Reintroduction（2024）12：1–10

ORIGINAL ARTICLE

Effects of the white stork friendly farming method on plantcommunity diversity in paddy fields in the Tajima region of Japan* Yosuke Fukushima1 and Kazuaki Naito1
Abstract In the paddy field ecosystem, plants provide food

Aimed at restoring biodiversity in paddy fields, a subset ofand shelter for animals and support biodiversity. However, thefarmers in the Tajima region of Hyogo Prefecture practices

diversity of plant communities in paddy fields is declining.

the White Stork Friendly Farming (WSFF) method for eco-

In the Tajima region of Hyogo Prefecture, Japan, farmers

friendly rice production. This method was established inhave been practicing the “White Stork Friendly Farming

2003 by the Hyogo prefectural government to support the(WSFF) method” for eco-friendly rice production since 2003.

reintroduction of the Oriental While Stork (Ciconia boyciana).

This method aims to conserve biodiversity within the rice

The areas of rice paddies cultivated using this method reachedproduction system and to support the reintroduction of the

445 hectares in 2022 (Toyooka City 2022). The WSFF

Oriental While Stork (Ciconia boyciana). This study assessed

method comprises rice production and water management

the effect of the WSFF method on plant community diversity

practices aimed at conserving biodiversity in paddies. Thesein paddy fields. Plant surveys were conducted in June, July,

practices include nonuse or reduced-use of agrochemicals,and August/September to identify plant species within sample

flooding paddy fields in winter and early spring, deep-plots in the paddy fields and levees managed under the WSFF

water management (i.e., keeping irrigated water at a depth

method and conventional rice production method, followed byof 8 cm for 40 days after seedling transplant), and mid-an assessment of plant species diversity using the Shannon–

summer drainage conducted a couple of weeks later than the

Weiner index. The sample plots were classified using two-

conventional rice farming method (Hyogo Prefecture 2019;

way indicator species analysis, and the relationship between

Nishimura and Ezaki 2019).

the sample plots and indicator species was identified throughStudies have examined the impacts of land improvement

detrended correspondence analysis. The WSFF methodand differences in farming practices on plant species

contributed to an increase in plant community diversity withincomposition in paddy fields (Noguchi 1992; Okubo andpaddy fields, indicating a positive impact on the conservation

Maenaka 1995; Yamaguchi et al. 1998; Ito et al. 1999;

of biodiversity in these fields through rice production.

Matsumura 2002). Naito et al. (2020) reported that the WSFF

Key words Farming method, Paddy field, Plant community

method is associated with an increased number of plant species

diversity

occurring in paddy fields. However, research on the effects of
the WSFF method on plant diversity remains scarce. In thisIntroduction
Rice paddy fields provide substitute habitats for plants
and animals living in wetland ecosystems in Japan (Hidaka

context, we hypothesize that the WSFF method increases plant
species diversity in rice paddies. Our aim is to assess its effectin both levees and paddy fields.

1998; Natuhara 2013; Ohtani et al. 2013). In the paddy fieldecosystem, plants play a crucial role by providing food andshelter for animals, thereby supporting biodiversity (Okubo

Materials and Methods

and Maenaka 1995). Unfortunately, plant community diversity

1．Study site

in these paddy fields has been declining (Kudoh 2017).

We conducted this study in Toyooka, Tajima region of
Hyogo Prefecture, Japan, focusing on three study sites: Mie,
Nitta, and Gonosho (Fig. 1). At each site, 20 paddy field areas1

Graduate School of Regional Resource Management, University ofwere selected: 10 under a conventional method (Conv.) and 10

Hyogo, 128 Shounji, Toyooka, Hyogo 668-0814, Japan

under the WSFF method. This resulted in a total of 60 paddy* E-mail: fukushima_yosuke@hotmail.com

field areas sampled. We identified these farming methods

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Reintroduction（2024）12：1–10

Fig. 1. Administrative area maps showing study site locations (lower left corner) and three rice paddy districts (Gonosho, Mie, and Nitta), eachencompassing 20 rice paddies (10 conventional paddy fields and 10 eco-friendly paddy fields, represented by circles and triangles, respectively).
These maps were created by processing digital national land information from the Ministry of Land, Infrastructure, Transport and Tourism, Japan(Ministry of Land, Infrastructure, Transport and Tourism, Japan, 2022).

based on the information provided by land managers.

