(Accession Number: ERDP-2012-01)

Title

Long-term hydrochemical monitoring in Oyasan Experimental Forest Watershed comprised of two small forested watersheds of Japanese cedar and Japanese cypress

Authors

Rieko Urakawa^1,*, Hiroto Toda², Kikuo Haibara², and Yoshinori Aiba²

¹ Asia Center for Air Pollution Research, Japan Environmental Sanitation Center

² Graduate School of Agriculture, Tokyo University of Agriculture and Technology

^*Corresponding author: Rieko Urakawa
Asia Center for Air Pollution Research, Japan Environmental Sanitation Center
1182 Sowa, Nishi-ku, Niigata 950-2144, Japan
Phone: +81-25-263-0560
Fax: +81-25-263-0567

Abstract

Forest ecosystems are self-fertilizing systems, and development of forest stands depends on nutrient supply via biogeochemical cycling within the ecosystem. Therefore, it is important to clarify the nutrient cycle, mediating growth and development. In addition, long-term hydrochemical monitoring is needed to understand the influence of environmental changes on biogeochemical cycling in the forest ecosystem.

The Oyasan Experimental Forest Watershed (OEFW) is located in the Field Museum Oyasan, the university forest of Tokyo University of Agriculture and Technology, in Gunma prefecture, Japan. OEFW comprises two small adjacent forested watersheds, which are A-watershed and B-watershed, with respective areas of 1.3 ha and 1.8 ha.

A-watershed is a reestablished forest planted with sugi (Japanese cedar; Cryptomeria japonica) and hinoki (Japanese cypress; Chamaecyparis obtusa) in 1976, and has been managed intensively with fertilizer application. By contrast, B-watershed is an established forest planted with sugi and hinoki in 1907. No forest practices have been carried out except for the thinning of suppressed trees in 1983. However, the sugi plantation on the lowest slope (18% of the watershed area) was cut in 2000, and sugi was replanted the following year.

In this data paper, we present data on the daily precipitation, discharge, pH, and concentrations of major nutrients (Ca²⁺, Mg²⁺, K⁺, Na⁺, NH₄⁺, Cl^-, NO₃^-, and SO₄^2-) in rainwater and stream water since November 1978.

The arithmetical mean pH of precipitation, stream water in A and B watershed from the beginning of the monitoring to the present were 4.77±0.67, 6.85±0.41 and 6.88±0.36 (average±S.D.), respectively. The arithmetical mean concentrations in precipitation in mmol_c L^-1 were 0.030±0.030 for Ca²⁺, 0.010±0.011 for Mg²⁺, 0.009±0.013 for K⁺, 0.020±0.024 for Na⁺, 0.035±0.041 for NH₄⁺, 0.026±0.029 for Cl^-, 0.033±0.038 for NO₃^-, and 0.046±0.043 for SO₄^2-. The mean concentrations in stream water in A-watershed were 0.180±0.032 for Ca²⁺, 0.073±0.013 for Mg²⁺, 0.018±0.009 for K⁺, 0.182±0.024 for Na⁺, 0.010±0.010 for NH₄⁺, 0.060±0.008 for Cl^-, 0.111±0.038 for NO₃^-, and 0.074±0.012 for SO₄^2-; whereas for B-watershed the mean concentrations were 0.169±0.025 for Ca²⁺, 0.079±0.016 for Mg²⁺, 0.018±0.005 for K⁺, 0.192±0.026 for Na⁺, 0.010±0.010 for NH₄⁺, 0.065±0.010 for Cl^-, 0.093±0.025 for NO₃^-, and 0.087±0.011 for SO₄^2-.

