Jpn. J. Environ. Entomol. Zool. 23（２）：89− 100（2012） 環動昆 第 23 巻 第２号：89 − 100（2012） 原 著

Species diversity of ground assemblages in the distinctive landscapes of the Yodo River flowing through northern Osaka Prefecture, central Japan

Takahiro Fujisawa, Cheol-Min Lee １）and Minoru Ishii

Entomological Laboratory, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, Osaka 599-8531 Japan

１）Present：Division of Forest Ecology, Korea Forest Research Institute, 57 Hoegi-ro, Dongdaemun-gu, Seoul 130-712, Korea

（Received：April 17, 2012；Accepted：May 29, 2012）

Abstract A field survey of ground belonging to Carabidae was carried out using unbaited pitfall trapping to clarify the faunal characteristics and species diversity of assemblages in the riverbeds of the Yodo River, which runs through northern Osaka Prefecture and is characterized by landscapes such as the reed community at Udono and the“ Wando” ponds at Shirokita. Ground beetles were captured at four sites, Sites 1-4, consisting of a total of 12 sub- sites for two weeks a month, from April-December, 2008. A total of 5,622 individual ground beetles belonging to 51 species were captured. Dominant species in the whole sites were Pheropsophus jessoensis, Pterostichus prolongatus, Pterostichus eschscholtzii, Dolichus halensis and Chlaenius pallipes in decreasing order, and these five species totaled 3,192 individuals, which accounted for 56.8 % of the total individuals captured in this study. Dominant species at most sub- sites, were also common to those in the whole sites. Three out of the five dominant species, P. jessoensis, P. prolongatus and P. eschscholtzii were known as hygrophilous species, which shows that most parts of riverbeds of the Yodo River could be characterized by these hygrophilous species. However, at all three sub-sites of Site 1 at Udono, dominant species were different from those of other sub-sites, and the three sub-sites formed a cluster in a dendrogram drawn by the cluster analysis using a similarity index α . The results suggest that abundance of hygrophilous species has decreased because of aridification of the riverbed at Site 1.

Key words：Carabid beetle assemblage, Species diversity, Riverbed, Reed community, The Yodo River.

such as the bitterling, Acheilognathus longipinnis, and Introduction the dragon fly, Stylurus annulatus（Osaka Prefecture, 2000b；Ishii et al., 2002）. The Yodo River is the largest river in Osaka Since 1971, these landscapes have been heavily Prefecture, central Japan, and is characterized by modified by river regulation works; ground water level landscapes of reed communities and“ Wando” ponds, has decreased and major beds have been dried because which are the calm flowing or dead waters created of extensive excavation, construction of the Amagase by accumulation of sediments on the groynes built to Dam in the upper stream and the Yodo River Weir in moderate water flow along the mainstream（Nishino, the lower stream has been carried out to stabilize the 2009）. At Udono, a large reed community, which has water level（Koyama, 1999；Aya, 2004；Nishino, 2009）, been maintained by periodical burning since the 1950s, and as a consequence, a number of play grounds have provides habitat for a variety of plants and been built on major beds（Aya, 2004）. （Koyama, 1988）. Similarly, a group of Wando ponds are Resulting from this modification, a number of nature rich in aquatic wildlife, including endangered species restoration projects have been recently carried out to

Corresponding author：[email protected]

― 89 ― Fujisawa et al.

