153

Restoration and Conservation of Aquatic Habitats in AgriculturalLandscapes of Japan
Tomohiro ICHINOSE
Institute of Natural and Environmental Sciences, University of Hyogo
Nojimatokiwa 954-2, Awaji, Hyogo 656-1726, Japan
Currently; Faculty of Environmental and Information Studies, Keio University
5322 Endo, Fujisawa-shi, Kanagawa 252-8520, Japane-mail: tomohiro@sfc.keio.ac.jp

Abstract
Land-use changes in Hyogo Prefecture from 1976 to 1997 were analyzed using Geographic Information Systems (GIS). Rice paddies in hilly and mountainous areas with a slope of 1:20 or greater wereextracted to aid biodiversity conservation efforts in these areas. I focused on changes in the total length ofthe edge between rice paddies and forests because the edges are an attractive habitat for some amphibian
species. I also extracted so-called “marginal” areas – areas in which at least 50% of the population is at least
65 years old – and “sub-marginal” areas – areas in which at least 50% of the population is at least 55 years
old – to determine whether agriculture was sustainable in that area.
The total area containing rice paddies decreased from 1971 to 1997, and there was no significant
indication that abandoned fields changed into forest. The total edge length between rice paddies and forests
decreased continuously over the same period. Almost half of the rice paddies were located in hilly andmountainous areas of Hyogo Prefecture, and much of these areas was classified as sub-marginal, raising thequestion of whether agriculture was sustainable in these areas. Finally, I considered three strategies forconserving aquatic habitats in hilly and mountainous areas.
Key words: aging population, hilly and mountainous area, Hyogo Prefecture, marginal area, rice paddy

1. Introduction
1.1 Biodiversity conservation in agriculturallandscapes
Since the 1980s traditional elements of agriculturallandscapes have been shown to play a role as important
habitat for many species in Europe. For example, hedgerows (Burel & Baudry, 1990), coppice forests (Fuller &Moreton, 1987) and rough pastures (Haase et al., 1992)
are used by specific species and contribute to maintaining biodiversity in agricultural landscapes.
In most regions of eastern and southeastern Asia,
paddy fields account for the majority of farmland.
Moriyama (1997) suggested that many species haveadopted this agricultural environment as habitat. Moriyama
et al. (1992) analyzed a traditional landscape pattern inthe northern part of the Kanto District of Japan andfound that bodies of water traditionally used for agriculture (e.g., irrigation ponds and canals) have been located approximately 1 km from each other, which isabout the distance some Sympetrum species can fly.
Since the 1990s, many studies have reported that agricultural landscape elements in Japan, including rice padGlobal Environmental Research
11: 153-160 (2007)
printed in Japandies, irrigation ponds and canals, paddy levees and coppice forest, maintain biodiversity (e.g., Takeuchi et al.,2003).
1.2 Japanese agriculture and the agriculturallandscapeThe nature of Japanese agriculture and the agricultural landscape have changed dramatically since WorldWar II. The Basic Law on Agriculture, enacted in 1961,
aimed to expand farmlands and modernize farming by
introducing large machines. Rice paddies were changed
through land consolidation and the introduction of modern irrigation techniques (e.g., the use of concrete
canals), all of which critically affected the distributionof organisms. Although the Japanese government continued to promote land consolidation, overproduction ofrice was reported in 1969. Adjustments in the amount ofrice produced began in 1970. Urbanization claimed alarge amount of farmland in suburban areas of metropolitan cities during this period of high economic
growth. At the same time, a significant number of people moved from mountainous agricultural areas, and thisdepopulation is still a serious social problem in some©2007 AIRIES154