Keywords

Forested watershed, forest practices, hydrochemical monitoring, Japanese cedar, Japanese cypress, long-term monitoring, precipitation, stream water chemistry, water discharge, rainwater chemistry

Introduction—History of Oyasan Experimental Watershed—

To clarify the effects of forest stand development and tending practices on nutrient cycling, hydrochemical monitoring has been performed since November 1978 on two small adjacent watersheds at the Oyasan Experimental Forest Watershed (OEFW) in Field Museum (FM) Oyasan, in Gunma Prefecture, Japan, which is part of the university forest of the Tokyo University of Agriculture and Technology. The respective area of A-watershed and B-watershed is 1.3 ha and 1.8 ha (Fig. 1). Soil parent materials are Paleozoic strata of sandstone and slate. Soil type in both watersheds is moderately moist brown forest soil (B_D) or the drier subtype of moist brown forest soil (B_D(d)) (Forest Soil Division, 1976) which correspond to Andosols (IUSS Working Group WRB, 2006).

Table 1 shows the tending practices at each watershed. The natural secondary forest at both watersheds was felled in 1907, and sugi (Japanese cedar; Cryptomeria japonica) was planted on the lower to middle slopes, while hinoki (Japanese cypress; Chamaecyparis obtusa) was planted on the upper slope. In A-watershed, planted trees were felled again in 1975, and sugi and hinoki plantations were reestablished in 1976. Since then, OEFW has been managed intensively with fertilizer application.

On the other hand, B-watershed, which had a stand age of 72 years at the beginning of monitoring in 1978, has been treated as an ecologically established control site for more than 20 years. Since 1978, no forest practices have been carried out, except for thinning of suppressed trees in 1983. Although, the sugi plantation on the lowest slope (0.3 ha, 18% of the watershed area) was felled in 2000, and sugi was replanted the following year.

Studies on biogeochemical cycles in the artificial forest of sugi and hinoki have previously been carried out. In particular, the effects of tending practices on nutrient cycling and budgets in A-watershed have been intensively studied (Aiba et al., 1981; 1983; 1985a; 1985b; Haibara and Aiba, 1990; Wang et al., 1991; Wang, 1992).

At B-watershed, the forest canopy has been closed for more than 50 years, and water and nutrient dynamics have been studied by measuring the amount of litterfall, water flux, and nutrient concentrations in precipitation, throughfall, stemfall, and stream water (Haibara and Aiba, 1982). In addition, basic information on above-ground biomass and nutrient allocation in sugi and hinoki old-aged stands, annual nutrient uptake by trees, and the amount of total and exchanged cations in the soil were investigated (Toda et al., 1991).

Invention of a simplified soil water extraction method (Toda et al., 1985) enabled understanding of the distribution of dissolved nutrients in soil profiles. The process of alteration in water chemistry from soil to stream water and the interactions between solutes in soil water and stream water have also been studied (Ohrui et al., 1993; 1995; Ohrui, 1995). Flow paths of the stream water were examined by monitoring the chemistry of several rainfall events (Ohrui et al., 1992; Ohrui and Mitchell, 1999). The effects of the environmental factors of watersheds, such as topography and geology, tree composition, and practice history on stream water chemistry, have also been investigated in more than 30 small forested watersheds at FM Oyasan, including the OEFW and FM Kusaki, which is located 5 km east of FM Oyasan (Ohrui et al., 1994; Ohrui and Mitchell, 1998).

The ion exchange resin bag method was invented to examine the ion fluxes percolating downward in soil profiles (Haibara et al., 1990), and the dynamics of dissolved base cations in A-watershed were studied using this method (Wu et al., 1996a).

In the latter half of the 1990’s, the following three additional investigations were carried out at A-watershed: 1) nutrient budget of 18-year-old stands (Ohrui and Mitchell, 1996); 2) separation of dry deposition and canopy leaching of dissolved elements in throughfall by multiple regression analysis using elapsed days from the last rainfall and the amount of precipitation as explaining variables (Wu et al., 1996b); and 3) the effect of nitrogen mineralization on soil water chemistry (Wu, 1997; Wu et al., 1998).

