11 results on '"Komatsu, Hikaru"'
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2. Scaling-up from tree to stand transpiration for a warm-temperate multi-specific broadleaved forest with a wide variation in stem diameter
- Author
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Chiu, Chen-Wei, Komatsu, Hikaru, Katayama, Ayumi, and Otsuki, Kyoichi
- Published
- 2016
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3. Canopy transpiration in two Japanese cypress forests with contrasting structures
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Tsuruta, Kenji, Komatsu, Hikaru, Kume, Tomonori, Shinohara, Yoshinori, and Otsuki, Kyoichi
- Published
- 2015
- Full Text
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4. 九州のマテバシイ林で計測された土壌水分減少による樹液流速の低下
- Author
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Komatsu, Hikaru, Katayama, Ayumi, Kume, Tomonori, and Otsuki, Kyoichi
- Subjects
森林 ,forest canopy ,蒸散 ,sap flow ,土壌水分減少 ,Lithocarpus edulis ,soil water deficit ,マテバシイ ,transpiration ,樹液流 - Abstract
This paper examines transpiration reduction due to soil water deficits observed in a Lithocarpus edulis forest on Kyushu Island, south-western Japan. Continuous sap flow measurements were performed on six trees to monitor changes in tree transpiration rates. A reduction in sap flow velocity was observed in the period between late-September and late-October 2003. Precipitation amounts for this period were limited resulting in a corresponding low soil matric potential. A clear reduction in sap flow velocity occurred when soil matric potential at a 10 cm depth was < - 70 ( kPa) . Sap flow velocity scaled for 1. 0 kPa vapor pressure deficit declined by 42 % when soil matric potential at a 10 cm depth was < - 70 (kPa) compared to ≥ - 70 ( kPa) . In addition, intensive leaf-scale physiological measurements were performed on two days that had contrasting soil matric potentials. The intensive measurements showed lower leaf transpiration rates and stomatal conductance on the day with the lower soil matric potential. This finding suggests soil water deficits caused stomatal closure and therefore reduction in tree transpiration. Sap flow velocity and leaf water potential data showed that stem hydraulic conductance did not decline with low soil matric potential when compared to the day with higher soil matric potential., 本論は,九州のマテバシイ林で計測された土壌水分減少による蒸散低下を調べたものである。蒸散の変化を観測するために森林内の6本の樹木において樹液流計測を行ったところ,2003年9月下旬から10月下旬にかけて樹液流速の低下が認められた。この期間は降水量が少なかったために,土壌マトリックポテンシャルが低下していた。樹液流速の低下は,深度10 cmの土壌マトリックポテンシャルが-70 kPa以下のときに顕著であった。大気飽差が1.0 kPaのときの樹液流速は,土壌マトリックポテンシャルが-70 kPa以下のとき,土壌マトリックポテンシャルが-70 kPa以上のときに比べて42%低下していた。樹液流計測に加えて単葉スケールでの樹木生理計測を,土壌マトリックポテンシャルの異なる2日を選んで行った。その結果,単葉の蒸散量と気孔コンダクタンスは,土壌マトリックポテンシャルが低い日において小さかった。このことは,土壌水分減少が気孔の閉鎖を引き起こし,その結果,樹木の蒸散が低下したことを示唆している。樹液流速と水ポテンシャルの関係から,土壌マトリックポテンシャルの低下による幹の通水コンダクタンスの低下は認められなかった。
- Published
- 2007
5. スギ人工林の冬季の蒸散 : 通年樹液流計測に基づく解析
- Author
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KOMATSU, Hikaru, KUME, Tomonori, YOSHIFUJI, Natsuko, HOTTA, Norifumi, and SUZUKI, Masakazu
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蒸散 ,Evergreen ,Cryptomeria japonica plantation ,常緑 ,Sap flow ,Winter ,スギ人工林 ,Transpiration ,樹液流 ,冬季 - Published
- 2007
6. Stand-scale transpiration of two Moso bamboo stands with different culm densities.
- Author
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Ichihashi, Ryuji, Komatsu, Hikaru, Kume, Tomonori, Onozawa, Yuka, Shinohara, Yoshinori, Tsuruta, Kenji, and Otsuki, Kyoichi
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BAMBOO ,HYDROLOGIC cycle ,SAP (Plant) ,EVAPOTRANSPIRATION ,PLANT water requirements ,CONIFEROUS forests - Abstract
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). [ABSTRACT FROM AUTHOR]- Published
- 2015
- Full Text
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7. Effects of sample size on sap flux-based stand-scale transpiration estimates.
