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Although changes in rainfall characteristics have been noted across the world, few studies have reported those in mountainous areas. This study was undertaken to clarify spatial and temporal variations in rainfall characteristics such as annual rainfall amount ( Pr), mean daily rainfall intensity ( η), and ratio of rain days ( λ) in mountainous and lowland areas in Taiwan. To this aim, we examined spatial and year-to-year variations and marginal long-term trends in Pr, η, and λ, based on rainfall data from 120 stations during the period 1978-2008. The period mean rainfall ( [ABSTRACT FROM AUTHOR]

In recent years, Moso bamboo ( Phyllostachys pubescens) forests have rapidly expanded in Japan by replacing surrounding coniferous and/or broadleaved forests. To evaluate the change in water yield from forested areas because of this replacement, it is necessary to examine evapotranspiration for Moso bamboo forests. However, canopy interception loss, one of the major components of evapotranspiration in forested areas, has been observed in only two Moso bamboo forests in Japan with relatively high stem density (~7000 stems/ha). There are, in fact, many Moso bamboo forests with much lower stem density. Thus, we made precipitation ( Pr), throughfall ( Tf) and stemflow ( Sf) observations for 1 year in a Moso bamboo forest with stem density of 3611 stems/ha and quantified canopy interception loss ( Ic). Pr and Ic for the experimental period were 1636 and 166 mm, respectively, and Ic/ Pr was 10%. The value was approximately the same as values for the other two Moso bamboo forests and lower than values for coniferous and broadleaved forests. On the other hand, Tf/ Pr and Sf/ Pr for our forest (86% and 4%, respectively) were approximately 10% of Pr larger and smaller than values for the other two Moso bamboo forests. These results suggest that the difference in stem density greatly affects precipitation partitioning (i.e. Tf/ Pr and Sf/ Pr) but does not greatly change Ic/ Pr. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

According to widely held belief, annual evapotranspiration (ET) for broadleaf forests is less than that for coniferous forests, resulting in higher annual runoff for broadleaf forests. We processed 82 catchment runoff and 126 interception loss data from temperate regions and found that although the belief is valid under conditions of broadleaf deciduous forests and high winter precipitation (e.g. the United States), it is invalid under conditions of broadleaf evergreen forests (e.g. New Zealand) or low winter precipitation (e.g. Japan). Thus, forest management policies based on this belief should be reconsidered on the basis of our results for regions with broadleaf evergreen forests or low winter precipitation. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Sap flow techniques are practical tools for estimating tree transpiration. Though many previous studies using sap flow techniques did not consider azimuthal variations of sap flux density ( F) on xylem trunk to estimate tree transpiration, a few studies reported that ignoring the azimuthal variations in F could cause large errors in tree transpiration estimates for some tree species. Therefore, examining azimuthal variations in F for major plantation tree species is critical for estimating tree transpiration. Using the thermal dissipation method, we examined azimuthal variations in F in six trees of Japanese cypress Chamaecyparis obtusa (Sieb. et Zucc.) Endl., which is one of the most common plantation tree species in Japan. We recorded considerable variations among F at four different azimuthal directions. The F value for one aspect was more than 100% larger than those for the other aspects. We calculated differences between tree transpiration estimates based on F for one to three azimuthal directions and those based on F for four aspects. The differences relative to tree transpiration estimates based on F for four aspects were typically 30, 20, and 10% in accordance with the F for one, two, and three measurement aspects, respectively. This finding indicates that ignoring azimuthal variations could cause large errors in tree transpiration estimates for Japanese cypress. [ABSTRACT FROM AUTHOR]

