Study on Rhizosphere Functions of Athyrium Yokoscense and Arabis Flagellosa Comunity

燕麦是一种蕨类植物，在日本矿区与阿拉伯鞭毛形成了一个植被群落。前者在组织中积累Cd、Pb、As，后者对Cd、Pb、Zn具有积累性质。然而，这两种植物的金属积累机制还没有完全阐明。本研究通过研究节肢动物群落中金属元素的动态变化，研究了节肢动物群落根际重金属和砷的迁移以及重金属和砷的积累机制。在盆栽试验中，土壤溶液中Cd、Pb、Zn的浓度在人工林过程中表现出与非种植样地相似的变化趋势，即在种植8周后，土壤溶液中的重金属含量呈上升趋势，直到8周后基本保持不变，而狗尾草样地(HN)或蹄盖蕨样地(HN+SS)则在8周后继续增加。因此，在后13周，与阿拉伯鞭毛样地相比，种植蹄盖蕨样地(HN和HN+SS)的土壤溶液中Cd、Pb和Zn的含量较高。推测该菌根系分泌分泌物，促进根际镉、铅、锌的活化。在播种期内，所有样地土壤溶液中的砷浓度都极低(~27μ)。这可能是因为As以阴离子的形式存在，所以在低pH条件下，As在土壤中被强烈吸附。另一方面，HN和HN+SS小区的土壤溶液中检测到顺丁烯二酸、柠檬酸和富马酸。由此可见，节节草根系分泌物可促进根际Cd、Pb、Zn的活化，提高土壤溶液中Cd、Pb、Zn的含量。

Athyrium yokoscense, a fern plant, forms a vegetation community with Arabia flagellosa in mining area of Japan. The former accumulates Cd, Pb, and As in its tissues and the latter has accumulation nature to Cd, Pb, and Zn. However, the metal accumulation mechanism of both plants has not been sufficiently clarified. In this study, by examining the dynamic state of the metallic elements in Athyrium yokoscense and Arabis flagellosa community, the mobilization of the heavy metals and arsenic in rhizosphere of Athyrium yokoscense and Arabis flagellosa community, as well as the accumulation mechanism of the heavy metals and arsenic, were investigated. In a pot experiment, Cd, Pb and Zn concentration of soil solution showed similar tendency during plantation, i.e., the metals concentration of soil solution in Arabis flagellosa plot(SS)showed similar trend with the non-plant plot, increasing up till the 8th week then became almost constant, but those of Athyriurn yokoscense plot (HN) or Athyrium yokoscense and Arabis flagellosa mix plot (HN+SS) increased continually even after 8 weeks. Thus, compared with Arabia flagellosa plot, soil solution of the plots (HN and HN+SS) planting Athyrium yokoscense contained higher Cd, Pb and Zn concentration in the latter 13 weeks. It was supposed that roots of Athyrium yokoscense secreted exudates, and enhanced mobilization of Cd, Pb and Zn in rhizosphere. Arsenic concentration of the soil solution was extremely low (< 27μgL^<-1>) in all plots during the planting periods. It probably because As occurs as anion so it is strongly adsorbed in soil at low pH. On the other hand, maleic acid, citric acid and fumaric acid were detected in the soil solution of HN and HN+SS plots. It is concluded that root exudates of Athyrium yokoscense might enhanced mobilization of Cd, Pb and Zn in the rhizosphere, and elevated their concentration in the soil solution.