桉树人工林取代长周期人工林对土壤入渗特性的影响

广西桉树人工林的前茬主要为轮伐周期较长的松杉类人工林,为探讨上述植被变化对林地土壤水分下渗的影响,采用单环法研究了8年生(06-EU),5年生(09-EU),4年生(10-EU)和1年生(13-EU)等第一代桉树(Eucalyptus urophylla E.grandis)人工林及其对照林21年生针阔混交(93-CM),第三代2年生桉树(12-EU3),18年生杉木(Cunninghamia lanceolate,96-CL)和马尾松(Pinus massoniana,96-PM)等人工林的土壤水分下渗特征,并采用BEST-intercept方法对土壤入渗特征参数进行估算。结果表明:(1)针阔混交和马尾松人工林改为桉树人工林后,土壤(0—20cm)容重分别降低13.5%和18.3%,孔隙度分别增加10.1%和14.8%,但土壤颗粒组成的变化不显著;(2)针阔混交林改为桉树人工林后,土壤初始入渗速率和前600s下渗量分别降低38.2%和25.3%,而杉木人工林、马尾松人工林则分别升高23.9%,148.1%和32.7%,97.2%;(3)连载代次的增加对桉树林土壤基本物理性质影响不显著,但会降低土壤水分下渗性能,第三代桉树林的初始入渗速率和前600s下渗量比第一代减少39.9%和32.4%。容重较大的林地在造林和抚育过程中的松土活动导致了土壤大孔隙增加,这是土壤水分下渗速率变化的主要成因。

Effects of Eucalyptus Plantation Replacing Long Rotation Plantation on Soil Infiltration

The previous stand types of eucalyptus plantation in Guangxi are mostly Coniferopsida long rotation plantation such as Pinus massoniana and Chinese fir.In order to ascertain the effect of vegetation changes on forest soil infiltration,infiltration of soils under deferent ages (8,5,4 and 1 years,abbreviation for 06-EU,09-EU,10-EU and 13-EU,respectively) first generation eucalyptus(Eucalyptus urophylla E.grandis)plantations were measured using single ring.Their control forest (21 a conifer-broadleaf mixed forest,93-CM,2 a third generation eucalyptus,12-EU3,18 a Cunninghamia lanceolate,96-CL,18 a Pinus massoniana,96-PM) were investigated at the same time.The soil infiltration parameters were calculated using BEST-intercept method.The study indicated that,compare with the previous stands (93-CM and 96-PM),the soil bulk densities of 06-EU and 13-EU significantly decreased by 13.5％ and 18.3％,respectively,and porosities increased by 10.1％ and 14.8％,but the change of soil particle-size distribution was not significant.The initial infiltration rate and 600 s cumulative infiltration of 06-EU were 39.9％ and 25.3％ lower than those of 93-CM;compare with the pre-stands(96-CL and 96-PM),the initial infiltration rate and 600 s cumulative infiltration of 10-EU and 13-EU increased by 23.9％,148.1％ and 32.7％,97.2％,respectively;there was no significant different of soil physical property between the first with third generation eucalyptus plantations;the initial infiltration rate and 600 s cumulative infiltration of 12-EU3 were 39.9％ and 32.4％ lower than that of 10-EU.The research results indicate that afforestation eucalyptus on long rotation plantation land will increase soil macropore rates,which induces the changes of soil infiltration.