Introduction

Abstract

The Bosco della Mesola (44°50′ N, 12°15′ E, 1058 ha), also called Boscone della Mesola or Gran Bosco della Mesola, is one of the main relics of lowland forest currently preserved in Italy. It is located in the southern deltaic lobe of Po, the longest Italian river, close to the Adriatic coast in North-Eastern Italy (Fig. 1.1). The Bosco della Mesola lies on geologically very recent terrain, consisting in fine-grained aeolian dune fields of late Medieval-Renaissance age (Stefani and Vincenzi 2005). Ground morphology is characterized by a system of topographic lows and highs formed of dune ridges with maximum elevation of about 7 m above sea level and dune slacks with minimum elevation of about 2 m below sea level. The orientation of the dune ridges is about 50° N, recording the direction of the dominant north-eastern winter wind, the so-called ‘bora’ (Fig. 1.1). Water supply to the nature reserve mainly originates from a network of canals providing freshwater from surrounding areas. However, the local aquifer is in hydraulic connection with the sea. This area has experienced strong subsidence especially since the half of the twentieth century when the subsidence rates strongly increased mainly due to anthropic causes, especially extraction of methane-bearing water, overexploitation of freshwater and riverbed deepening (Simeoni and Corbau 2009; Corbau et al. 2019). This implied a loss in altimetric elevation of about 2.5 m (Bondesan et al. 1995) and almost quintupled the rates of salt-wedge intrusion from the sea. Saltwater currently affects the topographic lows in the south-eastern part of the Nature Reserve (Gerdol et al. 2018).