宁夏引黄灌区农田排水沟渠水生植物物种多样性

Diversity of Aquatic Plants in Drainage Ditches in the Yellow River Irrigated Area of Ningxia

为探索宁夏引黄灌区农田排水沟水生植物物种组成和多样性,采用样方调查法在灌区农田选取典型支沟、斗沟和农沟,并在每条沟渠布设上、中、下游断面,断面上设置样方大小进行退水沟渠水生植物物种种类、数量、多度、盖度调查。结果表明:宁夏引黄灌区排水沟水生植物由11个科,13个属,20个种组成,其中,芦苇、藨草、水莎草、香蒲、龙须眼子菜和浮叶眼子菜是分布较广的优势种。群落垂直分层明显,但以芦苇及其伴生种组成的挺水群落多见。灌区农田排水沟各层次植物种类分布和多样性指数差异较大,表现为农沟>斗沟>支沟。水位和流速是影响沟渠水生植物形态及分布的主要因素。农沟中水流速度较慢,生长环境稳定,有利于多种植物的繁殖,为科学合理布局优势物种富集农田排水中的养分,以达到控制农田非点源污染目的提供了可能。

Aquatic plants in agricultural drainage ditches have been considered to play important roles in purifying nitrogen and phosphorus in ditch water. Here we investigated composition and diversity of aquatic plants in agricultural drainage ditches in the Yellow River irrigated area of Ningxia. Representative branch ditches, sub-branch ditches and grooves around farmland were selected for quadrate surveying. An area of 1 m× 1 m was set at the upper, middle, and lower reaches of each drainage ditch. In each quadrate, plant name, biomass, height, coverage and abundance of each species were recorded. In the investigated area, aquatic plants consisted of 20 species, representing 13 genera and 11 families.The widespread plant species were Phragmites australis （Cav.） Trin. ex Steud., Scirpus triqueter L. , Juncellus serotinus （Rottb.） C. B. Clarke, Juncellus serotinus（Rottb.） C. B. Clarke, Potarmogetonpectinatus L. and Potamogeton natans L. Plant communities had obvious vertical stratification in the drains. Plant species and community diversity were significantly different among drainage ditches, with groove〉 sub-branch ditch〉branch ditch. The depth and flow rate of water in the drains were the main factors influencing aquatic plant morphology and distribution. Unlike branch and sub-branch ditches, grooves had slow water flow and stable environment, facilitating growth of various plants. Therefore, grooves could be used to control nonpoint pollution from farmlands.