洱海沉水植物残体风浪输移量及其时空分布

为研究洱海沉水植物残体风浪输移特征,掌握由此而引起的N、P变动情况,通过为期1a的野外定点调查,研究了风浪对洱海湖滨带沉水植物作用引起的植物残体向滨岸的输移特征,估算了沉水植物残体带出的N、P质量. 结果表明:①洱海湖滨带有残体输出的沉水植物总计10种,分别为菹草(Potamogeton crispus)、黑藻(Hydrilla verticillata)、轮藻(Eichhornia crassipes)、穿叶眼子菜(P. perfoliatus)、扭叶眼子菜(P. intortifolius)、穗花狐尾藻(Myriophyllum spicatum)、金鱼藻(Ceratophyllum demersum)、马来眼子菜(P. malaianus)、苦草(Vallisneria natans)及微齿眼子菜(P. maackianus)；②沉水植物残体风浪输移量存在明显的时序变化,在4次采样中,2009年12月(冬季)风浪输移量最高；③微齿眼子菜和苦草的风浪输移量最大,植物残体风浪输移量主要受沉水植物的分布和生物量的影响；④单位岸线沉水植物残体风浪输移总量在空间上表现为西部(1.91t/km)>北部(1.73t/km)>南部(1.61t/km)>东部(0.86t/km)；⑤洱海湖滨带沉水植物残体风浪输移总量约为2.27×103t/a(以鲜质量计),由此可输出的TN为5.64t,TP为0.85t. 

Temporal-Spatial Distribution of Submerged Macrophyte Residues Transported by Wind Wave in Lake Erhai

Submerged macrophytes residues that were transported to the shore by wind wave are an important kind of substance cycling in lakeside. An investigation was carried out in Erhai lakeside to depict the characteristics of wave-transported residue of submerged macrophyte and quantify the consequent changes of total phosphorus and total nitrogen of Lake Erhai. Meanwhile, the amount of total nitrogen and total phosphorus in submerged macrophyte residues were estimated as well. The results showed that:(1) There were totally 10kinds of submerged macrohyte residues transported by wind wave in Lake Erhai including Ceratophyllum demersum, Eichhornia crassipes, Hydrilla verticillata, Myriophyllum spicatum, Potamogeton crispus, P. intortifolius, P. maackianus, P. malaianus, P. perfoliatus and Vallisneria natans. (2) The weights of submerged macrophyte residues significantly varied among different seasons with the maximum values in the winter. (3) Among 10species of submerged macrophyte residues observed in lakeside of Lake Erhai, the residue weights of P. maackianus and V. natans were the greatest among all species. The weights of residues were positively associated with the distribution scale and biomass. (4) The sequence of the weight of residues per unit length collected followed the decreasing order:the west (1.91t/km), the south (1.73t/km), the north (1.61t/km), east (0.86t/km). (5) The total mass of residues in the lakeshore in Lake Erhai was estimated as 2270t. It suggests that 5.64tons total nitrogen and 0.85tons total phosphorus can be exported by wind wave in the Lake Erhai per year.