| With the sustained and rapid development of China’s economy, the increase of per capita income and living standards improve, the focus of China’s urban residents gradually shift from the demand of material life to the demand of the quality of living environment.Urban greening is the living environment of urban residents at the very least, urban forest is the most intuitive performance urban greening. Urban forest offers protection with its powerful ecological service function to urban development. Urban forest can sterilization, sluggish dust absorption, dilution, decomposition, absorption, and fixed toxic and harmful substances from the atmosphere, purify the air, increase the amount of negative oxygen ions in the air. Urban forest can reduce noise, improve the quality of environment, landscaping, adjust and improve urban microclimate. Therefore, the urban forest ecological service function has become hot study topics of scholars both at home and abroad. The hydrological process of the urban forest ecosystem and nutrient elements flow is also an important part of forest ecosystem service functions. The four types artificial forest ecosystem hydrological processes of rainfall redistribution and the accompanying migration process of nutrient elements were deeply studied base on experimental forest farm of northeast forestry university, the conclusions were as follows:1) The total rainfall was 339.1 mm during the obsverved period (Jun～Aug,2015), and throughfall was the main constituents of hydrological process, then was the interception. The throughfall rate of J. Mandshurica, Q. Mongolica, L. Gmelinii and P. sylvestris var. Mongolica was 59.28%,8.27%,58.66% and 54.76% accounted for rainfall at the same period, and interception of them was 21.59%,23.24%,37.63% and 36.51%, respectively.2) The spatial variationon throughfall of four types urban plantation was different. The throughfall variable coefficient in different observation points of J. Mandshurica, Q. Mongolica, L. Gmelinii and P. sylvestris var. Mongolica was 14.83%,35.86%,17.52% and 30.70%, respectively, and with the minimal variable coefficient in J. Mandshurica, the maximal variable coefficient in Q. Mongolica. The observation on throughfall of Q. Mongolica occurred aggregation effect (the ratio of throughfall>100%).3) The sequence of average concentration of each nutrient element in atmospheric rainfall was as follows:Ca> SO42-> NO3-> PO42-> K> Cl-> F> Na> Mg> Cu> Fe> Zn> Mn, the anion accounted for 62.62% and the metal element accounted for 37.38% of the total concentration. The variation coefficient of nutrient concentrations was between 0.096 to 1.493, and the Na element has the greatest concentration range, Zn element conversel.4) In the throughfall and stemflow of four types urban plantation ecosystem, SO42- was the main anionic constitute, while, Ca and K were the main metal elements, and their concentrations and accounted for over 50% of the combined elements concentration. But, the Cu, Fe, Zn and Mn were four kinds of metal elements which had low parcentage of elementary composition, four of them were less than 4% of the total concentration.5) The sequence of nutrient elements flux in tmospheric rainfall (kg/hm2) was as follows:Ca (14.276)> SO42-(11.185)> NO3- (9.280)> K (6.068)> Cl- (5.204)> PO42- (2.117)> F-(1.879)> Na (1.442)> Mg (0.845)> Cu (0.232)> Fe (0.133)> Zn (0.126)> Mn (0.036).6) Leaching or absorption of different ion occured during the process of rainfall changed into throughfall and stemflow, and resulted in different flux changes. In four types of urban forest plantation, Mg, Fe, Mn flux of nutrient elements (kg/hm2) had increased, and the Ca and Cu flux were reduced, other nutrients flux change was not consistent.7) Canopy paly a different "source" or "send" effect on flux of various nutrient elements in four types of urban forest plantation. Canopy of J. Mandshwrica play a "send" effect on flux of F-, Cl-, NO3-, SO42-, Ca, Na, Cu, and play a "source" effect on flux of PO42-, K, Mg, Fe, Zn, Mn. Canopy of Q. Mongolica play a "send" effect on flux of F, Cl-, PO42-, SO42-, K, Ca, Cu and play a "source" effect on flux of NO3-, Na, Mg, Fe, Zn, Mn. Canopy of L. Gmelinii play a "send" effect on flux of NO3-, PO42-, SO42-,Ca, Na, Cu, Zn and play a "source" effect on flux of F, Cl", K, Mg, Fe, Mn. Canopy of P. sylvestris vsr.Mongolica play a "send" effect on flux of F, Cl-, PO42-, SO42-, K, Ca, Cu, Zn and play a "source" effect on flux of NO3-, Na, Mg, Fe, Mn. |
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