T. ICHINOSE

rural areas.
The Japanese agricultural situation has recently
worsened. External pressure for agricultural trade liberalization has increased in the course of negotiations with
the World Trade Organization (WTO) with regard to theFree Trade Agreement (FTA). Young people are still
moving away from rural areas because of better economic opportunities in urban areas. As a result, there is asignificant aging problem in most agricultural areas. The
Basic Law on Food, Agriculture and Rural Areas wasenacted in 1999, and it represented a turning point forJapanese agricultural policy. This law clearly addresses
the importance of the sustainable development of agriculture. Under this law, farmland development must be
conducted with attention to ecological and environmental concerns. The law also aims to promote a better infrastructure for agricultural production and expand the scaleof farm management. This law particularly emphasizes
the necessity of securing and fostering an agricultural
workforce to have effective and stable farm management.
1.3 Agriculture and biodiversity in hilly andmountainous areas
Although it should be possible to promote better
agricultural production infrastructure and expand thescale of farm management in flat areas, it is difficult to
introduce these types of improvements in hilly andmountainous areas because they are at a major disadvantage in terms of production efficiency. The Japanese
government identifies fields on steep slopes as disadvantaged areas. In the case of rice paddies, fields on aslope of 1:20 or more are considered to be steep. Froman ecological viewpoint, these agricultural hilly andmountainous areas still offer attractive habitats. Whilemost of the fields in flat areas have been consolidated
and are intensively used, there are many small unconsolidated paddies, unlined irrigation canals and paddy
levees covered with domestic plants in hilly and mountainous areas. Most of these areas are still traditionallymanaged. Moreover, the edge between rice paddies andforests is an important habitat for some species, forexample, Hynobius nebulosus (Natuhara et al., 2002)
and Butastur indicus (Momose et al., 2005).
In order to support agriculture in hilly and mountainous areas, Japan’s Ministry of Agriculture, Forestry and
Fisheries started a direct payment system in 2000. Thissystem supports farmers in hilly and mountainous areas
not for their products but for their farmland. Prior to this,most Japanese policies had focused on price adjustment
and distribution control. However, this was Japan’s firstpolicy to disconnect subsidies from production. The
system is similar to the one that provides direct farm
payments in the Common Agricultural Policy (CAP) of
the EU. The Japanese system pays 210,000 yen/ha forrice paddies on a slope of 1:20 or more and 115,000,
105,000, and 10,000 yen/ha for dry fields, meadows,
and pastures on a slope of 15 degrees or more, respectively. In addition, it conditionally pays 80,000 yen/ha
for rice paddies on a slope of 1:100 or more, and 35,000,

30,000, and 3,000 yen/ha for dry fields, meadows andpastures on a slope of eight degrees or more, respectively. Farmers within a settlement must agree to thesystem and satisfy certain other conditions and thenapply as group for the payments. Individual farmers
cannot apply. Half of the subsidy is paid to individual
farmers, and the other half is paid to the settlement for
use in local projects (e.g., maintenance of irrigation
facilities, mowing of paddy levees, etc.). The first phaseof the system lasted five years and ended in March 2005.
The second five-year phase began in April 2005. The
following conditions were added to the second phase.
Farmers have to make efforts to encourage efficient andstable farm management and to foster workforce
development. If farmers do not make these efforts, theyreceive only 80% of the subsidy.
In Hyogo Prefecture, a total of 887,333,000 yen wasprovided to farmers for 4,548 ha of farmland in hilly
and mountainous areas in the 2004 fiscal year (from
April 2004 to March 2005). A total of 802,817,000 yen
was provided to farmers for 4,549 ha in the 2005 fiscal
year. The 2005 subsidies decreased by about 10%
despite covering a similar area because many settlements received the 80% subsidy mentioned previously.
Some settlements were new to the system, and others
that received subsidies in the first phase did not apply
for them in the second phase. The most important reason
they quit applying is that many farmers were not surewhether they could continue farming for five more years
owing to their advanced ages.
In addition, many settlements in hilly and mountainous areas have not applied for either phase. The percentage of abandoned fields in these areas is much higher
than that in the subsidized areas. Local governments
have to pay a quarter of the cost of the subsidies, andsome local governments suffer from financial difficulties. It is also uncertain whether the direct payment
system will continue after the second five-year phase.
Although other policies also support agriculture in hilly
and mountainous areas, it is likely that the number ofabandoned fields will increase in these areas. Thischanging pattern of land use in hilly and mountainous
areas could cause drastic changes among organisms
inhabiting these areas.
1.4 Objective
In this paper, I analyze the current status of agricultural landscapes in Japan from the viewpoint of biodiversity conservation. In particular, I focus on species
using aquatic habitats. Because many species depend on
agricultural activities and habitats, they will most likely
be affected by changes in agricultural land use.
First, I comprehensively analyze land-use changes
across the entire Hyogo Prefecture for the period from1976 to 1997. I then extract only the hilly and mountainous areas, focusing on the length of the edges
between rice paddies and forests. Finally, I discuss andpresent three strategies for conserving aquatic habitats
in the agricultural landscape.

