1. INTRODUCTION
⌅Land take refers to the transformation of natural and/or agrarian areas to artificial surfaces destined to diverse uses such as residential, industrial, commercial, equipment, transport infrastructures, etc. (European Environment Agency, 2017European Environment Agency (2017). Land take indicator. Retrieved from https://www.eea.europa.eu/data-and-maps/indicators/land-take-3 ; Olazabal and Bellet, 2018Olazabal, E. & Bellet, C. (2018). Procesos de urbanización y artificialización del suelo en las aglomeraciones urbanas españolas (1987-2011). Cuadernos Geográficos, 57. https://doi.org/10.30827/cuadgeo.v57i2.5920 ). It is a direct indicator of urbanization processes (European Environment Agency, 2017European Environment Agency (2017). Land take indicator. Retrieved from https://www.eea.europa.eu/data-and-maps/indicators/land-take-3 ; Ministerio de Agricultura y Pesca, Alimentación y Medio Ambiente, 2017Ministerio de Agricultura y Pesca, Alimentación y Medio Ambiente (2017). El perfil ambiental de España. Retrieved from https://www.miteco.gob.es/es/calidad-y-evaluacion-ambiental/publicaciones/pae_2016_reducido_tcm30-439388.pdf ) that allows analysing the land cover spatio-temporal dynamics that could result from the socioeconomic and environmental pressures operating in a given territory. Due to its irreversibility, these changes are a potential threat to sustainability and have direct implications on the supply of ecosystem services (Prieto and Ruiz, 2013Prieto, F. & Ruiz, J.B. (2013). Costas inteligentes. Estudio realizado para Greenpeace España. Madrid. Retrieved from http://archivo-es.greenpeace.org/espana/es/reports/-Costas-inteligentes/ ). Land take is a process of relevance in all UE countries and one of the major environmental challenges Europe is facing (European Commission, 2011European Commission (2011). Communication of the EC to the European Parliament COM (2011) 571 of 20.09.2011. ; Wang, Liu & Peng, 2012Wang, J.F., Liu, X.H. & Peng, L. (2012). Cities evolution tree and applications to predicting urban growth. Population and Environment, 33, 186-201. https://doi.org/10.1007/s11111-011-0142-4 ). “No net land take by 2050” has been fixed as a goal in the UE due to its consequences such as losses in biodiversity, habitat fragmentation, soil sealing, urban sprawl, economic impacts derived from the loss of agricultural land, or impacts on the carbon and water cycles (Decoville and Schneider, 2015Decoville, A. & Schneider, M. (2015). Can the 2050 zero land objective of the EU be reliably monitored? A comparative study. Journal of Land Use Science, 11-3, 331-349. https://doi.org/10.1080/1747423X.2014.994567 ).
The increase of artificial surfaces has been recorded in Europe through the Corine Land CoverCopernicus (2008). Corine Land Cover (2000, 2006, 2012) [dataset]. Retrieved from https://land.copernicus.eu/pan-european/corine-land-cover (CLC) project since 1987. The European Environment Agency (EEA) publishes periodically the results of the indicator “urban land take” which measures the increase of artificial surfaces occurring at the expense of agricultural, forestry or seminatural covers since year 2000. This indicator shows that artificialization rates in Spain have always been above the European average, although the temporal trends are not totally coincident. Thus, for instance, the annual average value of the “urban land take” indicator in Europe for the periods 2000-2006 and 2006-2012 was 0.5% and 0.4% respectively, while in Spain they were 2.8% (the third in Europe) and 1.5% (the first in Europe) in the same periods. In fact, 23.5% of the European urbanization took place in Spain in the period 2000-2006, in contrast with 12.2% in France and 9.5% in Germany (Couch, 2016Couch, C. (2016). Urban Planning: An Introduction. London: Palgrave and Macmillan. ). These high rates were mainly associated with building activity connected with the dispersed urban model and the large investment in infrastructures (Observatorio de la Sostenibilidad, 2006Observatorio de la Sostenibilidad (2006). Cambios de ocupación del suelo en España: implicaciones para la sostenibilidad. Madrid, España: Mundiprensa.). As a consequence, the area covered by urban land classes increased in Spain by 25.4% in the 1990-2000 period, while the population rose up by only 5% (Greenpeace, 2010Greenpeace (2010). Destrucción a toda costa 2010. Retrieved from http://archivo-es.greenpeace.org/espana/es/reports/100713-25/ ).
This urbanization process was not homogeneous throughout the territory but is generally more intense in the littoral zone (Observatorio de la Sostenibilidad, 2006Observatorio de la Sostenibilidad (2006). Cambios de ocupación del suelo en España: implicaciones para la sostenibilidad. Madrid, España: Mundiprensa.), a phenomenon known as “littoralization” which consists in the concentration of the population, infrastructures, economic activities and settlements in the coastal areas (Barragán Muñoz, 1994Barragán Muñoz, J. (1994). Ordenación, planificación y gestión del espacio litoral. Barcelona, España: Oikos-Tau. ). A result of this pattern is that approximately 40% of the European population lives in the first 50 kilometers from the coastline and almost 40% of the European gross domestic product is generated in those maritime regions (European Environment Agency, 2013European Environment Agency (2013). Balancing the future of Europe’s coasts: knowledge base for integrated management. Retrieved from https://www.eea.europa.eu/publications/balancing-the-future-of-europes ). The increase in artificial areas in the European 10 km coastal zones was, on average, 12% between 1990 and 2000. This value was even higher in Portugal (34%), Ireland (27%) or the whole Spanish territory (18%) (Jiménez Herrero, Guaita García, López Hernández & Delgado Jiménez, 2009Jiménez Herrero, L.M., Guaita García, N., López Hernández, I. & Delgado Jiménez, A. (2009). Procesos de sostenibilidad en España: implicaciones territoriales y urbanas. Anales de mecánica y electricidad v. 2009, 32-39. ISSN 0000-2506), where the increase of artificial areas in the 10 km coastal zone between 1990 and 2006 represented about 1/3 of the total area built in the previous centuries. Simultaneously, the population living in Spanish coastal municipalities (which represent 8% of the territory) rose from 24% of the total population in 1960 to 44% in 2010 (Ministerio de Agricultura, Alimentación y Medio Ambiente, 2014Ministerio de Agricultura, Alimentación y Medio Ambiente (2014). Ecosystems and biodiversity for human well-being. Retrieved from https://doi.org/10.13140/2.1.2415.1842 ). The Observatorio de la Sostenibilidad (OSE) studied the urbanization process in the Spanish coastal area from 1987 to 2011 showing rates of 2.2 hectares per day in the first 500 meters from the coastline, with some areas showing a complete urbanization of the available space (Observatorio de la Sostenibilidad, 2016aObservatorio de la Sostenibilidad (2016a). 25 años urbanizando España. Retrieved from https://www.observatoriosostenibilidad.com/informes/ ). According to the Bank of Spain, the number of new houses built in Spain per 10000 inhabitants during the period 2004-2007 was 9.1, which contrasts with the value of 5.7 reported for Europe. Only in 2007, Spanish coastal municipalities approved the construction of nearly three million new dwellings (Greenpeace, 2010Greenpeace (2010). Destrucción a toda costa 2010. Retrieved from http://archivo-es.greenpeace.org/espana/es/reports/100713-25/ ).