Temperature data in the mountain forest regions are often extrapolated from temperature data recorded at base stations at lower elevation. Such extrapolation is often based on elevation differences between target regions and base stations at low elevation assuming a constant temperature lapse rate throughout the year. However, this assumption might be problematic where slope circulation is active and decoupled from the regional circulation. To model the seasonal change in the lapse rate, the authors compared daily maximum ( Tmax) and minimum temperatures ( Tmin) observed at a mountain forest site (Kog–Ma; 1300-m altitude) with those observed at the bottom of the basin (Chiang–Mai; 314-m altitude) in northern Thailand, where slope circulation is active and decoupled from the regional circulation. The difference in Tmax between Kog–Ma and Chiang–Mai (Δ Tmax; Kog–Ma minus Chiang–Mai) was relatively unchanged throughout the year. However, the difference in Tmin between Kog–Ma and Chiang–Mai (Δ Tmin) changed seasonally. Thus, assuming a constant lapse rate throughout the year could cause large errors in extrapolating Tmin data in mountainous areas in northern Thailand. The difference Δ Tmin was related to nighttime net radiation (Rn), suggesting that nocturnal drainage flow affects the determination of Δ Tmin. This relationship would be useful in formulating seasonal changes in the lapse rate for Tmin. As Rn data are generally unavailable for meteorological stations, an index that relates to the lapse rate for Tmin and is calculated from Tmax and Tmin data is proposed. This index might be useful for accurately estimating Tmin values in mountainous regions in northern Thailand. [ABSTRACT FROM AUTHOR]

Researchers and journalists in Japan recently proposed forest management as an alternative to dam reservoir development for water resource management. To examine the validity of the proposal, we compared the potential low-flow increase due to forest clearcutting with the increase due to dam reservoir development. Here, we focused on forest clearcutting as an end member among various types of forest management. We first analyzed runoff data for five catchments and found a positive correlation between annual precipitation and the low-flow increase due to deforestation. We then examined the increase in low-flow rates due to dam reservoir development (dQd ) using inflow and outflow data for 45 dam reservoirs across Japan. Using the relationship between annual precipitation and the low-flow increase due to deforestation, we estimated the potential increase in the low-flow rate for each dam reservoir watershed if forests in the watershed were clearcut (dQf ). Only 6 of the 45 samples satisfied dQf > dQd , indicating that the potential increase in the low-flow rate due to forest clearcutting was less than the increase due to dam reservoir development in most cases. Twenty-five of the 45 samples satisfied dQf <0.2 dQd , indicating the potential increase in the low-flow rate due to forest clearcutting was less than 20% of the increase due to dam reservoir development in more than half the cases. Therefore, forest management is far less effective for water resource management than dam reservoir development is in Japan. [Copyright &y& Elsevier]

The article presents a study on the effects of bamboo forest expansion on water resources. Spatial and seasonal variations in throughfall (Tf) and canopy structure (Rf) were observed. Results of the study indicate that the change in leaf area index (LAI) has little impact on Tf and that Rf is a critical factor. The study suggests a sampling design for Tf measurements and the effects of forest expansion to evapotranspiration.

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. [ABSTRACT FROM AUTHOR]

Summary: In Japan, forested areas are usually located upstream of urban and agricultural areas. Estimating annual water yield from such forested areas is therefore crucial for water resources management. For this purpose, estimating annual forest evapotranspiration is required. We developed an empirical model for estimating annual forest evapotranspiration E in Japan based on 43 catchment water balance datasets summarized from earlier publications. The model formulated E as E (mm)=31.4T (°C)+376, where T is mean annual air temperature. This model estimated E observed in forest catchments with an average 6% error relative to incident annual precipitation. This error was comparable to or smaller than the error included in precipitation data due to the spatial heterogeneity of precipitation. High-quality air temperature data are commonly available in Japan, thus this model is a practical tool for annual water yield estimates from forested areas and therefore water resources management. [Copyright &y& Elsevier]

To our knowledge, no one has examined the canopy conductance of a Cryptomeria japonica plantation, although such forests are very common in Japan. We plan to examine the canopy conductance of a Cryptomeria japonica plantation (canopy height 8 m) based on 1-year sap-flow data using the simplified Penman-Monteith equation. This study examines the effect of the aerodynamic control of transpiration before calculating canopy conductance using the simplified Penman-Monteith equation, because the equation assumes that the effect of aerodynamic control is negligible. To examine the effect of aerodynamic control, we examined the dependency of the relationship between the vapour pressure deficit (VPD) and transpiration on wind speed, when solar radiation, air temperature, and soil water content do not limit transpiration greatly. The relationship between VPD and the heat pulse velocity measured 11 m above the ground was dependent on wind speed only when the wind speed was < 0.7 m s-1. This suggests that the effect of aerodynamic control was negligible when the wind speed was < 0.7 m s-1, but that the effect was not negligible when the wind speed was < 0.7 m s-1. Therefore, we should use data from when the wind speed was ≥ 0.7 m s-1 for calculating canopy conductance Gc, based on the simplified Penman-Monteith equation. Although this criterion is site specific, the methods used to develop it are applicable to other sites. [ABSTRACT FROM AUTHOR]

