1. Introduction
Agricultural land abandonment is the largest land-use change process in Europe. The causes have been changing over time in the most developed European countries. While in the 19th century, the industrialization process and the end of World War II were the main causes of land abandonment [
1], nowadays, EU agricultural policies, market pressures, depopulation, rapid urbanization or environmental factors have highly contributed to exacerbating the process [
2]. In particular, land abandonment in European mountains and remote areas has been widely analysed [
3,
4,
5,
6,
7,
8] owing mainly to the depopulation of some areas (“rural exodus”), low incomes and productivity of farm activities because of new opportunities off-farm and unfavourable natural constraints. However, the land abandonment problem is widely spread beyond mountainous and marginal areas, and the situation varies from place to place due to economic, social and demographic situations, natural and environmental conditions, historical and regional context and local preferences [
9,
10].
A broad number of studies [
2,
6,
11,
12,
13,
14,
15] identify a set of drivers that are commonly referred to as the following categories: (1) The environmental factors that constrain agricultural production (soil quality, slope, elevation, fertility, soil depth, seasonal climate, etc.); (2) the socioeconomic situation that expresses the lack of (farm) economic and demographic viability and stability (farm size, supply of labour, age of farmers, productivity levels, policy schemes, low land market mobility, farm investment and industrialisation, trades, etc.); (3) the regional context that measures the level of accessibility (to infrastructure, services and market), distance variables (to major settlements, to forest patches, to remote areas), EU agricultural policy instruments, rapid urbanization processes, population distribution and rural-urban migration; and (4) the mismanagement of soil and water resources leading to land degradation, soil erosion, overexploitation of groundwater resources causing water scarcity and salinization of croplands.
Land abandonment affects millions of hectares in Europe with its associated implications [
16]. The combination of various mentioned factors produces very diverse impacts that alter biogeochemical and hydrological cycles, soil properties, an increase of forest fires, erosion, landslides, landscape transformation as well as affects socio-economic aspects [
17,
18,
19,
20]. However, revegetation is one of the positive options once land abandonment occurs and, if it naturally evolves, moves from herbaceous plants and shrubs to young forest. A successful recovery entails an improvement in soil properties and nutrients, land stabilization, among others, with the inherent increase of organic matter content [
21]. Beyond the environmental impacts, abandonment affects not only the abandoned area itself but also its local population and the whole society in terms of production of goods (e.g., foods, feed, fibre and biomass production) as well as other services provided by the multifunctionality of the agricultural land [
22,
23]. In this context, food security can be one of the major challenges for the future of the EU, aiming at keeping its agricultural production potential and considering the implications on important aspects of the rural economy [
13]. For many regions in Europe, the agricultural sector still plays a significant economic role [
24] and its eventual decline due to massive abandonment, among other factors, might cause a loss of jobs in the agricultural and related sectors, out-migration of young people and a decline in the management of agroecosystems [
17,
23]. The decrease in agricultural land influences agricultural outputs and management practices. Changes in management practices such as agricultural intensification and specialization lead to high productivity in more fertile areas, while producing marginalisation and abandonment in others [
25]. Many farming regions, especially in central and eastern parts of Europe, have been also affected by economic and political transformation (collapse of the former URSS, Common Agricultural Policy (CAP) subsidies system or market globalization), the loss of export markets, the reduction in domestic support, the transition to free-market economies, etc. causing the reduction of agricultural viability, stability and profitability triggering massive land abandonment processes [
22,
25,
26].
