1/ Ecological #rewilding has been proposed as an alternative to halting farmland abandonment. Mapping different factors and opportunities for rewilding on land projected to be abandoned are explored in this paper with #rewildingscience this week 
2/ Multiple factors including changes in technology, productivity, and markets have led to agricultural abandonment. In Europe cropland has decreased by ~19% from 1950-2010, whilst pastures and semi-natural grasslands have decreased by ~6%
3/ Despite this some of these areas still hold strong/ecological importance. The protection of these habitats under European policy focuses on extensive farmland, alongside CAP providing subsidies for traditional agricultural practices
4/ A proposed alternative to this is rewilding with an emphasis on the reduction of human influence on landscapes. To explore this the authors developed a framework investigating rewilding opportunities by mapping wilderness quality in areas projected to be abandoned by 2040
5/ Wilderness is measured in 4 metrices; artificial light at night, human accessibility, proportion of harvested primary productivity (nHPP) and deviation from potential natural vegetation (dPNV). These can be used to identify different management options for rewilding
6/ An investigation was also conducted into how protected area systems support rewilding in and around areas of projected abandonment (such as around Natura 2000 sites)
7/ Using land-use change projections of the dyna-CLUE model, 4 socio-economic scenarios which showed different policy and management choices were mapped out. These scenarios highlighted the relative percentage of abandonment…
8/ % of abandonment areas that fell within the 10%,25%,50%, and 75% highest levels of wilderness for accessibility, nHPP, & dPNV were identified. This meant wilderness values for abandoned farmland could be calculated for the 4 matrices (high scores correspond to low wilderness)
9/ The metrices outline human impact on ecosystem function and biodiversity e.g. the effect of artificial light are documented for invertebrates, fish, birds, and mammals. The strongest effect of these are direct mortality, as well as disruption to migratory routes
10/ Human accessibility also has impacts at individual, species, and community level through direct mortality of several taxa (including road traffic pollution)
11/ More than 87% of abandonment was predicted to occur in 33% of areas with the highest wilderness as defined by night light. In contrast, 8.4% of predicted abandonment occurred in 25% of areas with the highest wilderness as defined by dPNV
12/ Accessibility and nHPP had values of 17.4% and 17.5% in areas where 35% of land fell within the highest wilderness category. The authors interpret this as farmland areas being most prone to abandonment exhibiting low levels of infrastructure development and pop. density
13/ Conversely, areas of predicted abandonment in central Europe had higher accessibility due to higher infrastructure development than in other parts of Europe, highlighting the different options/management potential for rewilding
14/ Alongside the discussed marginal land and farmland, natural systems of protected areas coexist with Natura 2000. This network occupies ~18% of the EU territory and aims to maintain specific species habitats in a favourable condition…
15/ Importantly, over almost half of projected abandonment was predicted to occur in or within a 5km radius of Natura 2000 sites. It is suggested then that to potentiate rewilding in those regions, Natura 2000 management has to be expanded to include rewilding actions
16/ Policies and management for rewilding in these circumstances will need to consider time it takes for ecosystems to reach a new equilibrium, levels of natural herbivory/disturbance (may need reintroductions), and natural vs introduced species
17/ The biodiversity dynamics of rewilding abandoned land can come into question due to certain specialist species preferring open areas. At the same time, several species such as grey wolves have taken advantage of land abandonment due to new available resources….
18/ ...In fact, populations of megafauna spatially coincide with high values of wilderness metrics/projected areas of abandonment, therefore raising the possibility of migration into newly available spaces
19/ Whether these large herbivores can delay succession by selectively grazing open areas, particularly in the presence of predators is an open question. However the authors state that there would still be open habitats in a post-abandonment Europe due to herbivore migration
20/ How this will all fit into the current socio-economic landscape remains a discussion point. In the 1930s agricultural subsidies were designed to support farmers, whilst in more recent decades have been expanded to address environmental issues…
21/ Funding has now shifted towards mitigating impacts of agricultural intensification and funding for wildlife habitats has decreased, they write. Wilderness mapping can therefore support the development of rewilding strategies in these different agricultural contexts
22/ Different metrices show varied priorities. The authors conclude by saying that in marginal agricultural regions, where agricultural subsidies are politically difficult to remove, subsidies can be shifted to rewilding measures such as the creation of wildlife habitats
23/ Rewilding provides the opportunity to decrease the human pressure on ecosystems and restoring the more natural biodiversity dynamics and ecosystem services associated with wilderness
24/ Thank you @SilviaCeausu, Max Hofmann, @LM_Navarro, Steve Carver, @peterverburg11, and Henrique M. Pereira for a very interesting paper!
25/ Read the full paper here: conbio.onlinelibrary.wiley.com/doi/epdf/10.11…
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