- Author
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KUME, TOMONORI, TSURUTA, KENJI, KOMATSU, HIKARU, KUMAGAI, TOMO'OMI, HIGASHI, NAOKO, SHINOHARA, YOSHINORI, and OTSUKI, KYOICHI
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SAMPLE size (Statistics) ,PLANT transpiration ,SAPWOOD ,CYPRESS ,MONTE Carlo method ,WATER vapor transport - Abstract
In this study, we aimed to assess how sample sizes affect confidence of stand-scale transpiration (E) estimates calculated from sap flux (F
d ) and sapwood area (AS_tree ) measurements of individual trees. In a Japanese cypress plantation, we measured Fd and AS_tree in all trees (n = 58) within a 20 x 20 m study plot, which was divided into four 10 x 10 subplots. We calculated E from stand AS_tree (AS_stand ) and mean stand Fd (JS ) values. Using Monte Carlo analyses, we examined the potential errors associated with sample sizes in E, AS_stand and JS using the original AS_tree and Fd data sets. Consequently, we defined the optimal sample sizes of 10 and 15 for AS_stand and JS estimates, respectively, in the 20 x 20 m plot. Sample sizes larger than the optimal sample sizes did not decrease potential errors. The optimal sample sizes for JS changed according to plot size (e.g., 10 x 10 and 10 x 20 m), whereas the optimal sample sizes for AS_stand did not. As well, the optimal sample sizes for JS did not change in different vapor pressure deficit conditions. In terms of E estimates, these results suggest that the tree-to-tree variations in Fd vary among different plots, and that plot size to capture tree-to-tree variations in Fd is an important factor. The sample sizes determined in this study will be helpful for planning the balanced sampling designs to extrapolate stand-scale estimates to catchment-scale estimates. [ABSTRACT FROM AUTHOR]- Published
- 2010
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8. Estimation of vertical profiles of leaf drying times after daytime rainfall within a Bornean tropical rainforest.
- Author
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Kume, Tomonori, Manfroi, Odair J., Suzuki, Masakazu, Tanaka, Katsunori, Kuraji, Koichiro, Nakagawa, Michiko, Komatsu, Hikaru, and Kumagai, Torno'omi
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FOREST canopy ecology ,WETLAND plants ,LEAF temperature ,RAINFALL frequencies ,FOLIAGE plants ,PLANT canopies ,RAIN forests ,FOREST meteorology - Abstract
The article presents a study which examines the wet-canopy evaporation process within the forest canopy. It states that this process has been applied on eleven individual tress of various heights, ranging from two to fifty meters in Bornean tropical rainforests. It notes the area and structure of the forest, the sap flow and the meteorological measure. It also presents that the length of the canopy drying time after rainfall appears to be strongly related to meteorological conditions above and within the canopy.