The Galician coast was also affected by the substantial expansion of urbanization, with varying intensity depending on the area, but tending towards scattered settlements (Xunta de Galicia, 2011Xunta de Galicia (2011). Plan de ordenación do litoral de Galicia. Retrieved from http://www.xunta.es/litoral/ ). Several areas of the Galician region were subjected to an intense artificialization process in the period 1997-2007, with relatively large urban expansions, whereas in other areas this process was moderate. The physiography of the Galician coast presents significant differences between northern and western areas, being, in general, much more exposed and steep in the north and much sheltered in the west. The major singularities of the Galician coast are the rias, ancient valleys occupied by the sea with average depths in the mouth of about 50-60 meters. They are highly productive zones that concentrate a large part of the Galician population, where different uses coexist, therefore supporting a significant human pressure (Fernández, Álvarez-Salgado, Beiras, Ovejero & Méndez, 2016Fernández, E., Álvarez-Salgado, X. A., Beiras, R., Ovejero, A. & Méndez, G. (2016). Coexistence of urban uses and shellfish production in an upwelling-driven, highly productive marine environment: The case of the Ría de Vigo (Galicia, Spain). Special Issue on the World Harbour Project - Global harbours and ports: different locations, similar problems?, 8, 362-370. https://doi.org/10.1016/j.rsma.2016.04.002 ). The rugged coastal morphology of the rias occupies 34.5% of the Spanish peninsular coastline.
Data on artificial cover for Spain generally derives from the Corine Land Cover project, which is known to have several methodological limitations (Ovejero-Campos, Fernández, Ramos, Bento & Méndez-Martínez, 2019Ovejero-Campos, A., Fernández, E., Ramos, L., Bento, R. & Méndez-Martínez, G. (2019). Methodological limitations of CLC to assess land cover changes in coastal environments. Journal of Coastal Conservation, 23(3), 657-673. https://doi.org/10.1007/s11852-019-00696-w ), such as those related to the resolution due to the minimal cartographic unit (Batista e Silva, Lavalle & Koomen, 2013Batista e Silva, F., Lavalle, C. & Koomen, E. (2013). A procedure to obtain a refined European land use/cover map. Journal of Land Use Science, 8, 255-283. https://doi.org/10.1080/1747423X.2012.667450 ), the possible underestimation of the artificial coverages (Bach et al., 2006Bach, M., Breuer, L., Frede, H.G., Huisman, J.A., Otte, A. & Waldhardt, R. (2006). Accuracy and congruency of three different digital land-use maps. Landscape and Urban Planning, 78, 289-299. https://doi.org/10.1016/j.landurbplan.2005.09.004 ), or the existence of unlikely changes in the assigned land cover (Bach et al., 2006Bach, M., Breuer, L., Frede, H.G., Huisman, J.A., Otte, A. & Waldhardt, R. (2006). Accuracy and congruency of three different digital land-use maps. Landscape and Urban Planning, 78, 289-299. https://doi.org/10.1016/j.landurbplan.2005.09.004 ; Barreira González, González, Cascón & Sendra, 2012Barreira González, P., González, P.B., Cascón, V.G. & Sendra, J.B. (2012). Detección de errores temáticos en el Corine Land Cover a través del estudio de cambios: Comunidad de Madrid (2000-2006). Estudios Geográficos, 73, 7-34. https://doi.org/10.3989/estgeogr.201201 ; Catalá Mateo, Bosque Sendra & Plata Rocha, 2008Catalá Mateo, R., Bosque Sendra, J. & Plata Rocha, W. (2008). Análisis de posibles errores en la base de datos Corine Land Cover (1990-2000) en la Comunidad de Madrid. Estudios Geográficos, 69, 81-104. https://doi.org/10.3989/egeogr.2008.i264.80 ; Martínez-Fernández, Ruiz-Benito & Zavala, 2015Martínez-Fernández, J., Ruiz-Benito, P. & Zavala, M.A. (2015). Recent land cover changes in Spain across biogegraphical regions and protection levels: implications for conservation policies. Land Use Policy, 44, 62-75. https://doi.org/10.1016/j.landusepol.2014.11.021 ; Martínez-Fernández, Ruiz-Benito, Bonet & Gómez, 2019Martínez-Fernández, J., Ruiz-Benito, P., Bonet, A. & Gómez, C. (2019). Methodological variations in the production of CORINE land cover and consequences for long-term land cover change studies. The case of Spain. International Journal of Remote Sensing, 40, 8914-8932. https://doi.org/10.1080/01431161.2019.1624864 ; Pontius and Lippitt, 2006Pontius, R.G. & Lippitt, C.D. (2006). Can error explain map differences over time? Cartography and Geographic Information Science, 33, 159-171. https://doi.org/10.1559/152304006777681706 ). In this connection, Decoville and Schneider (2015)Decoville, A. & Schneider, M. (2015). Can the 2050 zero land objective of the EU be reliably monitored? A comparative study. Journal of Land Use Science, 11-3, 331-349. https://doi.org/10.1080/1747423X.2014.994567 monitored land take rates at a very accurate scale, and demonstrated that although the results from CLC seem acceptable at the country level, they lack precision when analysing smaller territories. Consequently, in this study we used data derived from the SIOSE project (reference scale 1:25000), as it represents a substantial improvement in the description and assignation of land cover.
Land cover and land use changes are closely related to the provision of ecosystem services (Burkhard, Kroll, Müller & Windhorst, 2009Burkhard, B., Kroll, F., Müller, F. & Windhorst, W. (2009). Landscapes’ capacities to provide ecosystem services - A concept for land-cover based assessments. Landscape Online, 15, 1-22. https://doi.org/10.3097/LO.200915 ). The analysis and mapping of ecosystem services is presently recognised as a key element of sustainable management, thus drawing the attention of policymakers (Bastian, Haase & Grunewald, 2012Bastian, O., Haase, D. & Grunewald, K. (2012). Ecosystem properties, potentials and services - The EPPS conceptual framework and an urban application example. Ecological Indicators, 21, 7-16. https://doi.org/10.1016/j.ecolind.2011.03.014 ; Burkhard et al., 2009Burkhard, B., Kroll, F., Müller, F. & Windhorst, W. (2009). Landscapes’ capacities to provide ecosystem services - A concept for land-cover based assessments. Landscape Online, 15, 1-22. https://doi.org/10.3097/LO.200915 ; Kandziora, Burkhard & Müller, 2013Kandziora, M., Burkhard, B. & Müller, F. (2013). Mapping provisioning ecosystem services at the local scale using data of varying spatial and temporal resolution. Ecosystem Services, 4, 47-59. https://doi.org/10.1016/j.ecoser.2013.04.001 ) in this paper we suggest returning to the landscape potential concept developed by landscape ecologists in the 1970s. Emerging from both concepts is the hereinafter discussed EPPS framework - ecosystem (or landscape as they allow estimating the impact of human activity (Hasan, Shi & Zhu, 2020Hasan, S., Shi, W. & Zhu, X. (2020). Impact of land use land cover changes on ecosystem service value - A case study of Guangdong, Hong Kong, and Macao in South China. PLoS ONE, 15, e0231259. https://doi.org/10.1371/journal.pone.0231259 ; Li and Zhou, 2016Li, J. & Zhou, Z.X. (2016). Natural and human impacts on ecosystem services in Guanzhong - Tianshui economic region of China. Environmental Science and Pollution Research, 23, 6803-6815. https://doi.org/10.1007/s11356-015-5867-7 ; Mendoza-González, Martínez, Lithgow, Pérez-Maqueo & Simonin, 2012Mendoza-González, G., Martínez, M.L., Lithgow, D., Pérez-Maqueo, O. & Simonin, P. (2012). Land use change and its effects on the value of ecosystem services along the coast of the Gulf of Mexico. Ecological Economics, 82, 23-32. https://doi.org/10.1016/j.ecolecon.2012.07.018 ; Riitters, Wickham, Vogelmann & Jones, 2000Riitters, K.H., Wickham, J.D., Vogelmann, J.E. & Jones, K.B. (2000). National land-cover pattern data. Ecology, 81, 10. https://doi.org/10.2307/177456 ).