To our knowledge, there is no information on the canopy conductance of Cryptomeria japonica plantations, although such forests are very common in Japan. We examined the canopy conductance Gc of a C. japonica plantation based on 1-year sap-flow data using the simplified Penman-Monteith equation. After selecting data based on the criterion proposed in part 1 of this study (Komatsu et al., 2006. Hydrological Processes 20: this issue), we now examine Gc responses to meteorological factors. Gc was expressed using functions of solar radiation S (W m-2), the vapour pressure deficit D (kPa), and air temperature T (°C). The resulting functions were f1(S) = [(1000 + 30)S]/[1000(S + 30)], f2(D) = exp(-0.54D)/exp(-0.54), and f3(T) = {[(30 - 5) + 14](T - 5)}/{(30 - 5)[(T - 5) + 14]), where f1(S), f2(D), and f3(T) are functions expressing the Gc responses to S, D, and T respectively. The functions were characterized by comparing general functions for coniferous forests, which showed that it was necessary to consider f3(T) to reproduce the 1-year transpiration at the site, and that f1(S) and f2(D) determined here were not very different from the general functions. This paper is the first to determine Gc responses to meteorological factors for a C. japonica plantation. When predicting transpiration from a C. japonica plantation using hydrological or ecological models, the functions determined here should be used instead of the default functions of the models. [ABSTRACT FROM AUTHOR]

• Models were developed to overcome shortcomings of traditional meta-analyses. • Models for smalls scales proposed around 1990 were not widely used. • Practical models focusing on specific contexts began to be developed around 2000. • Forest hydrologists should develop practical models for collective decision-making. There exist very few reviews of models that predict changes in evapotranspiration with forest management (e.g., clearcutting and thinning). This omission has potentially prevented forest hydrologists from effectively identifying critical research topics and collaborating with policymakers, practitioners, and researchers in related fields to assist policymaking. To remedy this omission, the current study elaborates why models were needed in the first place and how models were developed historically. Models were developed to overcome limitations of traditional meta-analyses of measurement studies (i.e., inability to explain between-site variations in evapotranspiration changes with forest management) that had been recognized since the 1960s. With the improvement of the understandings about evapotranspiration processes, forest hydrologists proposed models that could predict changes in evapotranspiration with forest management around 1990. Among the models proposed around 1990, models for large scales were widely used for practical purposes (e.g., assessing the impact of large-scale deforestation on the continental and global water cycle). However, models for small scales were not widely used for assessing the impacts of forest management on water resources and other practical purposes. One major reason for this was that models for small scales proposed around 1990 were primarily designed as research tools. To improve practical applicability, forest hydrologists then started developing simple, practical models for small scales that focused on applications to a particular area, species, and purpose around 2000. Considering the necessity of human society to adapt to emerging environmental challenges within a limited time frame, we conclude that the primary role of forest hydrologists in this era is to quickly detect emerging environmental challenges and then develop practical models for connecting different stakeholders for collective decision-making. This paper also suggests that the use of practical models can be a starting point to rearticulate the role of forest hydrologists in policymaking. [ABSTRACT FROM AUTHOR]

The overarching assumption of SDG 4, that progress towards 'quality education' will lead to greater sustainability, is not rooted in evidence but instead in ideology. From the outset, a wider set of sustainability indicators (such as ecological footprint) were excluded, and even today, after a decade of work, there exists no indicator to capture 'sustainability'. Instead SDG 4 discussions remain a mixed bag of routine monitoring of outcomes, advocacy for more funding, and banal policy recommendations. The development 'specialists' leading all of this have turned a blind eye to this obvious fact, and shown strikingly little willingness to think differently – a position that is intellectually irresponsible, politically unaccountable, and deeply unethical in the context of an accelerating climate crisis. The next 7 years should be refocused on highlighting alternatives and developing evidence for the post-2030 agenda. • No evidence exists showing SDG 4 leads to sustainability. • SDG 4 implementation further extends the unsustainable 'modern paradigm'. • A growing body of research highlights potential alternatives. • SDG 4 debates should be (re)focused on generating evidence for the post-2030 agenda. [ABSTRACT FROM AUTHOR]

