退耕还湖后不同植被群落湿地土壤剖面磷素形态分布特征

Distribution of Phosphorus Fractions in Wetland Soil Profiles Under Different Vegetation Communities After Returning Farmland to Lake

对菜子湖退耕还湖区不同植被群落(苔草、芦苇和酸模)下湿地剖面土壤进行分层采样,分析了土壤剖面有机磷(orP)、无机磷(inP)及无机磷组分铝磷(Al-P)、铁磷(Fe-P)、闭蓄态磷(O-P)和钙磷(Ca-P)的含量,探讨了植被群落对退化湿地生态恢复后土壤剖面磷素形态分布特征的影响。结果表明:研究区土壤剖面磷素以无机磷为主(301.94～645.17mg/kg)占全磷含量的52.59%～84.64%;除酸模群落下0～6cm土层外,土壤剖面有机磷含量范围为78.40～254.27 mg/kg。土壤剖面无机磷组分以钙磷和铁磷为主,分别占无机磷总量的29.67%～67.58%和21.90%～52.29%。除酸模群落下0～6 cm土层外,3种植被群落下土壤无机磷含量均随着剖面深度增加而增加,而有机磷含量则随着剖面深度增加先急剧降低后逐渐升高;土壤铝磷和铁磷含量总体上均随着剖面深度增加而降低;除酸模群落下0～6 cm土层土壤闭蓄态磷外,其他土壤剖面闭蓄态磷和钙磷含量总体均随着剖面深度增加而升高。研究区3种植被群落下土壤铝磷、铁磷和有机磷存在表聚现象,酸模群落下土壤剖面表现最为显著。研究区植物对土壤磷素吸收利用是磷素形态转化和表聚的驱动力,而钙磷是各形态磷表聚的主要来源。

Soils from the wetlands under different vegetation communities(Carex maximowiczii, Phragmites australis,Rumex acetosa Linn) were sampled to investigate the distribution of organic P, inorganic P and inorganic P forms in soil profiles.The results showed that inorganic P contents were ranged from 301.94 to 645.17 mg/kg, accounting for 52.59%–84.64% of total P in all soil profiles, while organic P contents were ranged from 78.40 to 254.27 mg/kg except for 0–6 cm layers under Rumex acetosa Linn. Ca-P and Fe-P dominated inorganic P in all soil profiles, accounting for 29.67%–67.58% and 21.9%–52.29% of inorganic P, respectively. Except for 0–6 cm layers under Rumex acetosa Linn, inorganic P contents decreased while organic P decreased seriously first and then increased with depth of soil profiles under all vegetation types. Except for O-P in 0–6 cm layers under Rumex acetosa Linn, Fe-P and Al-P contents decreased while Ca-P and O-P contents increased with depth of soil profiles.Al-P, Fe-P and organic P accumulated in surface layers under all vegetation types, especially under Rumex acetosa Linn. Plant uptake drives the form transformation and surface accumulation of phosphorus, while Ca-P is the main source of surface accumulated phosphorus.