| In this paper, the precipitation redistribution and the chemical property of precipitation in the Koelreuteria paniculata plantation in Xiangtan Manganese Mine were studied, to probe into the hydrological effects and the purification function of the Koelreuteria paniculata plantation, and provided scientific basis for the ecological restoration and soil restoration on Manganese mining waste area. The main results are as follows:(1) In2012, the total precipitation of this system was1618.15mm, the amount of through-fall,stem-flow,canopy interception were1244.8mm,17.7mm,355.6mm, accounted for76.93%,1.09%,21.98%of the total precipitation. The precipitation is mainly concentrated in3-9months, and the maximum precipitation was in spring while the minimum precipitation was in winter. There was a significant correlation between canopy interception,through-fall,stem-flow and precipitation of the Koelreuteria paniculata plantation, The relationship between canopy interception and precipitation was logarithmic function, The relationship between through-fall, stem-flow and precipitation were straight line function.(2) The average pH value of precipitation outside the forest was6.58, basically neutral. The average pH value of through-fall was6.38, of stem-flow was6.06and of leakage water was6.74. The maximum pH value of precipitation outside the forest, through-fall and stem-flow were in May while the minimum were in the December. The rainfall directly affects the pH value of precipitation outside the forest, through-fall and stem-flow.(3) Ca elements had the highest concentration in precipitation outside the forest, was4.416mgL-1, Fe elements had the lowest concentration, was0.004mgL-1; Ca elements had the highest concentration in through-fall, was8.634mg·L-1, Pb elements had the lowest concentration, was0.020mgL-1; K elements had the highest concentration in stem-flow, was12.133mg·L-1, Pb elements had the lowest concentration in stem-flow, was0.028mg·L-1. The average concentrations of elements were arranged as Ca>K>NH4+-N>NO3--N>Mg>Mn>Cu>Zn>Pb>P>Fe for precipitation outside the forest; Ca>K>NH4+-N>NO3--N>Mg>Mn>Zn>Cu>P>Fe>Pb for through-fall; K>Ca>NH4+-N>NO3--N>Mn>Mg>Fe>Zn>P>Cu>Pb for stem-flow; the mean concentrations of Heavy Metals were arranged as Mn>Fe>Zn>Cu>Pb>Cd for leakage water. The concentrations of elements in stem-flow were higher than through-fall and precipitation outside the forest.(4) The bulk density of each soil layer in the Koelreuteria paniculata plantation were lower than outside the forest. Compared with2004, the soil moisture content increased by1.68%, soil porosity increased by5.17%, soil bulk density reduced0.14g·cm-3. Water storage capacity of forest soil was higher than outside the forest, the maximum water storage in0-60cm soil layer was3024.66t·hm-2in the forest, which was2457.06t·hm-2outside the forest, a difference of1.23times; The effective water storage in the forest is678.42t·hm-2, which is541.31t·hm-2outside the forest, a difference of1.25times.(5) For the whole year, the leaching coefficient of Pb was less than1in through-fall, it showed that the Koelreuteria paniculata canopy can directly absorb Pb element, the leaching coefficients of all the other elements were greater than1, showing the incremental leaching. Leaching coefficient of each element were greater than1in stem-flow, it showed the incremental leaching, leaching coefficient of each elements were between1.04～22.25, the phenomena of nutrient enrichment is obvious.(6) The leaves, bark and roots of Koelreuteria paniculata had a strong capacity of absorption the elements of Mn,Cd,Pb. The concentration of Mn element in through-fall and stem-flow were higher than precipitation outside the forest, it showed that the canopy and stem of Koelreuteria paniculata had a strong capacity of adsorption Mn element, the deposition and leach of Mn element was caused by precipitation, and it had some purification to precipitation. With the deepening of the soil layers, the concentration of Mn element in leakge water decreased, it showed that the soil in Koelreuteria paniculata plantation can retain and filter Mn element, and purify the water through this ecosystem. |
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