Lianas (woody climbers) have a greater amount of leaves relative to basal area or standing biomass than trees, and very wide vessels that permit efficient water transport. These features suggest that lianas possibly consume proportionally more water through transpiration than trees. Despite their potential importance, researchers have made only limited attempts to evaluate effects of lianas on forest water dynamics., We conducted sap flow measurements for 1 year using a thermal dissipation method for four species each of lianas and trees in a liana-rich, warm-temperate forest in Japan and estimated the contribution of lianas to stand canopy transpiration., Based on a calibration measuring water uptake rates from cut-stem ends, the actual sap flux ( Fd) in liana stems was several times greater than those estimated from the original calibration provided for the method. In the field, lianas showed an average of 2-4 times greater Fd than trees throughout the year. Except for this difference, diurnal and seasonal patterns of relative changes of Fd were similar in both groups. The whole-plant transpiration ( Qt) of sample plants was exponentially related to basal diameter for both lianas and trees; Qt of lianas increased more steeply with basal diameter than that of trees. By extrapolating the relationships between Qt and basal diameter to the inventory data of the study plot, we estimated that lianas contributed 12·8% to the annual stand canopy transpiration while comprising 2·3% of stand basal area, which probably reflected the top-heavy architecture of lianas., Our results indicate that the contribution of lianas to forest water dynamics may be several times greater than their contribution to forest basal area. This implies that a slight increase of liana abundance might have greater effects on water dynamics and, through competitions with trees for limited water, the carbon sequestration capacity of forests than expected from the increase in basal area. This study underlines the necessity of evaluating the relative importance of lianas to forest water dynamics in forests world-wide., A is available for this article. [ABSTRACT FROM AUTHOR]

In the last several years, thinning has been conducted in coniferous plantations throughout Japan, mainly to secure water resources. Although canopy interception loss ( I c ) is a major component of evapotranspiration, this is among the first studies that have examined changes in I c while considering the effects of thinning in Japanese cedar ( Cryptomeria japonica ) forests, the most common type of plantation in Japan. We compared and contrasted three canopy interception models (Mulder, revised Gash, WiMo) before and after intensive thinning operations. The experimental Japanese cedar forest was intensively thinned with removal of 54% of all stems, reducing the basal area by 50% from 99.7 to 49.6 m 2 ha −1 . Prior to thinning, all three canopy interception models performed well with root mean square errors for the Mulder, revised Gash, and WiMo models of 2.96, 3.59, and 3.81 mm, respectively; while those after thinning were 1.32, 2.37, 2.38 mm, respectively. In addition, all three canopy interception models performed better than the mean before thinning as evaluated by the Nash–Sutcliffe model efficiency with values 0.51 (Mulder), 0.28 (revised Gash), and 0.19 (WiMo) but did not perform as well after heavy thinning. These results suggest that canopy interception models might not be applicable after intensive thinning of Japanese cedar forests. [ABSTRACT FROM AUTHOR]

