Based on the provided title and the opening sentence of the article, it can only be concluded that the study deals with how multi-species grasslands (i.e. meadows with a mixture of several types of grasses and herbs) can achieve a higher biomass yield with lower doses of nitrogen fertilization. The study is carried out across the climatic gradient, i.e. in different climatic conditions, and observes whether this effect applies in different climates. It follows from the above that the research compares yields with different species diversity of stands and different nitrogen inputs. Specific numerical data, effect size, number of locations, duration of the experiment, and statistical results are not given in the text provided, so they cannot be reliably summarized. It is neither specified which plant species were included nor the exact methodology for measuring yields. From the article, it can be safely summarized only that multi-species grasslands make it possible to obtain more crops with less use of nitrogen fertilizers in different climatic conditions.