华西雨屏区麻栎-喜树人工混交林林冠对降雨中钾和钠离子再分配的影响

2016年12月—2017年11月研究了都江堰灵岩山麻栎-喜树人工混交林林冠对不同物候期(无叶期、展叶期、盛叶期和落叶期)雨水中K⁺和Na⁺的再分配作用.结果表明: 大气降雨中K⁺和Na⁺浓度分别为1.87和1.46 mg·L^-1,穿透雨中分别为5.78和1.39 mg·L^-1,雨水中的K⁺浓度在展叶期最高,盛叶期最低,Na⁺在无叶期和展叶期较高,盛叶期和落叶期较低;大气降雨中K⁺和Na⁺的输入量分别为25.47和21.60 kg·hm^-2·a^-1;降雨对林冠中K⁺的淋溶量为13.64 kg·hm^-2·a^-1,无叶期、展叶期、盛叶期和落叶期的淋溶量分别为1.67、6.23、2.28和3.46 kg·hm^-2,在展叶期淋溶量最大;林冠对Na⁺的截留量为11.26 kg·hm^-2·a^-1,无叶期、展叶期、盛叶期和落叶期的截留率分别为32.6%、18.0%、44.9%和31.5%,盛叶期时截留量最大.可见,麻栎-喜树人工混交林林冠对大气降雨中K⁺和Na⁺的再分配作用随物候期而变化,这为深入了解华西雨屏区森林生态系统的K⁺和Na⁺循环提供了基础数据.

Effects of canopy on the redistribution of potassium and sodium ions in rainfall in Quercus acutissima and Camptotheca acuminata mixed plantation of the rainy area of western China

The role of canopy in redistributing rainwater K⁺ and Na⁺ at different phenological stages (leafless stage, leaf expanding stage, frondent leaf stage and senesced leaf stage) was investigated in Quercus acutissima and Camptotheca acuminata mixed plantation in Mt. Lingyan of Dujiangyan city from December 2016 to November 2017. The concentrations of K⁺ and Na⁺ were 1.87 and 1.46 mg·L^-1 in the rainfall, respectively, and 5.78 and 1.39 mg·L^-1 in the throughfall, respectively. The highest and lowest K⁺ concentrations in the rainwater were found at leaf expanding stage and frondent leaf stage, respectively. Meanwhile, higher Na⁺ concentration in rainwater was found at leafless stage and leaf expanding stage, and lower concentration at frondent leaf stage and senesced leaf stage. The inputs of K⁺ and Na⁺ through rainfall were 25.47 and 21.60 kg·hm^-2·a^-1, respectively. The leaching flux of K⁺ was 13.64 kg·hm^-2·a^-1 from canopy by rainfall, with the flux of 1.67, 6.23, 2.28 and 3.46 kg·hm^-2 at the leafless stage, leaf expanding stage, frondent leaf stage and senesced leaf stage, respectively. On the contrary, the canopy intercepted 11.26 kg Na⁺·hm^-2·a^-1, with the interception rate being 32.6%, 18.0%, 44.9% and 31.5% at leafless stage, leaf expanding stage, frondent leaf stage, and senesced leaf stage, respectively. In conclusion, the redistribution of K⁺ and Na⁺ in the rainfall affected by Q. acutissima and C. acuminata mixed plantation canopy varied greatly with phenological stages. The results could provide basic data for further understanding of the cycles of K⁺ and Na⁺ in the forest ecosystem in the rainy area of western China.