Besides the intrinsic interest of the spatial and temporal analysis of land cover and its effect on the ecosystem services, it is of particular relevance assessing the socioeconomic drivers behind those patterns. This research topic has been addressed in the literature using different approaches based on population (Carr, 2004Carr, D.L. (2004). Proximate Population Factors and Deforestation in Tropical Agricultural Frontiers. Population and Environment, 25, 585-612. https://doi.org/10.1023/B:POEN.0000039066.05666.8d ; Kamwi, Chirwa, Manda, Graz & Kätsch, 2015Kamwi, J.M., Chirwa, P.W.C., Manda, S.O.M., Graz, P.F. & Kätsch, C. (2015). Livelihoods, land use and land cover change in the Zambezi Region, Namibia. Population and Environment, 37, 207-230. https://doi.org/10.1007/s11111-015-0239-2 ; Orenstein and Hamburg, 2010Orenstein, D.E. & Hamburg, S.P. (2010). Population and pavement: population growth and land development in Israel. Population and Environment, 31, 223-254. https://doi.org/10.1007/s11111-010-0102-4 ), births, deaths and migration patterns (Clement and York, 2017Clement, M.T. & York, R. (2017). The asymmetric environmental consequences of population change: an exploratory county-level study of land development in the USA, 2001-2011. Population and Environment, 39, 47-68. https://doi.org/10.1007/s11111-017-0274-2 ) and household formation (Barbieri, Bilsborrow & Pan, 2005Barbieri, A.F., Bilsborrow, R.E. & Pan, W.K. (2005). Farm Household Lifecycles and Land Use in the Ecuadorian Amazon. Population and Environment, 27, 1-27. https://doi.org/10.1007/s11111-005-0013-y ).
The objectives of our research are: (1) to quantify the artificialization rate of the Galician coast in the last decade, (2) to map and estimate changes in ecosystem services resulting from the artificialization process and (3) to relate magnitudes and patterns of coastal artificialization to socioeconomic indicators a priori associated with the artificialization process itself, such as the construction of new dwellings or the generation of wealth (expansion of leisure activities, tourism, creation of industries…).
2. METHODS
⌅We estimated the artificial cover in the Galician coast (located in the NW of Spain) following two approaches. Firstly we analysed the 10 km coastal zone, which allows us to compare the results with those published by the OSE and the EEA. Secondly, we carried out the same procedure but in this case, considering the coastal zone as the area delimited by the coastal municipalities, as they are the territorial units of relevance for socioeconomic data (Instituto Galego de Estatística - IGE) (Fig. 1). Besides, municipalities are the minimum administrative unit with competence in spatial planning in the region.
The SIOSE project analyses land cover and land use. This work focuses on land cover, ie. physical and biological cover of the earth’s surface, including artificial surfaces, agricultural areas, forests, natural and seminatural areas, wetlands and water bodies. The concept of land use characterises the territory according to its functional dimension or its socioeconomic dedication, for example, residential, industrial, commercial, agricultural, forestry, recreational (Instituto Geográfico Nacional, 2015Instituto Geográfico Nacional (2015). Documento técnico SIOSE 2011. Retrieved from https://www.siose.es/SIOSEtheme-theme/documentos/pdf/Doc_tec_SIOSE2011_v1.1.pdf ; Valcárcel and Castaño, 2012Valcárcel, N. & Castaño, S. (2012). Cartografía de ocupación del suelo en España. Proyecto SIOSE. Retrieved from http://www.ign.es/web/ign/portal/libros-digitales/cartografia-siose ).
The SIOSE project does not follow a traditional thematic classification model, but assigns to each polygon one or several land cover classes (simple and composed), using occupation percentages and attributes. Simple classes present homogeneity in 100% of the surface and exceed the minimum surface requirement; they include crops, pastures, forests, scrubs, open spaces with little or no vegetation, wetlands, water bodies, and artificial surfaces. Composed classes are described from several land cover classes, which in turn can be simple or composed and, depending on the combination, are called “Association” (no-fixed distribution) or “Mosaic” (geometric distribution). Composed classes could be predefined or not predefined. Among the predefined ones, widely distributed by the study area, the class “Residential agricultural settlement”, includes fractions of herbaceous and/or woody crops, buildings, and may also contain forests, pastures, scrubs or any artificial classes (for example roads, parking lots or bare pedestrian zones) (Equipo Técnico Nacional SIOSE, 2015Equipo Técnico Nacional SIOSE (2015). Descripción del modelo de datos y rótulo SIOSE. Retrieved from http://www.siose.es/SIOSEtheme-theme/documentos/pdf/Doc_tec_SIOSE2011_v1.1.pdf ).
We used available SIOSE databases corresponding to 2005, 2009, 2011 and 2014, covering a 9 years period when the artificialization dynamics were explosive due to the “real estate boom” which occurred in Spain by that time. Vectorial format municipal boundaries supplied by the Instituto Geográfico Nacional (IGN) were included in the geodatabase. Alphanumeric data related to human pressures, population, and new buildings were obtained from the Instituto Gallego de Estadística (IGE) and related to the municipal geographic data.
The wide availability of artificial covers provided by the SIOSE database, justifies its use in this work. Nevertheless, this database also presents some limitations (Valcárcel and Castaño, 2012Valcárcel, N. & Castaño, S. (2012). Cartografía de ocupación del suelo en España. Proyecto SIOSE. Retrieved from http://www.ign.es/web/ign/portal/libros-digitales/cartografia-siose ). The exploitation of SIOSE data is laborious and has limitations when representing mixed land covers, frequently present on the Galician coast. Scattered settlements, widespread throughout the Northwest Iberian Peninsula, causes confusion in the SIOSE classification between the discontinuous urban fabric and non-urban classes, reflecting a continuous transfer between both land covers, which may cause slightly altered results (Olazabal and Bellet, 2017Olazabal, E. & Bellet, C. (2017). Análisis de las nuevas dinámicas de urbanización en España. Su estudio a través del uso de Corine Land Cover y SIOSE [Conference paper]. XXV Congreso de la Asociación de Geográfos Españoles, Madrid, Spain. https://libros.uam.es/uam/catalog/book/558.). Another limitation, common to this type of data, is the supposed “naturalisation” that occurs in some polygons, consisting of unlikely changes from artificial surfaces to agricultural or forest areas. The presence of a high contribution of disseminated settlements makes difficult the identification of classes such as “Residential agricultural settlement”, as it depends on the time of the year when the photograph is taken. On some occasions, polygons bordering road networks are classified as broad-leaved forest or scrubs as a consequence of the appearance of green masses (Olazabal and Bellet, 2017Olazabal, E. & Bellet, C. (2017). Análisis de las nuevas dinámicas de urbanización en España. Su estudio a través del uso de Corine Land Cover y SIOSE [Conference paper]. XXV Congreso de la Asociación de Geográfos Españoles, Madrid, Spain. https://libros.uam.es/uam/catalog/book/558.).
