[Hydrological functions of litters under five typical plantations in southern and northern mountains of Lanzhou City, Northwest China]

Combined with field observation and indoor water immersion test, water holding characteristics of litters from five typical plantations (Platycladus orientalis, Robinia pseudoacacia, Populus alba var. pyramidalis, P. orientalis+R. pseudoacacia, P. alba var. pyramidalis+R. pseudoacacia) in southern and northern mountains of Lanzhou City were examined. Results showed that litter mass under the plantations ranged from 13.50 to 47.01 t·hm^-2, with an order of P. alba var. pyramidalis+R. pseudoacacia＞P. orientalis+R. pseudoacacia＞P. orientalis＞R. pseudoacacia＞P. alba var. pyramidalis. The percentage of un-decomposed litters was greater than that of semi-decomposed litters in all plantations except for P. orientalis plantations. The maximum water-holding rate of litters ranged from 190.8% to 262.7%, with the greatest value in the P. alba var. pyramidalis+R. pseudoa-cacia and the lowest in P. orientalis plantations. The maximum water-holding capacity of litters was 35.29-123.59 t·hm^-2, with an order of P. alba var. pyramidalis+R. pseudoacacia＞P. orientalis+R. pseudoacacia＞R. pseudoacacia＞P. orientalis＞P. alba var. pyramidalis. Litter water absorption rate declined linearly within the first hour, and then decreased slowly. Semi-decomposed litters had a higher water-absorption rate than un-decomposed litters. The maximum water retaining amount and effective retaining amount of the litters were P. alba var. pyramidalis+R. pseudoacacia＞P. orientalis+R. pseudoacacia＞P. orientalis＞R. pseudoacacia＞P. alba var. pyramidalis. P. alba var. pyramidalis+R. pseudoacacia had the highest effective retaining rate. P. alba var. pyramidalis+R. pseudoacacia plantation had highest capacity for soil and water conservation in southern and northern mountains of Lanzhou City.