天津典型湿地芦苇种群生产力和氮磷营养结构与环境因子的关系

Productivity and N and P Nutrition of the Phragmites australis Community in Typical Wetlands in Tianjin and Their Relationships With Environmental Factors

天津芦苇（Phragmites australis）湿地是东亚—澳大利亚候鸟迁徙必经之地,具有重要的生态功能。近几十年来,随着城市化进程的快速发展和人口的增加,天津地区水体咸化、氮污染等问题严重。调查了天津典型湿地七里海、北大港和大黄堡湿地芦苇种群地上部生物量、形态特征及氮、磷营养状况,探讨其与环境氮、磷营养和含盐量的关系,结果表明：（1）天津典型湿地芦苇种群地上部最大生物量变化范围为978~1 263 g·m-2,并未随样地间含盐量和氮含量等环境因子的变化而显著改变;（2）在最大生物量时期（8月）,北大港湿地芦苇地上部氮含量和氮储量明显低于七里海和大黄堡;8月北大港湿地芦苇叶片氮磷比为12.48,氮限制植物生长;七里海和大黄堡湿地芦苇叶片氮磷比分别为14.89和15.72,氮、磷共同限制植物生长;（3）当前环境压力显著影响了芦苇地上部氮、磷营养状况。底泥含盐量增加可降低芦苇叶片氮、磷含量;随着底泥氮营养的增加,芦苇茎氮含量呈线性增加;而随着底泥磷营养的增加,芦苇叶和茎磷含量并未增加。虽然天津地表水体氮污染严重,但是氮而非磷成为芦苇生长的主要限制因子,天津芦苇湿地仍然具有吸纳环境氮污染物的潜力。

The reed（ Phragmites australis） wetlands in Tianjin region,generally being important staging areas for east Asian-Australian migratory shorebird,have some important ecological functions. In recent decades,due to rapid urbanization and population growth of the region,the surface waterbodies of Tianjin have been faced with problems like severe nitrogen（ N） pollution and salinization. Based on investigation of aboveground biomass,plant morphology,plant nitrogen（ N） and phosphorus（ P） nutrition in Qilihai（ QLH）, Beidagang（ BDG） and Dahuangpu（ DHP） reed wetlands, their relationships with environment factors,like N and P nutrients and salinity were explored. Results show that（ 1） the biomass of reeds in the wetlands varied in the range of 978- 1 263 g·m-2,but not so significantly in aboveground biomass with sediment salinity and nitrogen content;（ 2） during the season（ August） when the reeds peaked in biomass,the reeds in BDG was much lower than those in QLH and DHP in N content and N storage of P. australis,and the reeds in BDG were 12. 48 in N ∶ P ratio in leaf,indicating N was the limiting factor to plant growth,while the reeds in QLH and DHP were 14. 89 and 15. 72,respectively,indicating both N and P were limiting factors; and（ 3） the current environmental stresses significantly affected N and P nutrition of the reed shoots,like the increasing salinity of the sediment mud that lowered N and P content in the leaves of P. australis and the increasing N content in the sediment mud that linearly increased N content in the stems of P. australis; however,P content in the leaves and stems did not change much with any increase in P content in sediment mud. Although the surface water bodies of Tianjin are seriously polluted with N,and N rather than P is the major limiting factor to reed growth in the wetlands,the reed wetlands in the region still have some potential capacity for dissimilating environmental N pollutant