Quantifying Credit Portfolio sensitivity to asset correlations with interpretable generative neural networks

In this research, we propose a novel approach for the quantification of credit portfolio Value-at-Risk (VaR) sensitivity to asset correlations with the use of synthetic financial correlation matrices generated with deep learning models. In previous work Generative Adversarial Networks (GANs) were employed to demonstrate the generation of plausible correlation matrices, that capture the essential characteristics observed in empirical correlation matrices estimated on asset returns. Instead of GANs, we employ Variational Autoencoders (VAE) to achieve a more interpretable latent space representation. Through our analysis, we reveal that the VAE latent space can be a useful tool to capture the crucial factors impacting portfolio diversification, particularly in relation to credit portfolio sensitivity to asset correlations changes

Land-Cover mapping in the Biogradska Gora National Park with very-high-resolution Pléiades images

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The value of long-term history of small and fragmented old-growth forests for restoration ecology

International audienceThe long-term history of small and fragmented old-growth forests can provide insights into the legacies of past environmental changes and land-use history in the surrounding landscapes, which can support nature protection and restoration ecology measures

Exploring the long-term vegetation and fire-disturbance history of the Biogradska Gora old-growth forest (Montenegro)

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A millennium-long history of an iconic old-growth forest in south-east European mountains

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Legacies of past human activities on one of the largest old-growth forests in the south-east European mountains

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The role of fire disturbances, human activities and climate change for long-term forest dynamics in upper-montane forests of the central Dinaric Alps

International audienceWe present the first high-resolution Holocene pollen, plant-macrofossil, and charcoal records from the upper-montane zone in the central Dinaric Alps. Drawing on these new records from well-dated lacustrine sediments of Zminje Jezero (ca. 1500 m a.s.l.; Montenegro) and on independent chironomid-inferred summer temperatures, we explore long-term ecosystem responses to variations in climate, fire disturbances and land use, as well as legacy effects of past environmental changes. A mixed spruce-fir forest established in the upper-montane zone around 9500 cal BP, and Fagus sylvatica became co-dominant with the two conifers after 5000 cal BP. Prehistoric land-use pressure was overall remarkably low, but increased since 2000 cal BP and was highest after the Middle Ages. We found a significant positive relationship between biomass burning and summer temperature, indicating that fires were mostly climate driven. Picea abies was insensitive to summer temperature, biomass burning and human impact, which supports the view that spruce forests may not be significantly impacted by fire. In contrast, Abies alba and other disturbance-sensitive trees ( Tilia, Ulmus, Fraxinus excelsior-type) show significant negative responses to land-use pressure and positive responses to summer temperature. This supports the notion that these species may be well-adapted to warmer-than present summer temperatures and that their populations declined in recent millennia due to land-use activities. Conversely, F. sylvatica was sensitive to summer temperatures but was promoted by low biomass burning, indicating that its expansion in the spruce-fir dominated forest was enhanced by the onset of cooler and possibly also moister climatic conditions as well as by fire disturbances

Legacies of past human activities on one of the largest old-growth forests in the south-east European mountains

International audienceThe Dinaric Mountains are a region considered as a hotspot for remaining late-successional montane mixed Abies alba-Fagus sylvatica-Picea abies old-growth forests presumably because historical deforestation levels were substantially lower than in other European regions. We present new well-dated stand-scale palaeoecological records (pollen, spores, stomata, macrofossils, macroscopic charcoal, and magnetic susceptibility), an extensive dataset of current forest structures and a detailed land-cover types map from the Biogradska Gora forest to provide new insights into the long-term vegetation dynamics of old-growth forests in the montane zone of the Dinaric Mountains. Land use (cereal crop cultivation, cattle herding, and fire) during the Middle Ages caused a reduction of the A. alba and P. abies-dominated forest. After a major land-abandonment event around the Black Death pandemic (mid-14 th century) and more moderate land-use phases associated with fire episodes, which favoured the short-term expansion of light-demanding pioneer species (Corylus and Betula), F. sylvatica-dominated stands developed in the more accessible outer part of the forest. The legacy of past land uses is still visible as the structure of the almost pure F. sylvatica stands shows less old-growth characteristics. Most strikingly and markedly in contrast to decreasing tree cover due to generally intensifying land use elsewhere in Europe, tree cover increased several centuries before the formal protection of the forest (1878 CE), supporting the view that historical land-use pressures played an important role for the small extent and the continuity of disturbance-sensitive A. alba and P. abies-dominated old-growth stands