogenic stress factors on phytoplankton composition and structure. At present, the two most important environmental stressors are represented by climate change and eutrophication, which act globally and at regional/local scales, respectively. Along with effects mediated by many other legacy and emerging stressors (briefly reviewed), the effects of these two main changes have been analysed at different levels of phytoplankton organization, i.e. individuals, populations and communities. It is stressed that a better knowledge will be obtained by extending the focus of studies from organisms detectable by light microscopy to the whole range of protists and microbial populations detected with the use of “omics” technologies, including e.g. next generation sequencing and ecological metabolomic
The Tourism Area Life Cycle Hypothesis: a Micro-Foundation
Full text linkWe provide a simple micro-foundation of the tourism area life cycle hypothesis, based on tourists’ utility maximization. As a result of social interactions among tourists which determine destinations popularity, the market share of visitors which decides to visit a specific destination follows a logistic dynamics, consistent with what predicted by the tourism area life cycle hypothesis. We show that different preference drivers explain the duration of the different tourism area life cycle stages: the net benefit from visiting the destination characterizes the exploration, involvement, and development phases, while social effects associated with destination popularity characterize the phases of consolidation and stagnation Different from previous studies our results hold true independently of whether we focus on the repeating or non-repeating segment of the tourism market. We also provide a calibration of our model to the case of the city of Venice (Italy) showing that it performs well in capturing the evolution of tourism in the historical center of the city over the last 60 years, suggesting that TALC-like dynamics may occur even in the context of cultural and heritage destinations
Heterogeneous credit portfolios and the dynamics of the aggregate losses.
No full textWe study the impact of contagion in a network of firms facing credit risk.We describe an intensity based model where the homogeneity assumption is broken by introducing a random environment that makes it possible to take into account the idiosyncratic characteristics of the firms. We shall see that our model goes
behind the identification of groups of firms that can be considered basically exchangeable. Despite this heterogeneity assumption our model has the advantage of being totally tractable. The aim is to quantify the losses that a bank may suffer in a large credit portfolio. Relying on a large deviation principle on the trajectory space of the process, we state a suitable law of large numbers and a central limit theorem useful for studying large portfolio losses. Simulation results are provided as well as applications to portfolio loss distribution analysis
Rock glaciers and paraglacial features influence stream invertebrates in a deglaciating Alpine area
Full text linkThis is the pre-peer reviewed version of the following article: Brighenti, S, Tolotti, M, Bertoldi, W, Wharton, G, Bruno, MC. Rock glaciers and paraglacial features influence stream invertebrates in a deglaciating Alpine area. Freshwater Biology. 2020; 00: 1– 14. https://doi.org/10.1111/fwb.13658, which has been published in final form at https://doi.org/10.1111/fwb.13658. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions
Sedimente von vier Hochgebirgsseen unter unterschiedlichem Einfluß von Permafrost
Full text linkA paleolimnological survey of high mountain lakes in North- and South-Tyrol was conducted within the Interreg project Permaqua (permafrost and its effects on water balance and mountain water ecology) aiming at econstructing the ecological evolution of lakes in permafrost regions since the end of the Little ice Age (~1850), and to investigate possible effects of permafrost thawing on lake geochemistry and biology. Sediment
cores from four lakes located above ~2500 m a.s.l. on crystalline bedrock were radioistopically dated (210Pb, 226Ra, 137Cs and 241Am and 14C) and analyzed for lithological (wet density, water and organic content), geochemical (principal elements and heavy metals), and biological (diatom abundance and speceis composition) proxies. All the cores studied showed lithological and biological changes between the end of the Little Ice
Age and the first decades of the 20th century. Concentrations of heavy metals increased in the studied cores during the last ~ 150 years and reached highest values after the 1990s. On the contray, changes in diatom species composition which typically characterize many lower lakes of the northern hemisphere after the economic development in the 1960s were not recorded in the lakes investigated. However, it is not possible to explain these changes as completely related to the presence of active rock glaciers in the lake catchments. The long-term changes of biological and chemical indicators observed in the studied sediment cores appear to be the results of a set of combined factors, such as geochemistry, weathering, or catchment characteristics
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