In central Cambodia, rapidly growing non-endemic species are often planted for timber production. The introduction of non-endemic species into stands with native species has been found to alter the forest transpiration characteristics in this region with distinct dry and rainy seasons defined by the different rainfall patterns. However, less is understood about the underlying processes, especially the ecophysiological characteristics of native species that are adapted to the highly seasonal environments and the non-endemic species that acclimate to those environments. Leaf ecophysiological traits were measured for two native and two representative non-endemic tree species in central Cambodia to examine whether species-specific seasonal trends in transpiration could be explained by leaf ecophysiological traits. Photosynthetic capacity as represented by the maximum carboxylation rate ( V cmax25 ) of each species remained constant in the rainy and dry seasons. Native species had high stomatal conductance ( g sw ) and the parameter for its response to the environments ( m ) in the rainy season and lower levels in the dry season. Additionally, the seasonal change in g sw for non-endemic species was less clear despite the seasonality in the tree-level transpiration. A multi-layer model that incorporated the measured data related to the leaf ecophysiological traits and their seasonal changes successfully reproduced the daily canopy-scale transpiration rate ( E canopy ). The modeled E canopy successfully reproduced most of the seasonal and day-to-day changes in measured E canopy using sap flux measurements and showed the strong control of leaf ecophysiological traits over E canopy and the species-specific seasonal trends. Two reduction events in measured E canopy were, however, not explained by the simulation, possibly as a result of species-specific factors that were not considered in this study, i.e., the reduction in water uptake by a native species caused by drought and the hypoxic effects of flooding on the roots of a non-endemic species. [ABSTRACT FROM AUTHOR]

Highlights: [•] Tree sap flux was measured under changing water environments in Cambodia. [•] Seasonal change in the groundwater table depth lagged behind that of rainfall. [•] Species showed contrasting sap flux response to the groundwater table depth. [•] Changes in species composition may alter transpiration under climatic changes. [Copyright &y& Elsevier]

Difficult access to 40-m-tall emergent trees in tropical rainforests has resulted in a lack of data related to vertical variations in wood CO2 efflux, even though significant variations in wood CO2 efflux are an important source of errors when estimating whole-tree total wood CO2 efflux. This study aimed to clarify vertical variations in wood CO2 efflux for emergent trees and to document the impact of the variations on the whole-tree estimates of stem and branch CO2 efflux. First, we measured wood CO2 efflux and factors related to tree morphology and environment for seven live emergent trees of two dipterocarp species at four to seven heights of up to ∼40 m for each tree using ladders and a crane. No systematic tendencies in vertical variations were observed for all the trees. Wood CO2 efflux was not affected by stem and air temperature, stem diameter, stem height or stem growth. The ratios of wood CO2 efflux at the treetop to that at breast height were larger in emergent trees with relatively smaller diameters at breast height. Second, we compared whole-tree stem CO2 efflux estimates using vertical measurements with those based on solely breast height measurements. We found similar whole-tree stem CO2 efflux estimates regardless of the patterns of vertical variations in CO2 efflux because the surface area in the canopy, where wood CO2 efflux often differed from that at breast height, was very small compared with that at low stem heights, resulting in little effect of the vertical variations on the estimate. Additionally, whole-tree branch CO2 efflux estimates using measured wood CO2 efflux in the canopy were considerably different from those measured using only breast height measurements. Uncertainties in wood CO2 efflux in the canopy did not cause any bias in stem CO2 efflux scaling, but affected branch CO2 efflux. [ABSTRACT FROM PUBLISHER]

To clarify characteristics of carbon (C) allocation in a Bornean tropical rainforest without dry seasons, gross primary production (GPP) and C allocation, i.e., above-ground net primary production (ANPP), aboveground plant respiration (APR), and total below-ground carbon flux (TBCF) for the forest were examined and compared with those from Amazonian tropical rainforests with dry seasons. GPP (30.61 MgC ha year, eddy covariance measurements; 34.40 MgC ha year, biometric measurements) was comparable to those for Amazonian rainforests. ANPP (6.76 MgC ha year) was comparable to, and APR (8.01 MgC ha year) was slightly lower than, their respective values for Amazonian rainforests, even though aboveground biomass was greater at our site. TBCF (19.63 MgC ha year) was higher than those for Amazonian forests. The comparable ANPP and higher TBCF were unexpected, since higher water availability would suggest less fine root competition for water, giving higher ANPP and lower TBCF to GPP. Low nutrient availability may explain the comparable ANPP and higher TBCF. These data show that there are variations in C allocation patterns among mature tropical rainforests, and the variations cannot be explained solely by differences in soil water availability. [ABSTRACT FROM AUTHOR]