September in 2016 (prior to rice harvesting). We undertook
plant surveys in the levees (1) between late June and early

2．Methods

July, and (2) between late September and early October. The

We randomly selected three sides out of four levees fromsample size for the second levee survey was 174, as adverse

each of a rectangular-shaped paddy field and established aweather conditions and the subsequent mowing of study plots

2

sample plot of 1 m quadrat both in the levee and within the

impeded the survey of two paddy fields using the conventional

paddy field in each of the selected sides of the paddy field,

method in the Nitta area. The sample plots were establishedwhich resulted in three sample plots both in the levee andrandomly for each plant survey. The levees in the study sites

within the paddy field for each paddy field. In total, 180

were mowed once in a month and half, or four times during asample plots were established in the levees and 180 plots

cropping season.

within the paddy fields, respectively. The sample plots within

The Shannon–Weiner index (H') of the sample plots forthe paddy fields were placed within the paddy fields at aroundassessing plant species diversity was calculated using Equation

1 m inside from the levee where rice seedlings (Oryza sativa)

1.

were planted. The vascular plant species in the sample plots

H' = -Σ pi × ln（pi）(1)were identified and their coverage in percentage was estimated

where p i is the proportion of the total cover of the ith

through visual assessment. Plant surveys were conducted

species. We calculated the average H' value for each paddy

within paddy fields in (1) early June (just after rice seedlingfield by averaging the H' values from three plots withintransplant), (2) late July, and (3) between late August and mid-that field, representing the plant community diversity of the2

between the paddy fields of the conventional method and thoseof the WSFF method. H' was calculated using R version 4.2.1(R Development Core Team 2022) and the U test by SPSS(IBM SPSS Statistics 28.0.0.0). A two-way indicator species
analysis (TWINSPAN) (Hill 1979) was used to classify the
sample plots into groups with similar species abundanceand composition. The sample plots and plant species were
subjected to detrended correspondence analysis (DCA) for
ordination (Hill and Gauch 1980). We conducted both analyses
using PCORD version 7 (McCune and Grace 2002).

Total
Conv.
WSFF
1.36 (±0.74)
1.67 (±0.89)
3.38 (±1.69)
4.13 (±1.50)
5.66 (±2.10)
7.09 (±2.04)
10.64 (±3.38) 12.21 (±2.88)
11.56 (±2.91) 2) 13.23 (±3.15)
Mie
Conv.
WSFF
1.63 (±1.03)
2.23 (±0.97)
3.73 (±1.93)
3.67 (±1.56)
5.57 (±2.40)
6.60 (±1.69)
11.07 (±4.29) 13.80 (±2.80)
10.47 (±2.40) 13.33 (±3.07)
Nitta
Conv.
WSFF
1.30 (±0.54)
1.63 (±0.85)
3.57(±1.36)
4.97 (±1.45)
5.60 (±2.08)
8.50 (±1.80)
10.87 (±2.49) 11.97 (±2.55)
12.33 (±2.57)1) 12.70 (±3.00)

Conv., Conventional method; White Stork Friendly Farming method.
Standard deviations are presented in parentheses.
1)
The sample size of the plots of each method in each study site was 30 except for that of the conventional method in Nitta study site for the second survey in the levee (n = 24).
2)
The sample size of the plots of each method in total was 90 except for that of the conventional method for the second survey in the levee (n = 84)

U test was used to determine differences in the values of H'

GonoshoHabitatOrder of survey
Conv.
WSFF
Within the paddy 1st
1.13 (±0.43)
1.13 (±0.35)
2nd
2.83 (±1.64)
3.77 (±1.14)
3rd
5.80 (±1.85)
6.17 (±1.86)
In the levee
1st
10.00 (±3.13) 10.87 (±2.57)
2nd12.03 (±3.36) 13.67 (±3.40)

respective paddy field. For each study site, the Mann–Whitney

Table 2. Average number of species occurring in paddy fields under the different farming methods.

In the leveeConv., Conventional method; White Stork Friendly Farming method.