In particular, Spain is one of the countries in which more studies have been conducted to measure and assess the impacts of land abandonment. Despite the scope of many of these studies being on a local scale, they reflect the evolution of Spanish agriculture and the correlation with the climate, soil and terrain conditions [
27,
28]. However, many changes occurred during the last century in the agricultural production system of Spain, dealing with the real problem of land abandonment and its negative environmental, biological, hydrological, geomorphological, socioeconomic and cultural consequences [
2]. Hydraulic infrastructure began to be an important policy after the 1960s in order to increase productivity, diversification and intensification of cropland, especially in the semi-arid area of Spain resulting in many cases in overexploitation of water resources [
11]. After the implementation of the Common Agricultural Policy (CAP) in 1986 and its posterior reform in 1992, Spain underwent an inflexion point where the agricultural outputs declined, and the loss of utilised agricultural area (UAA) constantly increased [
27]. The CAP started to subsidize some crops to the detriment of others, producing a reallocation of agricultural systems from the humid north to the semi-arid regions [
11]. This situation led to the need of building new terrace structures in marginal and steep-slopes in order to host the expansion of vineyards and other orchard trees at the expense of forest, cereals fields and fodder crops [
29]. The CAP has also influenced other aspects with the application of the set-aside policy that potentially increases the risk of erosion and abandonment leaving the land uncultivated. Besides, by the 1980s, technological and industrial developments, demographic dynamics with important depopulation rates (especially in the most mountainous and rural areas) and the influence of international markets (demand and price) had an impact on the agricultural Spanish system.
The objective of this paper, therefore, is to present an assessment of future territorial patterns and the main drivers of land abandonment based on the outputs from the LUISA Territorial modelling platform under the 2017 Reference Scenario. The emphasis is to statistically and spatially analyse the extent and the location of agricultural land abandonment by 2030 at the national, regional and local levels in Spain. By agricultural land abandonment, we refer to land that was previously used for crop or pasture but has no more farming functions, which basically means a total cessation of agricultural activities. This article takes on board the most important novelties that were integrated in the spatial-explicit framework aiming at modelling future agricultural abandonment, in particular: (1) the dynamic character through the simulation period (2015–2030), (2) the spatial resolution of the abandonment and the EU risk map (100 m grid cell) and (3) future projections of the agricultural land abandonment while competing with other land uses (urban, industry, forest, etc.).
4. Discussion and Conclusion
LUISA, as a spatial-explicit model conceived to contribute to territorial impact assessment and analysis of EU trends and policies, can help to understand to what extent, in time and space, agricultural land abandonment will affect in different regions in Spain. However, the LUISA model, as any other model simplifying the complex process in reality, entails limitations and uncertainties in the design and system (i.e., thematic, spatial and temporal resolution, data availability, geographical coverage, assumptions, scientific-based methods, etc.). One of the most important limitations in this study is the fact that the model configuration is implemented for the whole EU rather than for a particular Member State. This, specifically, means that using better spatial data, higher resolutions, country-specific assumptions/rules based on previous studies, regional/local statistics and so on, outcomes might considerably improve. However, this is not the main role of LUISA that serves to a more ambitious purpose in terms of thematic indicators (population, employment, industry, built-up areas, access to services, transportation, accessibility, etc.), coverage, new methods and techniques, impact assessment analysis, decision-making policy support and so on. It is worth mentioning, as another limitation cause, the selected driving factors (
Table 1 and
Figure 4) to build the EU risk map from European data sources. It is evident that the lack of higher resolution for some spatial layers (for instance, length growing period) and the low accuracy and spatial variability of some others (salinity, precipitation or sodicity factors) influence the quality of the final results. Besides this, a data harmonization process is necessarily applied to make consistent the inputs related to the agroeconomic and farm structural factors due mainly to missing regional data or discrepancies between NUTS3 versions [
57,
58]. Thus, even though LUISA results provide actual figures, the herein presented quantitative assessment needs to be cautiously interpreted owing to all mentioned aspects. However, as described below, LUISA spatially captures and identifies, in a faithful manner, the hotspot areas affected by agricultural abandonment at the local and regional scale.