Abstract: This study was undertaken to identify critical and practical factors explaining spatial variations in soil respiration and to estimate stand-scale soil respiration in an aseasonal tropical rainforest on Borneo Island. To this aim, we conducted soil respiration measurements at 25 points in a 40m×40m subplot of a 4ha study plot between 2002 and 2006, and examined the spatial variation in soil respiration averaged over the 4 years in relation to soil, root, and forest structural factors. In addition, we examined the spatial representativeness of soil respiration measured in the subplot using a specific scaling procedure. Consequently, we found significant positive correlation between the soil respiration and forest structural parameters such as the mean diameter at breast height (DBH), total basal area, and maximum DBH within 6m of the measurement points. The most important factor was the mean DBH within 6m of the measurement points, which had a significant linear relationship with soil respiration. Using the derived linear regression and an inventory dataset, we estimated the 4ha plot-scale soil respiration. The 4ha plot-scale estimation (6.0μmolm−2 s−1) was nearly identical to the subplot-scale measurements (5.7μmolm−2 s−1), which were roughly comparable to the nocturnal CO2 fluxes calculated using the eddy covariance technique. In addition, we discuss characteristics of the stand-scale soil respiration at this site by comparing with those of other forests reported in previous literature in terms of the soil C balance. Soil respiration at our site was noticeably greater, relative to the incident litterfall amount, than soil respiration in other tropical and temperate forests probably owing to the larger total belowground C allocation by emergent trees. Overall, this study suggests the arrangement of emergent trees with larger DBH and their belowground C allocation could be primary factors controlling spatial variations in soil respiration in the tropical rainforest. [Copyright &y& Elsevier]

Summary We examined the effect of strip thinning on rainfall interception ( E i ) in a 32-year-old Japanese cypress plantation in central Japan. Strip thinning was conducted in the catchment in October 2011; that removed 50% of the stems. The gross precipitation ( P g ), throughfall ( TF ) and stemflow ( SF ) were monitored in a 12-m × 13-m plot before and after thinning. E i was calculated as the difference between P g and the sum of TF and SF . The interception processes were illustrated using the revised Gash model with quantifying interception parameters. The results showed that the Gash model successfully predicted E i on a rainy-season basis in both pre- and post-thinning periods. Thinning altered the interception components whereas the largest part during and after rainfall accounted for similar proportion in both periods. Additionally, after thinning, the annual TF rate was increased from 61.4% to 73.0%, whereas the annual SF rate was decreased from 9.8% to 6.1%, and the annual E i rate was decreased from 28.7% to 20.8%. The summarized findings of previous studies indicate that the degree of decline in the E i caused by thinning is related to P g and the thinning ratio. These results provide useful information for understanding the changes in interception processes induced by thinning, and for acquiring a more accurate forecast of the effects of forest management practices on water resources in the watershed. The response in rainfall partitioning to strip thinning can also help us to acquire an integrated understanding of the changes in canopy water balance under different forest practices. [ABSTRACT FROM AUTHOR]

Highlights: [•] We obtained reliable estimations of water use components in Japanese cedar stands. [•] We found a constant ratio of interception to rainfall (P) throughout a year. [•] Upper canopy transpiration contributes to total water use during scarce rainfall. [•] These result in a conservative ratio of evapotranspiration to P throughout the year. [ABSTRACT FROM AUTHOR]

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]

The prevalence of forestry practices such as thinning and pruning have gradually decreased since the 1980s. Researchers have noted an increased flood risk with decreased forestry practices for coniferous plantations in Japan on the basis of infiltration and overland flow measurements at a plot scale (typically several square meters). However, no studies have examined changes in peak flow with decreased forestry practices at a watershed scale (typically several tens or hundreds of square kilometers) even though flood disasters generally occur at this scale in Japan. We examined changes in frequency distributions of daily precipitation (P) and runoff (Q) during the period 1979-2007 at the Terauchi watershed, where forestry practices are known to have decreased. For this purpose, we divided P and Q data into 14 and 15 classes according to the magnitude, respectively, and examined changes in the frequency for each class during the period. We observed no significant increasing trend for any P or Q class. Even when taking into account the effect of interannual variations in precipitation on the frequency for each Q class, there was no significant increasing trend in the frequencies except for two Q classes with moderate Q values. These results suggest that the increase in flood risk due to decreased forestry practices might be less than expected., (Copyright © 2011 Elsevier Ltd. All rights reserved.)