Total
Native Alien
10
2
30
3
37
4
79
23
87
16
WSFF
Native Alien
7
1
21
3
28
3
61
11
85
10
Conv.
Native Alien
8
2
24
2
35
4
70
23
88
15
Order of survey
1st
2nd
3rd
1st
2nd
HabitatWithin the paddy

methods.

Table 1. Number of native and alien species found in paddy fields under the different farming

Fukushima and Naito：Effects of the white stork friendly farming method on plant community

Results
In the first plant survey within the paddy fields in June, 12
non-O. sativa species were identified. The total numbers of

Lemna aoukikusa (8.3%), Monochoria vaginalis (7.2%), andnative and alien species found in the paddy fields managed

Spirodela polyrhiza (6.7%). The first plant survey within

under the conventional method were 8 and 2, respectively,

the paddy fields revealed that 67 plots (74.4%) using theand those under the WSFF method were 7 and 1, respectively

conventional method and 51 plots (56.7%) using the WSFF

(Table 1). Among them, species with a high frequency of

method contained no species other than O. sativa. In addition,

occurrence (i.e., the number of times they occurred in 180

the average number of species, including O. sativa, per plot

sample plots) included Azolla cristata x filiculoides (15%),

was 1.36 (SD = 0.74) for the conventional method and 1.67

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Reintroduction（2024）12：1–10

the conventional method and 0.33% (SD = 1.22) for the WSFF
method (Table 3).
Within plots using the conventional method, A. cristata x
filiculoides and Echinochloa crus-galli had covers exceeding
10%. In contrast, only A. cristata x filiculoides had coverexceeding 10% within the plots using the WSFF method.
The second survey in July identified 33 non-O. sativa
Conv., Conventional method; WSFF, White Stork Friendly Farming method.
Standard deviations are presented in parentheses.
1)
The sample size of the plots of each method in each study site was 30 except for those of the conventional method in Nitta study site for thesecond survey in the levee (n = 24).
2)
The sample size of the plots of each method in total was 90 except for that of the conventional method for the second survey in the levee (n = 84).

Nitta
Conv.
WSFF
0.13 (±0.04)
0.13 (±0.03)
1.44 (±2.16)
5.44 (±6.26)
1.90 (±2.30)
14.96 (±11.50)
78.81 (±31.06)
60.03 (±18.15)
96.29 (±23.37)1) 128.21 (±28.67)
GonoshoConv.
WSFF
0.01 (±0.04)
0.13 (±0.03)
1.44 (±2.16)
5.44 (±6.26)
1.90 (±2.30)
14.96 (±11.50)
78.81 (±31.06) 60.03 (±18.15)
96.29 (±23.37) 128.21 (±28.67)
HabitatOrder of survey
Within the paddy 1st
2nd
3rd
In the levee
1st
2nd

Table 3. Average cumulative total plant cover per plot in the paddy fields under the different farming methods.

Mie
Conv.
WSFF
7.41 (±21.70)
0.89 (±2.01)
1.44 (±3.66) 26.65 (±32.40)
1.86 (±3.37) 21.03 (±23.31)
84.73 (±28.41) 103.16 (±12.22)
98.07 (±15.65) 81.24 (±20.30)

Total
Conv.
WSFF
2.49 (±12.88)
0.33 (±1.22)
1.32 (±2.55)
20.04 (±24.91)
2.15 (±2.80)
21.05 (±18.66)
80.35 (±28.30)
82.70 (±25.37)
102.93 (±22.08)2) 108.64 (±29.70)