This paper sets a hierarchical nomenclature derived from SIOSE, and similar to Corine Land Cover (CLC), which includes five land cover classes: artificial surfaces, agricultural areas, forests or seminatural areas, wetlands and water bodies. A reclassification of the SIOSE codes was performed to maintain the polygons and assign each one to a single class. Firstly, a direct reclassification to simple-classes polygons (Table 1) was performed, and secondly, codes of the polygons classified as “associations” or “mosaics” were split into simple classes and then reclassified attending to the dominant land cover class (Table 2).
SIOSE land cover classes | Reclassified land cover classes |
---|---|
Artificial surfaces | Artificial surfaces (1) |
Crops | Agricultural areas (2) |
Pastures | Forest and seminatural areas (3) |
Forests | |
Scrubs | |
Open spaces with little or no vegetation | |
Wetlands | Wetlands (4) |
Water bodies | Water bodies (5) |
SIOSE code | Percentages of land cover class | New code |
---|---|---|
A(60FDPpl_40MTR) | 100% (3) | 3 |
A(50SDN_35MTR_10PST_05FDP) | 100% (3) | 3 |
I(60CNF_15FDP_10MTR_05PRDsc_05MTRct_05SDNfc) | 95% (3), 5% (2) | 3 |
I(80ZEV_15MTRct_05A(90MTR_10FDP)) | 80% (1), 20% (3) | 1 |
I(80VAP_10EDFnv_10OCT) | 100% (1) | 1 |
R(35CHLsc_20EDFva_15PRDsc_10VAP_10LFNsc_05OCT_05MTRpc) | 60% (2), 35% (1), 5% (3) | 2 |
R(35EDFva_20PRDsc_15FDC_10VAP_10CHLsc_10CNF) | 45% (1), 30% (2), 25% (3) | 1 |
Once the information was generated, total areas were calculated for each land cover class and geoprocessing was performed, integrating land cover information, socioeconomic data, and digital aerial orthophotos derived from the “Plan Nacional de Ortofotografía Aérea” (PNOA).
In this study, we estimated the potential of the coastal zone to deliver ecosystem services from the ecosystem service potential matrix described in (Burkhard, Kandziora, Hou & Müller, 2014Burkhard, B., Kandziora, M., Hou, Y. & Müller, F. (2014). Ecosystem service potentials, flows and demands-concepts for spatial localisation, indication and quantification. Landscape Online, 34, 1-32. https://doi.org/10.3097/LO.201434 ). As that matrix derived from CLC classes, it was adapted to the land cover classes defined in our study which derived from the SIOSE 3-level classes. The ecosystem service classification used was based on 11 regulation services, 10 provisioning services and 6 cultural services (see supplementary material). The potential of each land cover class to produce the selected ecosystem services was assessed on a scale from 0 (no relevant potential) to 5 (very high relevant potential). Regulation, provisioning and cultural ecosystem services were mapped using the mean value of their components. The evolution of each ecosystem service from 2005 to 2014 was assessed taking into account the area occupied by each land cover class and then estimating annual changing rates.
3. RESULTS AND DISCUSSION
⌅3.1. Artificial land cover changes and fluxes in the Galician coast
⌅The land cover distribution observed in the Galician coast in 2014 (last year available) is shown in Figure 2. 65% of the coastal area was dedicated to forest and seminatural areas, occupying a total of 273534 hectares when the coastal municipalities were considered. Agricultural areas accounted for 21% of the coastal area whereas artificial surfaces, located mainly around the coastal cities, represented 12%. Wetlands and water bodies were much less represented. These results were very similar when the 10 km coastal zone or the municipalities’ coastal strip was considered, suggesting that both methodological approaches could be used indistinctly.
Figure 3A shows absolute and relative changes in land cover in the area delimited by the Galician coastal municipalities in the period 2005-2014. The largest relative change occurred in the artificial surfaces, which increased by ca. 7.4% in the study period. Agricultural areas decreased by 3% and the other land classes varied less than 1%. However, the most considerable absolute losses were found in the agricultural areas, showing a decrease of 2753 hectares, albeit only represented 3% in relative terms.
As expected, the same pattern was observed when the 10 km coastal zone was used, although differences were found in the absolute number of hectares, as the total extent of both areas differed (Fig. 1). Figure 3B shows daily rates of land cover changes in the municipalities of the coastal strip. In general, artificial areas increased and agricultural areas decreased. However, forest and seminatural areas decreased from 2005 to 2009, but increased in the 2009-2014 period. Artificial land cover rose from 47361 ha in 2005 to 50350 ha in 2009, which yields a daily growth rate of ca. 2 ha day-1 (i.e. /day) in that period, while in the 2009-2011 and 2011-2014 periods these rates were 0.2 and 0.4 ha day-1. The estimated rate for the 10 km coastal zone from 2005 to 2009 was 2.5 ha day-1 due to the large size of some coastal municipalities, which penetrate into the continent where exposition to anthropogenic pressures is less intense.
When the results obtained in this study (using SIOSE), are compared with the data published by the Observatorio de la Sostenibilidad (2016b)Observatorio de la Sostenibilidad (2016b). Cambios de ocupación del suelo en la costa en España 1987-2011. Retrieved from https://www.observatoriosostenibilidad.com/informes/ , derived from CLC, substantial differences were found in both the artificial area and the annual land cover change rate. According to CLC, 36054 hectares were classified as artificial surfaces in the 10 km coastal zone in 2011, which represents 6.8% of the total coastal area, whereas the results obtained in this study show that 11.4% of the 10 km coastal zone was covered by artificial surfaces (60963 ha) in the same year. Previous studies have warned about the underestimation of the artificial area along the Spanish coast due to the scale of CLC data, an error enhanced in areas with a dispersed settlement, for example, the Galician coast (Observatorio de la Sostenibilidad, 2016bObservatorio de la Sostenibilidad (2016b). Cambios de ocupación del suelo en la costa en España 1987-2011. Retrieved from https://www.observatoriosostenibilidad.com/informes/ ). In addition, the CLC project discards linear data such as roads and rail networks as artificial surfaces, thus reinforcing this underestimation (Olazabal and Bellet, 2018Olazabal, E. & Bellet, C. (2018). Procesos de urbanización y artificialización del suelo en las aglomeraciones urbanas españolas (1987-2011). Cuadernos Geográficos, 57. https://doi.org/10.30827/cuadgeo.v57i2.5920 ). These authors also reported the potential effect of the minimum percentage (5%) considered by each SIOSE polygon when digitising large polygons representing disseminated urban settlements, which may result in abnormally high values of urban surfaces. The above-mentioned differences are also reflected in the between-periods variability of annual artificialization rates (Table 3).
