Northward Invasion and Range Expansion of the Invasive Fern Thelypteris dentata (Forssk.) St. John into the Urban Matrix of Three Prefectures in Kinki District, Japan

2007·7.2 MB·English

by  Kentaro Murakami

American
Pern 186-
Journal 97(4): 198 (2007)
Northward
and Range
Invasion Expansion
of the
Fern
Invasive
Thelypteris dentata
(Forssk.) John
St.
Urban
into the Matrix of Three Prefectures Kinki
in
Japan
District,
Kentaro Murakami
1
Museum,
Natural History Kishiwada
City, Japan
Matsui
Rii;
Pacific Consultants
Co., Ltd., Japan
MORIMOTO
YUKIHIRO
Graduates School of Global Environmental
Studies, Kyoto
University, Kyoto, Japan
Abstract.—
This study investigated the current distribution of an invasive tropical fern, Thelypteris
and
dentata, its habitat type in three Japanese prefectures (Osaka, Kyoto, and Shiga) in the Kinki
The showed
District. results that dentata has expanded
T. distribution into highly urbanized
its
areas in Osaka Prefecture and has reached southern Kyoto and
Prefecture central Shiga Prefecture.
The
distribution of T. dentata populations thus seems have expanded northward based
to on
comparisons with was
the distribution determined
that the 1980s. Because
in the fern's habitat
types were mainly the side walls or bottoms of drainage channels, crevices stone walls and
in
roadsides, the urban matrix has not served as a barrier to the expansion of the range of dentata:
T.
on may
the contrary, be serving
it as a type? of heat island corridor that facilitating the spread of
is
his species.
I
Words.—
Kkv
Thelypteris dentata, range expansion, urban heat island, global warming, greenhouse
weed
downy
The maiden
fern {Thelypteris dentata
(Forssk.) John)
St.
is
considered to be an alien fern that invaded Japan from
tropical or subtropical
(Yamazumi,
countries Honshu
1988; Hotta, 2001). In the the
area,
first
occurrence of dentata was documented Wakayama
T. 1951 southern
in in
Prefecture of Kinki District (Yamazumi, 1988). Although the was
fern
initially
treated as a rare species (Yamazumi, 1988), by the 1970s had been reported
it
in several additional places, mainly southern Honshu
in coastal areas of such
Wakayama
southern and Mie
as
prefectures (Manago, The
1986). Japanese
distribution of T. dentata was described along with and
that of native ferns
fern allies by Kurata and Nakaike According
(1983). to their survey, the
in
Waka\
M
used map
to create this distribution dated mainly from
the 1960s
to the
1 Corresponding author. Current Museum
address: Natural History Kishiwada
of City, 6-5 Sakai-
maohi, Kishiwada Osaka
City, Prefecture,
Japan.
MURAKAMI ET RANGE EXPANSION OF THELYPTERIS DENTATA 187
AL.:
were
dentata
beginning of the 1980s. Detailed reports of the distribution of T.
map
Wakayama by Manago Nakajima however,
Prefecture (1986). (1998),
for
expanded
dentata might have since
predicted that the distribution of T.
warm
in
We
map
we
on
focused
investigate changes in the national distribution of T. dentata, its
trends in 3 prefectures (Osaka, southern Kyoto, and Shiga prefectures) in the
Kinki District of western Japan. These study areas were selected because the
and growth
urban heat island effect (which can facilitate the survival of
markabl
The term
Kida, 2002).
temperatures
and
by
rural areas because of the greater retention of heat buildings, concrete,
These and thus considered be important
asphalt. cities their outskirts are to
and
which the relationship between increasing temperature the
areas in
expanding distribution of plant species can be investigated.
Methods
Materials and
Field investigations were carried out by one or two investigators at each site
The on 500-m around
from 2004 October 2006. study focused a radius
July to
railway The main reason selecting railway stations as the center of
stations. for
each study was that has been reported that the primary habitats of the
site
it
human-made
such walls (Manago, 1986; Reis 2006)
fern are habitats as et a/.,
common
around
and that these habitats are features railway stations. In total,
we southern Kyoto
surveyed 79 railway stations in central Shiga Prefecture,
between
Prefecture, and Osaka Prefecture; these included 11 stations
Yamashina and Omi-Maiko on the Kosei Line of the Japanese Railways
(J.
between Nagahama and Osaka on Hokuriku Line Tokaido
the or
35 stations
R.),
Line of the 18 stations on the Osaka Loop Line of the R., and 15 stations
R.,
J.
