Connectivity of Natura 2000 Potential Natural Riparian Habitats under Climate Change in the Northwest Iberian Peninsula: Implications for Their Conservation

Climate projections for the near future suggest a general increase in temperatures and a decrease in precipitation in Castilla y León (Northwest Iberian Peninsula). In this context, hydrographic networks may be reduced due to the decrease in flow accumulation, which may compromise the connectivity of riparian habitats and aggravate fragmentation processes, thus potentially threatening the survival of various wild species. Regionalized climate projections were calculated based on the RCP models and the 8.5 and 4.5 scenarios for the years 2030, 2050 and 2100. From this climate modelling, flow variations in the hydrographic networks were determined for the period 2020–2100. The observed decrease in precipitation and increase in temperature point to a reduction in flow accumulation. Considering these variations, and after establishing the study habitats, the alterations in ecological connectivity were analysed using the MSPA (Morphological Spatial Pattern Analysis) and the PC (Probability of Connectivity) index. MSPA reveals a significant reduction in the number and size of potential riparian habitat cores towards the year 2100, while the PC index values decrease from 3.1% (∑ dPC) in 2020 to 2.5% (∑ dPC) in 2100. These results indicate a substantial loss of ecological connectivity and an increased fragmentation of potential riparian habitats, as well as a close relation between reduced connectivity and flow accumulation for future climate projections.