Intermediate snowpack melt-out dates guarantee the highest seasonal grasslands greening in the Pyrenees.

In mountain areas, the phenology and productivity of grassland are closely related to snow dynamics. However, the influence that snow melt timing has on grassland growing still needs further attention for a full understanding, particularly at high spatial resolution. Aiming to reduce this knowledge gap, this work exploits 1 m resolution snow depth and Normalized Difference Vegetation Index observations acquired with an Unmanned Aerial Vehicle at a sub-alpine site in the Pyrenees. During two snow seasons (2019-2020 and 2020-2021), 14 NDVI and 17 snow depth distributions were acquired over 48 ha. Despite the snow dynamics being different in the two seasons, the response of grasslands greening to snow melt-out exhibited a very similar pattern in both. The NDVI temporal evolution in areas with distinct melt-out dates reveals that sectors where the melt-out date occurs in late April or early May (optimum melt-out) reach the maximum vegetation productivity. Zones with an earlier or a later melt-out rarely reach peak NDVI values. The results obtained in this study area, suggest that knowledge about snow depth distribution is not needed to understand NDVI grassland dynamics. The analysis did not reveal a clear link between the spatial variability in snow duration and the diversity and richness of grassland communities within the study area.

Clearing shrubland and extensive livestock farming: Active prevention to control wildfires in the Mediterranean mountains.

Forest fires are one of the main environmental problems in Mediterranean environments and different fire prevention policies have been applied: livestock grazing, prescribed fires and a combination of both. However, none present satisfactory results. In that context, in 1986 the Regional Government of La Rioja started the Plan for Shrub Clearing (PSC), combining shrub clearings and livestock grazing to control fires and improve the land management of abandoned mountain areas. Our study aims to analyse the effects of shrub clearings on forest fires in La Rioja and to compare the main results with those observed in Spain in the last 30 years. We apply an interdisciplinary methodology based on the analysis of the evolution of cleared areas, the evolution of wildfires in La Rioja and Spain, mapping land use and land cover changes, and quantifying the combustibility. Results obtained in La Rioja are very positive compared with the evolution of Spain, both in the reduction of the number of fires and the burned areas. Decreases in the combustible material, fuel load and biomass and in the occurrence of fires (>1 ha) were observed. In addition, clearing shrubland and extensive livestock provided other environmental benefits (i.e. mosaic landscapes, ecosystem services). Finally, this study suggested that they are good and sustainable techniques to prevent and control wildfires and they could be used as a land management strategy in other Mediterranean areas.