A unifying modelling of multiple land degradation pathways in Europe

Land degradation is a complex socio-environmental threat, which generally occurs as multiple concurrent pathways that remain largely unexplored in Europe. Here we present an unprecedented analysis of land multi-degradation in 40 continental countries, using twelve dataset-based processes that were modelled as land degradation convergence and combination pathways in Europe’s agricultural (and arable) environments. Using a Land Multi-degradation Index, we find that up to 27%, 35% and 22% of continental agricultural (~2 million km2) and arable (~1.1 million km2) lands are currently threatened by one, two, and three drivers of degradation, while 10–11% of pan-European agricultural/arable landscapes are cumulatively affected by four and at least five concurrent processes. We also explore the complex pattern of spatially interacting processes, emphasizing the major combinations of land degradation pathways across continental and national boundaries. Our results will enable policymakers to develop knowledge-based strategies for land degradation mitigation and other critical European sustainable development goals.

Supplementary Fig. 3. Spatial pattern of interacting convergent processes in agricultural environments of Europe (all 40 investigated countries).a-e, Spatial distribution of the dominant (most frequent) co-occurring process types (combinations) in LMI agricultural classes 1 (a), 2 (b), 3 (c), 4 (d) and 5 (e).f-j, Absolute and percentage-based (% of the total continental agricultural lands) spatial footprint of the dominant co-occurring process types in LMI agricultural classes 1 (f), 2 (g), 3 (h), 4 (i) and 5 (j).Notes: in order to simplify the mapping of process combinations (which are very numerous for each LMI class, except for class 1), in this figure the twelve most important types of co-occurring processes in Europe were selected, which, in terms of area, cumulatively account for at least 50% of all LMI class combinations; to better highlight the mapped process combinations, pixel size was increased to 5 km × 5 km, but the quantification of process combination areas (in km 2 and %) was done using the original data resolution of 500 m × 500 m; compared to Fig. 3, the process combinations are spatialized here for all analysed states, considering that in some cases with incomplete data (Norway, Switzerland, Balkan countries, Cyprus and Malta) we still used a large number of process databases (9-10 input layers out of 12) in computing LMI (see Methods); consequently, LMI still has the potential to provide a good/very good picture of land degradation in these particular countries, even if their LMI combinations should be interpreted with some caution; LMI is the acronym for Land Multi-degradation Index; the source data for the graphs in this figure are provided as a Source Data file.Supplementary Fig. 4. Spatial pattern of interacting convergent processes in arable environments of Europe (all 40 investigated countries).a-e, Spatial distribution of the dominant (most frequent) co-occurring process types (combinations) in LMI arable classes 1 (a), 2 (b), 3 (c), 4 (d) and 5 (e).f-j, Absolute and percentage-based (% of the total continental arable lands) spatial footprint of the dominant co-occurring process types in LMI classes 1 (f), 2 (g), 3 (h), 4 (i) and 5 (j).Notes: in order to simplify the mapping of process combinations (which are very numerous for each LMI class, except for class 1), in this figure the twelve most important types of co-occurring processes in Europe were selected, which, in terms of area, cumulatively account for at least 50% of all LMI class combinations; to better highlight the mapped process combinations, pixel size was increased to 5 km × 5 km, but the quantification of process combination areas (in km 2 and %) was done using the original data resolution of 500 m × 500 m; compared to Fig. 4, the process combinations are spatialized here for all analysed states, considering that in some cases with incomplete data (Norway, Switzerland, Balkan countries, Cyprus and Malta) we still used a large number of process databases (9-10 input layers out of 12) in computing LMI (see Methods); consequently, LMI still has the potential to provide a good/very good picture of land degradation in these particular countries, even if their LMI combinations should be interpreted with some caution; LMI is the acronym for Land Multi-degradation Index; the source data for the graphs in this figure are provided as a Source Data file.
Notes: a -agricultural/arable lands unaffected by degradation processes; b -most frequently five concurrent processes, according to the LMI histograms for agricultural/arable areas (Supplementary Fig. 2b,e); % -the percentage-based area of the number of convergent processes (0, 1, 2, 3, 4, ≥5), related to the absolute area of continental agricultural (2,098,907 km 2 )/arable (1,143,149 km 2 ) lands; compared to Table 1, these European statistics are extracted here based on LMI data from all analysed states, considering that in some cases with incomplete data (Norway, Switzerland, Balkan countries, Cyprus and Malta) we still used a large number of process databases (9-10 input layers out of 12) in computing LMI (see Methods); consequently, LMI still has the potential to provide a good/very good pan-European picture of land degradation, even if it includes these particular countries, where LMI data should be interpreted with some caution.Notes: a -LMI class 1 strictly includes the twelve processes (I-XII) that act singularly (Supplementary Fig. 3a) and not synergistically in the degradation of agricultural lands: I (SPP), II (SNI), III (SPHM), IV (A), V (SA), VI (SC), VII (WaE), VIII (SOCL), IX (WiE), X (VD), XI (GD), XII (SS); these processes were organised from I to XII according to the descending order of their areas at continental level (Supplementary Fig. 3a,f), which does not necessarily apply nationally; process abbreviations: WaE -water erosion, WiE -wind erosion, SOCL -soil organic carbon loss, SS -soil salinization, SA -soil acidification, SC -soil compaction, SNI -soil nutrient imbalances, SPP -soil pollution via pesticides, SPHM -soil pollution via heavy metals, VD -vegetation degradation, GD -groundwater decline, A -aridity; country abbreviations: UK -United Kingdom, BH -Bosnia and Herzegovina; % -the percentage-based area of the processes, related to the absolute area of the countries' agricultural lands (which can be found in Supplementary Table 2); LMI statistics should be interpreted with some caution within several European countries (Norway, Switzerland, Balkan countries, Cyprus and Malta), where 9-10 of the 12 input geospatial databases (Fig. 1) were available for LMI computation.Notes: a -in this table, the most important (frequent) twelve types of co-occurring processes (I-XII) in Europe were selected (Supplementary Fig. 3b), which, in terms of area, cumulatively account for at least 50% of the LMI class 2: I (SNI + SPP), II (SPP + A), III (SPP + SPHM), IV (SNI + SPHM), V (SC + SNI), VI (WaE + SPP), VII (SA + SNI), VIII (SNI + A), IX (SC + SPP), X (SA + SPP), XI (SPHM + A), XII (SOCL + SNI); these types (combinations) of processes were organised from I to XII according to the descending order of their areas at continental level (Supplementary Fig. 3b,g), which does not necessarily apply nationally; process abbreviations: WaE -water erosion, SOCL -soil organic carbon loss, SA -soil acidification, SCsoil compaction, SNI -soil nutrient imbalances, SPP -soil pollution via pesticides, SPHM -soil pollution via heavy metals, A -aridity; country abbreviations: UK -United Kingdom, BH -Bosnia and Herzegovina; % -the percentage-based area of the types of convergent processes, related to the absolute area of the countries' agricultural lands (which can be found in Supplementary Table 2); LMI statistics should be interpreted with some caution within several European countries (Norway, Switzerland, Balkan countries, Cyprus and Malta), where 9-10 of the 12 input geospatial databases (Fig. 1) were available for LMI computation.Notes: a -in this table, the most important (frequent) twelve types of co-occurring processes (I-XII) in Europe were selected (Supplementary Fig. 3c), which, in terms of area, cumulatively account for at least 50% of the LMI class 3: I (SNI + SPP + SPHM), II (SPP + SPHM + A), III (WaE + SPP + SPHM), IV (WaE + SPP + A), V (SC + SNI + SPP), VI (WiE + SPP + A), VII (SNI + SPP + A), VIII (SC + SNI + A), IX (WaE + SNI + SPP), X (SC + SPP + A), XI (WaE + SNI + A), XII (SPP + GD + A); these types (combinations) of processes were organised from I to XII according to the descending order of their areas at continental level (Supplementary Fig. 3c,h), which does not necessarily apply nationally; process abbreviations: WaE -water erosion, WiE -wind erosion, SC -soil compaction, SNI -soil nutrient imbalances, SPP -soil pollution via pesticides, SPHM -soil pollution via heavy metals, GD -groundwater decline, A -aridity; country abbreviations: UK -United Kingdom, BH -Bosnia and Herzegovina; % -the percentage-based area of the types of convergent processes, related to the absolute area of the countries' agricultural lands (which can be found in Supplementary Table 2); LMI statistics should be interpreted with some caution within several European countries (Norway, Switzerland, Balkan countries, Cyprus and Malta), where 9-10 of the 12 input geospatial databases (Fig. 1) were available for LMI computation.Notes: a -LMI class 1 strictly includes the twelve processes (I-XII) that act singularly (Supplementary Fig. 4a) and not synergistically in the degradation of arable lands: I (SPP), II (SNI), III (A), IV (SC), V (SPHM), VI (SA), VII (WaE), VIII (SOCL), IX (WiE), X (VD), XI (GD), XII (SS); these processes were organised from I to XII according to the descending order of their areas at continental level (Supplementary Fig. 4a,f), which does not necessarily apply nationally; process abbreviations: WaE -water erosion, WiE -wind erosion, SOCL -soil organic carbon loss, SS -soil salinization, SA -soil acidification, SC -soil compaction, SNI -soil nutrient imbalances, SPP -soil pollution via pesticides, SPHM -soil pollution via heavy metals, VD -vegetation degradation, GD -groundwater decline, A -aridity; country abbreviations: UK -United Kingdom, BH -Bosnia and Herzegovina; % -the percentage-based area of the processes, related to the absolute area of the countries' arable lands (which can be found in Supplementary Table 3); the countries without values (Monaco and Andorra) do not hold any arable lands; LMI statistics should be interpreted with some caution within several European countries (Norway, Switzerland, Balkan countries, Cyprus and Malta), where 9-10 of the 12 input geospatial databases (Fig. 1) were available for LMI computation.

