Alpine Nardus stricta-dominated grasslands are important communities in terms of animal production and environmental conservation in the Cantabrian Range (northern Spain), which are rapidly declining in their extension as a result of land-use changes and the loss of traditional farming practices historically linked to mountainous environments. However, to date few data are available regarding their productivity and bromatological properties, which are key ecological parameters in order to implement effective conservation measures. We selected two types of Nardus grasslands (mesic and wet) and measured annual aboveground net primary productivity (ANPP), botanical components, forage utilisation and their respective seasonal patterns during a five-year period, using a method based on biomass clippings on non-permanent exclosures. In addition, during four years, we analysed their nutritional quality and for two years, we recorded soil moisture and temperature in order to construct models able to explain grassland productivity.
We found a marked seasonality of productivity, and that mesic grassland was significantly less productive than wet. Mesic grassland, with a more important contribution of forbs and legumes over graminoids in its botanical composition, was the preferred forage source and showed better bromatological properties in spring and early summer, but the rest of the season wet grassland had a higher utilisation thanks to its ability to maintain biomass production. This was partially explained by soil moisture, a limiting factor of mesic grassland productivity.