Restoration and Conservation of Aquatic Habitats in Agricultural Landscapes of Japan

2. Materials and Methods
2.1 Study area
I selected Hyogo Prefecture as the study area (Fig. 1)
because the southern part of Hyogo faces the Pacific
Ocean and the northern part faces the Japan Sea, andHyogo consists of metropolitan areas, including Kobe
City, and huge rural areas (e.g., small islands and areasof heavy snowfall). Hyogo is thus a typical example of
the Japanese agricultural landscape.
2.2 Materials
The following data were used in the analysis. I usedland-use data from the Digital National Land Information (DNLI) database, which consists of grid cells of
about 100-m (4.5 seconds latitude; 3 seconds longitude),for 1976, 1986, 1991, and 1997. I also used a digital
elevation model (DEM) consisting of grid cells of about
50-m issued by the Geographical Survey Institute in1997 and population data issued by the Statistical Information Institute for Consulting and Analysis in 2000,
which consist of grid cells of about 1-km (45 seconds
latitude; 30 seconds longitude) and were created from
National Census Data in 2000. Finally, I used the Digital
Map 25,000 (Administrative Boundaries and Coastal
Lines) issued by the Statistical Information Institute forConsulting and Analysis in 1997.
2.3 Analysis
In order to overlay all data sets, I resampled eachraster data set to a 100-m-grid cell on UTM zone 53N(CM 135E) / Bessel Tokyo by the nearest-neighbormethod. The data sets were then extracted within theborders of Hyogo Prefecture.
I calculated changes in land use from 1976 to 1997.
The categories from the various years are somewhat
different, so I adjusted the categories of 1976 and 1987
to those of 1991 and 1997. Then, I divided the entire
area of Hyogo into two slope categories using DEM:
1:20 or steeper and less steep than 1:20.

Fig. 1

Location of Hyogo Prefecture.

155

Next, I extracted the edges between rice paddies andforests using the land-use data. The edges are importantfor many organisms. For example, Hynobius nebulosus(Natuhara et al., 2002) and Rana ornativentris (Osawa& Katsuno, 2005) usually inhabit forests and use aquatic
habitats in agricultural areas to lay their eggs in spring.
Butastur indicus, which was ranked as an endangered
species in December 2006, uses the forest for breeding
and rice paddies for feeding. Some studies (e.g.,
Momose et al., 2005) have shown that the connectivity
between the two environments and the density of narrow
rice paddy fields in an area affected the number ofbreeding pairs. In addition, Ichinose and Morita (2002)
showed that the proportion of the circumference of anirrigation pond that touched the edge of a forest influenced the composition of dragonfly and damselfly
species.
Finally, I calculated the percentage of the population
who were at least 65 years old using population data andthen extracted the areas in which at least 50% were 65
or older. I also extracted the areas in which at least 50%of the population were at least 55 years old. Ohno
(1991) proposed that it is almost impossible for residents to maintain a settlement in a mountainous area
when more than 50% of the population are 65 or older.
He called these areas “marginal” settlements. He defined “sub-marginal” settlements as those in which morethan 50% of the population are at least 55 years old.
Residents can still maintain a sub-marginal settlement,
but it will become more difficult as time moves on.
Although Ohno (1991) proposed the idea of the settlement, I analyzed the data by grid cell because thisaligned better with the available land-use data. However,I use the terms marginal and sub-marginal in the samemanner as Ohno.
TNTmips72 (MicroImages, Inc., Lincoln, Nebraska,
USA) was used for all analyses.

