Metadata

(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 Urakawa1,*, 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 SO42-) 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 mmolc 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 SO42-. 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 SO42-; 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 SO42-.

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 (BD) or the drier subtype of moist brown forest soil (BD(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).

Fig-1
Table-1 Tending practices at the Oyasan Experimental Forest Watershed
Year Montd Water Year* A-watershed B-watershed
Stand Age Practice Stand Age Practice
1907 1 Planting of sugi and hinoki 1 Planting of sugi and hinoki
1975 Jul 69 Clear-cutting
1976 Jun 1 Planting of sugi and hinoki
Jul Fertilizer application (N: 33 kgN ha-1)
1977 Apr 2 Fertilizer application (N: 38 kgN ha-1)
Oct Weeding
1978 May 3 Fertilizer application (N: 60 kgN ha-1)
Jul Weeding
Sep Weeding
Nov 1 4 Beginning of hydrochemical monitoring 73 Beginning of hydrochemical monitoring
1979 Apr Fertilizer application (N: 100 kgN ha-1)
Jul Weeding
1980 Jul 2 5 Weeding
1981 Aug 3 6 Weeding
Nov 4 7 Pruning (50% of tree height)
1982 May Fertilizer application (N: 100 kgN ha-1)
1983 Mar 5 77 Thinning of suppressed trees
1984 Jun 6 9 Fertilizer application (N: 100 kgN ha-1)
1986 Mar 8 11 Pruning (40% of tree crown)
1987 Apr 9 12 Fertilizer application (N: 154 kgN ha-1)
1995 Mar 17 20 Thinning (38% of tree)
2000 Nov 23 95 Partial clear-cutting
(18% of watershed)
2001 May 23 95/1 Planting sugi in the clear-cut area

*: Water year is from November 1 to October 31 at the OEFW.

Fig-2

Metadata

1. Title

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

ERDP-2012-01

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

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

A. Begin

November 1978

B. End

October 2014

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 SO42-. Detailed information about methods and time period is shown below.

