Species-specific relationship between sapflux density and diameter growth rates for six years

Transpiration and photosynthesis are connected each other through stomata, therefore, biomass increment of trees should have close relationships with their water use. However, the relationship is species specific and it is also dependent on various biotic and abiotic factors. The purpose of this study is to investigate the relationship of sapflux with diameter increment of individual trees among six different species using Granier type sapflow sensors and diameter growth band installed from 2012. The growth of two conifer (Pinus koraiensis, Abies holophylla), five broadleaf (Quercus aliena, Q. variabilis, Q. serrata, Carpinus laxiflora, C. cordata) were investigated at Mt. Taehwa and Gwangneung National Arboretum. Net Primary Production was calcualted based on speceis specific allometric equations. The relationship between sapflux density and diameter growth was different among species. For example, Q. aliena and A. holophylla had positive relationship between sapflux density and diameter growth (p = 0.037 and p =0.001, respectively), while P. koraiensis did not follow the trend (p = 0.5). However, when tree level transpiration was calculated by mulitiplying sapflux density with its sapwood area. In general, all species showed significant positive correlations between the transpiration and NPP (e.g., P. koraiensis(p = 0.003), Q. aliena and A. holophylla(p <0.001). In addition, comparison between conifer and broad leaves species, the conifers show the bigger changes in diameter growth and eventually NPP than that of the broad leaves tree in the same change of transpiration. Therefore, WUE for biomass increment was higher in conifer than broadleaf species.