J.
between Nanba and Misaki Koen on the Nankai Honsen Line of the Nankai
Downy
Railways. maiden fern was not found in the additional investigations
conducted around Fukui and Tsuruga Stations (which are to the north of Shiga
2005 and August 2006.
Prefecture) in July
maximum
In order to investigate each site at an equivalent intensity, the
number
was h The individuals each
investigation time set at 2 per site. of at
The
was two (1-10 and 10-100 individuals).
classified into categories
site
was
microhabitat type for each fern classified into several categories: crevices
between
in stone walls, side walls or the bottom of drainage channels, alleys
The by
buildings, roadside habitats, or in planters. populations identified the
autumn of 2005 were investigated in the following spring in order to determine
The
whether each individual had survived the winter. meteorological data for
our study areas were collected from nearby meteorological stations by usin
Agency Agency,
the Japan Meteorological website (Japan Meteorological 2006).
AMERICAN FERN VOLUME NUMBER
JOURNAL:
188
97 4 (2007)
In order to investigate the increase in temperature each the
at site,
temperatures were compared between the two study periods (1970-1982 and
1983-2005). Two-tailed were performed
with
t-tests for statistical analysis,
<
P
significance
set at 0.05.
Results
The
shown
meteorological data for our study areas are in Table All
1.
temperatures were higher 1983 than most temperatures were
after before;
significantly higher, with the exception of those Torahime and Otsu
at
was
(Table This particularly true the highly urbanized Osaka
for cities of
1).
and Kyoto, and Hikone
for City in central Shiga Prefecture.
downy
Individuals of the maiden fern were discovered 34 of the 79
at sites
The number
(43.0%; Fig. Table of individuals in each population
1; 2).
shown
category recorded for each site is in Table 2; the total count was more
than 250 The main newly
individuals. habitats of the discovered populations
were human-made
hard-surfaced habitats such as side walls or the bottom of
drainage channels The was
or stone walls. frequency of occurrence higher
in
Osaka
southern Prefecture than in the other areas. The northernmost
was
population discovered Hikone The
Shiga
in City, in central Prefecture.
size of this population and of individual ferns were small, but the population
was
discovered in the winter of 2004, and had survived two years
for at least
The
until the spring of 2006. distance of this population from the population in
Wakayama
Prefecture reported by Kurata and Nakaike and Manago
(1983)
was
(1986) approximately 100 km, and the distance from southern Hyogo
which was
Prefecture, the northernmost location of the fern in Kinki District in
map
the distribution of Kurata and Nakaike was approximately 60 km.
(1983),
we
assume
If that the fern's distribution expanded northward for a total
km
distance of at least 60 during a period of about 20 years, the expansion
km
distance averages approximately
per
3 year.
Discussion
—
We
new
Distribution of Thelypteris dentata in Japan. recorded 34
populations
of Thelypteris dentata in three prefectures of Japan's Kinki
was
District. Thelypteris dentata recorded previously and
in local flora
lists
Museum,
publications (Nakaike, 1996; Kohata, 1997; Hiratsuka City 2001;
Hotta, 2001; Mitsuta, 2002; Matsui et aL, 2003; Murakami et 2003, 2004;
a/.,
Kita-Kawachi Nature Club, and some were
2004), of these reports Kinki
in
Murakam
Matsui
(Mitsuta, 2002; aL, 2003;
et
from
2004 Osaka and Kyoto
to in forests in Prefectures, including fragmented
and
forests, wildlife habitat, reclaimed forest in urban or suburban areas
Murakami
(Matsui
et aL, 2003; et aL, 2003, 2004). In an investigation of the
fern's distribution by the Kita-Kawachi Nature Club some populations
(2004),
of T. dentata were found from central to northern Osaka Prefecture. Mitsuta
URAKAMIET
AL.:
R
Table Temperat ure data eight meteorolo^ stations in and near the study area. (The data were obtained from the Japan Meteorological Agency
at ;ical
1.
;
comp
website, 2006.) The locations of each station are shown in Figure The statistical significance was determined by aring the temperatures during ANGE
1.
the two study perio ds (1970 to 1982 and 1983 to 2005).
EX1
>
A minimum maximum
Average annual temperature C) verage temperature C) Average temperature C) 7
( ( (
Significance Significance Significance
ISION
1970-1982 1983-2005
1970-1982 1983-2005 of difference 1970-1982 1983-2005 of difference of difference
i
—
-6.3
Torahime 13.2 13.9 n.s. 5.6 n.s. 33.7 34.8 n.s.
