A 3800 year-long radiocarbon-dated and highly-resolved palaeoecological record from Lake Fimon (N-Italy) served to investigate the effects of potential teleconnections between North Atlantic and mid-to-low latitudes at the transition from Marine Isotope Stage (MIS) 3 to 2. Boreal ecosystems documented in the Fimon record reacted in a sensitive way to millennial and sub-millennial scale Northern Hemisphere atmospheric circulation patterns. The high median time-resolution of 58 years allows the identification of five abrupt event-boundaries (i.e., main forest expansion and decline excursions) synchronous with the sharp stadial/interstadial (GS/GI) transitions within dating uncertainties. During Heinrich Stadial 3 (HS 3) we reconstruct more open and dry conditions, compared to the other GS, with a dominant regional scale fire signal. Linkages between local fires and climate-driven fuel changes resulted in high-magnitude fire peaks close to GI/GS boundaries, even exacerbated by local peatland conditions. Finally, palaeoecological data from the HS 3 interval unveiled an internal variability suggesting a peak between 30,425 and 29,772 cal BP (2σ error) which matches more depleted δ18O values in alpine speleothems. We hypothesise that this signal, broadly resembling that of other mid-latitudes proxies, may be attributed to the southward shift of the Northern Hemisphere storm tracks and the associated delayed iceberg discharge events as documented during other HS.

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This study investigates the distribution of vegetation and its modern pollen representation along an elevation gradient in the Italian Alps and explores the relationships with terrain and climate variables. Moss polsters were collected at 25 sites between ca. 300 and 1400 m asl from open areas, deciduous, and conifer forests. At each site vegetation was surveyed at 1.8 and 10 m radius according to the Braun-Blanquet method. Climatic data, bioclimatic indices, and terrain parameters were obtained for each sampling site. Three distinct pollen associations reflect the characteristic vegetation altitudinal belts present in the study area. Uphill dispersal, the regional load and the presence of high producers influence the abundance of pollen and the representation of taxa along the gradient. CCA ordination technique reveals the predictive power of environmental variables on modern pollen and vegetation datasets. The most relevant factors controlling vegetation distribution are identified in elevation, insolation, Pspring, Tsummer, the Ellenberg quotient, and Summer Water Balance (SWB). Elevation, insolation, summer P and T, the Ellenberg quotient, and the Gams’ hygric continentality index (GAMS) explain more variance within the pollen dataset. A qualitative comparison among pollen and the corresponding parent plant occurrence qualifies Abies alba, Fagus sylvatica, Poaceae and Cyclamen pollen as suitable indicators taxa of the local vegetation in the study area. Several high producers with very effective, long-distance anemophilous dispersal ( Pinus, Ostrya, Alnus, and Juglans) or mixed pollination mechanisms (anemophilous and insect-pollination: Fraxinus ornus, and Castanea) show no or little association with their parent plants.

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