The Po Delta Biosphere Reserve: Management challenges and priorities deriving from anthropogenic pressure and sea level rise

anglais. The Po Delta Biosphere Reserve is located in Northern Italy and has attained recognition by UNESCO in 2015 due to its unique natural and cultural value. The reserve covers an area of approximately 140 000 hectares, supporting a human population of 118 000, as well as a complex mosaic of ecosystems, which are found in this transitional waters landscape. Administratively the area is highly fragmented and this renders its management challenging. Besides administrative fragmentation between two Park Authorities and a number of local and provincial authorities, organizational challenges within the Authorities themselves make it increasingly difficult to ensure continuity in the maintenance, review and update of conservation priorities. The present study is intended to establish a comparative analysis of conservation priorities within the Po Delta Biosphere Reserve, in order to support relevant Authorities and conservation managers in ensuring the preservation of high value areas. The study was articulated according to five objectives, which were fulfilled by making use of publicly available data. Data was analysed by performing a weighted overlay analysis to address the research questions that were relevant to each objective. The first objective of the study was to determine parameters that could be used to characterize conservation value. In this context, the Conservation Value Index (CVI) was implemented, which enabled the localization of areas of value within the study area. The CVI was based on land cover characteristics, the presence of designated protected areas and the presence of protected species included in the International Union for Nature Conservation (IUCN) Red List. According to the CVI characterization, approximately 50% of the Biosphere Reserve area was defined as having high or very high conservation value, with a further 31% having medium conservation value. Upon determining the location of high conservation value areas, the effect of two different types of environmental pressure was assessed, both individually and in combination, by linking the effect of pressure to the distribution of conservation value within the Biosphere Reserve. This assessment was the subject of the subsequent three objectives of the study (objectives 2-4), whereby risk to water quality, risk deriving by sea level rising due to climate change and the combination of these risks were assessed. The first type of pressure, examined under the second objective of the study, was associated with the potential risk that human activities place on water quality. For this purpose, the distribution of agricultural and farming activities was assessed, as well as the distribution of tourism. It was considered that both these activities could potentially adversely affect water quality by contributing to the accumulation of organic nutrients, which could create imbalance in the most valuable areas for conservation. In this study, approximately 28% of the total Biosphere Reserve area was associated with high risk to water quality and 55% with medium risk, based on the types of activities supported. Upon linking risk to water quality to the distribution of areas of high and very high conservation value, it was determined that approximately 18% and 23% of the total high and medium risk areas were composed of high and very high value areas. The second type of pressure was examined under the third objective of this study and was associated with the risk of flooding deriving by climate-induced sea level rise. For this purpose, elevation information was taken into consideration, together with sea level rise estimates from the Intergovernmental Panel on Climate Change (IPCC). Overall, 75% of the Biosphere Reserve area was observed to be located below sea level. Under the worst-case scenario, corresponding to an increase in sea level of 0.82 m by 2100, the total area located below see level was estimated to increase to almost 90% of the total. Under these conditions, approximately 44% of the total flooded area would be made up of high and very high conservation areas, with a further 28% corresponding to areas of medium conservation value. The fourth objective of the study examined how the combination of risk factors relating to water quality and climate change-induced sea level rise would impact the distribution of conservation value within the Po Delta Biosphere Reserve. Overall, only 0.38% of the total area was free of from risk, whilst 12.5% would only be impacted by one type of risk. The remaining 87% of the Biosphere Reserve area is expected to be susceptible to combined risk factors, albeit with different intensity. Under the worst sea level rise predictions, high and very high conservation areas extended to over 37% of the combined medium and high risk areas for water quality. In the last part of the study, the fifth objective was addressed, which related to comparing current prioritization for conservation, which is based on three different conservation management types, with the prioritization in this study based on the combination of water quality and flooding risks. Results indicated that under the current practices, 50% of the area is identified as medium or high priority. However, under the newly proposed prioritization methodology, this area would increase to 60% of the total area. Furthermore, under the newly proposed prioritization, some 36% of the area would experience a positive change towards a higher priority status, whilst 13% would experience a negative change towards decreased priority. The most notable differences related to the extent of high priority areas in the Northern and Southern part of the Biosphere Reserve, which would increase in their extension. Similarly, medium priority areas would also increase their extension in the Southern part of the Biosphere Reserve, but would decrease in the central part of the Biosphere Reserve under the newly proposed prioritization regime. Overall, the study objectives were achieved and a new prioritization method for the management of areas within the Po Delta Biosphere Reserve is proposed. The proposed methodology sets the basis for advocating the inclusion of risk factors in the definition of conservation priorities.

anglais. In 1971 UNESCO initiated the Man and the Biosphere Programme (MAB) recognizing sites of unique interest, with the purpose of adding value to the way man interacts with its environment. One such site is the Po Delta Biosphere Reserve, located in Northern Italy. The area marks the boundary between the freshwater in the Po River and the marine ecosystems of the Adriatic Sea, supporting a complex mosaic of ecosystems. Current management of the area is based on the characteristics of individual zones, which are subdivided into transition, buffer and core areas, with increasing level of protection. Nevertheless, there is currently no account of intrinsic risks to which the area might be exposed. Specifically, no consideration is given to the potential risk experienced by the area in relation to water quality degradation and to the risk of flooding due to rising sea levels (Figure 1). The present study is intends to compare current conservation priorities, with a novel prioritization method, taking into consideration both area characteristics and risk factors. The latter are considered bot individually and in combination. In doing so, it provides a tool for conservation managers towards the preservation high value areas. Area characteristics were summarised by considering land cover characteristics, formal protected areas and protected species included in the International Union for Nature Conservation (IUCN) Red List. Accordingly, approximately 50% of the Biosphere Reserve area was defined as having high or very high conservation value, with a further 31% having medium conservation value. Human activities such as agricultural, farming and tourism activities place pressure on water quality by contributing to the accumulation of organic nutrients and eventually leading to imbalance. About one third of the total Biosphere Reserve area (28%) was associated with high risk to water quality and more than half (55%) with medium risk. Areas of high and very high value for conservation made up 18% of the total areas exposed to high and 23% of the areas exposed to medium risk. Overall, 75% of the Biosphere Reserve area is currently located below sea level. However, this could be expected to increase to almost 90% by 2100 under the worst-case estimates of 0.8 m increase in sea level. Under these conditions, high and very high conservation areas would compose 44% of the total flooded area, with medium value areas making up a further 28%. The combination of risk factors relating to water quality and climate change-induced sea level rise was most suited for the identification of conservation priorities. Only 0.38% of the total area was free of from risk, whilst 87% of the Biosphere Reserve area is expected to be susceptible to combined risk factors, albeit with different intensity. The novel value-risk approach to prioritisation proved more effective that the current approach based on area characteristics only. Currently, 50% of the area is identified as medium or high priority. Under the newly proposed prioritization methodology, this area would increase to 60% of the total area. Furthermore, 36% of the area would experience a positive change towards a higher priority status, whilst 13% would experience a negative change towards decreased priority. On the basis of the results, a new prioritization method for the management of areas within the Po Delta Biosphere Reserve is proposed, advocating the inclusion of risk factors in the definition of conservation priorities.