Area | Period | Artificialization rate (ha/day) | Annual change (%/year) | Data |
---|---|---|---|---|
Spain 10 km coastal zone | 1987-2011 | 15.4 | 2.3 | CLC |
Galicia 10 km coastal zone | 1987-2011 | 1.1 | 1.52 | CLC |
Spain 10 km coastal zone | 2006-2012 | 20.6 | 1.48 | CLC |
Galicia 10 km coastal zone | 2006-2012 | 0.64 | 0.67 | CLC |
Galicia 10 km coastal zone | 2005-2011 | 1.7 | 1.1 | SIOSE |
Annual artificialization rates in Spain and Galicia (10 km coastal zone, 1987-2012).
The artificialization of the 10 km coastal zone in Spain between 1987 and 2011 showed a rate of 15.4 ha day-1 according to CLC, increasing the artificial surface by 2.3% per year (Observatorio de la Sostenibilidad, 2016bObservatorio de la Sostenibilidad (2016b). Cambios de ocupación del suelo en la costa en España 1987-2011. Retrieved from https://www.observatoriosostenibilidad.com/informes/ ). Specifically, artificial surfaces in Spain increased by 1.48% per year in the period 2006-2012, the highest rate in the EU, where the average rate was 0.41% year-1 (i.e. /year) (Dirección General de Medio Ambiente de la Comisión Europea, 2017Dirección General de Medio Ambiente de la Comisión Europea (2017). Revisión de la aplicación de la normativa medioambiental de la UE. Informe de España. Retrieved from https://ec.europa.eu/environment/eir/pdf/report_es_es.pdf ). The annual growth rate of artificial surface in the Galician coastal zone (10 km) according to CLC between 1987 and 2011, was 1.52%, which meant 1.1 ha day-1 (Observatorio de la Sostenibilidad, 2016bObservatorio de la Sostenibilidad (2016b). Cambios de ocupación del suelo en la costa en España 1987-2011. Retrieved from https://www.observatoriosostenibilidad.com/informes/ ). However, the increase in artificial hectares in the Galician coastal zone (10 km) in the period 2006-2012 was 0.64 ha day-1, representing an increase of 0.67% per year. When these data are compared with those obtained in this work using SIOSE, and choosing the closest available interval, 2005-2011, the artificial surface increased by 1.1% per year, with an annual rate of 1.7 ha day-1. This is consistent with the underestimation of CLC and the overestimation of SIOSE in terms of artificial surfaces previously reported in the literature (Diaz-Pacheco and Gutiérrez, 2014Diaz-Pacheco, J. & Gutiérrez, J. (2014). Exploring the limitations of Corine Land Cover for monitoring urban land-use dynamics in metropolitan areas. Journal of Land Use Science, 9, 243-259. https://doi.org/10.1080/1747423X.2012.761736 ; Observatorio de la Sostenibilidad, 2016bObservatorio de la Sostenibilidad (2016b). Cambios de ocupación del suelo en la costa en España 1987-2011. Retrieved from https://www.observatoriosostenibilidad.com/informes/ , 2017Observatorio de la Sostenibilidad (2017). Sostenibilidad en España 2016 - SOS16. Retrieved from https://www.observatoriosostenibilidad.com/informes.; Olazabal and Bellet, 2017Olazabal, E. & Bellet, C. (2017). Análisis de las nuevas dinámicas de urbanización en España. Su estudio a través del uso de Corine Land Cover y SIOSE [Conference paper]. XXV Congreso de la Asociación de Geográfos Españoles, Madrid, Spain. https://libros.uam.es/uam/catalog/book/558., 2018Olazabal, E. & Bellet, C. (2018). Procesos de urbanización y artificialización del suelo en las aglomeraciones urbanas españolas (1987-2011). Cuadernos Geográficos, 57. https://doi.org/10.30827/cuadgeo.v57i2.5920 ; Ovejero-Campos et al., 2019Ovejero-Campos, A., Fernández, E., Ramos, L., Bento, R. & Méndez-Martínez, G. (2019). Methodological limitations of CLC to assess land cover changes in coastal environments. Journal of Coastal Conservation, 23(3), 657-673. https://doi.org/10.1007/s11852-019-00696-w ).
The relative contribution of the artificial land cover in the Galician coast in 2014 is represented in Figure 4, and shows the presence of areas intensely artificialized mainly linked to the main coastal cities. The municipalities with the highest percentage of artificialization were A Coruña (64%) and Vigo (51%).
The distribution of this variable (Fig. 4) agrees with the location of the urban aggregates defined in the regional littoral planning (Plan de Ordenación do Litoral de Galicia) which corresponds to areas of concentration of urban growth where favorable topographic conditions facilitate the development of multiple economic activities (Xunta de Galicia, 2011Xunta de Galicia (2011). Plan de ordenación do litoral de Galicia. Retrieved from http://www.xunta.es/litoral/ ). It also matches with the metropolitan areas of Vigo-Pontevedra and A Coruña-Ferrol.
Figure 5 shows the annual artificialization rate (%) of the Galician coastal municipalities calculated with respect to the municipal area, which represents the amount of natural surfaces (forest and seminatural areas, agricultural zones and land reclamation) has been “denatured”.
The highest artificialization rates with respect to the total area of the municipalities were found in the 2005-2009 period, in those areas contiguous to the larger coastal cities (Fig. 5). In the following period (2009-2011), clear differences were found between southern municipalities, showing relatively low land artificialization rates, and northern municipalities where this artificialization was practically non-existent. In the most recent period (2011-2014), a south to north artificialization gradient was observed, albeit rates were lower than in the first period (2005-2009).
To further investigate the patterns of land artificialization in this region, the Galician coast was divided into zones according to the different degrees of artificialization, derived from their physiographic characteristics, geographical location, climate, orientation, demographic burden, or even the economic and social characteristics. As a result, five groups of coastal municipalities were defined: Costa da Morte, Mariñas Coruñesas, Rías Altas, Rías Baixas and Sur de Galicia (Fig. 1). The maximum annual artificialization rates were generally observed in the period 2005-2009, albeit large differences among coastal groups were observed, with Mariñas Coruñesas almost doubling the artificialization rates of the Rías Baixas, Rías Altas and Costa da Morte, and the Sur de Galicia area showing an artificialization rate 5-fold lower than Mariñas Coruñesas. A similar pattern was observed in the 2011-2014 period. During the 2009-2011 period, land artificialization was only detected in the southern groups (Fig. 6).
Figure 7 shows fluxes between land cover classes in the municipalities’ coastal strip (2005-2014) resulting from the corresponding cross-matrix, as proposed by Pontius, Shusas & McEachern (2004)Pontius, R.G., Shusas, E. & McEachern, M. (2004). Detecting important categorical land changes while accounting for persistence. Agriculture, Ecosystem & Environment, 101, 2-3, 251-268. https://doi.org/10.1016/j.agee.2003.09.008 and Martínez-Fernández et al. (2015)Martínez-Fernández, J., Ruiz-Benito, P. & Zavala, M.A. (2015). Recent land cover changes in Spain across biogegraphical regions and protection levels: implications for conservation policies. Land Use Policy, 44, 62-75. https://doi.org/10.1016/j.landusepol.2014.11.021 . The total area transformed into the artificial class in this period was 4610 ha. Almost 3000 of them were previously classified as forest or seminatural areas, and around 1600 hectares as agricultural areas. 215 hectares of total land uptake by artificial surfaces correspond with land reclamation.
