We used Carver's (2010) wilderness quality map and the same quantile approach described earlier in Sect. 3.2, to produce a gradient of wilderness quality with qualitative values ranging between 1 and 4 (4 meaning the highest wilderness quantile and high supply of ecosystem services). We then grouped the ecosystem services into provisioning, regulating, and cultural services and followed the same splitting approach for each group of services. The ecosystem services maps were then overlaid with the wilderness map. To determine the relationship between gradients of both ecosystem services supply and wilderness quality, we display the overlay of high and low wilderness with high and low supply of ecosystem services (Fig. 3.2a, b, c and d). Furthermore, we used the projections of the CLUE model (Verburg and Overmars 2009) to assess the potential change in the provision of ecosystem services with scenarios of land abandonment and rewilding in Europe for 2030. We considered as potential land abandonment and rewilding the cells classified as arable land, pasture, irrigated arable land, permanent crops in 2000 and classified in 2030 in all four EURURALIS scenarios as (semi)-natural vegetation, forest, recently abandoned arable land and recently abandoned pasture land. For quantitative comparisons, we calculated the mean provision of ecosystem service (per km2) in agricultural areas (based on the 2000 land use map, in Verburg and Overmars 2009), in the top 5 % high quality wilderness, and in the areas currently under agricultural use but projected to become abandoned by 2030, in the Iberian Peninsula (Table 3.2). Differences between the distributions of the mean ecosystem service values for each type of land-use were assessed using a Kruskal-Wallis test. Finally, we calculated the ratio between the average supply of each indicator in either the top 5 % wilderness areas and in agricultural areas relative to the areas projected to be abandoned. All mapping and data extraction were done using ArcGIS version 10.3, while the statistical analysis was done using R version 2.15.3.
Wilderness and Ecosystem Services
Some high wilderness areas are associated to regions supplying high ecosystem services, particularly in mountain regions (Fig. 3.2a). As expected, the overlay of provisioning services and wilderness (Fig. 3.2b) exhibits relatively large areas of high supply of services and low wilderness (e.g. in France, Benelux and Germany), along with areas of low service supply and high wilderness (e.g. Northern Scandinavia). This is not surprising since wilderness areas are typically associated with low to no extraction of natural resources. There are nonetheless high provisioning services in some areas of high wilderness quality, mainly associated to mountain regions (e.g. some areas of the Alps and Apennines). This can be due to the occurrence of large quantities of resources for some provisioning services (i.e. timber and freshwater) in mountain regions, which still happen to be wilder than the rest of Europe.
Fig. 3.2 Ecosystem services and wilderness in Europe. For each map, the quantile splits of ecosystem services and wilderness were overlaid to present a gradient of both wilderness and service supply. For an easier representation, the values were grouped into “low” ( bottom 50 %) and “high” ( top 50 %) for both metrics and then grouped, e.g. low supply of services and low wilderness (see color key on the figure). a All indicators for all services versus wilderness; b Indicators of provisioning services versus wilderness; c Indicators of regulating services versus wilderness; and d Recreational service versus wilderness. (See Table 3.1 for details on the indicators used). (Sources: Carver 2010; Maes et al. 2011)
Table 3.2 Quantitative analysis of the supply of ecosystem services in the Iberian Peninsula, on agricultural land, top 5 % high wilderness areas (Carver 2010) and land currently cultivated and projected to be abandoned by 2030 (See Mapping methods section). The p value of the Kruskal Wallis test and the level of significance are given for each indicator: ***, p < 0.001 and NS, p > 0.05
The spatial distribution of wilderness coincides more with regulating services than with provisioning services (Fig. 3.2c). Areas of Europe containing both high supply of services and high degrees of wilderness include mountainous areas in Northern Iberia, Austria, and Italy. Most of the continent is still represented by areas of both low regulating services and low wilderness (e.g. Eastern UK, Poland), which also coincides with agricultural areas (Fig. 3.1b). Interestingly, several areas of high supply of regulating services and low wilderness also exist (Western France and Ireland).
Finally, for recreational services (Fig. 3.2d), we found a predominance of either areas of low service supply and low wilderness, or areas of high wilderness and high service supply, suggesting this is the category of services most strongly associated with wilderness. However there are some areas of low wilderness and high service supply or areas with high wilderness but low recreation potential. Typically, the flow of recreational services is calculated as the product between the capacity of an area to supply recreational services and the accessibility of this area (Maes et al. 2011). As a result, it can occur that an ecosystem would be of extreme beauty or wilderness quality but not accessible, leading to a low flow of recreation and other cultural services, or that an area would be less natural but still be an important cultural landscape that is easily accessible.
Taken as a whole, regulating and cultural services are often associated to high wilderness areas (Fig. 3.2b and c), particularly mountain systems. Mountain ecosystems cover approximately 41 % of Europe's territory, providing various services due to their multifunctionality. Mountains are “water towers” as they provide water for multiple uses, including irrigation, human consumption, and hydropower (Viviroli et al. 2007). Mountain systems supply cultural services, holding spiritual value to local inhabitants, and are recreation and ecotourism attractions (Price et al. 1997). In mountain systems there is a high proportion of habitat types with favorable conservation status (EEA 2010b), playing a key role in supplying many ecosystem services and maintaining ecological processes (Harrison et al. 2010). Forests make up 41 % of mountain systems (Körner et al. 2005) and can be regulators of natural disasters as the soils of mature forests have high infiltration rate, thus reducing peak flows and floods (Maes et al. 2009). Forests also provide a range of services such as carbon sequestration, air quality regulation, timber for fuelwood and non-timber products (game and medicinal plants), and climate regulation (Harrison et al. 2010; Maes et al. 2012b). Peatlands store large quantities of carbon and have played a fundamental role in climate regulation and are critical for water regulation. Grasslands are the habitat of a large number of species, such as wild pollinators (Kremen et al. 2002), which makes them essential in underpinning biodiversity and ecosystem services. Finally, mountains are also hotspots of endemism. In Europe, the highest number of endemic species can be found in the Alps and the Pyrenees (Väre et al. 2003).