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于2007年9月—2009年8月对中国西南茂兰喀斯特地区亚热带常绿落叶阔叶混交林大气降水、林冠穿透雨和树干茎流进行观测,分析了各降水分配中的养分离子(Ca2+、Mg2+、K+、Na+、NH4+、SO42-、NO3-、Cl-)浓度动态变化规律及年养分元素输入量。结果表明:7—9月,林外雨、林冠穿透雨和树干茎流中各养分离子浓度相对较低,12月—翌年2月,各降水分配中各养分离子浓度相对较高;降水通过林冠或树干后,除了Na+浓度无显著变化外,NH4+浓度表现下降趋势,Ca2+、Mg2+、K+、Cl-、NO3-和SO42-均表现增加趋势;林外雨的养分元素输入量顺序为Ca2+>SO42--S>NH4+-N>Cl->K+>Na+>Mg2+>NO3--N。在林冠穿透雨+树干茎流中的养分元素输入量顺序为K+>Ca2+>Cl->SO42--S>Mg2+>NH4+-N>NO3--N>Na+。与非喀斯特地区相比,林外雨中的各养分离子浓度较低,林冠穿透雨、树干茎流中的K+、Ca2+、Mg2+增加幅度较大。总体来看,独特的立地特征决定了该地区Ca2+、Mg2+的积极参与生态系统养分循环和K+高效循环的特征。
From September 2007 to August 2009, atmospheric precipitation, canopy penetration and canopy flow were measured in subtropical evergreen and deciduous broad-leaved mixed forest in Maolan Karst region of southwestern China. The effects of precipitation on nutrient ion (Ca2 + , Mg2 +, K +, Na +, NH4 +, SO42-, NO3-, Cl-) and the annual nutrient input. The results showed that from July to September, the concentration of nutrient ions in rainwater, rainforest, rainwater and canopy stems were relatively low. From December to next February, the concentrations of nutrients in each precipitation were relatively high. In addition to no significant changes in Na + concentration, NH4 + concentration showed a downward trend, Ca2 +, Mg2 +, K +, Cl-, NO3- and SO42- showed an increasing trend; Rainfall nutrient elements in the order of Ca2 + SO42 - S> NH4 + -N> Cl-> K +> Na +> Mg2 +> NO3 - N. The order of nutrient input in the canopy penetration and stem stem flow was K +> Ca2 +> Cl-> SO42 - S> Mg2 +> NH4 + -N> NO3 - N> Na +. Compared with non-karst regions, the concentration of nutrient ions in the rain outside the forest was lower, and the canopy penetration of rain increased the K +, Ca2 + and Mg2 + contents in the stem stream. In general, the unique site characteristics determine the active participation of Ca2 + and Mg2 + in the ecosystem and nutrient cycle of K +.