At B-watershed, the dynamics of the following topics in the old-aged artificial forest were investigated: 1) dissolved organic carbon and nitrogen (Oyanagi et al., 2002); 2) soil carbon and nitrogen (Oyanagi, 2002; Oyanagi et al., 2004); and 3) water-soluble ions in soil (Oyanagi et al., 2007).

In addition, changes in dissolved elements in soil water and stream water at B-watershed were examined before and after partial felling of the lowest slope in November 2000 (Urakawa et al., 2005; Urakawa, 2007). Results of laboratory experiments using the subsoil of B-watershed suggested nitrate adsorption by volcanic ash subsoil (Urakawa et al., 2007), and analysis using a numerical model showed that this characteristic affected the retardation of nitrate leaching (Urakawa et al., 2009).

Recently, nitrogen saturation in forest ecosystems has been occurring worldwide, including Japan. The annual amount of nitrogen input into A-watershed and B-watershed exceeded 10 kgN ha^-1 yr^-1 throughout most of the year from water year (Nov. 1 to Oct. 31) 17 to 32 (Fig. 2). Moreover, the annual amount of nitrogen leaching from each site exceeded the input amount, suggesting that both watersheds were in a state of nitrogen saturation (Ohrui and Mitchell, 1997; Ohrui, 1997; Toda, 2002).

Metadata

1. Title

Long-term hydrochemical monitoring in Oyasan Experimental Forest Watershed comprised of two small forested watersheds of Japanese cedar and Japanese cypress

2. Identifier

ERDP-2012-01

3. Contributor

A. Dataset Owner

Laboratory of Forest Ecology, Tokyo University of Agriculture and Technology

Contact address: 3-5-8 Saiwai-cho, Fuchu 183-8509, Tokyo, Japan

B. Contact Person

Hiroto Toda

Affiliation: Graduate School of Agriculture, Tokyo University of Agriculture and Technology
Address: 3-5-8 Saiwai-cho, Fuchu 183-8509, Tokyo, Japan
Phone: 042-367-5745
Email: todah@cc.tuat.ac.jp

4. Geographical Location

A. Geographic Description

Adzuma-cho Town, Midori-shi City, Gunma Prefecture, Japan

B. Geographical Coordinates

(Geographic coordinate system, WGS84)

Weir in A-watershed, 36° 33′ 41.68″ N, 139° 21′ 06.71″ E
Weir in B-watershed, 36° 33′ 43.75″ N, 139° 21′ 12.95″ E

C. Elevation

Weir in A-watershed, 797 m
Weir in B-watershed, 769 m

5. Temporal Coverage

A. Begin

November 1978

B. End

October 2014

6. Methods

A. Measurement of precipitation

A tipping bucket-type rain gauge was installed at the adjacent meteorological enclosure, and data was recorded on paper charts and read manually from 1978 to 1995. From 1996, the data was recorded by an electric data logger at 10-min intervals and cumulated to daily precipitation.

B. Measurement of streamwater discharge

The water level across the V-notch (opening angle, 60°) was measured at the stream gauging weirs of each watershed. From 1978 to 1997, the water level was measured by a water level gauge with a float and recorded on paper charts and read manually. Since 1998, the water level has been measured by a water-pressure sensor and recorded to an electric data logger at 10-min intervals. The water level is converted to flow rate by an empirical equation, and flow rate is cumulated to daily stream water discharge.

C. Rainwater sampling

Bulk rainwater is collected using a polyethylene apparatus consisting of a 30-cm diameter funnel, tubing, and a 5-liter reservoir. Samples were transferred to 250-mL plastic bottles weekly, and the apparatus was washed monthly.

D. Streamwater sampling

Stream water was sampled weekly using 250-mL plastic bottles at each stream gauging weir.