conserve biodiversity in the landscapes of the Yodo 1996；Gerisch et al., 2006；Follner et al., 2010）. In this River. For example, rehabilitation of dried Wando study, we investigated assemblages at ponds at Kuzuha and Shirokita led to 20 species of characteristic landscapes in the Yodo River to clarify fish returning and being recorded again in the areas faunal characteristics and species diversity, and to （Nishino, 2009）. Recently, an Udono water channel, in determine the relationship between ground beetle which water was being pumped from the Yodo River, assemblages and recent river regulation works. was cut and part of major bed dug down to prevent it from drying（Koyama, 1999；Aya, 2004；Nishino, Study site and Method 2009）. These projects have considerably influenced the terrestrial invertebrate fauna in riverbeds of the A field survey using unbaited pitfall trapping was Yodo River. Although some studies have surveyed the carried out at four sites, Sites 1-4, in the riverbed of the change of terrestrial invertebrate assemblages in the Yodo River in Osaka Prefecture from April-December, Yodo River（Yasui et al., 2011）, quantitative surveys 2008（Fig. 1）. Plastic cups（7 cm in diameter and 10 of terrestrial invertebrate are needed to clarify their cm in depth）with five holes（about 2 or 3 mm in actual condition. diameter）on the bottom for drainage were used for Ground beetles have been studied widely as trapping. Traps were placed in a row at intervals of bioindicators of ecosystems affected by farmland, about 3 m for two weeks a month and emptied one and human disturbance and fragmentation（Luff, 1987； two weeks after the traps placement. Each of the four Lövei, 1996；Ishitani, 1996；Rainio and Niemelä, 2003）, sites included two to four sub-sites, and 10 traps were because they are distributed in various terrestrial set up at each sub-site. The location and environment ecosystems, and each species has a different habitat of each site were as follows： preference（Ishitani, 1996, 2003；Hiramatsu, 2007）. In Site 1：The right bank of the Yodo River at Takatsuki riverbeds, ground beetles are considered bioindicators City located about 31 km upstream from the estuary. of human disturbance and flood events（eg. Ishii et al., The width of the river was about 150 m. This site is

Fig. 1 Location of four study sites in the riverbed of the Yodo River, central Japan. The contour interval is 200 m.

― 90 ― Species diversity of ground beetle assemblages in the distinctive landscapes

called“Udono”, which has the largest reed community from the Sugawara-shirokita-ohashi Bridge. Sub-site 4B in the Yodo River. The vegetation was predominately was an area of bare ground, dominated by S. glauca and Pharagmites australis, Miscanthus sacchariflorus, and T. repens in autumn, located about 50 m upstream from Humulus japonicus. Three sub-sites, Sub-sites 1Ra, the Akagawa Bridge. 1Rb and 1Rc（R stands for reed community）, were According to data obtained from field sampling of established in this site：Sub-sites 1Ra and 1Rb were ground beetles, Simpson’s index 1−λ was calculated burnt in March, 2008, but no burning was made at as a species diversity index by the following equation：