During the last decade, different works and assessments have been considered as a benchmark from a European perspective [
6,
7,
10,
12,
16,
64,
65,
66,
67,
68], though their methods, assumptions, nature of the work and results are considerably different. They have helped to explain and estimate to what extent land abandonment affects regions in terms of magnitude, location (spatial and temporal), but also, which are the driving forces and impacts. Many authors [
13,
14,
15,
16,
17] demonstrated and highlighted the effects of agroecological, socioeconomic and farm structure variables in determining abandonment patterns which are fully in line with the set of driving factors used in the presented analysis. Recent studies also propose a broader list taking into account other variables like distance to the nearest forest, distance to farms, land consolidation, isolated agricultural plots within forest, proximity to markets, road density, landscape structure or irrigation maps among others [
8,
14,
20]. Many of the mentioned works rely on spatially-explicit logistic regressions to assess the determinants of agricultural abandonment because they are relatively easy to understand and formulate [
69]. Soil type, topography (elevation and slope) and rural population change were the most important variables explaining land abandonment in western Ukraine while infrastructure density, land-use intensity and distance were low significant contrarily to the initial hypothesis [
25]. On the contrary, accessibility (distance to roads and to villages) was found an important driver of abandonment in the case of western European countries, age index and slope [
67].
From European data sources, we firstly analyse and compare in this section the observed local abandoned rates from [
6] (
Appendix A) and the ones modelled from LUISA (
Figure 11), especially the south-eastern part of Spain, Galicia, Pyrenees and the most inner and central part. Spain gathers the major number of case study areas mainly due to the large distribution of mountain ranges, from the north to the south, within the Iberian Peninsula. The spatially coinciding NUTS3 regions overlapping those observed abandonment hotspots are found in Cantabria, Asturias, Gipuzkoa, Madrid, Ávila, Salamanca, Lleida, Rioja, Zaragoza, Málaga, Granada and Almería. Thus, fifty-eight municipalities (
Appendix B) captured by LUISA were analysed at the local level, in which abandonment shares ranging from 30% to 84%, with the highest affected areas by abandonment in Lleida (El Pont de Suert, 84%), north of Madrid (Navarredonda, San Mames and Puentes viejas, 80%) and Zaragoza (Borja and Ainzon, 80% and 81%, respectively). Secondly, based on remote-sensing observations, [
15] predicted the likelihood of abandoned areas at the pan-European scale (European Union, Russia and Ukraine) using machine learning techniques based on a 5 km grid cell (pixel). Particularly, in the Iberian Peninsula, these predictions are not completely coincident with national studies carried out by many authors [
2,
6,
8,
20,
70,
71] and also with LUISA outputs. North-western Spain (Galicia), south-eastern Spain (Murcia region) and northern Portugal are highly affected by abandonment; however, those regions were not captured by the predictions from that study.
After analysing and comparing local studies to LUISA outputs (
Figure 9 and
Figure 11), this confirms that the biggest challenges in Spain are expected to take place, especially in its north-western part, where Lugo province will be affected the most by land abandonment in Galicia region. We reviewed the theoretical and qualitative work of [
27,
28] centred on concepts, drivers and consequences of the abandonment of agriculture with a focus on Galicia. A more quantitative approach can be seen in [
8,
27] using different statistical and cartographic data sources between 1956 and 2004, analysing the district of Terra Cha in Lugo Province. Variables such as slope and distance to farms were significantly correlated with high rates of abandonment while recovery for cultivation was related to accessibility, shape, slope and distance. The later article is contextualised on the IRENA Agri-Environmental Indicators (European Commission) where the indicator of “Risk of Farmland Abandonment” is calculated at the municipality level in Galicia. A response variable referred to as “abandoned.uaa” can be compared with what LUISA simulates. Particularly, a strong correlation can be seen between abandonment and slope, population density and travel time. In terms of location and extent in this study, we can find municipalities with abandonment shares over the total UAA ranging from 29.6–73%, similarly to the LUISA model, especially in the central and south-eastern part of Lugo and Ourense (bordering on Asturias, Leon and Zamora regions). Another cluster of regions can be found in the inner part of Pontevedra limiting to the north of Ourense, while abandonment declines when approaches the coastline (Atlantic coast).
