北亚热带3种典型森林群落对降水中氮、磷、硫的截留及分配特征

森林群落在净化空气、截留沉降污染物、改善地表水质等方面具有重要作用。本研究以北亚热带地区3种典型森林群落（毛竹林、杉木林、青冈阔叶林）为研究对象，通过分析沉降污染物（NH₄⁺-N、NO₃^--N、NO₂^--N、TP和SO₄^2-）在大气降水、林内穿透雨、树干茎流、枯透水和地表径流中的浓度和通量变化特征，探讨不同森林群落对氮、磷、硫的截留净化作用和分配特征。结果表明，该区域大气降水中NH₄⁺-N、NO₃^--N、NO₂^--N、TP和SO₄^2-年均浓度分别为1.06、0.61、0.04、0.07、1.84 mg/L，其年均pH为5.88；各森林群落林冠层能够调升降雨的pH且全年稳定，对TP和NH₄⁺-N均有吸附作用，截留率分别为79.09%-84.68%和30.88%-69.36%；而枯落物层则是林下氮、磷、硫的主要释放源，对NH₄⁺-N、NO₃^--N、TP和SO₄^2-均具有淋溶作用；此外，由地表径流（输出）与大气降水（输入）的对比分析可知，各林地对沉降污染物中氮、磷、硫的截留率均超过98%；3种森林群落对沉降污染物中氮、磷、硫的截留能力依次为：青冈阔叶林 > 毛竹林 > 杉木林，阔叶林对沉降污染物的净化能力要高于毛竹林及针叶的杉木林。

Interception characteristics of nitrogen, phosphorus and sulfur in precipitation by three forest communities in northern subtropical region of China

In the present study, Phyllostachys pubescens plantation, Cunninghamia lanceolata plantation, and Cyclobalanopsis glauca broadleaf forest, three typical forest types in northern subtropical China, were selected to investigate the fate and transport processes of inorganic nitrogen (NH₄⁺-N, NO₃^--N, NO₂^--N), TP, and SO₄^2- in various hydrological components (i.e. precipitation, throughfall, stemflow, litterfall, and surface runoff). Results showed that the average concentrations of NH₄⁺-N, NO₃^--N, NO₂^--N, TP, and SO₄^2- in rainfall were 1.06, 0.61, 0.04, 0.07 and 1.84 mg/L, respectively, with an average pH of 5.88. The canopies of the three forest communities increased the pH of precipitation and kept stable throughout the year. The canopies absorbed TP and NH₄⁺-N accounting for 79.09%-84.68% and 30.88%-69.36%, respectively in P. pubescens, C. lanceolata and C. glauca forests. The litter layer was the major releasing sources of nitrogen, phosphorus, and sulfur under the forests. Compared with atmospheric precipitation, the mass flux of NH₄⁺-N, NO₃^--N, NO₂^--N, TP, and SO₄^2- in surface runoff decreased significantly, with a minimum of 98% being trapped. According to the total interception rates of three forest communities, the C. glauca broadleaf forest most effectively trapped nitrogen, phosphorus, and sulfur in atmospheric precipitation, followed by P. pubescens plantation and C. lanceolata plantation.