安徽老山亚热带常绿阔叶林降雨中的养分动态

摘要

森林生态系统对降雨化学性质的影响十分明显,降雨经过森林植被后,其养分种类和数量都发生很大变化.通过降雨输入的养分不仅对森林群落的生长和演替具有重要意义,而且是森林生态系统生物化学循环的重要组成部分,构成森林生态系统养分平衡的基础.国内外有关森林降雨化学的研究较多,涉及到不同的森林类型( Parker,1983;Amezagaet al.,1997;Schmitta et al.,2005;Xu et al.,2005;刘菊秀等,2003;巩合德等,2005;武秀娟等,2008).自20世纪70年代以来,欧洲、北美及日本就森林降雨化学进行了长期监测(Staelens et al.,2008),结果表明森林降雨化学表现出高度的时间和空间异质性(Cronan et al.,1983;Parker,1983;Staelens et al.,2008),难以得出普遍规律.为了深入认识森林植被降雨化学的形成机制,需要系统和长期的定位观测.我国有关森林降雨化学的研究多集中在温带和南亚热带地区的落叶松(Larixgmelinii)、油松(Pinus tabulaeformis)、云杉(Piceaasperata)、杉木(Cunninghamia lanceolata)和马尾松(Pinus massoniana)等单一群落,而对亚热带常绿阔叶林复杂群落的研究较少.本研究探讨安徽老山自然保护区亚热带常绿阔叶林的降雨化学动态,以期了解森林水文过程中养分元素的迁移规律和循环特点,为其生态功能评价和科学经营提供依据.%In this study, the seasonal dynamic patterns of nutrients in the bulk precipitation, throughfall and stemflow were investigated in a subtropical evergreen broad-leaved forest over one year in Laoshan Natural Reserve, southern Anhui. The results showed that the concentrations of nutrients were significantly increased after rain passed through forest canopies. The mean concentration of K+ , Ca2+ , Mg2+ , NH4+-N , NO3-N, PO3-4 were, respectively, 1.40 mg-L , 3.08 mg-L-1, 0.056 mg.L-1, 0.42 mg-L-1, 0.51 mg-L-1, and 6.86 μg.L-1 for the bulk precipitation; 3.88 mg.L-1, 4.69 mg.L-1, 0.27 mg.L-1, 0.44 mg.L-1, 0.94 mg.L-1 and 10.73 μg.L-1 for the throughfall; and 5.78 mg.L-1, 8.02 mg.L-1, 0.45 mg.L-1, 0.94 mg.L-1, 1.03 mg.L-1 and 19.98 μg.L-1 for the stemflow. The nutrient concentrations of precipitation fluctuated with rainfall intensity. The nutrient concentrations of throughfall and stemflow were affected by not only atmospheric conditions but the growth stage of trees.