杭州湾鹭科鸟类集群栖息区表层土壤的磷饱和度和磷流失风险

Phosphorus Saturation Degree and Phosphorus Leaching Risk of Surface Soils in Cluster Habitats of Ardeidae Birds in Hangzhou Bay

为了评估杭州湾鹭科(Ardeidae)鸟类栖息地土壤中磷元素的流失风险,在杭州湾国家湿地公园中,选择鹭科鸟类集群栖息的水杉(Metasequoia glyptostroboides)林地、女贞(Ligustrum lucidum)林地和无鹭科鸟类栖息的水杉林地、女贞林地(对照林地)布设采样地,分别于2018年11月(鹭科鸟类迁出后)、2019年5月(集群栖息且繁殖期)、2020年1月(鹭科鸟类迁入前),采集0~10 cm深度和10~20 cm深度的土壤样品,测定了土壤样品的有机碳含量、全氮含量、全磷含量、水溶性磷含量、有效磷含量、pH和电导率;采用Mehlich-3浸提法和草酸铵提取法,估算土壤磷饱和度;以土壤的磷饱和度和有效磷含量作为土壤中磷的流失风险的评估指标,评估表层土壤中磷的流失风险水平。研究结果表明,在杭州湾鹭科鸟类集群栖息的水杉林地和女贞林地,0~10 cm深度土壤的有机碳含量、全氮含量、全磷含量、水溶性磷含量、电导率都显著大于10~20 cm深度土壤,而其0~10 cm深度土壤pH却小于10~20 cm深度土壤;有鹭科鸟类集群栖息的水杉林地0~20 cm深度土壤的全磷含量和水溶性磷含量都大于无鹭科鸟类集群栖息的水杉林地,有鹭科鸟类集群栖息的女贞林地0~20 cm深度土壤的水溶性磷含量大于无鹭科鸟类集群栖息的女贞林地;有鹭科鸟类集群栖息的水杉林地0~20 cm深度土壤的磷饱和度和有效磷含量都大于无鹭科鸟类集群栖息的水杉林地,有鹭科鸟类集群栖息的女贞林地0~10 cm深度土壤的磷饱和度和有效磷含量都大于无鹭科鸟类集群栖息的女贞林地;有鹭科鸟类集群栖息的水杉林地0~20 cm深度土壤的磷饱和度和有效磷含量都明显大于有鹭科鸟类集群栖息的女贞林地;采用草酸铵提取法得到的土壤磷饱和度和土壤的有效磷含量可以作为杭州湾鹭科鸟类集群栖息地土壤中磷的流失风险评估指标;有鹭科鸟类集群栖息的水杉林地0~20 cm深度土壤中磷的流失风险大于有鹭科鸟类集群栖息的女贞林地。

In order to assess the risk of phosphorus leaching from soils of the habitats of Ardeidae birds in Hangzhou Bay,sampling plots in Metasequoia glyptostroboides and Ligustrum lucidum forest lands with habitation of Ardeidae birds were selected as affected area and the forest lands without Ardeidae birds were taken as control area in this study.Soils were sampled in Hangzhou Bay National Wetland Park in November 2018(after Ardeidae birds leave),May 2019(habitation season of Ardeidae birds)and January 2020(before Ardeidae birds arrive),respectively.Soil samples with a depth of 0-10 cm and 10-20 cm were collected,and the contents of organic carbon,total nitrogen,total phosphorus,water-soluble phosphorus and available phosphorus,pH and electrical conductivity of the soil were measured.Mehlich-3 extraction method and ammonium oxalate extraction method were used to estimate degree of phosphorus saturation,and the degree of phosphorus saturation of soil and available phosphorus content were taken as indicators to assess the risk of phosphorus leaching.The results showed that the contents of organic carbon,total nitrogen,total phosphorus,water-soluble phosphorus and electrical conductivity of the soil in Metasequoia glyptostroboides and Ligustrum lucidum forest lands with habitation of Ardeidae birds were significantly higher at the depth of 0-10 cm than those at the depth of 10-20 cm,while the soil pH at the depth of 0-10 cm was lower than that at the depth of 10-20 cm.The total phosphorus and water-soluble phosphorus contents of the soil at the depth of 0-20 cm in Metasequoia glyptostroboides forest land with habitation of Ardeidae birds were higher than those in Metasequoia glyptostroboides forest land without Ardeidae birds.The water-soluble phosphorus content of the soil at the depth of 0-20 cm in Ligustrum lucidum forest land with habitation of Ardeidae birds was higher than that in Ligustrum lucidum forest land without Ardeidae birds.The phosphorus saturation degrees estimated by Mehlich-3 extraction method and ammonium oxalate extraction method,and available phosphorus content of the soil at the depth of 0-20 cm in Metasequoia glyptostroboides forest land with habitation of Ardeidae birds were higher than those in Metasequoia glyptostroboides forest land without Ardeidae birds.The phosphorus saturation degrees estimated by Mehlich-3 extraction method and ammonium oxalate extraction method,and available phosphorus content of the soil at the depth of 0-10 cm in Ligustrum lucidum forest land with habitation of Ardeidae birds were higher than those in Ligustrum lucidum forest land without Ardeidae birds.The phosphorus saturation degrees estimated by Mehlich-3 extraction method and ammonium oxalate extraction method,and available phosphorus content of the soil at the depth of 0-20 cm in Metasequoia glyptostroboides forest land with habitation of Ardeidae bird were significantly higher than those in Ligustrum lucidum forest land with habitation of Ardeidae birds.In conclusion,the phosphorus saturation degrees estimated by ammonium oxalate extraction method and available phosphorus content could be used as risk assessment indicators for phosphorus leaching from soil of habitat of Ardeidae birds in Hangzhou Bay.The phosphorus leaching risk from soil at the depth of 0-20 cm in Metasequoia glyptostroboides forest land with habitation of Ardeidae birds was higher than that in Ligustrum lucidum forest land with habitation of Ardeidae birds.