Climate Change Effects on Temperate Grassland and Its Implication for Forage Production : A Case Study from Northern Germany

 The effects of climate change on agricultural ecosystems are increasing, and droughts
affect many regions. Drought has substantial ecological, social, and economic consequences for the
sustainability of agricultural land. Many regions of the northern hemisphere have not experienced a
high frequency of meteorological droughts in the past. For understanding the implications of climate
change on grassland, analysis of the long-term climate data provides key information relevant for
improved grassland management strategies. Using weather data and grassland production data from
a long-term permanent grassland site, our aims were (i) to detect the most important drought periods
that affected the region and (ii) to assess whether climate changes and variability significantly affected
forage production in the last decade. For this purpose, long-term daily weather data (1961–2019) and
the standardized precipitation index (SPI), De Martonne index (IDM), water deficit (WD), dryness
index (DI), yield anomaly index (YAI), and annual yield loss index (YL) were used to provide a
scientific estimation. The results show that, despite a positive trend in DI and a negative trend in WD
and precipitation, the time-series trends of precipitation, WD, and DI indices for 1961–2019 were not
significant. Extreme dry conditions were also identified with SPI values less than −2. The measured
annual forage yield (2007–2018) harvested in a four-cut silage system (with and without organic
N-fertilization) showed a strong correlation with WD (R = 0.64; p < 0. 05). The main yield losses
were indicated for the years 2008 and 2018. The results of this study could provide a perspective for
drought monitoring, as well as drought warning, in grassland in northwest Europe.