【作者】 石盛莉；

【导师】 潘根兴；

【作者基本信息】 南京农业大学 ， 土壤学， 2000， 博士

【摘要】 本文以庐山植物园的日本柳杉针叶林和阔叶林样地为对象，采集不同季节、不同植被下的根区土和非根区土，并对生态系统水相进行长期定位监测和动态监测方法，分析大气沉降硫在森林生态系统土壤和地表水酸化过程中的化学行为及其动态特点，试图为阐明酸沉降下硫对土壤酸化的生态效应及大气酸沉降的控制提供科学依据。研究得到的认识如下。1．庐山森林土壤总硫含量高达365.17±115.89mg/kg，且以吸附态为主。亚表 层土壤中吸附态硫的含量高达178.82±94.62mg/kg。无机硫和有机硫间存 在互为消长的关系。针叶林土壤吸附态硫和水溶态硫显著高于阔叶林土 壤，针叶林下土壤对S的吸附能力和S的移动性高于阔叶林下。针叶林下 根区土壤的总硫含量，水溶态硫和有机硫都高于非根区土，针叶林根系对 土壤硫形态的分布有明显影响。2．森林凋落物年分解速率在25％左右，阔叶林凋落物比针叶林凋落物分解 快，但腐殖化系数低。凋落物分解趋向于使针叶林土壤硫的移动性增强， 而增加阔叶林土壤中吸附性硫。3．庐山98年降雨中SO₄^2-浓度平均为2.97mg/L，庐山降雨S的沉降量达 1.03kmol/（ha a）。森林冠层可明显缓冲酸雨，阔叶林冠层的缓冲能力大于 针叶林。透冠水和树干流中SO₄^2-浓度明显高于降雨，针叶林对干沉降的 吸收大于阔叶林。两种林种相比，阔叶林SO₄^2-的输入较低而输出较高。4．季节变化：水相pH和透冠水、树干流的SO₄^2-浓度季节变化格式与降雨 吻合，冬季较高而夏季较低，差异性显著；针叶林下透冠水和树干流的 SO₄^2-浓度季节变异较大。树干流中SO₄^2-浓度的季节变异比透冠水强。针 叶林渗漏水中SO₄^2-浓度在冬季最高，而阔叶林的则在春季最高。径流水 中SO₄^2-浓度变化较小，针叶林在春季高而秋季最低，阔叶林是冬季最低； 土壤硫形态有明显季节变化，在春季水溶态硫高，春夏季根区土壤水溶态 硫高于非根区土壤。针叶林亚表层土壤吸附态硫明显高于阔叶林土壤，阔 叶林根区土壤在夏季吸附态硫明显高于非根区土壤。根系，尤其是阔叶林 根系活动对土壤对硫的吸附能力影响显著。盐酸可溶态硫在非根区土壤中 受林型影响较小。而在根区土壤中，针叶林盐酸可溶性S在秋季大幅度增 高，阔叶林下则在夏季较高。土壤有机硫的秋季明显积累。5．降雨事件对森林生态系统S化学的影响十分活跃：降雨的化学成分变率较 大，SO4z是控制进人生态系统酸沉降的关键化学组分；小雨、秋季降雨对 生态系统酸沉降有重要作用。透冠水成份有活跃变化，并且与大气降雨性 质密有关。降雨使地表径流pH降低，电导率升高。降雨对阔叶林径流水 的pH影响幅度都较大，针叶林电导率则对降雨的脉冲效应响应突出。针 叶林雨后恢复较快。阔叶林下径流水So／’浓度高于针叶林下，阔叶林径 流水中 SO4‘”浓度变化较针叶林滞后约 4 ，J’时。 综上所述，庐山硫沉降量很大的，并有逐渐增加的趋势。两种林型的森林生态系统对酸沉降的反应不一。阔叶林冠层比针叶林冠层可消耗更多的矿，而针叶林土壤系统比阔叶林土壤系统消耗更多的矿，其总体效应表现出两种林型对H”的消耗量相近。针叶林系统较阔叶林系统能固持更多的S，但其非根区土壤A层也己吸附了大量S，预示着针叶林土壤对S的吸附已渐趋饱和。一旦达到饱和，针叶林土壤将不能继续延缓土壤酸化，而可能促进酸化。针叶林植被的根系活动及凋落物的作用可延缓这一过程。阔叶林土壤则是输入的硫较针叶林少，而输出较多。保持了S在系统中的相对稳定，从而对因吸附S的饱中造成的土壤酸化的危险较小。从S化学来看，阔叶林对酸沉降的缓冲与抗性较针叶林系统更为明显和活跃。野外生态系统下酸沉降对系统酸冲击及其生态化学过程除考虑土壤过程外，必须更多地注意大气一植物一上壤一水各相的相互作用及其季节动态。也就是说，生态系统的化学过程及其 可能比土壤一水体的化学动态更能反映酸沉降下生态系统酸化的实质。更多还原

