| Rainfall distribution of forest vegetation and nutrient cycling is important. Enter the forest after rainfall, canopy interception, throughfall and stem-flow water form a new distribution pattern, reflecting the forest canopy on rainfall storing function. Meanwhile, rainfall redistribution, due to trees on chemical precipitation with physical, chemical and biological adsorption, absorption and leaching effects, changed the chemical properties of precipitation, reflecting the trees on the water quality regulation. In this study, forest structure and hydrological process, through an observation of atmospheric precipitation, the nutrient analysis of the precipitation distribution and nutrient cycling, To better understand the nutrient ecosystems to provide the scientific basis for ecological and hydrological functions. The main results are as follows:(1) Liquidambar formosana Plantation canopy interception, throughfall and stem-flow, accounting for the total precipitation 29.11%,69.28%,1.62%; monthly precipitation, canopy interception, throughfall and stem-flow of water and atmospheric precipitation was significantly positive correlated (p<0.01), correlation coefficients were0.993,0.925 and 0.906; With the precipitation level increases, the rate of canopy interception,penetration and stem-flow reduced accordingly; for canopy interception, autumn crown retention largest, followed in spring, winter rate of the minimum; Penetration rate of water flow rate and stem the performance of the highest in spring, summer, second, and lowest in autumn.(2) Precipitation pH value changed in the range of 5.31～7.24, the average precipitation pH value is 6.45, basically as neutral; during observed periods, there was three times acid rain, which pH values is below 5.6; the pH values was changed after through the canopy of Liquidambar formosana Plantation; the throughfall pH value was 6.81 and stem-flow was 5.85, which tendency is:stem-flow> precipitation> throughfall.(3) During observed periods, the mean concentrations (weighted average)of elements of NH4+-N,NO3--N,PO3-,K,Ca,Mg were:0.96 mg. L-1,2.29 mg.L-1,0.23 mg. L-1,4.38 mg. L-1,5.02 mg. L-1,0.41 mg. L-1, The sequence of Ca>K > NO3--N> NH4+-N> Mg> PO3-; sequence of microelements in precipitation was Zn>Fe>Mn>Pb>Cu, concentrations were::0.134 mg. L-1,0.086 mg. L-1,0.038 mg. L-1,0.023 mg. L-1,0.021 mg. L-1, showed obviously seasonal variation; there was significantly correlation between macro-elements concentrations and monthly precipitation (p<0.05), microelements are mainly related with the precipitation frequency; the concentrations of Canopy interception,throughfall and stem flow are changed largely after through the canopy of Liquidambar formosana, but the overall trend is through the canopy of Liquidambar artificial the concentrations of precipitation was increased, which is stem flow> throughfall> precipitation.(4) After through the canopy of Liquidambar formosana Plantation the concentrations chemical element were increased. Throughfall and stem-flow performed significant nutrient enrichment, nutrient leaching significantly, with seasonal variation.the Average coefficient of macro-elements of throughfallless than 1,showed negative eluviate, which were NH4+-N,NO3--N,PO3-; K,Ca,Mg Elements of annual eluviate coefficients were1.08,3.35,3.29, showed significant nutrient enrichment; the macro-elements of stem-flow showed negative eluviate in addition to the PO3- element,which were eluviate coefficient large than 1, stem-flow nutrient enrichment significantly. For microelements,Liquidambar artificial canopy showed significant purification,except Mn element, the elements of Zn, Cu, Fe, Pb of stem-flow which eluviate coefficients were less than 1, showing a negative cream dissolve. |
