Change in evapotranspiration partitioning after thinning in a Japanese cypress plantation
Thinning resulted in evapotranspiration decrease and caused the relative contributions of each component to evapotranspiration to become very close.
To increase the understanding of forest management to control water cycles, we examined the effect of 50% strip thinning on evapotranspiration (ET) and its partitioning into canopy interception (Ei), tree transpiration (Et), and forest floor evaporation (Ef) in a Japanese cypress (Chamaecyparis obtusa Endl.) plantation. Intensive measurements were employed to monitor each component of ET during the pre- and post-thinning periods. The results showed the annual Et was the dominant component of ET followed by Ei, whereas Ef was the smallest component in both periods. Thinning has significant impact on the process of ET partitioning. In such that it decreased from 42.3 to 33.7% in Ei/ET and from 45.0 to 34.9% in Et/ET, and increased from 12.7 to 31.4% in Ef/ET on an annual scale. The relative contributions of each ET component to the whole ET became more or less the same after thinning. Additionally, the monthly Ei/Pg had relative stable values in both pre- and post-thinning periods, contributing significantly to the ET/Pg during heavy rainfall conditions. After thinning, ET decreased by 21.4% from 629.3 to 494.8 mm during the growing season and by 20.4% from 979.8 to 780.1 mm at the annual scale, demonstrating that thinning results in an increase in water availability in the forested watershed. This study can improve the understanding of forest water budget in response to thinning and aid in development of appropriate forest management practices accordingly.
KeywordsChamaecyparis obtusa Forest management Forest floor evaporation Canopy interception Tree transpiration
- Allen RG (2008) Why do we care about ET? Southwest Hydrol 7:18–19Google Scholar
- Japan Forestry Agency (2014) Data for Japanese cedar and cypress plantations. http://www.rinya.maff.go.jp/j/sin_riyou/kafun/data.html. Accessed Mar 2012
- Shimizu T, Kumagai T, Kobayashi M, Tamai K, Iida S, Kabeya N, Ikawa R, Tateishi M, Miyazawa Y, Shimizu A (2015) Estimation of annual forest evapotranspiration from a coniferous plantation watershed in Japan (2): comparison of eddy covariance, water budget and sap-flow plus interception loss. J Hydrol 522:250–264CrossRefGoogle Scholar
- Vesala T, Suni T, Rannik U, Keronen P, Markkanen T, Sevanto S, Gronholm T, Smolander S, Kulmala M, Ilvesniemi H, Ojansuu R, Uotila A, Levula J, Makela A, Pumpanen J, Kolari P, Kulmala L, Altimir N, Berninger F, Nikinmaa E, Hari P (2005) Effect of thinning on surface fluxes in a boreal forest. Glob Biogeochem Cycle 19:GB2001CrossRefGoogle Scholar
- Zimmermann B, Zimmermann A, Lark RM, Elsenbeer H (2010) Sampling procedures for throughfall monitoring: a simulation study. Water Resour Res 46:W01503Google Scholar