6:15 PM - 7:30 PM
[HTT31-P06] Effect of atmospheric deposition to alpine ecosystem in Mt. Tateyama
Keywords:Asian dust, Alpine, Sr isotope, plant ecophysiology, Forest hydrology, material cycle
Result of observation of material dynamics on canopy of Pinus pumila Regal in Jodo-daira (2839m a. s. l.) in Chubu-Sangaku mountainous area in central Japan, P. pumila uptakes ~70% of inorganic nitrogen supplied from rain and fog adhering to the needle surface. In addition, considerable amounts of potassium (K+) and magnesium (Mg2+) ions are supplied to the soil as throughfall, which was derived from canopy leaching. The 87Sr/86Sr ratio of groundwater and surface water are almost identical to that of soil and bed rock, suggesting that Sr in the surface and ground water is largely derived bedrock through chemical weathering. The 87Sr/86Sr ratio of forest rain of P. pumila is 0.70934, and similar to rain and sea water value. The ratio of leaf and branch of P. pumila are different from surface water and bedrock, and similar to yellow sand dust. The most notable feature is that P. pumila has high 87Sr/86Sr ratios. Most small alpine plants have lower 87Sr/86Sr ratios.
In order to examine the nutrient circulation changes in each forest types at different altitude in Tateyama, we measured chemical properties of forest rain and 87Sr/86Sr ratio of shoot and litter and surface horizon soil at Bijo-daira (Cryptomeria japonica, 977m a. s. l.) , Buna-daira (Fagus crenata, 1200m a. s. l.), and Midaga-hara (Abies mariesii forest, 1930m a. s. l.). 87Sr/86Sr of C. japonica and A. mariesii leaves, branches, litter and forest rain are close to rain, but F. crenata leaves and forest rains are almost the same as the value of the yellow sand dust. Results of ion analyses suggested the existence of interaction between canopy and rain in any type of canopies. A large amount of K+ leaching has occurred in the F. crenata forest and calcium (Ca2+) leaching has occurred in the A. mariessi forest. In addition, the values of 87Sr/86Sr in the surface horizon soil of any soils closed to the value of yellow sand dust.
These results suggested that in any of the forest stand in Tateyama, ion supply from atmosphere forms a main body of material circulation, the influence of the bedrock is very small, and also yellow sand dust has become an important cation source, nutrients such as Ca2+ supplied to the forest floor salts, to form a nutrient pool in root zone containing litter, and nutrients are used by circulating to resorption by root.