Sub-site 1Rc in 2008. However, at Sub-site 1Rc part of 1−λ = 1−Σn（i ni−1）/ N（N−1） the reed community was mown twice in August and where ni and N are numbers of individuals of ith November, 2008. species and total numbers of individuals（Simpson, Site 2：The right bank of the Yodo River at 1949）, respectively. Takatsuki City located about 2 km downstream The degree of overlap of species captured between from the Hirakataohashi Bridge. This site is the two sub-sites was calculated by the quotient of lower riverbank immediately downstream from the similarity（Qs）： confluence of the Akuta River with the Yodo River. Qs = 2c /（a + b） The width of the river was about 300 m. Two sub-sites, Where a and b are the numbers of species captured at Sub-sites 2W and 2G（W and G stand for woodland sub-sites a and b, respectively, and c is the number of and the grass, respectively）, were established in this species common to both sub-sites（Sφrensen, 1948）. site：Sub-site 2W was woodland dominated by Salix Moreover, we made an UPGMA（the unweighted spp. and Celtis sinensis, while Sub-site 2G was grassland pair group method with arithmetic mean）cluster dominated by Artemisia indica, Solidago canadensis, and analysis using the Pianka’s α index（Pianka, 1973）to Setaria glauca. examine differences in the structure of ground beetle Site 3：The right bank of the Yodo River at assemblages among the 12 sub-sites. The index was Settsu City located about 1 km downstream from the calculated by the following equation： Torigainiwajiohashi Bridge. The river was about 300 2 2 m wide with Wando ponds in the riverbed. This site αab = Σpaj・pbj/ Σ（ paj） ・ Σ（pbj） consisted of three sub-sites, Sub-sites 3R, 3W and 3G： paj= naj / Na pbj= nbj / Nb Sub-site 3R was a reed community dominated by M. sacchariflorus and P. karka at the major bed, and part where naj and nbj, and Na and Nb are numbers of of the reed community was mown in December, 2008. individuals of jth species and total numbers of Sub-site 3W was woodland dominated by Salix spp. and individuals collected at sub-sites a and b, respectively. C. sinensis at the minor bed. Sub-site 3G was grassland In this survey, we could not classify three individuals dominated by A. indica, S. canadensis and Trifolium repens into particular species, although they were regarded adjoining a Wando pond at the minor bed. Part of the as species belonging to the genus Harpalus on the Sub-site 3G grass was mown in October, 2008. basis of morphology. Therefore, we dealt with them Site 4：The left bank of the Yodo River at Osaka as Harpalus spp. in the species list, but excluded them City, with abundant Wando ponds, located about 12 from comparisons of species richness, species diversity, km upstream from the estuary. Four sub-sites, Sub- and similarity indices among sites or sub-sites. sites 4R, 4W, 4G and 4B（B stands for bare ground）, were established at the lower riverbank. Sub-site 4R Results was a reed community, dominated by P. australis, M. sacchariflorus and P. karka, which was mown three A total of 5,622 individuals of ground beetles times in July, August and November, 2008. Sub-site 4W belonging to 51 carabid species were captured at the was woodland dominated by Salix spp. and C. sinensis, four sites in the riverbed of the Yodo River（Table and the undergrowth was mown three times in May, 1）. The number of species was highest at Site 2（41 July and September, 2008. Sub-site 4G was the grass species）, followed by Site 4（36）and Site 1（34）, and adjoining Wando ponds dominated by Bidens frondosa, lowest at Site 3（33）. Among all the 12 sub-sites, the Fatoua villosa and S. glauca, and the grass was mown number of species was highest at 2G（38）and lowest three times in May, July and November in 2008. The at 4W（10）. Density（number of individuals caught three sub-sites were located about 500 m upstream per trap）was highest at Site 2（4.68）, followed by

― 91 ― Fujisawa et al. ) ) 51 (1) (1) (8) (1) (6) (5) (8) (5) (1) (3) (3) (4) (1) (4)

l (69)

Tota 0.004 0.001 0.003 0.003 0.004 0.001 0.001 0.003 0.001 0.002 0.002 0.002 0.001 0.002 0.108 (212) 0.090 (177) 0.014 (78) 0.258 (506) 0.028 (55) 0.040 (78) 0.016 (31) 0.157 (308) 0.461 (903) 0.026 (51) 0.201 (394 0.012 (24) 0.035 0.016 (32) 0.019 (38) 0.039 (76) 0.022 (44) 0.039 (77) 0.021 (41) 0.015 (30) 0.017 (34) 0.011 (21) 0.008 (16) 0.006 (11) 0.068 (134) 0.012 (24) 0.006 (11) 0.181 (355 0.178 (348) 0.010 (19) 0.005 (10) 0.023 (46) 2.868 (5622) 0.528 (1034) - 0 .006 (12) - - - -- 0 .010 (20) 0 .011 (21) - - - - 0 .016 (31) - 29 0.89 4B 0.04 (7 ) 0.12 (22) 207(1.17) 0.01 (1) 0.06 (10) 0.28 (50) 0.09 (16) 0.55 (97) 159(0.90) 0.16 (28) 0.01 (1) 0.03 (5) 0.01 (1) 0.10 (18) 0.02 (3) 0.01 (1) 0.01 (2 ) 0.01 (2) 0.14 (24) 0.01 (2) 0.01 (2) 0.02 (4) 0.01 (1) 0.02 (3) 0.07 (12) 0.70 (124) 0.73 (129 ) 0 .102 (200) 0.66 (117) 1.36 (240) 7.31(1294) ------0 .03 (6) ------21 0.92 ) 4G 5 3 6 0.10 (18) 0.02 (4) 0.01 (1) 0.03 (5) 0.02 (3) 0.01 (2) 0.07 (12) 0.01 (1) 0.05 (9) 0.02 (3) 0.09 (15) 0.04 (7) 0.09 (15) 0.21 (36) 0.09 (15) 6 1 ( 3

