酸雨区典型林种降水再分配及其水化学效应研究----以庐山森林流域为例

Under the influence of the global environmental changes and anthropological activities, precipitation nutrients input and its cycles in forest ecosystem have been considered the hotspot issues in the forest ecohydrological field at present. This research project was designed to establish an observatory in a forest watershed of Mt. Lu along different altitudes and landscapes (coniferous, deciduous broad-leaved, evergreen-deciduous broad-leafed, and evergreen broad-leafed forest). Based on the combination of the manual and frequently automatic monitoring on the hydrochemical processes, the research will elucidate the variations of soil properties, micrometeorological, and forest canopy characteristics; analyze the temporal and spatial heterogeneity of throughfall, stemfall and interception of forest canopy and its factors; identify the dominant factors on the hydrochemical ions of throughfall and stemfall based on the statistical methods, and reveal the mechanisms of hydrochemeical ions exchange and leaching changes among various forest via the simulation models; establish the quantitative relationships between the spatiotemporal variations of hydrochemeical ions from throughfall, stemfall and precipitation redistribution, and finally illustrate the mechanisms between hydrochemical processes, soil properties and forest water quality in this watershed. These findings will be important for antiacid-deacidification species selections and water environment management in the forest watershed of Mt. Lu.

在全球环境变化和人类活动的影响下，森林降水养分输入和内部养分循环是当前森林生态水文学领域研究所关注的热点问题。以酸雨区庐山森林流域为例，本项目沿着海拔梯度建立不同景观单元（针叶林、落叶阔叶林、常绿-落叶阔叶混交林、常绿阔叶林）观测样地，基于人工和高频自动监测相结合的水文水化学过程野外监测，明确海拔梯度上土壤性质、微气象和林冠特征的变化规律，辨析林内穿透雨、树干茎流和林冠截留量时空变化及其主要影响因素，利用统计方法定量识别林下穿透雨和树干茎流中水化学离子组成变化的关键控制因子，基于模型模拟揭示森林典型林种水化学离子交换与淋溶变化的内在机理，建立林下穿透雨、树干茎流水中水化学离子组成的时空异质性及其与降水再分配过程间定量关系，揭示庐山森林流域水文水化学过程、土壤性质与水质变化机制，将为庐山森林流域抗酸降酸林种遴选与水环境管理具有重要科学意义。

在全球环境变化和人类活动的影响下，森林降水养分输入和内部养分循环是当前森林生态水文学领域研究所关注的热点问题。本项目以酸雨区庐山森林流域为例，开展了庐山森林流域典型林种（马尾松、构树、麻栎树和苦槠）不同场次降水再分配过程（穿透雨、树干茎流和林外降水）及水化学样品采集等工作。结果表明：（1）10min，30min和60min最大降雨强度、风速、气温是影响有叶期穿透雨空间变异的主要因素,在无叶期平均降雨强度是穿透雨变异的主控因素。树干茎流量主要受到林外降雨总量、30min和60min最大雨强的影响，林冠截留则主要受降雨总量和降雨历时的影响，降雨量对穿透雨、树干茎流、林冠截留量的相对贡献率分别为70%、75%和50%。（2）通过对林外降水的水化学组成分析发现降水阴离子（SO42-、NO3-）和阳离子（Ca2+和NH4+）是庐山地区大气降水中主要的离子成分，其中Ca2+和NH4+对降水酸度中和起主导作用，这是庐山地区降水pH值偏大主要原因之一。庐山降水中SO42-/NO3-比值呈现逐渐减小的趋势，这表明庐山降水中硝酸根（NO3-）离子浓度不断增大，降水由早期硫酸型转变为硫酸型和硝酸型混合型，这归结于我国近年来能源结构和使用方式的改变，大量使用清洁能源，有效地降低了燃煤过程中SO2的排放量，致使向大气释放的SO2排放量不断减少。（3）降水SO42-和NO3-约90%以上由人为大量排放的SO2和NOx气体贡献，而降水Cl－主要是海源输入为主，贡献比例达60.2%。研究结果有利于酸雨区水源地水质的保护与水环境管理具有重要科学意义。（4）依托本项目发表了10篇学术论文，其中7篇SCI论文，1篇EI论文，2篇中文核心期刊（CSCD），参加学术会议多次。