5. CONCLUSIONS
In summary, our findings indicate that inter-annual precipitation fluctuation, rather than nutrient addition or AM fungal suppression, determines ANPP and plant species composition in desert steppe in the Northwest China. Furthermore, we also found that annual plant species in plant communities are more sensitive to precipitation than are other plant species, particularly in dry years. Therefore, we recommend that interactions among annual precipitation, fertilisation and AM fungi be incorporated into grassland management models when evaluating desert steppe ecosystem responses. Finally, our study indicate that the responses of plant communities in arid grassland to soil nutrient enrichment and symbiotic fungi vary over time. Unfortunately, our study was carried out across only two growing seasons with contrasting precipitation patterns, which limits our ability to understand plant community dynamics under various rainfall scenarios in the long term. Therefore, further studies are obliged to examine whether the responses of plant communities to nutrients input and AM fungi are consistent over longer periods.