excluding O. sativa, in the plot) was 2.49% (SD = 12.88) for

species within paddy fields. The total numbers of native andalien species found in the paddy fields managed under theconventional method were 24 and 2, respectively, and thoseunder the WSFF method were 21 and 3, respectively. Species
with a high frequency of occurrence included M. vaginalis(43.3%), Sagittaria trifolia (32.8%), Ludwigia epilobioides(22.2%), and Lindernia procumbens (22.2%). The average
number of species per plot was 3.38 (SD = 1.69) for theconventional method and 4.13 (SD = 1.50) for the WSFF
method. The average cumulative total plant cover per plot
was 1.32% (SD = 2.55) for the conventional method and20.04% (SD = 24.91) for the WSFF method. Only A. cristata
x filiculoides had cover exceeding 10% within the plots
employing the conventional method. However, M. vaginalis,
S. trifolia, and Lindernia dubia var. dubia had cover exceeding
10% in the plots using the WSFF method.
The third survey conducted in August/September uncovered
41 non-O. sativa species within paddy fields. The total
numbers of native and alien species found in the paddy fields
managed under the conventional method were 35 and 4,
respectively, and those under the WSFF method were 28 and3, respectively. Species with a high frequency of occurrence
included L. procumbens (68.9%), M. vaginalis (43.9%),
Persicaria hydropiper (37.2%), and L. epilobioides (36.1%).
The average number of species per plot was 5.66 (SD = 2.10)
for the conventional method and 7.09 (SD = 2.04) for the
WSFF method. The average cumulative total plant cover per
plot was 2.15% (SD = 2.80) for the conventional method and21.05% (SD = 18.66) for the WSFF method. Only A. cristata
x filiculoides and E. crus-galli had cover exceeding 10%
within the plots using the conventional method. Conversely,
M. vaginalis, S. trifolia, L. dubia var. dubia, L. procumbens,(SD = 0.89) for the WSFF method (Table 2).
The plant cover of species other than O. sativa was small.
The average cumulative total plant cover per plot (i.e., theaverage value of the summation of coverage of species,

4

Paspalum distichum, Eleocharis kuroguwai, and Ceratopteris
gaudichaudii var. vulgaris had cover exceeding 10% in theplots utilizing the WSFF method.
The first plant survey in the levees conducted in June/July

Conv., Conventional method; White Stork Friendly Farming method.
Standard deviations are presented in parentheses.
1)
The sample size of the plots of each method in each study site was 10 except for those of the conventional method in Nitta study site for the second survey in the levee(n = 8).
2)
The sample size of the plots of each method in total was 30 except for that of the conventional method for the second survey in the levee (n = 28).
*P <0.05 by Mann–Whitney U test.

Nitta
Conv.
WSFF
0.03 (±0.02) 0.11 (±0.04)
0.09 (±0.02) 0.74 (±0.10) *0.18 (±0.03) 0.94 (±0.09) *1.68 (±0.06) 1.79 (±0.06)
1.72 (±0.12)1) 1.80 (±0.07)
GonoshoConv.
WSFF
0.01 (±0.00) 0.01 (±0.00)
0.10 (±0.02) 0.31 (±0.06) *0.14 (±0.03) 0.65 (±0.08) *1.63 (±0.14) 1.84 (±0.11)
1.66 (±0.12) 2.03 (±0.11)
HabitatOrder of survey
Within the paddy 1st
2nd
3rd
In the levee
1st
2nd

Table 4. Shannon–Wiener diversity indices under the different farming methods.

Mie
Conv.
WSFF
0.19 (±0.10) 0.20 (±0.06)
0.10 (±0.04) 0.61 (±0.15) *0.13 (±0.03) 0.60 (±0.12) *1.77 (±0.17) 1.88 (±0.09)
1.45 (±0.11) 1.99 (±0.09) *

Total
Conv.
WSFF
0.07 (±0.04) 0.11 (±0.03)
0.10 (±0.01) 0.55 (±0.07)
0.15 (±0.02) 0.73 (±0.06)
1.69 (±0.07) 1.84 (±0.05)
1.60 (±0.07)2) 1.94 (±0.06)

Fukushima and Naito：Effects of the white stork friendly farming method on plant community