(a)
* * -4.8 -3.7
Hikone 34.3 35.1
14.0 14.7
(b)
-3.6 -3.4
Otsu 14.8 14.9 n.s. n.s. 34.7 35.2 n.s. THEL
(c)
* * -4.2 -3.2
36.4 37.0
Kyoto 15.3 15.9 3
(d)
Osaka 16.9 * * -2.5 -1.6 35.9 36.7
16.1
(e)
—
>TER1
Sakai 15.3 15.8 n.s. -3.9 3.2 n.s. 34.5 36.4 **
(f)
S
* -2.6 -2.1
Kumatori 14.9 15.6 n.s. 33.1 34.0 *
(g)
Wakayama * * -2.6 -1.7 35.3 35.7
16.0 16.7 n.s.
(h)
DENT
p< p<
Differences betweei periods were determined using a two-tail ed Mest: n.s not significant; *, 0.05; **, 0.01 A
i
,,
2
CO
CD
6
AMERICAN VOLUME NUMBER
FERN JOURNAL:
190
07
4 (2007)
135° E
136
,--'
A
1
dapan Sea
*»jy*"*^ f* ^
\r
a_.
f
J
H-<* -"-/"'
Av'
'
1^.XX J
<
Lake
P
Biwa 00
o
Q
1 Q
\T~
Kyoto
Pref.
r o
\ o o
Kyoto urban area
I
U20
l8
%oo
N
G 22 21
- x
Hyogo *12
Pref.
l\
JQ^T*
Osaka urban area
n-
J
30
y
Osaka
j
Osaka Bay <^31^
<
Pref,
33^32
bni
Mie
Pref.
^\
Awaji Island
</
^-T'
"-*
/-^/3 Nara Pref
34° N //"
40km
Wakayama
Pref.
_j
V
,^
Lie. Locations (the gray circles with numbers from to 34) of newly discovered populations of
1.
1
Tholypteris dontata in Osaka. Kyoto, and Shiga prefectures of Japan's Kinki District. The open
circles represent the study sites in which T. dentata was nol discovered. Letters a through h
represent the meteorological stations Table
in
1.
(2002) also recorded dentata and Kyoto
T. in a list of ferns fern allies in
Prefecture, but did not report the locations of collected specimens
or their
The was
distribution. fern not reported in Shiga Prefecture before the present
new
investigation. Outside Kinki populations have been
District, recently
km
reported from Funabashi which
City (Nakaike, 500
1996), lies east of
Museum, km
Osaka; in Isehara City (Hiratsuka City 2001), which 350 east
lies
km
Osaka; Anjoh which
of in City (Hotta, 2001), lies 150 east of Osaka; and in
Okayama km
which
City (Kohata, 1997), lies 140 west of Osaka. Because areas
west our study were unknown
east or of area not investigated, whether the
is
it
fern's distribution continuous from eastern Shiga Prefecture Kanto
is to
Prefecture from western Osaka Chugoku
or Prefecture southern
to the part of
Prefecture.
Some
new
researchers noted that dentata species invades
T. a that habitats
is
by escaping from greenhouses and
other (Uemura,
artificial habitats 2000;
Yamazumi, unknown
whether
1988), but dentata followed
pattern
is T. this
it
However, many we
in Japan. likely that of the individuals observed
it is
MURAKAMI
ET RANGE EXPANSION OF THELYPTERIS DENTATA
AL.:
191
originated in this manner because T. dentata a greenhouse weed that has
is
been reported from around the world (Wagner and Smith, 1993; Possley,
2004],
and has been observed domestic greenhouses accompanying
in or potted
it
We
(Yamazumi,
plants in Japan 1988). also found T. dentata in a greenhouse in
Kyoto
City in January 2006. Therefore, the probability of the fern's dispersal
via greenhouses in each region seems be high.
to
The
current results do not clarify whether the Shiga and Kyoto populations
Wakayama
genetically resemble the Osaka and populations. Thelypteris
dentata must have spread from greenhouses or potted plants purchased
at
each whether
floriculture stores in area, but not clear northern individuals
it is
migrated from the southern Kinki District. However, the most important issue
from
the perspective of population genetics not the dispersal routes of this
is
km
species, but rather the has dispersed approximately 100 from
fact that the
it
Wakayama
which was
population, the primary location colonized by
this
The Moriyama
species in the early 1980s (Fig. population identified in City,
2).
in central Shiga Prefecture, included more than 20 full-grown individuals,
thus will not be difficult for this population to survive in the future.
it
The
distribution of tropical species can usually be explained by the
minimum
winter temperature by The mean
or cold index. lowest
a
temperature Hikone which
in City, contained the northernmost population
in our survey, was -3.7 C from 1983 to 2005 (Table Although more detailed
1).
study is required to understand the ecology of T. dentata, this value provides
a good preliminary indication of the threshold temperature for growth and
survival of dentata.