Therefore, 61.4% of the new artificial areas derive from forests or seminatural areas, 33.8% from agricultural areas, 4.7% from areas reclaimed from the sea and 0.1% from wetlands and water bodies.
We further explored fluxes involving land artificialization to analyse and characterise their dynamics, aiming at a better understanding of the processes involved in the generation of artificial land (Table 4). It is worth mentioning that artificialization fluxes in the coastal municipalities strip and in the 10 km coastal zone coincide.
Land cover annual change with respect to the total area | ||||
---|---|---|---|---|
05-09 | 09-11 | 11-14 | 05-14 | |
Agricultural zones to artificial surfaces | 0.073 | 0.008 | 0.028 | 0.042 |
Forest or seminatural areas to artificial surfaces | 0.132 | 0.016 | 0.071 | 0.076 |
Land reclamation | 0.009 | 0.002 | 0.005 | 0.006 |
Land cover annual change with respect to the area of each class | ||||
05-09 | 09-11 | 11-14 | 05-14 | |
Agricultural zones to artificial surfaces | 0.338 | 0.039 | 0.133 | 0.193 |
Forest or seminatural areas to artificial surfaces | 0.199 | 0.025 | 0.107 | 0.115 |
Land reclamation | - | - | - | - |
Land cover annual change rates (%) with respect to the total area of each land cover class in the initial year of each period, and with respect to the area of each class; agricultural zones changing to artificial surfaces; forests or seminatural areas changing to artificial surfaces, and land reclamation (classified as artificial surfaces). Municipalities’ coastal strip. (Periods: 2005-2009; 2009-2011; 2011-2014; 2005-2014).
The largest changes were concentrated again in the period 2005-2009, being the forest and seminatural classes those presenting the more intense annual changes. During that period, 0.13% of the municipalities’ coastal strip became artificialized at the expense of forests or seminatural areas. The most noticeable change from agricultural areas to artificial surfaces occurred in the same period (0.07% of the total area of the strip per year). When land cover annual changes (%) with respect to the total area of each class were considered, the agricultural class presented the higher rates in all the periods. A total of 1211 agricultural hectares were artificialized between 2005 and 2009, representing a rate 17-fold higher than in the 2009-2011 period and more than 3-fold higher than in the last one (2011-2014). In the forestry class, 2180 hectares classified as forest or seminatural areas in 2005 were transformed into artificial surfaces until 2009, 16-fold higher than in the period 2005-2009 and 2.5 higher than in the last period.
The high demand for human settlements and the development of economic activities in the coastal zone triggers a high rate of land consumption. In this study, we found the largest changes in the artificial class, which increased by more than 7% in the studied period, at the expenses of forest and seminatural areas. In most cases, the spatial pattern of this artificialization process was associated with disorganised growth detached from traditional urban settlements, resulting in a diffuse transformation of the Galician coast leading to significant territorial and landscape fragmentation. This fragmentation directly affects ecological connectivity, thereby amplifying several environmental problems such as soil sealing, deforestation, water, soil or air pollution, as well as biodiversity losses (Celliers and Ntombela, 2016Celliers, L. & Ntombela, C. (2016). Urbanization, coastal development and vulnerability, and catchments. In José Paula (Ed.), Regional State of the Coast Report (pp. 386-404). Nairobi, Kenya: Nairobi Convention Secretariat. https://doi.org/10.18356/dd8dca69-en ; Pasquali and Marucci, 2021Pasquali, D. & Marucci, A. (2021). The effects of urban and economic development on Coastal Zone Management. Sustainability, 13, 6071. https://doi.org/10.3390/su13116071 ).
3.2. Impact of artificialization on ecosystem services
⌅Figure 8 shows the spatial distribution of land cover and the potential to provide ecosystem services (ES) of the three main categories (regulation, provisioning and cultural).
The lower potential to provide ecosystem services is generally associated with the anthropogenic land cover types (except some cultural ecosystem services), while agricultural and forest or seminatural areas show high potential in the regulation and provisioning ecosystem services. The two divisions characterised by the highest artificialized areas present the lowest values of ES (Mariñas Coruñesas and Rías Baixas).
Local Climate Regulation and Erosion Regulation showed the highest values within the regulation services whereas Wild Foods and Resources and Wood Fuel scored high in provisioning services. Recreation and Tourism, Landscape aesthetics and Inspiration and Knowledge Systems were the most important cultural services. Regulation and provisioning services were largely associated with forest and seminatural areas (the predominant land cover class in the study area, 65%). On the contrary, all the land cover classes contributed to cultural services.
The potential to deliver ecosystem services showed a temporal declining trend in the study period, showing annual decreasing rates of -0.13% (provisioning services), -0.05% (regulation services) and -0.003% (cultural services). The highest annual loss rates corresponded with two provisioning services, crops (-0.35%) and livestock (-0.32%), and it is related to the decreased by 3% of the agricultural areas.
Ecosystem services have been presented as a useful tool to assess de parallel evolution between natural and human processes (Burkhard et al., 2009Burkhard, B., Kroll, F., Müller, F. & Windhorst, W. (2009). Landscapes’ capacities to provide ecosystem services - A concept for land-cover based assessments. Landscape Online, 15, 1-22. https://doi.org/10.3097/LO.200915 ; Hasan et al., 2020Hasan, S., Shi, W. & Zhu, X. (2020). Impact of land use land cover changes on ecosystem service value - A case study of Guangdong, Hong Kong, and Macao in South China. PLoS ONE, 15, e0231259. https://doi.org/10.1371/journal.pone.0231259 ). This study revealed that land cover changes produced in the study area had a direct effect on ecosystem services, as previously detected by other authors (Burkhard, Kroll, Nedkov & Müller, 2012Burkhard, B., Kroll, F., Nedkov, S. & Müller, F. (2012). Mapping ecosystem service supply, demand and budgets. Ecological Indicators, 21, 17-29. https://doi.org/10.1016/j.ecolind.2011.06.019 ; Hasan et al., 2020Hasan, S., Shi, W. & Zhu, X. (2020). Impact of land use land cover changes on ecosystem service value - A case study of Guangdong, Hong Kong, and Macao in South China. PLoS ONE, 15, e0231259. https://doi.org/10.1371/journal.pone.0231259 ; Kandziora et al., 2013Kandziora, M., Burkhard, B. & Müller, F. (2013). Mapping provisioning ecosystem services at the local scale using data of varying spatial and temporal resolution. Ecosystem Services, 4, 47-59. https://doi.org/10.1016/j.ecoser.2013.04.001 ; Yirsaw, Wu, Temesgen & Bekele, 2016Yirsaw, E., Wu, W., Temesgen, H. & Bekele, B. (2016). Effect of temporal land use / land cover changes on ecosystem services value in coastal area of China: the case of Su-Xi-Chang region. Applied ecology and environmental research, 14, 409-422. http://dx.doi.org/10.15666/aeer/1403_409422 ). Therefore, it would be desirable to integrate the ecosystem services approach into land use planning as it demonstrated to be a useful tool for environmental sustainable management or (Baral, Keenan, Fox, Stork & Kasel, 2013Baral, H., Keenan, R.J., Fox, J.C., Stork, N.E. & Kasel, S. (2013). Spatial assessment of ecosystem goods and services in complex production landscapes: A case study from south-eastern Australia. Ecological Complexity, 13, 35-45. https://doi.org/10.1016/j.ecocom.2012.11.001 ; Bastian et al., 2012Bastian, O., Haase, D. & Grunewald, K. (2012). Ecosystem properties, potentials and services - The EPPS conceptual framework and an urban application example. Ecological Indicators, 21, 7-16. https://doi.org/10.1016/j.ecolind.2011.03.014 ; Burkhard et al., 2014Burkhard, B., Kandziora, M., Hou, Y. & Müller, F. (2014). Ecosystem service potentials, flows and demands-concepts for spatial localisation, indication and quantification. Landscape Online, 34, 1-32. https://doi.org/10.3097/LO.201434 ; Müller and Burkhard, 2007Müller, F. & Burkhard, B. (2007). An ecosystem based framework to link landscape structures, functions and services. In Ü. Mander, H. Wiggering, & K. Helming (Eds.), Multifunctional Land Use: Meeting Future Demands for Landscape Goods and Services (pp. 37-63). Heidelberg, Germany: Springer. https://doi.org/10.1007/978-3-540-36763-5_3 ; Vihervaara, Kumpula, Tanskanen & Burkhard, 2010Vihervaara, P., Kumpula, T., Tanskanen, A. & Burkhard, B. (2010). Ecosystem services-A tool for sustainable management of human-environment systems. Case study Finnish Forest Lapland. Ecological Complexity, 7, 410-420. https://doi.org/10.1016/j.ecocom.2009.12.002 ).
