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In recent years, moso bamboo (Phyllostachys pubescens) forest areas in Japan have rapidly expanded, and bamboo is now invading nearby natural or plantation forests. To date, only one study has examined the rainfall interception of a moso bamboo forest. In that study, it was reported that the interception ratio (interception/rainfall) of the bamboo forest did not exceed the interception ratios of other natural and plantation forests (n = 4) in Japan. To expand the current state of knowledge about rainfall interception of bamboo forests, we measured throughfall and stemflow at another bamboo forest site. Annual rainfall (Rf), throughfall (Tf), and stemflow (Sf) during the measurement period were 2,105, 1,556, and 322 mm, respectively. Annual rainfall interception at the plot (I) was 228 mm. Tf/Rf, Sf/Rf, and I/Rf were 73.9, 15.3, 10.8%, respectively. I/Rf was less than 20% throughout the year except in October, the month with lowest rainfall. We also summarized rainfall interception data from 19 other natural and plantation forests. The I/Rf value of our site did not exceed the I/Rf values of these natural and plantation forests (n = 19). Our data will be useful for assessing changes in water resources that result from replacement of natural or plantation forests by bamboo forests.

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Abstract:We investigated the spatial and seasonal variations in throughfall (Tf) in relation to spatial and seasonal variations in canopy structure and gross rainfall (Rf) and assessed the impacts of the variations in Tf on stand-scale Tf estimates. We observed the canopy structure expressed as the leaf area index (LAI) once a month and Tf once a week in 25 grids placed in a Moso bamboo (Phyllostachys pubescens) forest for 1 year. The mean LAI and spatial variation in LAI did have some seasonal variations. The spatial variations in Tf reduced with increasing Rf, and the relationship between the spatial variation and the Rf held throughout the year. These results indicate that the seasonal change in LAI had little impact on spatial variations in Tf, and that Rf is a critical factor determining the spatial variations in Tf at the study site. We evaluated potential errors in stand-scale Tf estimates on the basis of measured Tf data using Monte Carlo sampling. The results showed that the error decreases greatly with increasing sample size when the sample size was less than ¾8, whereas it was near stable when the sample size was 8 or more, regardless of Rf. A sample size of eight results in less than 10% error for Tf estimates based on Student's t-value analysis and would be satisfactory for interception loss estimates when considering errors included in Rf data.

The large‐scale expansion of Moso bamboo forests in Japan raises concerns about how vegetation will affect the hydrological cycle and local water resources. However, information on transpiration (E) is limited to study on a single bamboo stand with low culm density (4 000 ha−1). The present study conducted a year‐round measurement of E in a high‐density (11 000 ha−1) stand using sap‐flow measurements, and additional measurements were made during summer in the previously studied low‐density stand and a neighbouring Japanese cedar stand for comparison. Annual E of the high‐density stand was estimated at 455 mm. Although the value was greater than those reported for neighbouring coniferous forests (250–370 mm), it was lower than previous measurements made in the low‐density stand (567 mm). The daytime sap flux density of the high‐density stand was generally less than half that in the low‐density stand, resulting in similar daily maximum E values in those stands. In addition, E typically peaked before midday in the high‐density stand followed by a rapid decline; the midday suppression of E led to decreased total E in the stand. Based on present and previous measurements of E, combined with the lower rainfall interception (I) reported for bamboo stands, water loss through evapotranspiration would be comparable between bamboo and coniferous forests. Present results also suggest that the E of bamboo stands does not have strong positive relationships with stand structural parameters (e.g., culm density and sapwood area) but possibly depends more on the sites' microenvironments (e.g., solar radiation). Copyright © 2014 John Wiley & Sons, Ltd.

Abstract:To investigate the impacts of the invasion by bamboo on fluxes of nutrients and pollutants, the nutrient/pollutant fluxes and canopy interactions, including neutralization of acidity, leaching and uptake of nitrogen (N), were characterized in conjunction with rainfall partitioning in a Moso-bamboo (Phyllostachys pubescens) forest. Measurements of precipitation volume, pH, major ions, and silicate (SiO 2 ) in rainfall, throughfall and stemflow were collected weekly in a Moso-bamboo forest located in Munakata City, Western Japan for 1 year. Results showed that rainfall partitioning into stemflow was larger than that for other types of forest, which may be due to the properties of Moso-bamboo forest structure, such as a straight and smooth culm. Inorganic N (NO 3 C NH 4 C ) and S (SO 4 2 ) fluxes of throughfall and stemflow were approximately 1Ð6 and 1Ð3 times higher than that of rainfall, respectively. Contribution of stemflow flux to inorganic N and S fluxes to the forest floor was high. This could be due to lower uptake of inorganic N through culm and a higher rainfall partitioning into stemflow than that for other types of forest. The Moso-bamboo canopy neutralized rainfall acidity, reducing the fluxes of potentially acidifying compounds via throughfall and stemflow. Canopy leaching of K C was distinctly higher than that of Mg 2C and Ca 2C and could be related to the high mobility of K C in plant tissues. Cl and SiO 2 were readily leached as for K C . The impact of the invasion by bamboo on nutrient cycling was discussed.

. J. Jpn. For. Soc. 91: 366 370. Although sap flux measurement is one of the most robust techniques for stand-scale transpiration estimates, its applicability to bamboo is unclear. Ultimately we aim to establish a method for sap flux-based stand-scale transpiration estimates in a bamboo forest. This study focused on establishing a method for individual-scale transpiration estimates. We conducted sap flux measurements using hand-made 1-cm length sensors, and water absorption measurements in cut-bamboo. The sensors could detect water uptake in individual plants i.e., sap flux in moso bamboo . The diurnal changes in sap flux density reasonably well corresponded to those in water absorption. We found there was an underestimation of whole-tree water use with the 1-cm Grainer sensor; thus we suggested a modified equation for the calculation of sap flux density. In this study we could estimate individual-scale transpiration in moso bamboo using sap flux measurements.