Effect of rainfall pulses on plant growth and transpiration of two xerophytic shrubs in a revegetated desert area: Tengger Desert, China

Rainfall is one of the most important abiotic factors limiting physiological processes and ecological adaptability of plants in arid regions. In this study, the leaf area index (LAI), new branch length (NBL) and sap flow scaled transpiration of Caragana korshinskii and Artemisia ordosica in response to rainfall pulses were investigated during the growing season from 2008 to 2012, and then the plant acclimation was discussed. Results indicated that rainfall intervals and depth can trigger a cascade of plant physiological and acclimation responses of C. korshinskii and A. ordosica at different time scales. The approximate water consumption of C korshinskii and A. ordosica were 15.54 +/- 2.89 mm and 3.40 +/- 0.07 mm for every 1 cm of branch growth, respectively. In daily time scales, rainfall pulses of 0-5 mm would result the plant transpiration to increase by 14 +/- 2%-31 +/- 9%; however, when the rainfall is larger than 5 mm, daily plant transpiration was reduced by about 7 +/- 1%-39 +/- 2%, and restored its pre-rainfall values within 1-2 days. Rainfall intervals of 0-5 days (d) and 5-10 d have a dominant impact on the increment of LAI NBL and transpiration of C kotshinskii and A. ordosica, which accounted for approximately 50%-80% of the total. On interannual scales, plant growth and transpiration were linearly correlated with annual rainfall.A. ordosica acclimated to drought by losing some or all parts of the plant, and C korshinskii survived during the dry period mainly by losing its leaves and by entering dormancy and ceasing growth. (C) 2015 Elsevier B.V. All rights reserved.