PDF《六盘山典型森林伴随降水的总有机碳 （ TOC） 通量变化特征》

2 College of Forestry, Central South University of Forestry and Technology, Changsha 410004, China Abstract: Both flux and concentration of total organic carbon(TOC)from rain water were documented and analyzed from six regional forests growing in the small watershed of Xiangshuihe inside Liupan Mounatins in NW China during the

2011 growing season. The results indicated that TOC concentration of all six forests was increased in term of rain water under canopy. Although the rain water volume under canopy was decreased due to the canopy interception, the TOC flux carried by the rain water under canopy was increased for all six forests as compared them with that carrying by the open field rainfall (53.17 kg/ hm2 ) because of carbon exchange or wash out from canopy. The corresponding TOC flux (kg/ hm2 ) of rain water http:/ / www.ecologica.cn under canopy was 132.28 for Larix principis鄄rupprechtii plantation, 106.56 for the secondary forest of Pinus armandii, 94.10 for the plantation of Pinus tabulaeformis, 79.49 for the shrub of Prunus salicina, 66.52 for the secondary forest of Betula platyphylla, and 63.01 for the secondary forest of Quercus liaotungesis. The canopy leaching (or wash out) effect of TOC was high for the coniferous forests, but weak for the broad鄄leaved forests. The difference of TOC concentrations in the leakage under humus layer was low among the six forest types, with an average of 24.51 mg/ L, which was still higher than the TOC concentration in throughfall. As an integrated result of the humus interception loss and the TOC exchange with humus layer, the TOC flux carried by the humus leakage was increased than that carried by throughfall for four forests and they were 84.35 (kg/ hm2 ) for the stand of Betula platyphylla, 129.35 for the bush of Prunus salicina, 79.21 for the stand of Quercus liaotungesis, 114.93 for the stand of Pinus tabulaeformis, but the TOC flux carried by the humus leakage was decreased to 90.76 and 104.90 kg/ hm2 for the stand of Larix principis鄄rupprechtii and Pinus armandii respectively. In the leakage under the soil layer of main root zone (0―30 cm), the TOC concentrations were reduced compared with that in humus leakage for the stands of Larix principis鄄rupprechtii and Pinus armandii. Affected by the water volume decrease and the TOC exchange with mineral soil, the TOC flux carried by the soil leakage under main root zone was significantly reduced, compared with the TOC flux of humus leakage, to 43.04 kg/ hm2 for the stand of Larix principis鄄rupprechtii and to 66.33 kg/ hm2 for the stand of Pinus armandii. In conclusion, the TOC input flux through open field rainfall played an important role in the TOC flux input to forest soil. The canopy of all six forest types could increase the TOC flux due the TOC leaching from canopy surface. The TOC flux in humus layer leakage were usually increased or decreased. However, the mineral soil at the main root zone greatly reduced the TOC flux output, thus the soil layer should be the most important pool for fixing the TOC. Key Words: representative forests;

hydrological processes;

total organic carbon;

flux 摇摇降水在携带各种元素进入森林生态系统的同 时,随着与植被的接触,还会发生水量与元素浓度的 明显变化,这些变化都对森林生长和其功能发挥具 有重要作用[1鄄3] . 碳元素虽然不是营养元素,但由于 森林固碳功能........