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- 2008
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9. Less than 20-min time lags between transpiration and stem sap flow in emergent trees in a Bornean tropical rainforest
- Author
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Kume, Tomonori, Komatsu, Hikaru, Kuraji, Koichiro, and Suzuki, Masakazu
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PLANT transpiration , *FORESTS & forestry , *STATISTICAL correlation , *BIOTIC communities - Abstract
Abstract: Sap flow velocities in stems (Sfs) were measured in four 50-m tall emergent trees in a Bornean tropical rainforest. Cross-correlation analysis was used to estimate time lags between diurnal patterns of Sfs and canopy-scale transpiration (Tr) calculated from a big-leaf model validated by water-vapor flux measurements at this site. The time lags between Sfs and Tr were found to be less than 20min in these trees in both wet and medium dry conditions. In addition, the time lags between Sfs and sap flow velocities measured in a branch at the top of an emergent tree were also less than 20min. These results are in contrast to those of previous studies conducted in a neo-tropical forest ecosystem, which reported significant time lags of 40–120min between transpiration and stem sap flow in emergent trees. The results of this study suggest that hydraulic resistance along the conductive pathway and internal water storage between tree crown and stem are insignificant for this forest. Our results also suggest that sap flow measurements conducted at accessible points can be used to estimate canopy transpiration on a diurnal time scale without accounting for the time lags between canopy transpiration and stem sap flows, despite the 50-m tall forest canopy at our site. [Copyright &y& Elsevier]
- Published
- 2008
- Full Text
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10. Relationship between stem diameter and transpiration for Japanese cypress trees: Implications for estimating canopy transpiration.
- Author
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Tsuruta, Kenji, Komatsu, Hikaru, Kume, Tomonori, Otsuki, Kyoichi, Kosugi, Yoshiko, and Kosugi, Ken'ichiro
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CYPRESS ,SPATIAL variation ,ACTINIC flux ,FOREST management ,DIAMETER ,TREES - Abstract
Previous studies reported relationships between stem diameter at breast height (DBH) and whole‐tree transpiration (Qt) across a variety of species and locations. It might be possible to develop a relationship between DBH and Qt with smaller variations when we focused on a single species. We attempted to develop such a relationship for Japanese cypress (Chamaecyparis obtusa), which is one of the major plantation species in Japan. We collated Qt for 51 Japanese cypress trees from nine different‐sized and different‐aged stands using the sap flux method. We found a strong linear correlation between DBH and the reference value of Qt at a vapour pressure deficit of 1 kPa (R = .883). This was a consequence of a strong correlation between DBH and sapwood area (AS_tree; R = .973) and the absence of a correlation between DBH and sap flux density (R = −.043). We confirmed that using the relationship between DBH and AS_tree, while assuming typical responses of sap flux density to meteorological factors, provides reasonable Qt estimates. This study also demonstrated how the DBH–Qt relationship can be applied to estimate changes in EC with changing forest management. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
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11. Ten-year evapotranspiration estimates in a Bornean tropical rainforest
- Author
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Kume, Tomonori, Tanaka, Nobuaki, Kuraji, Koichiro, Komatsu, Hikaru, Yoshifuji, Natsuko, Saitoh, Taku M., Suzuki, Masakazu, and Kumagai, Tomo’omi
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RAIN forests , *EVAPOTRANSPIRATION , *RAINFALL , *EDDY flux , *METEOROLOGY , *DROUGHTS , *PLANT ecology - Abstract
Abstract: This study was undertaken to quantify interannual variations of total evaporation (ET) in a tropical rainforest in Sarawak, Malaysia. To this end, we conducted 10-year meteorological measurements and formulated a simplified big-leaf model that reproduces transpiration (Et), rainfall interception (Ei), and ET as the sum of these. The model was validated independently using eddy covariance fluxes, rainfall interception based on throughfall and stemflow measurements, and sap flow measurements conducted for more than 2 years. Using the model, Et, Ei, and ET were estimated for the period 2000–2009. Annual Et, Ei, and ET averaged over 10 years were estimated as 1114, 209, and 1323mm, respectively, with small seasonal fluctuations. The derived estimates showed conservative year-to-year variations in annual Et, Ei, and ET (CV=5–7%) in contrast to considerable year-to-year variations in annual rainfall (CV=11%). Specific rainfall characteristics (e.g. intense short duration storms) at this site can explain the conservative year-to-year Ei variations. Small interannual variations in meteorological conditions and absence of severe drought during the study period can explain the small year-to-year Et variations. To characterize ET at our site, we also compared Ei and ET at our site with those of other tropical forests. Based on the derived ET characteristics, we discuss possible ET changes in response to changes in rainfall regime at this site. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
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