water year date pH Ca2+ Mg2+ K+ Na+ NH4+ Cl- NO3- SO42-
from to P S P S P S P S P S P S P S P S P S
1 1978/11/1 1979/10/31 N.D. N.D. AA AA AA AA FP FP N.D. N.D. NM NM N.D. N.D. PM PM N.D. N.D.
2 1979/11/1 1980/10/31 N.D. N.D. AA AA AA AA FP FP N.D. N.D. N.D. N.D. N.D. N.D. PM PM N.D. N.D.
3 1980/11/1 1981/10/31 N.D. N.D. AA AA AA AA FP FP FP FP N.D. N.D. N.D. N.D. PM PM N.D. N.D.
4 1981/11/1 1982/10/31 N.D. N.D. AA AA AA AA FP FP FP FP N.D. N.D. N.D. N.D. PM PM N.D. N.D.
5 1982/11/1 1983/10/31 N.D. N.D. AA AA AA AA FP FP FP FP IM N.D. N.D. N.D. SM SM N.D. N.D.
6 1983/11/1 1984/10/31 N.D. N.D. AA AA AA AA FP FP FP FP IM N.D. N.D. N.D. SM SM N.D. N.D.
7 1984/11/1 1985/10/31 N.D. N.D. AA AA AA AA AA AA FP FP N.D. N.D. N.D. N.D. SM SM N.D. N.D.
8 1985/11/1 1986/10/31 N.D. N.D. AA AA AA AA AA AA FP FP N.D. N.D. N.D. N.D. SM SM N.D. N.D.
9 1986/11/1 1987/10/31 N.D. N.D. AA AA AA AA AA AA FP FP N.D. N.D. N.D. N.D. N.D. SM N.D. N.D.
10 1987/11/1 1988/10/31 N.D. N.D. AA AA AA AA AA AA AA AA ICa N.D. ICa ICa ICa ICa ICa ICa
11 1988/11/1 1989/10/31 GE GE AA AA AA AA AA AA AA AA ICa N.D. ICa ICa ICa ICa ICa ICa
12 1989/11/1 1990/10/31 GE GE AA AA AA AA AA AA AA AA ICa N.D. ICa ICa ICa ICa ICa ICa
13 1990/11/1 1991/10/31 GE GE AA AA AA AA AA AA AA AA ICa N.D. ICa ICa ICa ICa ICa ICa
14 1991/11/1 1992/10/31 GE GE AA AA AA AA AA AA AA AA ICa N.D. ICa ICa ICa ICa ICa ICa
15 1992/11/1 1993/10/31 GE GE AA AA AA AA AA AA AA AA ICa N.D. ICa ICa ICa ICa ICa ICa
16 1993/11/1 1994/10/31 N.D. N.D. N.D. N.D. N.D. N.D. N.D. N.D. N.D. N.D. N.D. N.D. N.D. N.D. N.D. N.D. N.D. N.D.
17 1994/11/1 1995/10/31 GE GE AA AA AA AA AA AA AA AA ICa ICa ICa ICa ICa ICa ICa ICa
18 1995/11/1 1996/10/31 GE GE AA AA AA AA AA AA AA AA ICa ICa ICa ICa ICa ICa ICa ICa
19 1996/11/1 1997/10/31 GE GE AA AA AA AA AA AA AA AA N.D. N.D. ICa ICa ICa ICa ICa ICa
20 1997/11/1 1998/10/31 GE GE AA AA AA AA AA AA AA AA ICa ICa ICa ICa ICa ICa ICa ICa
21 1998/11/1 1999/10/31 GE GE AA AA AA AA AA AA AA AA ICa ICa ICa ICa ICa ICa ICa ICa
22 1999/11/1 2000/10/31 GE GE AA AA AA AA AA AA AA AA ICa ICa ICa ICa ICa ICa ICa ICa
23 2000/11/1 2001/10/31 GE GE ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa
24 2001/11/1 2002/10/31 GE GE ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa
25 2002/11/1 2003/10/31 GE GE ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa
26 2003/11/1 2004/10/31 GE GE ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa
27 2004/11/1 2005/10/31 GE GE ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa
28 2005/11/1 2006/10/31 GE GE ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa
29 2006/11/1 2007/10/31 GE GE ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa
30 2007/11/1 2008/10/31 GE GE ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa ICa
31 2008/11/1 2009/10/31 GE GE ICb ICb ICb ICb ICb ICb ICb ICb ICb ICb ICb ICb ICb ICb ICb ICb
32 2009/11/1 2010/10/31 GE GE ICb ICb ICb ICb ICb ICb ICb ICb ICb ICb ICb ICb ICb ICb ICb ICb
33 2010/11/1 2011/10/31 GE GE ICb ICb ICb ICb ICb ICb ICb ICb ICb ICb ICb ICb ICb ICb ICb ICb
34 2011/11/1 2012/10/31 GE GE ICc ICc ICc ICc ICc ICc ICc ICc ICc ICc ICc ICc ICc ICc ICc ICc
35 2012/11/1 2013/10/31 GE GE ICc ICc ICc ICc ICc ICc ICc ICc ICc ICc ICc ICc ICc ICc ICc ICc
36 2013/11/1 2014/10/31 GE GE ICc ICc ICc ICc ICc ICc ICc ICc ICc ICc ICc ICc ICc ICc ICc ICc

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.

A. Latest Update:

April 2016

B. Latest Archive date:

April 2016

C. Metadata status:

Metadata are complete.

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.

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

Variable name Variable definition Unit Storage type Precision
water year Water year is from Nov. 1 to Oct. 31 N/A Integer 1
date yyyy/mm/dd N/A Date 1
precipitation Daily precipitation amount mm d-1 Real number 0.1
A Daily discharge from A-watershed mm d-1 Real number 0.01
B Daily discharge from B-watershed mm d-1 Real number 0.01

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

Variable name Variable definition Unit Storage type Precision
ID Type of water samples: precipitation, precipitation samples; A, streamwater samples of A-watershed; B, streamwater samples of B-watershed N/A Character N/A
water year Water year is from Nov. 1 to Oct. 31 N/A Integer 1
date yyyy/mm/dd N/A Date 1
pH pH in water samples N/A Real number 0.01
Ca Ca2+ concentration in water samples mmolc L-1 Real number 0.001
Mg Mg2+ concentration in water samples mmolc L-1 Real number 0.001
K K+ concentration in water samples mmolc L-1 Real number 0.001
Na Na+ concentration in water samples mmolc L-1 Real number 0.001
NH4 NH4+ concentration in water samples mmolc L-1 Real number 0.001
Cl Cl- concentration in water samples mmolc L-1 Real number 0.001
NO3 NO3- concentration in water samples mmolc L-1 Real number 0.001
SO4 SO42- concentration in water samples mmolc L-1 Real number 0.001

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

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.

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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)

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