the conventional method and 12.21 (SD = 2.88) for the WSFF
method. The average cumulative total plant cover per plot was
80.35% (SD = 28.30) for the conventional method and 82.70%(SD = 25.37) for the WSFF method.
The second survey in the levees in September/October
identified 103 species. The total numbers of native andalien species found in the paddy fields managed under theconventional method were 88 and 15, respectively, andthose under the WSFF method were 85 and 10, respectively.
The species with a high frequency of occurrence included
Digitaria ciliaris (83.9%), E. arvense (70.1%), Kyllinga
brevifolia var. leiolepis (67.8%), and H. ramiflora (78.2%).
The average number of species per plot was 11.56 (SD = 2.91)
for the conventional method and 13.23 (SD = 3.15) for the
WSFF method. The average cumulative total plant cover per
plot was 102.93% (SD = 22.08) for the conventional method
and 108.64% (SD = 29.70) for the WSFF method.
For the first survey within the paddy field, the values of H'
for the plant community in the paddy fields managed under theconventional method in Gonosho, Nitta, and Mie were 0.01,
0.03, and 0.19, respectively, whereas those in the paddy fields
managed under the WSFF method were0.01, 0.11, and 0.20,
respectively (Table 4).
The values of H' for the plant community for the second
survey within the paddy fields in the paddy fields managed
under the conventional method in Gonosho, Nitta, and Miewere 0.10, 0.09, and 0.10, respectively, whereas those in
the paddy fields managed under the WSFF method were0.31, 0.74, and 0.61, respectively. The values of H' for theplant community for the third survey within the paddy fields
managed under the conventional method in Gonosho, Nitta,
and Mie were 0.14, 0.18, and 0.13, respectively, whereas thosein the paddy fields managed under the WSFF method were0.65, 0.94, and 0.60, respectively. For the first survey in thelevees, the values of H' for the plant community in the paddy
fields managed under the conventional method in Gonosho,

uncovered 102 species in total. The total numbers of native

Nitta, and Mie were 1.63, 1.68, and 1.77, respectively,

and alien species found in the paddy fields managed underwhereas those in the paddy fields managed under the WSFF

the conventional method were 70 and 23, respectively, andmethod were 1.84, 1.79, and 1.88, respectively. The values

those under the WSFF method were 61 and 11, respectively.

of H' for the plant community in the second survey in the

The species with a high frequency of occurrence included

levees in the paddy fields managed under the conventional

Hydrocotyle ramiflora (85%), Equisetum arvense (72.2%),

method in Gonosho, Nitta, and Mie were 1.66, 1.72, and 1.45,

Trifolium repens (68.9%), and Setaria viridis (51.1%). The

respectively, whereas those in the paddy fields managed under

average number of species per plot was 10.64 (SD = 3.38) for

the WSFF method were 2.03, 1.80, and 1.99, respectively.

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Reintroduction（2024）12：1–10

Fig. 2. Classification dendrograms of plant community types identified by TWINSPAN. The number attached to Group is the code name of thegroup. Indicator species for the negative (0) or positive (1) group and number of conventional and/or WSFF plots in each division are also shown.

The first survey within the paddy fields revealed nosignificant difference in H' values between the paddy fields

groups (Group 10 and Group 11) were very small and included
only 3 and 2 plots.

managed under conventional and those managed under the

For the second survey within the paddy fields, the

WSFF methods. However, the second and third plant surveys

TWINSPAN classified the plots into 2 groups (Group 0

within the paddy fields revealed that the values of H' for theand Group 1) at the first split with L. dubia var. dubia, M.

plant community in the paddy fields managed under WSFF

vaginalis, S. trifolia, and S. polyrhiza as negative indicators

method significantly exceeded those in the paddy fields

and with P. hydropiper as a positive indicator. Group 0 mainly

managed under the conventional method in all three study

included WSFF plots and was further divided into 2 groups

sites. The first survey in the levees revealed no significant(Group 00 and Group 01) with L. procumbens, L. epilobioides,

difference in H' values between the paddy fields managed

and M. vaginalis as negative indicators and S. trifolia and S.

under the two methods. The H' values for the plant community

polyrhiza as positive indicators. The Group 00 included onlyin the second levee survey in the paddy fields managed under

WSFF plots. Group 1 mainly included conventional plots andthe WSFF method markedly exceeded those in the paddy fields

was further divided into 2 groups (Group 10 and Group 11)

managed under the conventional method, but this differencewith S. trifolia as a negative indicator and Cardamine occulta,

was observed only at the Mie study site.

