• 关键词：三峡库区  消落带  芦苇  土壤含水量  氮  生物量

• 基金项目：三峡库区生态环境教育部重点实验室自由探索研究基金项目(2007);重庆市自然科学基金(No.CSTC-2007BB7376);国家自然科学基金(No.30370279)

• 冯大兰
• 西南大学资源环境学院, 三峡库区生态环境教育部重点实验室, 重庆 400716

• 刘芸
• 西南大学资源环境学院, 三峡库区生态环境教育部重点实验室, 重庆 400716

• 黄建国
• 西南大学资源环境学院, 重庆 400716

• 摘要：通过设置T1(淹水超过土壤表面2cm)、T2(土壤含水量为田间持水量的70%～100%)和T3(土壤含水量为田间持水量的40%～60%)3个不同处理组,模拟了三峡库区消落带土壤含水量变化特征,并以嘉陵江江边芦苇(Phragmites communis(reed))为实验材料,研究了三峡库区不同消落带带位土壤不同含水量条件下芦苇地上部分氮含量和生物量的动态变化,同时,探讨了芦苇地上部氮的积累和合适的收割时期.结果表明,三峡库区消落带土壤不同含水量条件下芦苇地上部氮含量随季节变化而变化,在一个生育周期内,芦苇的叶片、叶鞘和茎的氮含量呈典型的单峰曲线.其中,T1、T2和T3的叶片和叶鞘中氮含量的峰值出现在9月底(抽穗期),叶片氮含量的峰值分别为23.1、26.5和26.2mg·g^-1,叶鞘氮含量的峰值分别为14.4、12.4和13.2mg·g^-1;而茎氮含量的峰值出现在10月底(穗期),其峰值为9.5、9.1和9.0mg·g^-1.与其他地区芦苇的氮吸收相比,在三峡库区消落带3种水分条件下的芦苇对氮都具有很强的吸收能力.不同处理芦苇的生长曲线呈典型的单峰曲线,其中,T1和T2处理地上生物量的最大值均出现在9月底(抽穗期),分别为11.86g·株^-1和11.81g·株^-1;而T3的最大值出现在8月底(迅速生长晚期),其值为8.04g·株^-1;T1和T2条件下芦苇地上部氮的积累也在9月底达到最大值,分别为241.9mg·株^-1和279.4mg·株^-1,而T3在8月底达到最大值,其值为154.5mg·株^-1,表明在三峡库区消落带的芦苇具有很强的氮积累能力.研究同时证实,土壤不同含水量条件下芦苇对三峡库区消落带氮的吸收和积累均具有较好的效果,可以根据芦苇的生长规律和地上部分氮积累对芦苇及时收割,以便充分发挥芦苇去除氮的功能.因此,芦苇可作为三峡库区消落带生态环境治理和解决水体富营养化问题的禾本科先锋物种.

• Abstract：After researching the soil moisture contents of the hydro—fluctuation belt in the Three Gorges Reservoir Area,three different water treatments were applied to the reed(Phragmites communis) to determine the changes of nitrogen and aboveground biomass. The treatments T1(with soil completely submerged under 2 cm of water),T2(with soil water content 70% to 100% of field capacity),and T3(with soil water content 40% to 60% of field capacity) simulated the conditions in the hydro-fluctuation belt. In all three treatments,nitrogen content and the aboveground biomass of P. communis showed single-peak curves corresponding to seasonal changes. The maximum nitrogen content in leaf and leafstalk of all three treatments appeared in late September;N values in leaf were 23.1、26.5 and 26.2 mg·g^-1,and in leafstalk were 14.4、12.4 and 13.2 mg·g^-1 respectively,but the contents of nitrogen in the stem of P. communis reached peak values of 9.5、9.1 and 9.0 mg·g^-1 in late October. Compared to reeds in other areas,P. communis is known to have a higher water absorption capacity. The aboveground biomass in treatments T1 and T2 was largest in late September:11.86 g per plant and 11.81 g per plant,respectively,but for T3 biomass was largest in late August,at 8.04 g per plant. The nitrogen accumulation in the whole plant also peaked in late September for T1 and T2,at 241.9 mg per plant and 279.4 mg per plant respectively,but T3 peaked in late August at 154.5 mg per plant. This indicated that these plants had the best accumulative ability of nitrogen in the hydro-fluctuation belt in the Three Gorges Reservoir Area. It was also demonstrated that P. communis could not only absorb nitrogen well but also had better N accumulation ability. In addition,according to the growth and nitrogen accumulation of P. communis,we can ensure the best harvest time to reduce the content of nitrogen in the area. Therefore,P. communis could be a precedent species for restoration and rehabilitation of vegetation in the hydro-fluctuation belt of the region around the Three Gorges reservoir.

• Key words：Three Gorges Reservoir Area  hydro-fluctuation belt  reed(Phragmites communis)  soil moisture content  nitrogen  biomass

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