T.
we
Because of the limited area covered by our research, the populations
that
discovered cannot be used to predict the northern limit of populations of this
species Kinki More information must be acquired
in District. in the future
to
confirm However,
this limit. the climatic conditions in central Shiga
may
Prefecture be close to the northern distribution limit of the fern because
the frequency of occurrence (25% survey remarkably lower
of there
sites)
is
than that in southern Osaka Prefecture (91.6% of survey
sites).
—
Habitats of Thelypteris dentata. During our investigation, a large popula-
was
tion of Thelypteris dentata discovered in the urban areas of Kinki
District.
Some
individuals were also identified in central Osaka City, which highly
is
The was
urban. occurrence ratio lower in central Osaka City (37.5%) than in
the northern and southern Osaka areas (50% and 91.6%, respectively). This
may
have resulted from the lack of crevices the edges of roads and the
at fact
may
that fern not be found in highly developed areas. However, some
were
individuals nonetheless observed with expanses
in locations large of
broken pavements and walls with deep from where was
in crevices,
difficult
it
remove
rhizome.
the
to fern's
Most
M
(Manago,
1986; Hotta, 2001;
side walls of drain channels, crevices in stone walls, roadsides, and alleys
Some
between were
buildings. individuals discovered in pots or planters along
may
with potted plants such Aloe Cymbidium. These have
as or ferns
2
CO
number
Table Locations of newly discovered populations of Thelypteris dentata and the associated of individuals in each habitat type in Osaka,
2.
Kyoto and the Shiga prefectures of Kinki District, Japan. The open circles represent the T. dentata populations that survived from winter 2005 to
spring 2006.
Number
dentata of individuals in each microhabitat type
T.
Number
populations
of sites at
which dentata survived Sidewalls
that
T.
were recorded/ from winter or bottom Inner Alleys
Number between
of sites 2005 to (Crevices of) of drainage planted >
Name
Location surveyed spring 2006 stone walls channels pots Roadside buildings
re
Shiga Prefecture 8 32 (25.0%)
/
>
1-10
Kawase N35 13' E136-13'
1
Aduchi N35 08' E136 08' 1-10 1-10
2
re
Moriyama N35 03' E135 59' 10-100
3
Z
N35 01' E135 57' 1-10 10-100
Kusatsu
4
o
N34 59' E135 55' 10-100
5 Seta
G
N34 0-1
Lshiyama 58' E135°53' 00
6
1 7Z
Nishi-Otsu N35 01' E135 51' 1-10
7 >
-
Otsu N35 00' E135 51' 1-10 re
8 1
1
<
Keihanshin area (southern Kyoto Pref. and 6 12 (50.0%) C
/
re
northern Osaka C
Pref.)
Yamashina N34 59' E135 49' 1-10
9
re
N34 58' E135 43' 1-10 1-10
10 Nishi Oji
CD
Mukoh-machi N34 57' E135 42' 1-10
11
a
Yamazaki N34 53' E135 40' 1-10
1
13 Senrioka N34 47' E135 33' 1-10
N34 46' E135 32' 1-10 re
14 Kishibe
4^
n:
3
•^
a
Table Continued
2.
>
Number
dentata
T. of individuals in each microhabitat type
>
Number
populations
of sites at
which -
dentata that survived Sidewalls
T.
