Temporal evolution of ecosystem services in Sierra Nevada
Lead Author: UGR
Introduction
Human activities have heavy consequences on ecosystem structures and functions decades or centuries after they have occurred. Due to the combined effects of climate change and shifts in land use, the distribution and structure of the vegetation of the Sierra Nevada has been undergoing rapid change, which in turn affects the associated ecosystem services. The cover of tree formations in Sierra Nevada has expanded from 15% to 51.23% over the last 60 years, while the areas of scattered tree cover and natural forests have densified, and the area of cultivated fields has declined (from 17.8% to 4.72%) (Zamora, et al, 2016). The variation in anthropogenic use have conditioned the capacity of mountain ecosystems to produce ecosystem services over time, resulting in trade-offs between provisioning and regulating services. Therefore, it is important to ascertain historical land-use change, as well as its effects on vegetation and ecosystem services.
The main purpose of this study is to facilitate the land-use management of Protected Areas (PAs) based on ecosystem services (ES). We assessed the past and present situation of the land use. Historical land use maps of Sierra Nevada (years 1956, 1977, 1984, 1999 and 2007) were the main input information for several ecosystem services assessment models. Afterwards we studied the trade-offs between ecosystem services (provisioning and regulation) due to changes in land use. This tool will help decision makers to determine where and how they can allow different types of agricultural practice and land uses in Sierra Nevada.
Methodology
For supporting services, we quantified the pastures available for livestock with a model developed by Robles et al., (1993), which provides Metabolizable Energy Available for livestock from several types of pastures.
Provisioning services were quantified via the production of the variety of agricultural practices. We mapped the areas of the different type of vegetation and crops along time and all milestones. Then, we obtained from official statistics the harvest yield of the variety of crops in both agricultural systems: rain-fed and irrigated practices. The ecosystem services were measured in kilograms of products.
Other provisioning and regulating services (aquifer recharge, water flow regulation (runoff), control erosion) were evaluated with WiMMed model. WiMMed (Watershed Integrated Model in Mediterranean Environments) is a physically-based, fully distributed hydrological model. It uses hourly and daily meteorological data, along with certain physical properties of the soil and subsoil to perform the spatial interpolation and temporal distribution of meteorological variables, rainfall interception, snowmelt, infiltration, runoff, surface slope circulation, calculation of the water in aquifers, and basin flow circulation (Aguilar, 2008; Herrero et al., 2007; Herrero et al., 2009; Herrero et al., 2014; Millares, 2008).
Results
The results show shifts in the provision of ecosystem services in Sierra Nevada due to changes in land use. One of the most interesting results is the increase in the availability of grassland areas due to a gradual naturalization of abandoned crop areas. Figure 1 shows the spatial distribution of this areas. 
Fig.1. Net increase in pastures in Sierra Nevada between 1956 and 2007.
Changes in land use due in many cases to fires or an increase in anthropomorphized areas have led to an increase in runoff. In some of the land uses, this increase in runoff has resulted in an increase in runoff. Figures 2 and 3 show how most of these changes have occurred in the southern and western Sierra Nevada.
Fig.2. Runoff change rate in Sierra Nevada between 1956 and 2007.
Fig.3. Erosion change rate in Sierra Nevada between 1956 and 2007.
A trade-off and synergies analysis (correlation analysis) between pastures and crop production was assessed in Sierra Nevada. The figure 4 shows the spatial distribution of the ES relation. 
Fig.4. Spatiotemporal trade-off and synergies analysis between pastures and crop production between 1956 and 2007.
References
Aguilar, C. 2008. Efectos de escala en procesos hidrológicos. Aplicación a la cuenca del río Guadalfeo (Granada). Tesis doctoral. Grupo de Hidrología e Hidráulica Agrícola. Universidad de Córdoba.
Ávila Armella, A. 2007. Multiple scale processes in the evolution of the coastline. PhD thesis. Environmental Flow Dynamics Group. University of Granada.
Herrero, J. 2007 Physical model of snow accumulation and melting. Application to Sierra Nevada (Spain). PhD thesis. Environmental Flow Dynamics Group. University of Granada.
Herrero, J., Milares, A., Aguilar, C., Díaz, A., Polo, M.J., Losada, M. 2009. WiMMed 1.0. Theoretical basis. Environmental Flow Dynamics Group. University of Granada. Agricultural Hydrology and Hydraulics Group. University of Cordoba.
Herrero, J., Millares, A., Aguilar, C., Egüen, M., Losada, M.A., Polo, M.J. 2014. Coupling spatial and time scales in the hydrological modelling of Mediterranean regions: WiMMed. 11th International Conference on Hydroinformatics. New York City, USA.
Millares, A. 2008 Integration of the base flow into a distributed basin model. Study of underground inputs in mountain rivers. PhD Thesis. Environmental Flow Dynamics Group. University of Granada.
Robles A.B.; González Rebollar J.L.; Morales C.; Fernández P.; Passera C. y Boza, J. (1993). Evaluation of the carrying capacity of semi-arid pastures of the Iberian S.E. (Ministry of Agriculture and Fisheries, Ed.).
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Last update: May, 2019