Notable difference of stemflow in unmanaged Japanese cypress plantations

Hyewan Jun¹*, Sugyeong Jeon¹, Hyunshik Moon²,³, Hyun Kim4, Seonghun Jeong²,³

(¹Department of Forest Resources, Gyeongsang National University,

²Department of Forest Environmental Resources, Gyeongsang National University,

³Institute of Agriculture and Life science, Gyeongsang National University,

4Division of Environmental Forest Science, Gyeongsang National University)

Abstract: Stemflow (SF) plays a crucial role in water resources within forest ecosystems, constituting up to 53.3 % depending on forest stand structures in coniferous plantations. Numerous studies of SF have globally been reported; however, very few SF studies have been reported with chemical characteristics for different forest types (n = 20) and no information is available about the difference in SF with forest stand structures in Korea. This study aimed to quantify the relationship between SF and forest stand structures in Japanese cypress plantations. Two study plots were established (10 m x 10 m, each) in unmanaged Japanese cypress plantations under the same stem density (SD: 2500 stems/ha) (hereafter P1 and P2). Almost all forest stand structures (canopy projection area, tree height, DBH, the number of live and dead branches, the ratio of canopy length to canopy width), including canopy volume using mobile LiDAR device were investigated. To evaluate the effect of tree biomass on SF, funneling ratio (FR) as one of useful SF index was employed. Results demonstrated that the ratio of SF to gross rainfall was 17.0 % in P1 and 18.5 % in P2, respectively. Compared to those reported in previous studies (range: 0.2 % - 5.8 % with a mean of 2.0 %), the current ratios of SF at the stand-scale were much higher. These ratios were within the high range because of the mutual interaction between high SD and many branches including under-canopy dead branches. FR at the stand-scale accounted for 22.3 and 29.2, which were within the high range because of the negative relationship between FR and mean DBH. At the individual-scale, FR was the most correlated to DBH (R2 = 0.51). This study highlights the importance of not only throughfall but also SF in water resources in Japanese cypress plantations.

Key Words: Funnelling ratio, Japanese cypress, Stem density, Stemflow, Tree traits

Acknowledgement: This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIT) (grant number: RS-2023-00212756).