E. Measurement of major nutrient concentrations in streamwater and rainwater

All water samples were measured for pH using a glass electrode immediately after each sampling session and stored below 5 °C in the refrigerator. Chemical analysis of water samples was conducted after filtration with filter papers (5B Advantec, Tokyo, Japan) or DISMIC filters (0.20 µm, Cellulose Acetate, Advantec) using flame photometry, atomic adsorption, and ion chromatography for Na⁺ and K⁺; atomic adsorption and ion chromatography for Mg²⁺ and Ca²⁺; colorimetric methods and ion chromatography for NH₄⁺ and NO₃^-; and ion chromatography for Cl^- and SO₄^2-. Detailed information about methods and time period is shown below.

P, precipitation.
S, streamwater.
N.D., no data.
GE, glass electrode method. Equipment, HM-60S; TOA.
AA, atomic absorption spectrophotometry. Equipment, 170-10; Hitachi.
ICa, ion chromatography. Equipment, HIC-6A; Shimadzu.
ICb, ion chromatography. Equipment, 120; Dionex.
ICc, ion chromatography. Equipment, ICS-1100; Dionex.
FP, flame photometry. Equipment, not specified.
NM, Nessler method. Spectrophotometer, UV-120-01; Shimadzu.
IM, Indophenol method. Spectrophotometer, same as NM.
PM, phenol disulfonic acid method. Spectrophotometer, same as NM.
SM, sulfanilamide-naphthylethylenediamine method after reduction by Cd-Cu column. Spectrophotometer, same as NM.

7. Data Status

A. Latest Update:

April 2016

B. Latest Archive date:

April 2016

C. Metadata status:

Metadata are complete.

8. Accessibility

A. Usage Rights:

Please inform the contact person about the use of the dataset when the publication based on or derived from this dataset is distributed.

B. Data Updates:

The dataset will be updated or recalculated according to the modification of the measuring methods. Please check the latest version of the dataset.

C. Disclaimer:

In no event shall the authors and the dataset owners be liable for loss of profits, or for any indirect, incidental, or consequential damages arising from the use of the dataset.

D. Contact Person:

See 3.B.

9. Data Structure

A. Precipitation and discharge data

A-1. Data set files

Identity: precipitation_discharge.csv
Format and storage mode: ASCII text, comma separated. No compression scheme was used.
Temporal Coverage: November 1 1978 to October 31 2014
Header information: The first row of the file contains the variable names below.

A-2. Variable information

Missing value codes: ‘N.D.’ represents the missing values.

B. Water chemistry data

B-1. Data set files

Identity: waterchemistry.csv
Format and storage mode: ASCII text, comma separated. No compression scheme was used.
Temporal Coverage: November 14 1978 to October 31, 2014
Header information: The first row of the file contains the variable names below.

B-2. Variable information

Missing value codes: ‘N.D.’ represents the missing values.

10. Acknowledgements

Investigations contributing to this data paper were supported by a number of grants from the Ministry of Education, Science, Sports and Culture of Japan. Please refer to each cited reference for details.

The authors would like to thank the technical staff of FM Oyasan, Kiichiro Kaneko, Kuniharu Kaneko, Shigeru Kuwabara, Makoto Kuwabara, Minoru Kaneko, Hiroyuki Kinoshita, and Yoko Takakusaki for maintaining the watersheds and collecting water samples. We also thank the graduate students of the Laboratory of Forest Ecology of TUAT, Yoshihiro Kinoshita, Akira Kondo, Naoya Ikeda, Tatsuji Yamada, Ning Wang, Kiyokazu Ohrui, Ryuta Etoh, Shin Ashizawa, Guonan Wu, Michiyo Takebe, and Nobuhiro Oyanagi, as well as our colleagues, for compiling data and performing water analysis.

