The rising productivity of alpine grassland under warming, drought and N-deposition treatments
Abstract. We conducted a four-year warming × moisture × N-deposition field-experiment (AlpGrass) with 216 turf monoliths from six different subalpine pastures (sites of origin). At a common location, the monoliths were replanted at six climate scenario sites (CS) along an altitudinal gradient from 2360 to 1680 m a.s.l., representing an April–October temperature change of −1.4 °C to +3.0 °C, compared to CSreference with no temperature change and with climate conditions comparable to the sites of origin. We further applied an irrigation treatment (+12–21 % of ambient precipitation) and an N-deposition treatment (+3 kg and +15 kg N ha−1 a−1), the latter simulating a fertilizing air pollution effect. Moderate warming led to increased productivity. Across the four-year experimental period, the mean annual yield peaked at intermediate CSs (+43 % at +0.7 °C and +44 % at +1.8 °C), coinciding with c. 50 % of days with dry soil during the growing season (growing-season-days with soil moisture