【Abstract】 Taking a example of a ecodessetera in the Botalcal Garden, Mt. Lushan underintense acid deposition, both of sulfur chendstry and its dynamics of in forestecosystem was studied by means of field monitoring and sulfur fraction analysis.Both the rooting zone soil and non-rooted soil under different vegetation and indifferent season were smpled, and the fOrest ecosystem resPOnse to aciddeposition was monitored in sitU. The purpOse of this Wor is to describe theecological effects on sulfur distributions of dynamics of the fOrest ecosystem by theacid dePosition and to help enhancement of scientific data for atmosphericdeposition control. The results were as follows:l. The total sulfur in soil of Mt. Lushan was up to 365. l7 t l l5.89mg/kg, of which40.3% being adsorbed sulfuL In the subsurface soil, adsorbed sulfor was l78.82I94.62mg/kg. Whn In-organic sulfur increased, orgboc sulfor decreases, vice versa.Adsorbed sulfur and soluble sulfur in soil under coniferous forest was higher thanthat under deciduous forest, indicating bigger caPacity for adsorbed sulfur of soilunder coniferous forest. In the rooting zone soil under coniferous forest, the totalsulfur soluble sulfur and organic sulfur were higher than tha of none-rooted soil.The roots of coniferous significantlY innuenced distribndon of sulfur fractions.2. The annua decomPOsihon rate of the litters was about 21.l% under coniferousand 24.l% under deciduous. DecomPosition the of deciduous litters were biggerthan that of coniferous litters. DecomPOsition of litters tends to enhance mobile ofsulfur in soils under coniferous foreSt, While increase adsorbed sulfor in soils underdeciduous forest.3. The average sulfate concentraion in precipitation was 2.98mg/L in l998 in thestUdied area. The anntal sulfor dePOsition by preciPitation was l.03kInOU(ha a).Acid rain was greaily buffered by forest canopy, and the canopy of deciduous wasable to bther more acidity of acid taln than canOPy of coniferous. The sulfateconcentration in throughfall and stem-flow were sighficanly higher than that inprecipitation. As comPared with coniferous ecosystem, the inPut of SO4’-deciduous ecosystem was more, while output less.4. The seasonal change pattem of acidity in water Phase and sulfate concefitrationin throughfall and stem-flow were consistent with precipitation, being signiflcanlyhigher in winter than in sununeL Sulfate concentration in throughfail andstem-flow under coniferous fOrest change greatly in differeni seasons. Fractionationof sulfur has apparently seasonal changes. Soluble sulfur was high in spring, andcontent of sulfate in rooting zone soils was higher than that of in non-rooted soil.Organic sulfur accumulated in autumn. In A horizon of soil under coniferous, therewere accumulation of adsorbed sulfate in spring and winter, while in subsoil underdeciduous adsorbed sulfated increase sharply’ showing that rootS of deciduousgreatIy improved adsorption of sulfate in soils.5. The chemical coopnent in rain were various during precipitation, and thesulfate dominated the asid dePOsition to eco-system. Ligh rain and rains in auumnmade greater contribution for acid dePOsition. The chemical components inthroughfall aiso changed actively, and had close relationship with charaCer ofprecipitation. The runoff chemical under forest give prompt resPOnd tOprecipitation. During precipitation, pH of runoff declined, While electricity rose.The pH of runoff under deciduous forest was more susceptible than that ofconiferous fOrest, while the electricity of runoff under coniferous fOrest noticeabIyresponded to precipitation pulse effect. After precipitation, the nmoff chemicalunder coniferous forest recovered qulcker than that under deciduous forest. Thechange sulfate concelltr8ion in runoff under deciduous went in a pattem 4 hoursbehind under coniferous forest.In summarize, the sulfur dePOsition fiux in Mt. Lushan was great, andgradually increased.更多还原