3.3. Relationship between artificialization rates and demographic and economic variables
⌅In Figure 10, the temporal evolution of the population, artificial area and number of new buildings in the coastal municipalities of the Galician coast is shown.
The three variables show a sharp increase from 2005 to 2009, when the registration of new buildings was 6-fold higher than in the rest of the periods studied. Population increased until 2011, then decreased in the last period, although the number of new buildings was similar and, consequently, the artificialized area still increased with respect to the previous period. The number of hectares classified as artificial surfaces per capita raised continuously from 322 m2 of artificial surface per inhabitant in 2005 to 343 m2 in 2014.
Galicia showed a negative demographic growth (-0.06% year-1) in the period 2005-2014. However, in the coastal municipalities, the temporal evolution of this variable was positive (+0.10% year-1). Spanish population growth in the period 1991-2011 was positive (1.02% year-1) and slightly lower (0.87% year-1) when the 10 km coastal zone was considered (Observatorio de la Sostenibilidad, 2016bObservatorio de la Sostenibilidad (2016b). Cambios de ocupación del suelo en la costa en España 1987-2011. Retrieved from https://www.observatoriosostenibilidad.com/informes/ ).
The domestic gross disposable income was also used in this analysis as it measures the income of the residents of a given territory used for consumption and savings operations. This indicator, therefore, may reflect if the artificialization process carried out in the territory directly reverts to the families’ economy or, on the contrary, it does not represent an improvement in economic terms for the local populations.
A correlation analysis was performed among the different variables, including artificialization (artificialized hectares excluding those dedicated to transport networks or industrial development, which represent 55% of the total artificialized area between 2005 and 2014), the variation in the number of inhabitants, the number of new buildings and the changes in the domestic gross disposable income (by municipality in the period 2005-2014). Two municipalities were excluded from the analysis: Ferrol and Arteixo due to their demographic and economic singularities (supplementary material).
A bivariate Pearson correlation was calculated to assess the relationship between the selected variables in the coastal zone and in each of the geographical divisions. The four variables are significantly correlated when all the coastal municipalities were considered (Table 5). The significant correlation between population and land cover/land use changes found in this study is consistent with the results reported in previous investigations focused on the drivers of land use and land cover (Clement and York, 2017Clement, M.T. & York, R. (2017). The asymmetric environmental consequences of population change: an exploratory county-level study of land development in the USA, 2001-2011. Population and Environment, 39, 47-68. https://doi.org/10.1007/s11111-017-0274-2 ; Kamwi et al., 2015Kamwi, J.M., Chirwa, P.W.C., Manda, S.O.M., Graz, P.F. & Kätsch, C. (2015). Livelihoods, land use and land cover change in the Zambezi Region, Namibia. Population and Environment, 37, 207-230. https://doi.org/10.1007/s11111-015-0239-2 ; Oreinstein and Hamburg, 2010Orenstein, D.E. & Hamburg, S.P. (2010). Population and pavement: population growth and land development in Israel. Population and Environment, 31, 223-254. https://doi.org/10.1007/s11111-010-0102-4 ).
A | Artificialization | New buildings | Population | Domestic gross income |
---|---|---|---|---|
Artificialization | 1 | 0.611** | 0.460** | 0.540** |
New buildings | 1 | 0.706** | 0.641** | |
Population | 1 | 0.519** | ||
Domestic gross income | 1 | |||
B | N | Artificialization- New buildings | Artificialization- Population | Artificialization- Domestic gross income |
Costa da Morte | 14 | 0.817** | 0.587* | 0.726** |
Mariñas Coruñesas | 13 | 0.592* | 0.603* | 0.782** |
Rías Altas | 13 | 0.083 | 0.052 | 0.310 |
Rías Baixas | 29 | 0.782** | 0.432* | 0.435* |
A:
Pearson correlation matrix. Variables: artificialization, new
buildings, changes in the number of inhabitants, changes in the domestic
gross disposable income along the coastal municipalities’ zone (except
Ferrol and Arteixo). B: Correlations in the coastal divisions (Sur de
Galicia is ruled out because of the low number of municipalities to
perform a statistical analysis).
** Correlation is significant at the
0.01 level. * Correlation is significant at the 0.05 level.
Neither of the tested variables showed statistically significant correlations in the Rías Altas division. This area is characterised by the absence of large urban centers concentrating the population and economic activity and, consequently, transforming the environment. Despite this division showed the second highest averaged rates of artificialization (3.33 ha year-1), it is not related to parallel population increases (70% of the municipalities in this division show a demographic decrease between 2005 and 2014), nor to domestic gross income variability. Several processes could account for the observed pattern, such as second home developments, which accounted for a large fraction of the total artificialization process in some municipalities or the dispersed occupation of the territory, mainly with single-family buildings, surrounded by small yards, whose designation in the SIOSE classification represents an overestimation of artificial land cover (Olazabal and Bellet, 2017Olazabal, E. & Bellet, C. (2017). Análisis de las nuevas dinámicas de urbanización en España. Su estudio a través del uso de Corine Land Cover y SIOSE [Conference paper]. XXV Congreso de la Asociación de Geográfos Españoles, Madrid, Spain. https://libros.uam.es/uam/catalog/book/558.).
Almost half of the artificialization of the Galician coast (41.5%) occurring from 2005 to 2014, derived from non-artificial land covers corresponding to the categories: “Residential agricultural settlement” (areas with mainly residential use, characterised by a dispersed settlement of buildings, accompanied by arable and/or woody crops), or “Discontinuous urban fabric”, ie. areas occupied by buildings mainly for housing associated with vegetated areas and bare surfaces, including urban areas that may be consolidated or in the process of consolidation. In both cases they do not represent crowded areas of buildings, so it is unlikely that the number of buildings could account for the whole of the artificialized area. The existence of these scattered settlements is the reason why many polygons appeared as transformations from non-artificial land cover to discontinuous urban fabric land covers, thereby yielding inconsistent results.
