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Jun’ichiro Ide Tomonori Kume Yoshifumi Wakiyama Naoko Higashi Masaaki Chiwa Kyoichi Otsuki 《Forest Ecology and Management》2009
Japanese cypress (Chamaecyparis obtusa) is one of the most common plantation species in Japan. In most Japanese cypress plantations, closure of the forest canopy hinders understory growth because of insufficient management practices. Thus leaf litter barely covers the soil surface. Such plantations are vulnerable to surface erosion triggered by rainfalls, and could yield large amounts of suspended sediment (SS). However, few studies have investigated the annual SS yield. This study aimed to develop a modified model of SS yields, and to accurately estimate and characterize the annual SS yield from a Japanese cypress plantation. For this, hydrological surveys were conducted for 5 years, and stream water was sampled weekly as well as sequentially at 15–60 min intervals in each of 14 rain events in a small forested watershed of Japanese cypress. The root mean square error (RMSE) and the annual SS yield estimates were obtained using three different equations: the rating curve derived from instantaneous SS concentration versus stream discharge relationship (SSC − Q equation); the rating curve derived from cumulative SS yield versus cumulative specific discharge relationship (∑SS − ∑Q equation); and the multiple regression of cumulative SS yield expressed as functions of cumulative specific discharge and antecedent rainfalls (∑SS − ∑Q × AR equation). The ∑SS − ∑Q × AR equation is a modified model considering the effects of antecedent rain history on the SS yield. The parameters in each equation were determined by a nonlinear least square method. Of the three equations, the RMSE was the highest using the SSC − Q equation. Although the ∑SS − ∑Q equation and the ∑SS − ∑Q × AR equation gave similar RMSE values, the SS yields extrapolated by the ∑SS − ∑Q equation would be overestimated. Thus, the 5-year average of annual SS yield estimated by the ∑SS − ∑Q equation was three times larger than that estimated by the ∑SS − ∑Q × AR equation. These results indicate that the ∑SS − ∑Q × AR equation more accurately estimates the annual SS yield, compared with the other two equations. The results also suggest that antecedent rain history, as well as stream discharge, should be considered for appropriately estimating the annual SS yield. The annual SS yield estimated by the ∑SS − ∑Q × AR equation was the largest among 25 undisturbed forested watersheds, except for two watersheds dominated by sandstone. Our results suggest that the annual SS yield is greater from a Japanese cypress plantation under current management practices than from other undisturbed forests. 相似文献
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Rainfall, stemflow, and throughfall were collected from 1996 to 1999 at two types of forest sites: (1) forests near the traffic roads and urban areas and (2) forests away from the urban areas at Mt. Gokurakuji, Hiroshima, western Japan in order to estimatethe effects of anthropogenic activities on atmospheric deposition. Rainfall deposition for major ions showed small differences between the sites. The NO3 - and SO4 2-concentrations in stemflow were higher at the urban-facing slope than at the mountain-facing slope. Throughfall deposition of NO3 - and SO4 2- was also higher at urban-facing slopes. Net throughfall (NTF) deposition (throughfall minus rainfall) of NO3 - and SO4 2- accounted for 77 and50% of the total throughfall deposition on urban-facing slopes, respectively, while it accounted for 44 and 23% on themountain-facing slopes, respectively. These results indicated a higher contribution from dry deposition on urban-facing slopes compared to mountain-facing slopes. Atmospheric N (NO3 - +NH4 +) deposition from throughfall was estimated to be around 17–26 kg N ha-1 yr-1 on urban-facing slopes, which was greater than the threshold of N deposition that could cause nitrogen leaching in Europe and the United States. The highload of atmospheric N deposition may be one of the factors bringing about the decline of pine forests on urban-facing slopesof Mt. Gokurakuji. 相似文献
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Masaaki Chiwa Tomotaka Uemura Kyoichi Otsuki Hiroshi Sakugawa 《Water, air, and soil pollution》2012,223(8):5473-5481
