Titolo della tesi: Biodiversity priority regions and their role for preserving Nature’s Contributions to People
Biodiversity and ecosystems support human societies worldwide, but our levels of exploitation of natural resources are unsustainable, and this has resulted in the anthropogenic loss of several important biodiversity areas. The conservation world is at a crossroad while governments are negotiating targets for the next 10 years of international biodiversity commitments through the post-2020 Framework of the CBD. Yet, evidence on where the most important areas for biodiversity are located remains misaligned and often contradictory. In parallel, it remains unclear how the conservation of regions of high biodiversity value contributes to the preservation of Nature’s Contributions to People (NCP), and whether future climate change will reduce or increase such contributions. Therefore, the overarching goal of this PhD thesis is to quantify the risk that global change poses to priority areas for biodiversity conservation, and the services they provide to humanity. More specifically, with this work I wanted to identify the regions of high biodiversity value that will contribute the most to the provision of different regulating NCP under different socioeconomic development scenarios, and how some indicators of NCP provision could simultaneously act as driver of extinction risk.
In an effort to guide actions to conserve biodiversity, different approaches have been suggested in recent decades for identifying areas of importance for biodiversity conservation, but having several discording maps of biodiversity priorities is problematic because it results in redundance and competition, rather than complementary priority sets. Therefore, as first step to optimize comprehensive strategies aimed at ensuring the persistence of biodiversity and related ecosystem services, I have developed a framework to systematically identify these consensus regions of high biodiversity value from published spatial conservation prioritization maps, while accounting for the methodology with which maps were derived. I retrieved 63 articles presenting global conservation prioritization maps and grouped these into three separate clusters based on their underlying common characteristics. By combining these maps, weighted according to their cluster characteristics, I generated a map of scientific-consensus regions with the highest overlap of independently generated priorities.
My results indicate that priorities identified as consensus are mostly located in the tropics, but there are several regions identified in temperate regions. I found that less than one third of the top-30% ranked consensus regions are currently protected. Thus, there is high potential for targeting area-based conservation interventions in regions that represent immediate priorities for biodiversity conservation (according to multiple independent analyses) and have high potential for policy support.
I have also investigated whether the top-ranked biodiversity consensus regions could reduce the risk of diminishing the provision of NCP, thus contributing to the achievement of various Sustainable Development Goals (SDGs). I analysed four different scenarios of global environmental change from CMIP6, selecting few data proxies of the potential NCP indicators in order to measure the change status of NCP in the future. I evaluated the risk to the provision of three regulating NCP: air quality (NCP 3), climate (NCP 4), and freshwater quantity (NCP 6). For each NCP indicator, I evaluated whether risk from environmental change is higher or lower within biodiversity consensus regions compared to control regions with similar environmental characteristics. I found that all NCP had higher values within biodiversity consensus regions compared to their counterparts, and that two of the NCP will also increase their values within such regions in the future (more so than in control regions). This was not the case for NCP 6 which decline globally especially in South and central America, however, regions of high biodiversity value will face a proportionally lower reduction in future water availability compared to control regions.
Climate change poses a challenge to both biodiversity and NCP through extreme events such as fire, droughts and extreme temperature. While this represents a global risk to nature and humans, it also provides opportunities for shared intervention strategies. I have investigated the potential for synergies between biodiversity conservation and NCP preservation under scenarios of increased extreme events impact. I developed a comparative extinction risk model for mammal species sensitive to fire, drought, and extreme temperatures, and used it to predict their probability of extinction under future climate change. I also projected risk to several NCP affected by the same stressors, and then produced global maps to identify hotspots of biodiversity and NCP risk. Under a pessimistic climate change scenario (projecting an average 4°C global worming), the probability of extinction increased for 299 species out of 476 analysed. I found several areas where high cumulative risk for these species matches high risk of NCP loss from global warming, for example Amazon, Caatinga region in north-eastern Brazil, tropical shrubland and dry forest of South-Central Africa, and northern Australia.
This PhD thesis provides important insights on the spatial coherence between areas of high biodiversity value, areas that have high potential to deliver regulating NCP, and hotspot of mammal’s extinction risk. This knowledge, generated under alternative socio-economic development scenarios, can help moving a step forward in the implementation of a coupled approached to reach both climate and biodiversity global target.
In conclusion, my results prove that reaching biodiversity targets is essential to safeguard many NCP, and vice versa losing areas that are important for biodiversity would have negative effects on NCP availability. There is a growing body of evidence that NCP underpin the achievement of the SDG targets, for example, protecting areas of high biodiversity value will preserve different NCP and protect life on land (SDG 15), providing clean water (SDG 6) and mitigating the effects of climate change (SDG 13). Thus, it is essential to prioritizing synergies and avoiding trade-offs across the Sustainable Development Goals (SDGs) and targets in order to achieve biodiversity conservation and human-wellbeing.