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We classified the streamside plant community by phyto-sociological method and analyzed the relationship between environment factors and vegetation structure by using the classification and ordination method. We found that twenty one plant communities were classified according to dominant species at the natural streamside valley forest with surveying the 65 quadrats (10 m × 10 m). From the survey results, the hardwood plant communities were classified as streamside valley forest and the softwood plant communities as riparian forest according to the degree of flooding. The valley forest had a distribution of 17 plant communities which was 65% (42 quadrats) of 65 quadrats: Maackia amurensis community, Betula davurica community, Quercus variabilis community, Pinus densiflora community, Q. serrata community, Prunus sargentii community, and Meliosma oldhamii community etc. The riparian forest had a distribution of four plant communities which was 35% (23 quadrats) of 65 quadrats: Salix koreensis community, S. rorida community, S. purpurea var. japonica community, and S. glandulosa community, etc. From the two-way indicator species analysis (TWINSPAN) analysis, we found indicator species Oplismenus undulatifolius and Lindera obtusiloba for the streamside valley forest and Humulus japonicus, Phragmites japonica, and S. koreensis for the riparian forest. From the results of the canonical correspondence analysis (CCA), coordinates, altitude, and stream structure showed low correlation to the distribution of the plant community. Therefore, it seemed that valley forest and riparian forest were distinguished by the stream gradient and waterway width which determined by the stream water level.

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Background: This study investigated the temporal variation in soil CO 2 efflux and its relationship with soil temperature and precipitation in the Quercus glauca and Abies koreana forests in Jeju Island, South Korea, from August 2010 to December 2012. Q. glauca and A. koreana forests are typical vegetation of warm-temperate evergreen forest zone and sub-alpine coniferous forest zone, respectively, in Jeju island. Results: The mean soil CO 2 efflux of Q. glauca forest was 0.7 g CO 2 m −2 h −1 at 14.3°C and that of A. koreana forest was 0.4 g CO 2 m −2 h −1 at 6.8°C. The cumulative annual soil CO 2 efflux of Q. glauca and A. koreana forests was 54.2 and 34.2 t CO 2 ha −1 , respectively. Total accumulated soil carbon efflux in Q. glauca and A. koreana forests was 29.5 and 18.7 t C ha −1 for 2 years, respectively. The relationship between soil CO 2 efflux and soil temperate at 10 cm depth was highly significant in the Q. glauca (r 2 = 0.853) and A. koreana forests (r 2 = 0.842). Soil temperature was the main controlling factor over CO 2 efflux during most of the study period. Also, precipitation may affect soil CO 2 efflux that appeared to be an important factor controlling the efflux rate. Conclusions: Soil CO 2 efflux was affected by soil temperature as the dominant control and moisture as the limiting factor. The difference of soil CO 2 efflux between of Q. glauca and A. koreana forests was induced by soil temperature to altitude and regional precipitation.