南方稀土矿区水土保持植物根际土壤碳氮及pH特征

选取南方稀土矿区芒萁、宽叶雀稗、枫香和木荷四种典型水土保持植物,研究其根际与非根际土壤各种形态氮素和有机碳含量特征以及pH的变化。研究表明,根际较非根际土壤全氮、铵态氮和硝态氮平均分别高出79.7%、34.2%和30.7%,土壤有机碳平均高出164.9%,pH平均高出0.13个单位。除pH外,根际土壤与非根际土壤全氮、铵态氮、硝态氮和有机碳之间均差异显著(p0.05)。四种植物根际土壤全氮、硝态氮、铵态氮和有机碳的含量均较非根际土壤含量高。宽叶雀稗的根际土壤pH大于非根际土壤,而木荷、芒萁和枫香的根际土壤p H与非根际土壤无显著差异。在根际与非根际土壤中,土壤全氮与土壤有机碳之间呈显著正相关,而土壤全氮与土壤铵态氮、土壤全氮与土壤硝态氮之间均无相关性。即稀土矿区四种植物对碳氮主要养分均具有较强的截存效应,可作为稀土矿区生态恢复的主要植物。

Carbon, Nitrogen and pH in Rhizosphere of Soil-Water Conserving Plants in Rare Earth Mining Area in South China

Dicranopteris dichotoma, Paspalum wetsfeteini, Liquidambar formosanaand Schima superba are four typical species of plants used for soil and water conservation in a rare earth mining area in South China, and were selected as subjects in this study to investigate changes in contents of various forms of nitrogen and organic carbon and pH in the rhizospheres of the plants and in the bulk soil as well. Results show that on average, total nitrogen, ammonium nitrogen and nitrate nitrogen was 79.7%, 34.2% and 30.7%, respectively, higher in the rhizosphere soil than in the bulk soil; soil organic carbon was 164.9% higher and soil pH was 0.13 unit lower. The difference between the rhizosphere soil and the bulk soil was quite obvious except in soil pH. The content of total nitrogen, ammonium nitrogen, nitrate nitrogen and organic carbon was higher in the rhizosphere soil, regardless of plant type, than in the bulk soil. The soil pH in the rhizosphere soil of Paspalum wetsfeteini was higher than that in the bulk soil, but no significant difference was found between soil pH in the rhizosphere and bulk soil of Dicranopteris dichotoma, Liquidambar formosanas and Schima superbas. Soil total nitrogen was positively related to organic carbon both in the rhizosphere soil and the bulk soil, but neither to ammonium nitrogen nor to nitrate nitrogen. All the findings in this study indicate that the all the four types of plants in the rare earth mining area have strong sequestration effects on both carbon and nitrogen, and can be used as main pioneer plants to restore vegetation and ecology of the rare earth mining areas in South China.