In order to deeply understand effects of atmospheric nitrogen deposition on herbaceous plant diversity and productivity in desert grassland. A nitrogen addition experiment was carried out in desert grassland of the Loess Plateau. The short-term response of species diversity and productivity of herbaceous plants to different levels of nitrogen additions were studied. The results showed that the Margalef species richness index and Shannon-Wiener diversity index decreased significantly with nitrogen addition increased. Compared to control, in middle and high nitrogen addition level the Margalef species richness index and Shannon-Wiener diversity index were decreased by 39.14%, 47.07% and 25.57%, 31.52% respectively. As the nitrogen addition increasing, the relative importance value of the main dominant species increased, relative importance value of the main companion species increased at low levels of nitrogen addition but showed decreasing change trend in high nitrogen addition level, and some companion species in week position disappeared from plant communities. With nitrogen addition increasing, community productivity increased especially at low level of nitrogen addition. Nitrogen addition can promote growth of dominant species, but restrain growth of companion species in week position. Nitrogen addition can improve the community productivity and induce changes in community composition and species diversity of herbaceous plants in desert grassland of Loess Plateau.
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