Other regions in the western Mediterranean basin, which are likely to face significant land abandonment, are located in Murcia, Málaga, Almería, Valencia and Alicante. [
2] showed the prediction of a land abandonment map in Murcia using random forest techniques where the higher potential of abandonment appears in the northeast of the province (Yecla, Jumilla, Albanilla, Calasparra, Cieza, Fortuna, Albaran, etc.). LUISA also captures these hotspots ranging from 7% up to 20% of abandonment over the total UAA in the municipalities leading the ranking by 2030 if this trend continues over time. Guadalentin basin (southwest of Murcia limiting with Andalusia) is identified as an abandonment hotspot area by other authors [
72,
73] and also by the modelled LUISA results. The main difference compared to these studies is found in the Huerta y Campo de Murcia region (south-east of Murcia) where LUISA project less abandonment. Local studies in Valencia region (east Spain), Málaga and Almería regions (south-east Spain) has been carried out as representative Mediterranean areas prone to land abandonment, emphasizing the environmental impacts (soil erosion, increase in organic matter, infiltration capacity, vegetation recovery, etc.) when the phenomenon occurs [
18,
19,
21,
29]. The last Spanish regions with high potential of future abandonment according to LUISA are placed mainly in the Central Pyrenees, northern part of the Iberian Range and the inner side of the Ebro basin (Huesca, Navarra, La Rioja, Zaragoza and Teruel) whilst less pronounced in the Catalan Prelitoral (Lleida, Barcelona and Tarragona). During the last decades, many studies were focused on these areas at plot, catchment, local or regional scale, mainly dealing with the hydrological, geomorphological or land-use change effects of land abandonment rather than, in most cases, the abandonment of agricultural use per se [
20,
29,
74,
75,
76,
77,
78,
79].
The lack of a homogeneous and continuous database or inventory of agricultural abandonment makes difficult further studies on this topic. As mentioned, most of the studies are local or regional, therefore, difficultly can be used for a straightforward comparison due to the usage of different territorial boundaries or the temporal component. The spatial data and statics currently used are not accurate enough for assessing farmland abandonment. Estimations based on remote sensing diverge from case studies due to the difficulties in land cover interpretation to distinguish between abandoned farmland and grazing area [
80]. In Spain, some studies have used the SIOSE map for comparison and calibration of different model results [
2,
73]. Concerning statistical data [
8,
10] stated that this complex and local phenomenon should be studied at a finer scale (LAU2, municipality level) rather than the usual NUTS3 level approach.
Agricultural land abandonment has been occurring over time and its expansion seems to continue happening not necessarily only in mountain and marginal areas but also in vulnerable regions. Spatial patterns of abandonment projected by the LUISA model have reflected a good spatial coincidence with the most affected areas observed in Spain which demonstrates that it can be a useful tool for case studies. LUISA, in the case of Spain, identifies a first group of regions located in the western Mediterranean belt (Valencia, Alicante, Murcia and Almería), Galicia region (Lugo, Ourense, Pontevedra and A Coruña), Central Pyrenees/Ebro Depression/North Iberian Range (Navarra, La Rioja, Huesca, Zaragoza, Teruel and Barcelona) where agricultural land abandonment is expected to be particularly prominent and, a second group in the Cantabrian mountains (Asturias and Cantabria) and the Central System (Madrid and Ávila). In summary, these findings indicate that agricultural abandonment is not equally spread across the country, ranging from less than 0.4% to more than 44% at the regional level (province) with an average greater than 10%. Spain is expected to undergo an abandonment process that will reach roughly 5% (1.1 million ha) of the total agricultural land by 2030. Special attention must be paid to mountainous and natural protected areas (HNV farmland and Natura 2000 network) which cover an important proportion of its national area. Although LUISA does not integrate a specific artefact to directly prevent land abandonment within those policy-related layers, the results suggest that abandonment has a lower impact on them compared to outside places, likely due to the conservation measures to, among other purposes, prevent abandonment. The predicted abandonment in HNV and Natura 2000 areas to lead to a loss in farmland biodiversity and more intensive forms of agriculture.
Current work is focused on a validation exercise of the European risk map of agricultural land abandonment by means of regressions models. From a technical point of view, future work will improve the resolution (spatial and temporarily) of the main drivers and, in particular, remoteness areas (origin points) and the integration of irrigation maps. As we discussed in this article, agricultural land abandonment has a direct and indirect impact on the rural population and economy. An assessment of different socioeconomic and demographic factors in rural areas will take into account depopulation, ageing population, economic performance in the primary sector (employment, among other factors) and an attractiveness index in rural areas.