3. Land-use Changes and the Distribution of
Hilly and Mountainous Areas in Hyogo
Prefecture
3.1 Land-use changes from 1976 to 1997
The categories of land use in Hyogo Prefecture
in 1976, 1987, 1991, and 1997 are given in Table 1.
Forests (5,751.73 km2) and rice paddies (1,128.05 km2)
are by far the two largest uses of land in the prefecture.
Figure 2 shows the distribution of land use in 1997.
From 1976 to 1997, the area being used for ricepaddies decreased by 121.8 km2, or about a 10%
decrease. About 187 km2 of rice paddies was lost and
65 km2 was added in this same period. About 79.74 km2
of rice paddies was transformed into built-up areas,
26.55 km2 into other urban areas, and 25.66 km2 into
forest (Table 2). Conversely, about 31.27 km2 of forest
was transformed into rice paddies; that is, the amount ofland that was converted from rice paddies to forest wasless than the amount of land that went from forest to ricepaddies. In this time period, the area once occupied by

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T. ICHINOSE
Table 1 Land uses in Hyogo Prefecture in 1976 and 1997.

(data source: Digital National Land Information; all units are in km2).

Land userice paddies
other agricultural fields
forests
waste lands
built up areas
traffic facilities
other urban areas
open water bodies
seacoasts
golf courses
sum

1976
1,249.85
112.36
5,923.79
139.07493.3933.41
246.41172.05
5.33—
8,375.66

1987
1,179.87
107.54
5,904.06
133.47583.4539.25
256.78176.02
4.34—
8,384.78

1991
1,168.79
107.835,819.37
132.91604.4152.62
223.86178.084.36
97.28
8,389.51

1997
1,128.05
114.185,751.73
114.42675.6379.28
225.51
187.624.28
110.098,390.79

Table 2 Land uses of land that was converted from rice paddies and ofland that was converted to rice paddies from 1976 to 1997.
(all units are in km2).

other agricultural fields
forests
waste lands
built up areas
traffic facilities
other urban areas
open water bodies
seacoasts
golf courses
sum

decreased rice paddy area
12.29
25.66
8.06
79.74
17.83
26.55
14.22
0.06
2.68
187.09increased rice paddy area
6.56
31.27
2.23
12.34
0.98
5.05
6.84
0.02
—
65.29

rice paddies was mostly lost to urbanization, and there
was no significant shift from abandoned rice paddies
into forests.

Fig. 2Land uses in Hyogo Prefecture in 1997.

3.2 Distribution of rice paddies on steep slopes
I extracted rice paddies on steep slopes (1:20 ormore) using land-use data from 1997 and the DEM. The
percentage of rice paddies on steep slopes rose fromabout 43% to 45% over the 21-year period. The area ofrice-paddy land located on steep slopes in Hyogo Prefecture decreased from 541.26 km2 in 1976 to 494.38 km2
in 1997. During the same years, the area of rice-paddy
land located on gentler slopes (<1:20) also decreased
from 708.59 to 633.67 km2. About 10.6% of the land
occupied by rice paddies on gentler slopes wasconverted into other land uses and 8.7% of the land
occupied by rice paddies on steep slopes was converted
into other land uses. Of the approximately 4,500 ha forwhich subsidies were provided by the direct payment
system in 2005, about 4,134 ha were rice paddies on
steep slopes. Thus, 8% of rice paddies on steep slopes
were maintained by this system, although it is not easy
to compare them because of differences between the
precision of the land-use data and the counting method
used in the direct payment system.

Restoration and Conservation of Aquatic Habitats in Agricultural Landscapes of Japan

3.3 Distribution of edges between rice paddies andforests, and changes in this parameter
The extracted edges between rice paddies and forests
in 1997 are shown in Fig. 3. The total edge length was
8,053 km. Edges were found all over Hyogo Prefecture,and they were concentrated in the northern and central
parts of Awaji Island and to the north of the Rokko
Mountains (Fig. 3). I classified the edge lengths into
four categories: 0-99 m, 100-499 m, 500-1,499 m, and1,500+ m. Figure 4 shows the total edge length withineach 1-km grid cell for 1997 for each length category.
Figure 5 shows the same data for 1976. The two longest

157

length classes, which are shown as orange and red in the
figures, tended to decrease throughout the prefecture
between 1976 and 1997. I calculated the total length ofthe edges for each year, and found the total length decreased steadily over the study period (Fig. 6). The lossof edges between rice paddies and forests could havebeen caused by the decreasing area of rice paddies andthe disappearance of small forests owing to landconsolidation. In this analysis, I was not concerned
about the quality of either habitat; thus, edges that are
attractive to organisms may actually be much more
limited.