were recorded/ from winter bottom
or Inner Alleys
>
Number
of sites 2005 to (Crevices of) of drainage planted between
Name
Location surveyed spring 2006 stone walls channels Roadside
pots buildings *
>
Osaka Osaka
City (central Prefecture) 9 23 (39.1%)
z
/
15 HigashiyodogawaN34 40' E135 30' 1-10
O
16 Fukushima N34 41' E135 29' 10-100
1-10
X
N34
17 Nocla 41' E135 28'
1-10 1-10 1-10
>
18 Taishn N34 39' E135 29' 10-100 1-10 1-10
z
19 Tsuruhashi N34 40' E135 31'
1-10 10-100 1-10 C/3
c
Momodani N34
20 39' E135 31' 1-10
2
N34
21 Terada-cho 38' E135 31' 1-10 1-10 G
22 Tennohji N34 38' E135 30'
1-10
Suminoe N34
23 36' E135 29'
0-1 00
1
I
Southern Osaka
Prefecture 11 12 (91.6%)
/
24 Minato N34 34' E135 27'
1-10
0-1 00
1
25 Hagoromo N34 32' E135 26'
10-100 10-100
26 Takaishi N34 31' El 35 25' 10-100 10-100 CO
27 [zumiotsu N34 30' E135 24' 10-100 10-100 fa
28 Tadaoka N34 29' E135 23' 10-100
29 Kishiwada N34 27' E135 22' 10-100 10-100
30 Kaiduka N34 26' E135 21' 1-10 2
31 Izumisano N34 24' E135 19' 1-10 1-10
N34
32 Tarui 22' E135 15' 1-10 10-100
33 Ozaki N34 21' E135 14'
1-10 1-10
34 Misaki-koen N34 19' E135 09'
1-10
Total 34
11 16 6 13 8
CO
VOLUME NUMBER
AMERICAN
FERN JOURNAL:
104 97 4 (2007)
Fie. 2. Change in the distribution of Thalyptcris dent at a from 1083 lo 2006. The open circles
represent the distribution in 1083 (Kurata and Nakaike, 1083), and the gray circles represenl the
-4
additional records of 2004-2006. The dashed line represents the C isothermal line of the
minimum
average temperature (1000-2003) based on the data from the Japan Meteorological
Agency
website.
MURAKAMI RANGE EXPANSION OF THELYPTEHIS DENTATA
KY 195
AI,:
may
purchased and
originated as spores in the potting soil of plants, the ferns
have survived due supply of water by humans. However, some ferns that
to a
may removed owners
invaded planters have been the did not like the
if
and
invaders enough retain them. Therefore, data from planters gardens
to
when
should not be used rigorously evaluating habitat suitability for the
downy we
maiden have information Table
Nonetheless, retained this in 2
fern.
Even garden
the sake of completeness. the absence of a fern in a planter or
for if
does not provide evidence of absence in a region, the presence of a fern does
its
provide evidence of presence in that region.
its —
Can expansion
heat island corridors explain of the fern's distribution?.
Mormon
Northward expansion of the range of the great butterfly [Papilio
km
memnon
occurred a rate of about 400 over 22 years, from 1981 to
L.) at
2003 (Yoshio, 2004; Yoshio and 2004). The annual average expansion
Ishii,
thus equals about 18 km. In contrast, the results of the present study
rate
speed Thelypteris dentata
indicate that the dispersal of the fern is
km
km
approximately 60 to 100 over 20 years, for a rate of 3 to 5 per year.
Although the fern has expanded distribution more slowly than the butterfly,
its
this likely because the butterfly can fly freely, whereas the fern sporophytes
is
downy
maiden grows urban
are sessile. Because the fern in artificial habitats
rather than in a natural environment such as that of forest-floor ferns, the city
may
matrix not function as a barrier to northward expansion of the distribution
of this species. Our study focused on areas along railway lines, and almost all
were urban suburban these the matrix almost
sites in or areas. In areas, city is
continuous and there are few geomorphic obstacles between the study sites. If
warm
this spatial structure represents a continuous corridor from Shiga to
Wakayama
Wakayama, grow
tropical or subtropical species that often in the
may
invade northern
region be capable of dispersal along these corridors to
fragmented surrounded by hard-surfaced
areas In contrast, forests a
(Fig.
2).
from expanding
urban matrix generally prevent species of the forest interior
two
even an urban heat island corridor connects patches of forest.
easily,
if
more
Urban weeds can expand their distribution rapidly because the city
warming
matrix functions as a source of habitat, not as a barrier. global
If
expand and
continues, the distribution of such species will further the species
common
become wider range urban
will across a of areas.
—
The Crinum Line and heat islands. In Japan, the Crinum Line and effect
its
known
on phytogeography well (Koshimizu, 1938; Nakanishi, 1980). This
is
line represents a border formed by the line representing an average annual
temperature approximately 15°C and an annual lowest temperature of
of
-3.5°C (Koshimizu, 1938), and regarded as the standard distribution limit
is
subtropical or tropical species (Nakanishi, 1980). This line used as
for is still
Crinum japonicum,
the distribution borderline for not only asiaticum L. var.
and
name,
the species that gives the line but also for various subtropical
its
hamabo
tropical species, including Hibiscus Sieb. et Zucc, Canavalia lineata
DC,
(Thunb.) Chloranthus glaber (Thunb.) Makino, Debregeasia edulis
many
(Siebold & Zucc.) Wedd. and more (Taniguchi, 1956; Murata, 1968;
The and
Horikawa, 1976; Nakanishi, 1980). annual average temperature