11. Literature cited

Aiba Y, Haibara K, Kinoshita Y (1981) The effects of intensive tending works on soil productivity (I) Nutrient status and discharge of a young stand (sapling stage) compared with an established stand. J Jap For Soc 63: 425-434 (in Japanese with English summary)

Aiba Y, Haibara K, Kawabata S (1983) The effects of intensive tending work on soil productivity (II) Decomposition and movement of potential nutrients of fallen sugi (Cryptomeria japonica D. DON) foliage from green pruning. J Jap For Soc 65: 215-219 (in Japanese with English summary)

Aiba Y, Haibara K, Kondo A, Ikeda N (1985a) The effects of intensive tending works on soil productivity (III) Nutrient discharge from young stands caused by weeding, fertilization and the first pruning. J Jap For Soc 67: 73-81 (in Japanese with English summary)

Aiba Y, Haibara K, Kondo A (1985b) The effects of intensive tending works on soil productivity (IV) Nutrient movement for a small watershed of young sugi and hinoki stands. J Jap For Soc 67: 297-304 (in Japanese with English summary)

Forest soil division (1976) Classification of forest soil in Japan (1975). Bull Gov For Exp Sta 280: 1-28 (in Japanese with English summary)

Haibara K and Aiba Y (1982) The nutrient circulation and budget for a small catchment basin of an established Sugi (Cryptomeria japonica D. DON) and Hinoki (Chamaecyparis obtusa S. et Z.) stand. J Jap For Soc 64: 8-14 (in Japanese with English summary)

Haibara K and Aiba Y (1990) Effects of tending practices on nutrient dynamics in a young stand of sugi (Cryptomeria japonica) and hinoki (Chamaecyparis obtusa). For Ecol Manage 30: 233-246

Haibara K, Aiba Y, Kawashima Y (1990) Use of exchange resin (IER) to study the movement of elements in forest soil. Jpn J Ecol 40: 19-25

IUSS Working group WRB (2006) World reference base for soil resource 2006. World Soil Resources Reports No.103, FAO, Rome, pp128

Ohrui K (1995) Study on mechanisms of stream chemistry formation in small forested watersheds. Ph.D. dissertation, 242 pp., United Graduate School of Agric Sci, Tokyo Univ of Agric and Technol, Tokyo (in Japanese with English summary)

Ohrui K (1997) Nitrogen saturation in forest ecosystems: the existing conditions in Japan. Jpn J For Environ 39: 1-9 (in Japanese)

Ohrui K, Haibara K, Aiba Y (1992) Characteristics of dissolved matters in stream water and separation of runoff components of storm events. J Jpn For Soc 74: 203-212 (in Japanese with English summary)

Ohrui K, Haibara K, Aiba Y (1993) Changes in chemical characteristics of water from soil to stream in forest watersheds. J Jpn For Soc 75: 389-397 (in Japanese with English summary)

Ohrui K, Haibara K, Aiba Y (1994) The effects of some factors on stream chemicals of small forested watersheds. J Jpn For Soc 76: 383-392 (in Japanese with English summary)

Ohrui K, Haibara K, Aiba Y (1995) Processes of changes in water chemistry in small forested watersheds. J Jpn Soc Hydrol & Water Resour 8: 367-381 (in Japanese with English summary)

Ohrui K and Mitchell MJ (1996) Elemental dynamics of a Japanese watershed with sugi ( Cryptomeria japonica) and hinoki (Chamaecyparis obtusa) plantations. Can J For Res 26: 2160-2169

Ohrui K and Mitchell MJ (1997) Nitrogen saturation in Japanese forested watersheds. (1997) Ecol Appl 7: 391-401

Ohrui K and Mitchell MJ (1998) Stream water chemistry in Japanese forested watersheds and its variability on a small regional scale. Water Resour Res 34:1553-1561

Ohrui K and Mitchell MJ (1999) Hydrological flow paths controlling stream chemistry in Japanese forested watersheds. Hydrol Proc 13: 877-888

Oyanagi N (2002) Study on dynamics balance between carbon and nitrogen of soil system in a small forested watershed. Ph.D. dissertation, 200 pp., United Graduate School of Agric Sci, Tokyo Univ of Agric and Technol, Tokyo (in Japanese with English summary)