0 - 99 m
100 - 499 m
500 - 1499 m
1500 m+Fig. 3 Edges between rice paddies and forests in
Hyogo Prefecture in 1997.

Fig. 5 Distribution of four edge-length classes
between rice paddies and forests in 1-km
grid cells in 1976.

Total edge length between rice paddies and forests

0 - 99 m
100 - 499 m
500 - 1499 m
1500 m+Year

Fig. 4 Distribution of four edge-length classes
between rice paddies and forests in 1-km
grid cells in 1997.

Fig. 6 The total length of edges between ricepaddies and forests in Hyogo Prefecturefrom 1976 to 1997.

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T. ICHINOSE

3.4 Population and aged percentage in hilly andmountainous areas
According to the national census in 2000, the total
population of Hyogo Prefecture was approximately
5,550,000. The total population of each 1-km grid cellis presented in Fig. 7. The total populated area was
4,351.62 km2. Grid cells that have more than 10,000
people are easily seen in the Hanshin area and in Akashi
City. Other than in this coastal area, few cells of the grid(e.g., central Toyooka City in the north and central
Sumoto City in the south) have even 5,000 people.
The percentage of the population who are at least
65 years old is shown in Fig. 8. In contrast with population concentrations, many grid cells with high percentPopulation
20000
15000
10000
5000
0

Fig. 7 Total population of each 1-km grid cellin 2000.
Proportion of the aged population (%)
100
90
80
70
60
50
40
30
20
10
0

Fig. 8 Percentage of the population who wereat least 65 years old in each 1-km gridcell in 2000.

ages can be seen in the northern, middle, and westernparts of Hyogo and Awaji Island. Marginal areas (thosewith percentages of 50% or more) totaled 97.16 km2, orabout 2.2% of the total populated area. Marginal areas
were clearly limited in 2000, but sub-marginal areas(those in which at least 50% of the population was atleast 55 years old) totaled 386.15 km2 (about 9% of thetotal). Sub-marginal areas will not necessarily become
marginal areas in ten years because the age compositionof the future population in these areas depends on manyfactors. About 92% of marginal and sub-marginal areas
are located in hilly and mountainous regions. Although I
did not overlap the locations of rice paddies and the
distribution of the aged in the population, many disadvantaged areas must be also be home to a rapidly
aging population.

4. Conserving Aquatic Habitats inAgricultural Landscapes
4.1 Options for conserving the aquatic habitats ofhilly and mountainous areas
Traditional agricultural landscape elements such as
rice paddies, irrigation canals, and ponds have also
played a role as aquatic habitat. Some of these elements
have been lost to urbanization in flatter areas, and habitat quality has been changed as the result of landconsolidation. Now, we face a land-use management
crisis, as aquatic habitats that have been previously
maintained through agricultural activities in the hilly
and mountainous areas will be changed because the land
will no longer be being used for these activities. There
are many species-rich habitats in these hilly and mountainous areas because it has been difficult to implement
intensive cultivation practices in these regions. About
72% of farmers in Hyogo Prefecture are at least 65 years
old, raising the question of how much longer they cancontinue farming. Strategies to conserve these aquatic
habitats are thus needed immediately.
There are three options for conserving aquatic habitats in hilly and mountainous areas: maintain the habitats and conserve biodiversity using methods other thanagriculture; continue the same agricultural practices; andmaintain farmlands not as rice paddies but as, for example, meadows for grazing. Of course, another option is
to do nothing, and aquatic habitats will be lost as a resultof vegetative succession in the future. I will not discuss
this option further.
4.2 Conservation by methods other than agriculture
Three types of programs that employ methods otherthan agricultural activities have been implemented tomaintain aquatic habitat. Some land has been designatedpreservation areas, field museums or parks. In otherareas, land is maintained by volunteers to conserve
biodiversity. There are also set-aside programs thatencourage farmers to preserve biodiversity on their land.
I discuss each in greater detail below.
Some agricultural landscapes have already been con-Restoration and Conservation of Aquatic Habitats in Agricultural Landscapes of Japan

