Nitrate (NO₃^-) and dissolved organic carbon (DOC) concentration in stream water after clear-cutting of trees and subsequent strip-cutting of understory vegetation, dwarf bamboo (Sasa spp.) were investigated to understand the effect of these disturbances on biogeochemical processes in forested watershed in Teshio Experimental Forest, one of the JaLTER site, in northern Japan. Trees of 8 ha watershed except riparian zone were clear-cut in January?March of 2003. Sasa was strip-cut in October of 2003 and larch seedlings were planted on the cut line immediately after the Sasa cutting. Stream water and soil solution at the cut area on the slope and riparian slope area were sampled every two or three weeks from 2002 to 2008. Tree-cutting did not cause a significant increase of NO₃^- concentration in stream water during the growing season after the cutting. Subsequent Sasa-cutting caused significant increase of stream NO₃^- concentration to ca. 15 μmol L^-1. These results suggested that nitrogen uptake by Sasa was very important in preventing nitrogen leaching after tree-cutting, and decline of this nitrogen uptake after Sasa-cutting lead to marked NO₃^- leaching to the stream. Five years following trees and Sasa cutting, nitrate concentration fluctuated in the range of < 0.1 to 22 μmol L^-1 depending on year. NO₃^- concentration did not get back to pre-cutting level during five years after the tree-cutting.?DOC concentration in stream water was not changed after both cuttings of tree and Sasa and had clear seasonal pattern that peaked in late summer (August - September). Stream DOC concentration increased in growing period with low runoff from late May to August and then decreased after runoff increased in fall, indicating that dilution by the runoff reduce stream DOC concentration after late summer. However, DOC concentration remained low during winter when runoff was stably low, suggesting that high temperature also promote DOC production in soil during the dry period of early summer. These results suggests that riparian area is the main source of DOC rather than cut area on the slope, and thus DOC loss from ecosystem was not influenced by the cutting of trees and Sasa in this watershed. These results indicate the response to cutting is different between NO₃^- and DOC by the different source area of these solutes in the watershed with cool climate and the gentle basin topography.