西南亚热带典型林分枯落物层对酸沉降的响应

Responses of Typical Forest Litters to Acid Deposition in Southwestern Subtropical Region

通过模拟酸雨实验,研究了缙云山马尾松×四川大头茶×四川杨桐混交林(林分Ⅰ)、广东山胡椒×四川山矾混交林(林分Ⅱ)、毛竹林(林分Ⅲ)、四川山矾×杉木混交林(林分Ⅳ)、马尾松林(林分Ⅴ)、灌丛(林分Ⅵ)枯落物淋滤液的化学性质。结果表明:①6种典型林分的枯落物淋滤液pH值均随模拟酸雨pH的降低而减小;林分Ⅴ的枯落物层对模拟酸雨pH值的缓冲效果最好。②6种典型林分枯落物淋滤液中的盐基离子(Ca2+、Mg2+、K+、Na+、NH+4)浓度随模拟酸雨pH值的降低而增加。在pH值2.7和3.5的强酸雨作用下,林分Ⅴ枯落物淋滤液中的盐基离子浓度均是最高的,达到了0.143 6 mmol/L和0.074 0mmol/L,在pH值4.5的酸雨作用下,林分Ⅱ枯落物淋滤液的盐基离子浓度是最高的,达到了0.138 9mmol/L。③在模拟酸雨pH值为2.7时,6种典型林分淋滤液中Al3+、Fe、Mn、Zn急剧增加,且林分Ⅴ枯落物淋滤液中Al3+(0.018 2 mmol/L)、Fe(0.004 4 mmol/L)、Mn(0.010 7 mmol/L)、Zn(0.002 5 mmol/L)均高于其他林分,林分Ⅴ更易受到这几种元素的毒害。

The hydro-chemical properties of litter layers of 6 typical forests including Pinus massoniana×Adinandra bockiana×Gordonia acuminata Chang mixed forest（forest type Ⅰ）,Lindera kwangtungensis×Symplocos setchuanensis mixed forest（forest type Ⅱ）,Phyllostachys pubescens forest（forest type Ⅲ）,Symplocos setchuanensis×Cunninghamia Lanceolata（forest type Ⅳ）,Pinus massoniana forest（forest type Ⅴ） and shrub forest（forest type Ⅵ）in Jinyun mountain were studied by the simulated acid rain experiment.The results showed： ①Litter leaching pH values of 6 typical forest stands reduced with the decrease of pH of simulated acid rain.The acid buffer ability of litter layer in forest type Ⅴ was best.②Base cation（Ca2＋,Mg2＋,K＋,Na＋,NH＋4） concentrations of all 6 typical forest litter leaching increased with the decrease of pH of simulated acid rain.Under the eluviation of different simulated acid rain（pH value： 2.7,3.5）,the base cation concentrations of litter leaching of forest type Ⅴ were always largest： 0.143 6 mmol/L（pH 2.7）,0.074 0 mmol/L（pH 3.5）.Under the eluviation of pH 4.5 simulated acid rain,the base cation concentrations of litter leaching of forest type Ⅱ were the largest： 0.138 9 mmol/L.③The concentrations of Al3＋,Fe,Mn,Zn in litter leaching of 6 typical forest stands increased dramatically when the pH value of simulated acid rain was 2.7.And the concentrations of Al3＋（0.018 2 mmol/L）,Fe（0.004 4 mmol/L）,Mn（0.010 7 mmol/L） and Zn（0.002 5 mmol/L） in forest type Ⅴ litter leaching were larger than that of the others.It indicated that forest type Ⅴ was more vulnerable to these toxic elements.