| Understanding the response of Leymus chinensis biomass production and rainfall-use efficiency to changes precipitation variation is critical to predicting the productivity of semiarid grassland in Northern China.Recently,numerous studies were conducted on the relationship between Leymus chinensis biomass production and rainfall amount,but the impact of rainfall interval and the interactive effects of rainfall amount and interval on Leymus chinensis biomass production and RUE is rarely mentioned.Here,through artificial rainfall experiment was conducted to evaluate the impacts of rainfall amount(R-: 233.42mm;R0: 333.45mm;R+:433.48mm)and rainfall interval(with 6-day,9-day,12-day,15-day,18-day and21-day)on the biomass and RUE of the dominant species of Leymus chinensis in the eastern end of Eurasia,provide a scientific basis for predicting the response of the local ecosystem to future changes in rainfall.The research results were showed as follows:(1)In addition to extreme rainfall treatment,increasing rainfall and extending rainfall interval significantly increase plant height,number of branches and number of leaf,which is beneficial to the growth of Leymus chinensis.(2)Different rainfalls have different effects on the above-ground biomass.No matter how the rainfall interval changes,the aboveground biomass increases with the increase of rainfall,but D21 treatment causes the aboveground wither away different.The extension of the moderate rainfall interval is beneficial to the production of Leymus chinensis biomass and RUE,but this result is affected by rainfall.R-treatment shows.The normal single-peak curve reaches the maximum value at D15,while the R0 and R+ treatments show a skewed single-peak curve and reach the maximum value at D18.Without the D21 rainfall interval treatment,biomass allocation the ratio of stem to leaf Leymus chinensis(S/L)was significantly negatively correlated with RUE.(3)The RUE changes under different rainfall intervals are exactly the similar as the biomass changes.(4)Interaction of precipitation amount and rainfall interval for biomass was significantly negatively correlated with RUE,but not with biomass allocation(S/L ? R/S).(5)Increased amount of rainfall significant decreased the soil available nitrogen but increased the soil water content.The soil available nitrogen content showed a trend of firstdecreasing and then increasing.The above results not only verified the close relationship between rainfall and aboveground biomass even under future climate change,but also further indicated that under different rainfall,the rainfall interval has different effects on RUE,aboveground biomass,and the conditions for future rainfall pattern change.That is,under the condition of rainfall interval prolonged,the Leymus chinesis will increase the aboveground biomass production and leaf biomass.These findings have important implications for understanding and predicting the effect of future climate change on grassland production in semiarid grassland in Northern China. |
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