氮、磷添加对鄱阳湖典型苔草湿地土壤养分和植物生物量的影响

Effects of nitrogen and phosphorus addition on soil nutrients and plant biomass in a typical Poyang Lake marshland

在人为活动不断干预的背景下,开展湿地对氮、磷添加响应的研究对于合理保护和维持湿地生态系统功能至关重要。为评估氮、磷添加对湿地土壤养分及植物生物量的影响,在鄱阳湖南矶湿地国家级自然保护区选取典型苔草湿地分别进行对照、3种氮添加水平(5、10和30 g N·m^(-2)·a^(-1))和3种磷添加水平(0.6、1.2和3.0 g P·m^(-2)·a^(-1))处理。结果表明:1)氮、磷添加显著增加土壤氮、磷的全量和有效氮、磷的含量;2)苔草群落地上和地下生物量虽均随氮、磷添加量的增加而显著增加,但氮、磷对苔草根冠比的影响各异,其中,氮添加降低苔草群落的根冠比,而磷添加增加苔草群落的根冠比;3)外源氮、磷添加后,相应营养元素全量及有效态含量与植物生物量关系密切。总体上,鄱阳湖湿地土壤和植物对外源氮和磷添加均表现敏感。

Under constant anthropogenic disturbance,it is critical to understand the response of wetlands to nitrogen( N) and phosphorus( P) addition for protecting and maintaining wetland ecosystem functions. To evaluate the effects of N and P addition on soil nutrients and plant biomass in wetlands,a field experiment was conducted in a typical Carex wetland from the Poyang Lake Nanji National Nature Reserve. There were seven treatments: control,three levels of N addition( 5,10 and 30 g N·m^(-2)·a^(-1)),and three levels of P addition( 0.6,1.2 and 3.0 g P·m^(-2)·a^(-1)). The results showed that N and P addition significantly increased soil total and available N and P concentrations. Both the above-and below-ground biomass of Carex community significantly increased with increasing N and P addition levels. The effects of N and P addition on the root/shoot ratios of Carex community were different,in that N addition reduced but P addition increased the root/shoot ratios. Both total and available contents of the corresponding added elements in soils were closely related to plant biomass. Overall,soils and plants in the Poyang Lake wetlands were relatively sensitive to N and P inputs.