By Ana Belén Ruiz Sánchez
Abstract:
Almeria province is a heterogeneous area with high biodiversity and nature value that is under severe human pressure. Land use change constitutes one of the main drivers in the dynamic economy present. The intensification of agricultural areas (intensive crops and greenhouses) together with urban development because of increase of tourism close to the coastland are the principal impacts on ecosystems.
To study the state of ecosystem functioning of the province, the spatial pattern of the fraction of Absorbed of Photosynthetically Active Radiation (fAPAR) by vegetation based on the annual dynamic of the Normalized Difference Vegetation Index (NDVI) and its derivative attributes was examined. NDVI is a spectral index related to primary productivity, as an integrative indicator of ecosystem functioning. The annual integral NDVI (NDVI-I), and the Relative Range (RREL) are indicators of seasonability of the vegetation. Maximum and Minimum NDVI (MMAX and MMIN) provide additional descriptions of vegetation phenology, indicating the intra-annual distribution of the period with maximum and minimum photosynthetic activity.
To assess the impact of land use change on the ecosystem functioning, Regression Tree analysis was applied to predict the potential NDVI (P-NDVI) and then to examine the patterns of deviation of actual NDVI (A-NDVI) in terms of land uses. It came up that urban areas, not-irrigated and mixed land uses have lower A-NDVI than P-NDVI during the time series considerate; irrigated land uses have a greater A-NDVI than P-NDVI and natural vegetation cover present slight higher value of A-NDVI than P-NDVI.