served as preservation areas, field museums and parks.
These habitats cannot be left alone because they needsome disturbance to stop succession. Some field museums and parks have well-maintained habitats, but they
are, for the most part, owned by governmental units.
Sanuki Manou National Government Park in Kagawa
Prefecture, Chigasaki Satoyama Prefectural Park in
Kanagawa Prefecture, and Arimafuji Prefectural Park in
Hyogo Prefecture are good examples of such areas. A
huge amount of funding would be necessary to implement such programs across the entire area. The Kobe
area of Akashi Kaikyo National Government Park,
located in Kobe City, has been developed to conserve
the rice-paddy terrace landscape. The total plan area is233.9 ha in Kobe City and another 96.1 ha in the northof Awaji Island. The total projected expense including
for the Awaji area is 110 billion yen. Funds are also
necessary for managing the park. Although this park has
functions other than conserving the agricultural landscape, it is clearly not a viable option for all of Japan’srural areas owing to budgetary limitations. This option ismore appropriate for selected locations, such as thosewith endangered species habitats.
Many abandoned rice paddies are being maintained
through the voluntary activities of citizens dedicated toconserving biodiversity in aquatic habitats. Some suchgroups have a long history. Most of their activities, however, have been limited to areas surrounding metropolitan cities. This is not a viable option for hilly and mountainous areas because the volunteers cannot easily
access these rural areas, but it would be useful for areas
near larger cities.
Some fields have been set aside as habitat to be
maintained by farmers. Hyogo Prefecture has such a
program, called the “Biotope Paddy.” One large project
being conducted in Toyooka City involves reintroducing
the oriental white stork (Ciconia boyciana), which has
been extinct in the wild since 1971. Even though somestorks have been released since 2005, it is not clear
whether there are sufficient food resources to support
them. Therefore, Hyogo Prefecture and Toyooka City
have also initiated a program at the same time to secure
feeding areas. The program pays subsidies to farmers toconvert rice paddies into more attractive aquatic habitats.
There are two ways to do this. The first is to manage
paddies as feeding areas only, with no rice cultivated.
The other is to keep the level of water in the rice paddies
high for the whole year. Farmers usually control waterlevels very carefully during rice production in order toproduce the highest yields, and there is usually no waterleft in the field after the harvest. Controlling the waterlevel affects the distribution of aquatic species. To apply
for the program, farmers have to maintain rice paddies
of more than 1 ha in area. The program pays 540,000
yen/ha for uncultivated paddies and 400,000 yen/ha for
paddies with high water levels. In fiscal year 2006,
the program cost 16,666,769 yen and covered 35.4 ha(16.2 ha of uncultivated paddies; 19.2 ha of high waterlevel paddies). The program’s costs were split equally159

