日本地球惑星科学連合2018年大会

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[EE] Eveningポスター発表

セッション記号 A (大気水圏科学) » A-HW 水文・陸水・地下水学・水環境

[A-HW22] 水循環・水環境

2018年5月24日(木) 17:15 〜 18:30 ポスター会場 (幕張メッセ国際展示場 7ホール)

コンビーナ:長尾 誠也(金沢大学環日本海域環境研究センター)、町田 功(産業技術総合研究所地質調査総合センター)、飯田 真一(国立研究開発法人森林研究・整備機構森林総合研究所森林研究部門森林防災研究領域水保全研究室、共同)、林 武司(秋田大学教育文化学部)

[AHW22-P02] Stemflow and canopy structure: revelations from the NIED large-scale rainfall simulator

*飯田 真一1Delphis Levia2南光 一樹1Xinchao Sun3篠原 慶規4酒井 直樹5 (1.国立研究開発法人森林研究・整備機構森林総合研究所、2.デラウェア大学、3.天津大学、4.宮崎大学、5.国立研究開発法人防災科学技術研究所)

キーワード:樹幹流、樹冠構造、人工降雨装置

Stemflow plays an important role in both the hydrologic and elemental cycling of forest ecosystems. Although the amount of stemflow is relatively minor compared with the amount of throughfall, significantly concentrated inputs of stemflow water around tree bases have notable effects on near-trunk water dynamics and soils. Thus, the main factors controlling the amount of stemflow should be well understood. However, our knowledge of stemflow generation still has gaps because stemflow yields are affected by a myriad of interacting factors- the amount and the intensity of rainfall, and by differences in canopy structure among and within species, including leaf type, branch angle, and trunk lean, among other factors. In order to better understand the factors controlling stemflow funneling ratios among trees with differing canopy structures, we used the large-scale rainfall simulator at the National Research Institute for Earth Science and Disaster Resilience (NIED) with planted trees to measure stemflow under an artificially controlled environment with six different rainfall intensities (15, 20, 30, 40, 50, and 100 mm/h). Test tree species were Cryptomeria japonica D. Don (Japanese cedar), Chamaecyparis obtusa (Siebold & Zucc.) Endl. (Japanese cypress), and Zelkova serrata Thunb. (Japanese zelkova). We measured the detailed canopy projection areas for both foliated and defoliated conditions, branch number, and trunk lean via LiDAR and manual measurement techniques. Under controlled meteorological conditions, funneling ratios showed complex and different trends with respect to canopy structure. Hence, we used a Bayesian framework to obtain the relative influence of various canopy structural metrics. The preliminary results revealed that diameter at breast height and total amount of biomass were the two most influential factors affecting the funneling ratio among six test trees under foliated conditions. On the other hand, the differences in funneling ratios among defoliated six trees were mainly controlled by branch angle. Because raindrops directly contact with the surfaces of branches and stem without leaves, branch angle would have a relatively large influence on stemflow generation. These findings will contribute to better understanding the rainfall interception process, especially for its seasonality and dependency on tree species.