Enhanced aboveground biomass by increased precipitation in a central European grassland

Background: Global climate change is projected to increase temperature and alter precipitation pattern, which could affect grassland ecosystem. Long-term observation at a field experiment can be a powerful approach to explore the impacts of climate change on biomass productivity in grassland. In attempting to understand how climatic variability regulates biomass productivity, we analyzed long-term records of temperature and precipitation to examine how variation of temperature and precipitation across 19 years affect biomass productivity. 

Methods: We established the experiment with 64 plots in two blocks and planted 31 species in 30 different mixtures. We harvested aboveground biomass twice a year, sorted biomass by functional groups, and weighed dry biomass. The site was mown after each harvest. We did not apply any fertilizer and water. Using linear regression model, we examined the influences of growing season temperature and precipitation on biomass productivity. 

Results: The results showed that aboveground biomass productivity in September and annual were significantly increased in post-drought (2003–2015). The relationships of aboveground biomass productivity with growing season precipitation were significantly positive. The results showed that aboveground biomass productivity in June and annual were sensitive to growing season temperature. The relationships of aboveground biomass productivity of the functional group of grasses with early growing season temperature were significantly negative. Early growing season precipitation had a significant positive effect on aboveground biomass productivity of the functional groups of grasses and legumes. Post-drought aboveground biomass productivity of the functional groups of grasses in June and September were declined, whereas legumes significantly increased, which suggests that the role of dominant grasses may shift by legumes with global climate change. 

Conclusions: Our results highlight that early and late growing temperature and precipitation variability may reduce the aboveground biomass productivity in grassland. Our study implies that the combination of several functional groups is essential for the maintenance of stable productivity in temperate grassland ecosystem.