L. procumbens, L. epilobioides and P. hydropiper as positive

The TWINSPAN results classified the sample plots of eachplant survey into four groups at the second level of division(Fig. 2).

indicators.
For the third survey within the paddy fields, the TWINSPAN
classified the plots into 2 groups (Group 0 and Group 1) at the

For the first survey within the paddy fields, the TWINSPAN

first split, with Limnophila sessiliflora, M. vaginalis, and S.

classified the plots into 2 groups (Group 0 and Group 1) at thetrifolia as negative indicators and C. occulta and P. hydropiper

first split with A. cristata x filiculoides and E. crus-galli asas positive indicators. Group 0 mainly included WSFF plots

positive indicators. Group 0 was further divided into 2 groups

and was further divided into 2 groups (Group 00 and Group(Group 00 and Group 01) with L. aoukikusa, M. vaginalis, and01), with C. gaudichaudii var. vulgaris, L. aoukikusa, L.

Murdannia keisak as negative indicators and with O. sativa

epilobioides, and M. vaginalis as negative indicators andas a positive indicator. Group 01 was the largest group, with

S. trifolia as a positive indicator. Group 00 included only

163 plots where almost only O. sativa occurred. Group 00 was

WSFF plots and Group 01 included more WSFF plots thana small group that only included WSFF plots. The other two

conventional plots. Group 1 was further divided into 2 groups

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Fukushima and Naito：Effects of the white stork friendly farming method on plant community

Fig. 3. Diagram of sample plots in DCA ordination. The community types identified by TWINSPAN, as well as farming methods, were related
to those identified by the DCA using symbols. Indicator species identified by TWINSPAN are indicated by abbreviations as follows: Acf: Azolla
cristata x filiculoides, Ecr: Echinochloa crus-galli, Lao: Lemna aoukikusa, Mva: Monochoria vaginalis, Mke: Murdannia keisak, Osa: Oryza
sativa, Ldd: Lindernia dubia var. dubia, Str: Sagittaria trifolia, Spo: Spirodela polyrhiza, Phy: Persicaria hydropiper, Lpr: Lindernia procumbens,
Lep: Ludwigia epilobioides, Coc: Cardamine occulta, Lse: Limnophila sessiliflora, Cgv: Ceratopteris gaudichaudii var. vulgaris, Cmi: Centipeda
minima, Eth: Eclipta thermalis, Hra: Hydrocotyle ramiflora, Dci: Digitaria ciliaris, Icy: Imperata cylindrica, Efe: Eragrostis ferruginea, Pal:
Pennisetum alopecuroides, Aim: Artemisia indica var. maximowicaii, Cco: Commelina communis, Ear: Equisetum arvense, Rja: Rumex japonicus,
Zja: Zoysia japonica.

(Group 10 and Group 11), with C. occulta, Centipeda minima,

alopecuroides as positive indicators. Group 0 was further

and Eclipta thermalis as negative indicators and L. aoukikusa

divided into 2 groups (Group 00 and Group 01), withand S. trifolia as positive indicators. Both Group 10 and Group

Artemisia indica var. maximowicaii, Commelina communis,

11 mainly included conventional plots.

Equisetum arvense, and Rumex japonicus as negative

For the first survey within the levee, the TWINSPAN

indicators. Group 1 only included conventional plots and wasclassified the plots into 2 groups (Group 0 and Group 1) atfurther divided into 2 groups (Group 10 and Group 11), withthe first split, with H. ramiflora as a negative indicator and D.

I. cylindrica and Zoysia japonica as negative indicators andciliaris as a positive indicator. Group 0 was further divided

D. ciliaris, E. ferruginea, and P. alopecuroides as positive

into 2 groups (Group 00 and Group 01), with Imperata

indicators. Group 11 mainly included WSFF plots, but thecylindrica as a negative indicator. Group 1 only included

other groups did not have clear features in relation to farming

conventional plots and was further divided into 2 groups

methods.

(Group 10 and Group 11), with E. crus-galli as a negative
indicator.