between Hyogo Prefecture and Toyooka City. In a sense,
the program is a special direct payment system by the
local government. For the areas with uncultivated paddies, the program pays more than 2.5 times as much as
the direct payment system of the Ministry of Agriculture,
Forestry and Fisheries.
Although there might be other examples of programsfor maintaining biodiversity, they may not be applicable
to all of Japan. The aquatic habitats of agricultural landscapes have been maintained primarily through agricultural activities. A great deal of effort and money will beneeded to maintain them by non-agricultural means.
4.3 Continuation of agriculture in hilly andmountainous areas
From the viewpoint of both biodiversity conservationand food self-sufficiency, it is highly desirable that agricultural activities be continued in the hilly and mountainous areas. However, this is not possible under current conditions. Therefore, we need to discuss how we
can maintain disadvantaged farmlands. The direct payment system seems to be one of the most efficientmethods. Other methods include promotion of rural
tourism, and there are some legal protections offered,for example, by the Law for the Protection of Cultural
Properties and the Law for the Landscape. Thesemethods can only be applied to limited areas, and overuse by tourists has also damaged aquatic habitats.
The Japanese direct payment system requires that
farmers agree to conserve the agricultural landscape on
their land for five years. Even if farmers practice
ecologically friendly farming, they receive no additional
subsidies. Although the details differ from country tocountry, many direct payment options exist for biodiversity and environmental conservation in the EU. Even
though there are clear differences in environment andagricultural practices between the EU and Japan, similar
additional payments for ecologically or environmentallysound actions could help to conserve biodiversity inJapan.
How do we determine conditions for additional payment? I propose that the system should pay additional
subsidies to farmers with rice paddies within a particulardistance (e.g., 50 or 100 m) of the edge of a large forest.
As previously mentioned, rice paddies, irrigation canals
and ponds within this distance are important spawning
habitats for some salamander species. The forest size
condition will promote reforestation and constructionof ecological networks. The golden eagle, Aquila
chrysaetos, an endangered species on the Ministry ofEnvironment’s red list, needs at least 1,000 ha of forest
as habitat.
The total area of rice paddies within 50 m of theedge of a large (>1,000 ha) forest on a 1:20 or steeper
slope in Hyogo Prefecture is about 220 km2. This represents about 45% of the total area of rice paddies in hilly
and mountainous areas. Using this information, I calculated a budget for providing additional subsidies in
Hyogo Prefecture. In 2005, the direct payment system

160

T. ICHINOSE

provided support to farmers for 4,134 ha of rice paddies
in hilly and mountainous areas. If 45% of this area islocated within 50 m of the edge of a large forest, an
additional subsidy would need to be paid for about
1,860 ha of rice paddies. If farmers representing 10%(186 ha) of the area agreed to keep high water levels intheir rice paddies and received 190,000 yen/ha as anadditional subsidy, the cost would be about 35 million
yen per year. If 20% received subsidies, the cost would
be 70 million yen per year. Considering that the total
amount of subsidies paid in Hyogo Prefecture decreased
by about 85 million yen from 2004 to 2005 owing tochanges in the direct payment system, these estimatedadditional expenses seem acceptable. I set the additional
subsidy at 190,000 yen/ha so that farmers could receive,in total, 400,000 yen/ha from the current system(210,000 yen/ha) and the new subsidy. The total subsidies were considered from the Toyooka program.
4.4 Maintenance through other agricultural uses
Despite the previously mentioned efforts, continuing
to produce rice in some hilly and mountainous areas will
be difficult, but there are other agricultural options.
Cattle grazing has recently been widely observed inabandoned rice paddies. Although there have been suggestions to grow crops for bioethanol in these abandoned fields, the cost would be a significant obstacle inhilly and mountainous areas.
Grazing in abandoned rice paddies has two merits:
maintaining the fields (Arita, 2005) and producing safe,
high-quality meat. Some reports indicate that grazing
has reduced damage to agricultural products by wildlife.
Naito and Takahashi (2000) showed that grazing
contributed to the maintenance of herb biodiversity in an
abandoned meadow.
Even though grazing in abandoned rice paddies has
become more common in Japan, there are no reports thathave studied what role grazing plays in maintaining thebiodiversity of aquatic species. Aquatic species cannot
usually inhabit grazing fields because there is generally
no water in these fields. However, cattle mow herbs andshrubs, even if there is water in the abandoned paddies.
Thus, it should be possible to maintain wet, abandoned
fields with grazing to conserve aquatic species. A
method of conserving habitat using grazing needs to be
developed. One concern that will have to be addressed isthat cattle feed may contain seeds of non-domestic
species. Care will have to be taken not to spread invasive species.

Acknowledgements
Special thanks to Dr. Izumi Washitani, Dr. Stefan
Hotes, Dr. Ittoku Uchida, Dr. Naoki Hayashi, Dr.
Yoshitaka Takahashi, Mr. Toshihiko Waza and Mr.
Noriyuki Fujita. This study was supported in part by theJapan Society for the Promotion of Sciences.

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(Received 6 June 2007, Accepted 6 September 2007)