关键词: 浮叶植物, 高原湿地, 叶经济性状, 微环境, 生态响应

Abstract: Exploring the response strategies of natural Brasenia schreberi to water environment can provide a theoretical basis for the scientific protection of natural populations. The relationships between leaf economic traits of B. schreberi and water environmental factors were detected in natural B. schreberi community in 17 sites from Beihai wetland in Tengchong,  Western Yunnan Province. We measured functional traits and environmental factors of the sampling sites, and analyzed the response strategies of natural B. schreberi in high altitude area to water environment. The results showed that, compared to that under 100% coverage, B. schreberi with a coverage of 60%-70% had larger leaf area, and lower mass fractions of nitrogen, phosphorus, iron, and zinc (P<0.05).  Water dissolved oxygen content, volume fractions of nitrogen, phosphorus, and ammonium nitrogen, and water temperature were the main factors affecting leaf economic traits of B. schreberi. Photosynthetic rate was significantly positively correlated with water dissolved oxygen content and the volume fractions of ammonium nitrogen and nitrate nitrogen (P<0.05). Leaf thickness was significantly positively correlated with biochemical oxygen demand. Leaf area was significantly positively correlated with water dissolved oxygen content, volume fraction of ammonium nitrogen, and water temperature, and negatively correlated with water biochemical oxygen demand, chemical oxygen demand, and potassium permanganate index (P<0.05). Leaf mass fraction of nitrogen was significantly positively correlated with water volume fractions of nitrogen and ammonium nitrogen (P<0.05). Leaf mass fraction of phosphorus was also significantly positively correlated with water volume fraction of nitrogen, while it was significantly negatively correlated with water dissolved oxygen content and water temperature (P<0.05). Leaf nitrogen to phosphorus ratio was significantly positively correlated with dissolved oxygen content and volume fraction of ammonium nitrogen, but negatively correlated with chemical oxygen demand and potassium permanganate index (P<0.05). Potassium, magnesium, silicon, calcium, iron and zinc in B. schreberi leaves were mainly correlated to water dissolved oxygen content, water temperature, and the nutritional conditions of nitrogen and phosphorus. Our results will provide a theoretical basis for the scientific conservation of natural B. schreberi communities.

Key words: floating-leaved plant, plateau wetland, leaf economic trait, microenvironment, ecological response