| The influence of climate disturbance on hydrological processes and especially on hydrochemistry in forest ecosystem had been frontier issues in global change ecology. To emphasize the understanding in this field will be help for accurate estimation of varying forest serves as hydrological regulation which caused by increasing climate extreme.This paper suduties the change of the hydrochemstry of the rainfall,throughfall,stemflow,litters and surface runoff, catchment runoff aimed at long time studying the damage by the snow and ice disater how to influence on the hydrologic process and the water quality after the great2008Chinese ice storm in the damaged seriously northen area of Guangdong. It is selected as the study plot that the subtropic evergreen broadleaved forest which has the main dominant tree species Castanopsis fissa in the damaged seriously NanLing Mountains. It was imated that the snow and ice disater damaged the structure of the forest by removing the forest canopy unnarurely and adding dry branches and fallen leaves to the plot. The14rainfall buckets were set for collecting the throughfall and12sample trees were selected to measuring the stemflow in the imitating damaged sample plot and the comparing sample plot. The water sample was gathering46times that was828bottles during February of2013to January of2014. The pH, salinity, NO3-、NH4+、Cl-、Na+、Ca2+、 Mg2+、K+and SO42-were test, by which the change rules of forest rainfall are studied after the structure damaged. The main results follow as:(1)The northern area of Guangdong is located in sub-tropic areas and have the obviously dry seasons and rains. The ionic concentraitions of NH4+、Ca2+、Na+、Mg2+、 K+and SO42-in the rain of outside of forest is dry seasons’more than rains’. The ionic concentraition of NO3-is higher in the rain outside of forest in July. It was because that thunderstorms were more in this month. The ionic concentraition of rain outside of forest would be down with the rain more and more. The ionic concentraition get smaller slowly, when the rain is more than50mm. It is the man reason that typhon became frequent, the ion increased in July to September at the northern of Guangdong. The ionic concentraition of Ca2+is more,because of the local mining industry(2) The throughfall of the damaged forest is different from the undamaged forest’s. From the quentity point of view, the throughfall ratio of the damaged sample plot is80.6%, when the troughfall ratio of the impared forest is72.7%. From the quality point of view, the ions of NO3-、Cl-and Ca2+increased compared with the undamaged forest, when the ions of NH4+、Na+、Mg2+、K+and SO42-were on the contray. The results showed that:the canopy of the sub-tropic evergreen broadleave forest which has the main dominant tree species Castanopsis fissa absorbed NO3-more or less; the NH4+、Na+、Mg2+、K+、SO42-of the throughfall were leached from canopy class. The K+of those five types ions was leached most easily. In addition, the pH became lower, when rainfall flowed through the canopy of Castanopsis fissa, because the rainfall exchanged ions with the leaves of canopy.(3) The rainfall soured the trunk more seriously which lead to the change of the water chemistry of the stemflow. The results showed that:the Na+、K+、Mg2+、Ca2+of the stemflow in the damaged plot increased more or less impared with the undamaged sample plot, which mean that the rainfall supplied cation to the stemflow after the canopy damaged. The NO3-of the stemflow in the damaged plot were more than the stemflow’s in the undamaged plot. Although the stemflow has less percentage of rainfall, it is good for recovering the damaged forest that all kinds of chemical element and ion of stemflow are more and more.(4) NH4+、Na+、Mg2+、K+、SO42-of the litter water were more than the rainfall’s outside of the forest and the throughfall’s, which was related to that the litter decomposed, when the rain flowed through the litter. The pH of the litter water went down more contrasting with the rainfall’s, the throughfall’s and the stemflow’s, when the pH is5.999. The litter absorbs Ca2+more easily, which was measured1.638mg/L.(5) Because of canopy damaged, the splash erosion by the rain changed the water quality of the runoff through dripping on the floor. K+, Mg2+, NO3-, NH4+of the runoff in the damaged plot were more than the runoff’s in the undamaged plot. The density of Ca2+is7.241mg/L in the runoff of the damaged plot, while which is3.681mg/L in the undamaged plot, the matter is that the rainfall erodes the floor more seriously without the protect of canopy,which lead to more Ca2+enter into the runoff. Comparing with the litter water, the pH of the runoff is higher, the pH of the runoff in the damaged forest is6.491,while which is6.094in the undamaged forest.(6) The rivulet water quality of the northen area of Guangdong changes by seasons in the mountain. The damaged canopy would have influenced on the water quality of rivulet. Except NO3-、NH4+、Na+、Cl-、Ca2+、Mg2+、K+、SO42-average content of rivulet by year, are catchment1(damaged)> catchment2(undamaged). NO3-, NH4+、Na+、SO42-of rivulet are more diffirent by seasons. NO3-content of rivulet is more than other seasons in spring.; the content of NH4+is highest at autumn,on the contrary at spring; the content of Na+in the damaged plot is more at summer and autumn, while which in the undamaged plot is more at autumn and winter; the content of SO42-in the damaged plot is more at spring and winter, while which in the undamaged plot is more at summer and winter. The change pattern of the four ions is no same by seasons. Except SO42-, the other ions content of the two catchments all are closed, which proves that the forest adjust to the water quality.(7) The four ions content of NO3-、NH4+、Mg2+、K+in the soil water are:the undamaged plot> the damaged plot., which is related to that the plant repairs itself after the canopy damaged. The root absorbs the ions better. NH4+、Na+、SO42-contents of the two sample plots are:10cm soil water>20cm soil water; NO3-and Cl-contents of the two sample plots are:10cm soil water<20cm soil water, the matter is that the ions move in the soil. |
PDF Full Text Request