Table 2 .
Spatial extent (in km 2 and %) of agricultural areas and of convergent land degradation processes in agricultural environments of all 40 European countries several European countries (Norway, Switzerland, Balkan countries, Cyprus and Malta), where 9-10 of the 12 input geospatial databases (Fig.1) were available for LMI computation.Supplementary

Table 3 .
Spatial extent (in km 2 and %) of arable areas and of convergent land degradation processes in arable environments of all 40 European countries

number of convergent land degradation processes)
Notes: a -arable lands unaffected by degradation processes; b -most frequently five co-occurring processes, according to the LMI histogram for arable areas (Supplementary Fig.2e); % -the percentage-based area of the number of convergent processes (0, 1, 2, 3, 4, ≥5), related to the absolute area of national arable lands; country abbreviations: UK -United Kingdom; BH -Bosnia and Herzegovina; the countries without values (Monaco and Andorra) do not hold any arable lands; LMI statistics should be interpreted with some caution within several European countries (Norway, Switzerland, Balkan countries, Cyprus and Malta), where 9-10 of the 12 input geospatial databases (Fig.1) were available for LMI computation.Supplementary

Table 4 .
Spatial extent (%) of process types featured in LMI class 1, in agricultural environments of all 40 European countries

Table 5 .
Spatial extent (%) of process types (combinations) featured in LMI class 2, in agricultural environments of all 40 European countries

Table 6 .
Spatial extent (%) of process types (combinations) featured in LMI class 3, in agricultural environments of all 40 European countries