The slopes of the linear regressions between changes in population or new buildings and artificialization rates did not significantly differ depending on the zone (ANCOVA p = 0.852 and p = 0.467, respectively). By contrast, significant differences were found in the slope of the regression lines derived from the relationship between artificialization rates and domestic gross income in the different divisions, although the p-value resulting from the correlation between artificialization and domestic gross income (0.08) is close to the reference value (0.05), it does not seem correct to rule out the existence of significant differences (Amrhein, Greenland & McShane, 2019Amrhein, V., Greenland, S. & McShane, B. (2019). Scientists rise up against statistical significance. Nature, 567, 305-307. https://doi.org/10.1038/d41586-019-00857-9 ) since, as shown in Figure 11, the regression line corresponding to Costa da Morte shows a different pattern from the other divisions.
On average, 700 m2 became artificialized per each new building and 96 m2 of the territory were transformed into artificial per each new inhabitant when the 2005-2014 period was considered. These values can be compared with the data provided by the European Environment Agency, although this comparison should be made with caution since they referred to the whole country and are divided into two periods (2000-2006 and 2006-2012). According to EEA, 115 m2 was artificialized in Spain per each new inhabitant in the first period and 29 m2 new inhabitant-1 in the second one, while the values for France were 149 and 126 m2 new inhabitant-1 and 438 and 426 m2 new inhabitant-1 in the case of Portugal. It is worth noting that despite the higher number of artificialized hectares per new inhabitant estimated for Spain or France, the subtle demographic growth of Portugal in this period causes the higher amount of surface assigned to each new inhabitant.
Sanxenxo, located in the Rías Baixas division, was the municipality with the highest artificialization rates (12.79 ha), and the city of Vigo showed the largest number of new buildings built, with 104 new buildings year-1. Unlike the other divisions, in which population decreased, more than 50% of the municipalities belonging to the Rías Baixas division increased their population (2005-2014). The highest averaged domestic gross income and population are concentrated in the Mariñas Coruñesas division, although this division did not show the highest average number of new buildings per year. This observation can be explained by the patterns found in urban areas of A Coruña and Ferrol, characterised by an increase in population and domestic gross income. These municipalities form a supramunicipal area, with one of the most important industrial conglomerates in Spain, where energy, construction, shipyards, clothing and metallurgy industries are concentrated. Both divisions (Rías Baixas and Mariñas Coruñesas) present very similar patterns, as shown in Figure 11, and as evidenced by the correlation analyses discussed above.
The relationships between artificialization and domestic gross income present different patterns in the divisions considered in this study. As noted earlier, Mariñas Coruñesas and Rías Baixas present similar results, with 1-2 m2 of territory required to increase the domestic gross disposable income by one unit (thousand of €). On the contrary, the division Costa da Morte, characterised by decreasing population and domestic gross income values, required 12 m2 to achieve the same goal. Two municipalities under the influence of the urban area of A Coruña, A Laracha and Carballo, stand out with respect to the others, concentrating the largest increases both in inhabitants and domestic gross income and presenting artificialization rates 2 to 3-fold higher than the average of the division, respectively. In the case of this division, the slopes of the regression lines between artificialization and population or income were positive. Most of the municipalities of this division showed increases in artificialization and new buildings that are not associated with parallel increases in population or income. This division contains 5 of the 6 most extensive municipalities of the Galician coastal zone, with a high percentage of non-coastal territory and with a markedly disseminated settlement, ie. the dominant land cover class is the “discontinuous urban fabric”, which as mentioned above, may involve an overestimation of the artificial surface resulting from the SIOSE classification. It should also be noted that, unlike the other two divisions, Costa da Morte has not any urban aggregate with the potential for development and growth, thus constraining population growth and economic development of this area.
The results obtained in this study show that land take occurring in the Galician coastal zone, mainly at the expense of forest and seminatural territories, affected the potential services provided by ecosystems but was not generally related to demographic or domestic economic drivers.
4. CONCLUSIONS
⌅Land use change (especially urbanization) directly affect the food provisioning and regulation services, being an anthropogenic driver which modulates ecosystem functioning and structure. The artificialization process led to the reduction of ecosystem services related to local and global climate regulation. Processes derived from land use changes, such as the increase of impervious surfaces or the artificialization of riverbanks give rise to a lower response capacity of the territory, resulting in territories less resilient to climate change. Riparian ecosystems contribute to ecological adaptation to climate change, particularly facing the observed and expected increases in extreme meterological events, in the magnitude and seasonality of precipitation and run-off, and in atmospheric and water temperature. The increase in impervious surfaces prevents infiltration and increases surface run-off, making the territory vulnerable to extreme meteorological events. In addition, the increase in artificial surfaces also has a direct effect on the territory’s ability to mitigate climate change, altering its function of carbon sink. When replacing forests with artificial surfaces, fewer areas contribute to carbon dioxide uptake, so the amount of CO2 in the atmosphere increases.
In this context, the location of a substantial part of urban spaces in the coastline exposes them to the impact of extreme coastal events and sea level rise while, at the same time, lead to a loss of environmental quality and value of coastal ecosystems.
The significant loss of forests and seminatural areas observed in our study was related to a loss of regulation services and a decrease in the provision of ecosystem services. Soil sealing irreversibly affects highly productive agricultural areas since it causes loss of productive capacity and, ultimately the decline of the primary sector, traditionally very important in the Galician economy. The progressive contraction of agricultural, livestock and forestry activities is parallel to the decrease in the absolute and relative importance of the population employed in the sector. In the 2009-2014 period, the population employed in the “Agriculture, livestock, hunting and forestry” represented 6.2% in mid-2009 and decreased to 4.9% in 2014 (IGE-INE, Economically Active Population Survey, data consulted 03-22-2022).
The results obtained in this study indicated that despite the decrease in population of the Galician coastal zone in the last period of this study, the number of artificialized hectares and the construction of new buildings increased.
The observed changes in the land cover patterns in Galicia, and their effect on ecosystem services and impact on the regional economy, warn of the need to reverse this trend of land occupation. This reversing process should be based on solid territorial planning that integrates the dimensions of urban and rural development, considering energy, housing, infrastructures, economic development and human well-being. In this regard, two relevant planning instruments were established in Galicia in 2011, aiming at the sustainable development of the territory: the “Directrices de Ordenación del Territorio” and the “Plan de Ordenación Litoral”. Although both territorial planning instruments were already operative during the second period analysed in this study, the results of our investigation suggest that they have not been capable of reversing the artificialization trend of the Galician territory. The regional scale of these planning instruments and the diversity of processes and conditions taking place in the littoral strip, makes difficult establishing and implementing territorial indicators leading to the limitation of coastal artificialization. However, the definition of land consumption or land artificialization ratios at the municipal planning scale, or even at more detailed scales, can help promoting compactness and rational use of the territory. In this sense, the definition of one or several strips from the coastline, where anthropization, or some of its components, such as urbanization, could not exceed predetermined values, such as the municipal average, might be an action leading to a more rational territorial management of the coastal areas.
Our results suggest that modification of the existing planning instruments fostering a sustainable articulation of the territory and improving resilience is needed. The assessment of changes in the ecosystem services provided by the territory introduces a new relevant element to be considered in the evaluation of its use-value and highlights the role of the territory at the service of human well-being.