Oyanagi N, Urakawa R, Haibara K, Toda H (2002) The dynamics of dissolved organic nitrogen and dissolved organic carbon in a small watershed of established Japanese cedar and cypress plantation. Jpn J For Environ 44: 11-20 (in Japanese with English summary)

Oyanagi N, Toda H, Kuboi T, Haibara K (2004) Characteristics of carbon and nitrogen dynamics in a small watershed of aged Japanese cedar and cypress stands in the Northern Kanto region, Japan. J Jpn For Soc 86: 134-143 (in Japanese with English summary)

Oyanagi N, Kuboi T, Toda H, Haibara K (2007) Dynamics of water-soluble ions in soil by slope position in an artificially forested watershed with aging Japanese cedar and cypress. J Jpn For Soc 89: 151-159 (in Japanese with English summary)

Toda H (2002) Outline of nitrogen pollution by nitrogen saturation in nutrient circulation of terrestrial ecosystems. J Resour Environ 38: 1067-1072 (in Japanese)

Toda H, Haibara K, Aiba Y (1985) Characteristics of soil-water extracted with an easy soil-water sampler (the suction method). Trans Jap For Soc 96: 253-256 (in Japanese)

Toda H, Haibara K, Arai M (1991) Nutrient circulation in a small watershed under an established sugi (Cryptomeria japonica) and hinoki (Chamaecyparis obtusa) stand. Bull Exp For Tokyo Univ of Agric and Technol 28: 1-22 (in Japanese with English summary)

Urakawa R (2007) Effects of forest cutting in a lower slope on soil water and stream water chemistry in a watershed of old aged Japanese cedar and cypress stands. Ph.D. dissertation, 178 pp., United Graduate School of Agric Sci, Tokyo Univ of Agric and Technol, Tokyo (in Japanese with English summary)

Urakawa R, Toda H, Haibara K (2005) Effects of forest cutting in a lower slope on soil water and stream water chemistry in a watershed of old Japanese cedar and cypress stands. J Jpn For Soc 87: 471-478 (in Japanese with English summary)

Urakawa R, Toda H, Haibara K (2007) Retardation of nitrogen leaching by the NO₃^- adsorption in the subsoil in a watershed of old Japanese cedar and cypress stands. J Jpn For Soc 89:190-199 (in Japanese with English summary)

Urakawa R, Toda H, Haibara K, Choi DS (2009) Effects of anion adsorption characteristics of a volcanic ash soil on long-term NO₃^- leaching from a partial clear-cut cedar and cypress watershed. J Jpn For Soc 91: 184-191 (in Japanese with English summary)

Wang N (1992) Studies of nutrient dynamics in a young stand sugi ( Cryptomeria japonica) soon after crown closure. Ph.D. dissertation, 155 pp., United Graduate School of Agric Sci, Tokyo Univ of Agric and Technol, Tokyo (in Japanese)

Wang N, Haibara K, Aiba Y (1991) Effects of the leaf biomass on the addition of cations to the soil of a young sugi (Cryptomeria japonica) stands. J Jpn For Soc 73: 118-127 (in Japanese with English summary)

Wu (1997) Characteristics of nutrient cycle with the water movement in middle-aged Japanese cedar and cypress plantations. Ph.D. dissertation, 150 pp., United Graduate School of Agric Sci, Tokyo Univ of Agric and Technol, Tokyo (in Japanese)

Wu G, Haibara K, Koike T, Aiba Y (1996a) Dynamics of water-soluble base cations in a forest soil measured by an in situ combined IER method. Jpn J For Environ 38: 92-97

Wu G, Haibara K, Aiba Y, Toda H (1996b) Separations of dry deposition and canopy leaching of dissolved elements in throughfalls of Japanese cedar and cypress stands. J Jpn For Soc 78: 461-466 (in Japanese with English summary)

Wu G, Toda H, Haibara K, Aiba Y (1998) The effects of nitrogen mineralization on water-soluble ions of soils. J Jpn For Soc 80: 21-26 (in Japanese with English summary)