华南典型人工林凋落物的持水特性

WATER HOLDING CHARACTERISTICS OF LITTER IN PLANTATIONS IN SOUTH CHINA

对于华南地区的杉木(Cunninghamialanceolata)林、马尾松(Pinusmassoniana)林、湿地松(Pinuselliottii)林、马占相思(Acaciamangium)林和尾叶桉(Eucalyptusurophylla)林的凋落物的储量、持水量、持水率和吸水速率进行了研究。结果表明,杉木林的凋落物的干重(6 .5×10 3 kg·hm-2 )最大,其次是马尾松林和马占相思林(5 .5×10 3 kg·hm-2 ) ,而湿地松林(4.1×10 3 kg·hm-2 )和尾叶桉林较小(4.0×10 3 kg·hm-2 )。凋落物持水量呈现杉木林>马占相思林>尾叶桉林>马尾松林>湿地松林。各林分凋落物的最大持水量为杉木林17.9×10 3 kg·hm-2 ,马占相思林14 .8×10 3 kg·hm-2 ,尾叶桉林14 .0×10 3 kg·hm-2 ,马尾松林10 .6×10 3 kg·hm-2 ,湿地松林9.8×10 3 kg·hm-2 。尾叶桉林、杉木林、马占相思林、湿地松林和马尾松林的凋落物最大持水率分别为35 1%、2 74 %、2 6 9%、2 35 %和191%。凋落物持水量和凋落物持水率随着浸泡时间的增加按照对数方程增加。5种林分中尾叶桉林的凋落物吸水速率在各浸泡时间后居首位,杉木林和马占相思林中等,湿地松林较小,而马尾松林最小,各林分的凋落物的吸水速率随浸泡时间的增长按方程Y =a +b·t-1下降。

Litter characteristics, such as standing crop, water holding capacity, and proportional water holding capacity and absorption rates, were studied in plantations of Cunninghamia lanceolata, Pinus massoniana, Pinus elliottii, Acacia mangium and Eucalyptus urophylla. The dry litter standing crop of C. lanceolata plantation was the largest (6.5×10 3 kg·hm -2 ) among the five plantations, followed by the P. massoniana and A. mangium plantations (5.5×10 3 kg·hm -2 ), the P. elliottii plantation (4.1×10 3 kg·hm -2 ) and the E. urophylla plantation (4.0×10 3 kg·hm -2 ). The order of total water holding capacity of litter was C. lanceolata plantation (17.9×10 3 kg·hm -2 ) > A. mangium plantation (14.8×10 3 kg·hm -2 ) > E. urophylla plantation (14.0×10 3 kg·hm -2 ) > P. massoniana plantation (10.6×10 3 kg·hm -2 ) > P. elliottii plantation (9.8×10 3 kg·hm -2 ). The proportional water holding capacity as a percentage of the litter dry weight in E. urophylla, C. lanceolata, A. mangium, P. elliottii and P. massoniana plantations were 351%, 274%, 269%, 235% and 191%, respectively. The total water holding capacity and proportional water holding capacity of litter increased logarithmically with increasing time immersed in water. The water absorption rate of litter in E. urophylla plantation was the largest among the five plantations, medium in the C. lanceolata and A. mangium plantations, lower in the P. elliottii plantation, and lowest in the P. massoniana plantation. Water absorption rates of litter in all plantations decreased according to equation Y=a+b·t -1 with increasing time immersed in water.