Nitrogenous air pollutants including nitrogen dioxide (NO2), nitric acid (HNO3), nitrate (NO 3 ? ), ammonia (NH3), ammonium (NH 4 + ), and nitrous acid (HONO) were characterized at an urban forested (UF) site in Hiroshima and at a suburban forested (SF) site in Fukuoka, western Japan, using an annular denuder system for 1?year from May 2006 to May 2007 to compare the concentrations and chemical species of atmospheric nitrogenous pollutants between UF and SF sites. The proximity of the urban area was reflected in higher NO2 concentrations at the UF site than at the SF site. NO2 was more oxidized at the SF site because it is farther from an urban area than the UF site, which was reflected in higher concentrations of HNO3 at the SF site than the UF site. HNO3 and acidic sulfate is neutralized by NH3, existing as ammonium nitrate (NH4NO3) and ammonium sulfate [(NH4)2SO4] at the UF site. At the SF site, acidic sulfate is neutralized by NH3, existing as (NH4)2SO4, but NH4NO3, had scarcely formed at the SF site. A much higher HONO concentration was observed at the UF site than at the SF site, especially in winter and spring at night, which could be explained by higher NO2 concentrations at the UF site because of its proximity to an urban area and stagnant meteorological conditions. Atmospheric HONO determination was critical in evaluating the possibility of damage to trees in UF areas. 相似文献
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Nobutake Nakatani Takayuki Miyake Masaaki Chiwa Norichika Hashimoto Takemitsu Arakaki Hiroshi Sakugawa 《Water, air, and soil pollution》2001,130(1-4):397-402
Photochemical formation rates and sources of the hydroxyl (OH) radical were determined in dew water formed on the surface of Japanese red pine (Pinus densiflora) needles of declining (NO2 polluted area) and healthy pine stands at Mt. Gokurakuji located west of Hiroshima city in western Japan. The measured OH radical photoformation rates in dew water (n=10), which were normalized to the rate at midday on May 1 at 34°N, ranged from 0.67 to 5.18 µM h?1 (1M=1mol L?1). The mean value (2.69 µM h?1) was higher than that in dew water collected on a Teflon board and higher than the mean value in rain water published previously. Of the total OH radical formation rate observed in dew water on the pine needles, 16.4 % was estimated to originate from N (III) (NO2 ? and HNO2) and 24.6 % was estimated to originate from NO3 ?. There were other sources of OH radical photochemical formation in dew water on the pine needles besides photolysis of NO2 ? and NO3 ?. 相似文献
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Yuka Onozawa Masaaki Chiwa Hikaru Komatsu Kyoichi Otsuki 《Journal of Forest Research》2009,14(2):111-116
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. 相似文献
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Jun'ichiro Ide Osamu Nagafuchi Masaaki Chiwa Atsushi Kume Kyoichi Otsuki Shigeru Ogawa 《Journal of Forest Research》2007,12(1):45-56
The behavior of dissolved and particulate components of stream nitrogen (N) and phosphorus (P) were measured for 2 years in
a small mountainous watershed covered primarily with a plantation forest of Japanese cypress (Chamaecyparis obtusa). The load of dissolved N and P bore a consistent relationship to discharge while the load of particulate N and P varied
by up to two orders of magnitude at a given discharge level. Most N was exported in a dissolved form (DN) while most P was
exported in a particulate form (PP), which bears similarity to loads from agricultural watersheds. Owing to the different
behaviors of DN and PP, changes in the total nitrogen (TN) load were primarily attributed to variations in discharge unlike
changes in the total phosphorus (TP) load. High flow conditions, resulting from heavy rainfall, displayed PP release significantly
larger than expected. The TP load in high flow conditions was severely underestimated using a regression equation expressed
as a function of discharge, which was based on the weekly sampling data biased toward low flow conditions. In addition, the
TN load during peak discharges in heavy rain events was underestimated by the regression equation because of unpredictable
increases in the particulate component. Our study shows that the particulate component ratio determines whether discharge
can explain changes in load regardless of chemical species. The results suggest that plantation forests in rainy regions can
be a diffuse source of particulate nutrients depending on soil surface conditions. 相似文献
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