马尾松人工林林冠层对氮、磷、硫的截留效应

Effect of Canopy Interception on Nitrogen,Phosphorus and Sulfur in Pinus Massoniana Plantations

观测宜宾高县来复镇18,32年生马尾松人工林以及马尾松针阔混交林在雨季的大气降雨量、穿透雨量和树干茎流量,并对其全磷(TP)、硝态氮(NO-3-N)、铵态氮(NH+4-N)、硫(S)进行同步取样分析。结果表明:(1)马尾松针阔混交林对降雨截留能力要高于马尾松纯林,但在秋末落叶后马尾松针阔混交林截留能力显著减弱;(2)林龄对茎流、穿透雨中氮、磷和硫的月平均含量没有显著影响。针阔混交林中NO-3-N、NH+4-N月平均含量显著低于两个马尾松纯林,秋末落叶后针阔混交林的TP、NO-3-N、NH+4-N、S月平均含量都显著降低;(3)从穿透雨、树干茎流的氮、磷、硫总含量来看,32年生马尾松人工林最高,针阔混交林含量最低,经过针阔混交林冠层后,穿透雨中的NO-3-N、TP、S和NH+4-N总含量降低;(4)林型对树干茎流穿透雨中氮和硫的总含量都有显著影响,而对磷的总含量没有显著影响;(5)在降雨观测期内,大气降雨中P的输入量为0.028kg/hm2,NH+4-N的输入量为0.238kg/hm2,NO-3-N的输入量为0.344kg/hm2,S的输入量为5.471kg/hm2。S在经过32年生马尾松人工林,18年生马尾松人工林以及马尾松针阔混交林林冠层后,总的净输入量分别为-3.770,-4.692,-6.131kg/hm2,说明3个人工林林冠层对S具有一定的吸附能力。TP、NH+4-N、NO-3-N、S在经过针阔混交林后总的净输入量分别为-0.009,-0.272,-0.156,-6.131kg/hm2,说明针阔混交林林冠层对其都有吸附能力。因此,在马尾松人工纯林内混交阔叶树种可以起到很好的提高截留过滤氮、磷和硫的作用。

The penetration of rainfall, throughfall and stemflow during the rainy season were observed in Pi- nus massoniana plantations of 18, 32-years-old and mixed broadleaf-conifer forest at Laifu town of Yibin city, and its total phosphorus（TP）, nitrate（NO3- --N）, ammonium（NH＋ --N）, sulfur（S） were sampled and ana- lyzed simultaneously. The results showed that： Rainfall interception capability of mixed broadleaf-conifer forest was higher than that of pure masson pine, and it reduced significantly after the litterfall of mixed for- est. Forest age had no significant impact on the monthly average content of P, NO3 --N, NH＋ --N and S in throughfall and stemflow, NO3- --N, NH＋ --N in mixed broadleaf-conifer forest was significantly lower than that in two pure masson pine forest. After the leaves fallen, the P, NO3- --N, NH＋ --N and S~ monthly av- erage contents reduced significantly. From view of total content of nitrogen, phosphorus and sulfur of throughfall and stemflow, 32-year-old masson pine plantation was highest and mixed broadleaf-conifer forest was lowest, the content of TP, NO3- --N, NH＋ --N and S in throughfall through canopy decreased. Forest type had a significant impact on the TN, S content of stemflow and throughfall, but no significant effect on P content. Nutrient inputs via rainfall were 0. 028 kg/hm2 of P, 0. 238 kg/hm2 of NH＋-N, 0. 344 kg/hm2 of NO3- --N, and 5. 471 kg/hm2 of S. Negative fluxes were found for S in the net input across three plantationcanopy, showing that canopy of three plantation had certain adsorption capacity to S. The total net input of N, P and S were all negative through mixed forest which canopy had adsorption ability in N, P and S. There- fore, the pure Pinus massoniana plantations mixing broadleaf species could improve intercept filtering ability toN, PandS.