Figure 3 shows the DCA ordination diagram for each plantsurvey. In the first survey within the paddy fields, the WSFF

For the second survey within the levee, the TWINSPAN

method had the most plots clustered around the diagram

classified the plots into 2 groups (Group 0 and Group 1)

origin. The eigenvalues of the first and second axes wereat the first split, with D. ciliaris as a negative indicator

0.73 and 0.38, respectively. However, in the second and thirdand Eragrostis ferruginea, I. cylindrica, and Pennisetum

surveys, the WSFF method showed a widespread distribution

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Reintroduction（2024）12：1–10

of plots along both axis-1 and axis-2 compared to those ofdiversity between the two methods.

the conventional method. While the eigenvalues of the first

Comparing the H' values from the second and third surveys

and second axes of the second survey were 0.30 and 0.11,

within the paddy fields, our results indicated that plant species

respectively, they were in the same order, 0.21 and 0.12, in the

exhibited greater diversity within the paddy fields using thethird survey. The DCA ordination diagrams of the second and

WSFF method compared to those using the conventional

third surveys within the paddy fields also indicated that themethod. The results of TWINSPAN for the second survey

plots of the WSFF method were associated with M. vaginalis

within the paddy fields showed that a group of plots, i.e.,

and the plots of the conventional method with C. occulta. M.

Group 00, included only the plots of WSFF method. Thosevaginalis and C. occulta appeared opposite sides along axis-1

plots in the group were relatively widely dispersed along theon the DCA ordination diagram, and WSFF plots of Group 00

axis-1 in the DCA ordination diagram. These results suggested

were relatively associated with M. vaginalis in both surveys.

that the WSFF method increased plant community diversity.

The diagram of the third survey showed that the plots of the

The reduced or no application of herbicides within WSFF

WSFF method mainly including Group 00 were associatedpaddy fields may be associated with high plant community

with L. sessiliflora. S. trifolia was associated with the plots

diversity.

of Group 01 on the DCA ordination diagrams of the second

The DCA ordination diagram and TWINSPAN results also

and third surveys within the paddy fields. Group 01 mainly

suggested that the WSFF method was associated with M.

included the plots of the WSFF method and some from thevaginalis occurrence. These results corroborate those of Naito

conventional method.

and Sagawa (2014). The WSFF method aims to suppress weed

The DCA ordination diagrams of the first survey in levees

growth by flooding paddy fields in winter as an alternative toshowed that the plots of the WSFF and conventional methods

the use of herbicides. However, previous research suggested

appeared mixed together. E. ferruginea and P. alopecuroides

that winter-time flooding and deep-water management alone

were associated with the plots of Group 11 on the diagram ofwere ineffective in controlling M. vaginalis (Inaba 1999).

the second survey in levees. Group 11 mainly included the

Kaneko and Nakamura (2009) also reported that the volume

plots of the WSFF method and some from the conventionalof M. vaginalis in paddy fields practicing winter-time flooding

method.

markedly exceeded that of paddy fields using the conventional
method.
The findings of the present study also revealed a higher

Discussion

occurrence of L. sessiliflora in paddy fields using the WSFF

The results of plant surveys within the paddy fields did

method compared to those using the conventional method.

not show significant difference in the total number of species

Previous research has reported that deep-water management

as well as in the number of alien species between the paddy

increased L. sessiliflora (Tanaka and Kanou 2002). Therefore,

fields managed under the conventional method and thosethe WSFF method may also increase L. sessiliflora occurrence

managed under the WSFF method. The results of plant

owing to deep-water management and reduced or no herbicide

surveys in the levees found that the total number of species asapplication.

well as the number of alien species were larger in the paddy

Our results also demonstrated that C. occulta was more

fields managed under the conventional method than in those

associated with the conventional rice cultivation method.

managed under the WSFF method. These results suggest thatC. occulta did not appear either in the paddy fields of thepracticing the WSFF method does not increase the number ofconventional method or in those of the WSFF method foralien species in the paddy fields.

the first survey within the paddies. However, the species was

The first plant survey within the paddy fields found that

identified in the 15 plots of the conventional method, whereas

most plots of both the conventional and WSFF methods had

it was not found in the plots of the WSFF method during

no species other than O. sativa. The cover of the non-O.

the second survey. We also found C. occulta in 32 plots ofsativa species, which were identified in the plots, was small.

the conventional method and in only one plot of the WSFF

This resulted in no significant difference in plant community

method for the third survey. The DCA diagram indicated the8Fukushima and Naito：Effects of the white stork friendly farming method on plant community

association between the species and conventional method.
Previous research has reported that winter-time flooding
suppressed C. occulta germination (Arihara and Koyama

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