Shrub encroachment in grasslands and savannas has been widely reported over the past few decades and variation in precipitation was regarded as one of the most important drivers. Therefore, previous studies usually tested the effect of precipitation through increasing or decreasing 30% or 50% of the natural precipitation. However, because of lacking enough natural precipitation, this kind of precipitation experiment is not practical for some regions where annual precipitation is very low. We are planning to conduct such precipitation experiments within shrub-encroached grasslands in Inner Mongolia, where annual precipitation is less than 200 mm in certain year, to test the effects of precipitation on the encroachment of shrubs into grasslands. Because of lacking enough natural precipitation, we would like to irrigate our experimental plots, instead of using natural precipitation. Our preliminary design is following: (1) Four levels of precipitation: Decreasing 30% of the natural precipitation, No change, Increasing 30% of precipitation through irrigation, and Increasing 50% of precipitation through irrigation; (2) We will set three replications for each level because of the difficulty of irrigation; (3) Water source for irrigation is from local underground water, which is distilled before using to remove salts.
Can you please give us any comments and suggestions on the above experimental design? Many thanks! Best wishes! Huifeng Hu Ph.D State Key laboratory of vegetation and environmental change Institute of Botany, the Chinese Academy of Sciences (IBCAS) No. 20 Nanxincun, Xiangshan Beijing 100093, P.R. China