- 0 .05 (9) ------0 .02 (3) -- -- - 0 .07 (12) - -- 0.90 St. 4 7 10 3 . 2 0.92 4W 0.02 (4) 0.01 (1 )- 0.01 (1) 0.01 (1 )- 0.01 (1 ) 0 .01 (2) 0.01 (2) 0.01 (2 ) 0 .02 (3) 0.01 (2) 0.02 (3) 0.02 (3 ) 0 .06 (10) 0.12 (20 ) 1 .07 (185) ------17 0.81 4R 0.01 (2 )- 0.19 (32) 0.14 (24) 0.04 (7) 0.01 (1 )- 0.01 (1 )- 0.01 (2 )- 0.01 (2 )- 0.26 (43) 0.01 (1) 0.04 (7 )- 0.81 (136) ------0 .03 (5 )- - 26 0.66 3G 0.03 (4 ) 0.01 (1 ) 0.13 (20 )0.11 (18) 0 .01 (2) 0.01 (2 ) 0 .02 (3 )- 0.01 (1 ) 0.12 (19 ) 0 .01 (2 )- 0.01 (1 ) 0.01 (1 ) 0.01 (2) 0.01 (1 ) 0.01 (1 ) 0.01 (2 ) 0.01 (1 ) 0 .01 (1 )- 0.01 (1 ) 0 .01 (1) 0.16 (26) 0.01 (1 ) 0.03 (5) 1.37 (218) 5.63 (895) 2.94 (468 ) -- -- - 0 .04 (6 ) ------0 .01 (1 ) ------) 1 21 9 7 7 0.81 3 7 1 . 3 ( 3W

0 St. 3 8 0.07 (12) 0.14 (25 ) 0 .46 (73) 0.51 (90) 0.02 (4 ) 0 .01 (2 ) 0.05 (9) 0.01 (1 )-0.01 (1 )- 0.02 (3 )- 0.02 (3) 0.01 (1 ) 0 .11 (17) 0.01 (1 ) 0 .02 (3) 0.02 (4) 0.03 (6 )- 0.02 (3 )- 4 0.01 (2) 0.03 (5) . 0.69 (123) 2.04 (363) 3 - 0 .01 (2 )------17 0.72 3R 0.01 (1 )- 0.03 (6 ) 0 .08 (15) 0.03 (5) 0.11 (19) 0.01 (1) 0.06 (11 )- 0.03 (5 ) 0 .10 (18) 0.01 (1) 0.03 (5) 0.03 (5) 0.02 (3) 0.01 (1) 0.01 (1) 0.55 (98 ) 0 .20 (35) 0.02 (3 )- 0.84 (149) 1.23 (219) 2.99 (533) ------38 0.91 ) 2G 5 5 5 2 0.01 (1 ) 0.02 (4) 0.08 (14) 0.03 (6 ) 0.05 (9) 0.28 (49 ) 0.01 (1 ) 0.02 (3 ) 0.02 (4 ) 0.13 (23) 0.04 (7 ) 0.51 (88) 0.01 (1) 0.02 (4 ) 0.02 (3) 0.05 (8) 0.08 (14 ) 0.01 (1) 0.20 (35) 0.14 (24) 0.01 (1 ) 0.05 (9 ) 0.03 (5) 0.02 (3 ) 0.01 (1 ) 0.01 (1 ) 0.02 (4) 0.03 (6) 0.01 (2 ) 0.37 (63) 0.55 (94) 0.01 (1)

0.70 (121) 0.90 (154) 5.73 (986) 1 1 . ( t 4 - - - 0 .20 (35) ------0 .19 (33) -- - 0 .02 (4 ) ------

0.94 S 8 27 6 . 0.90 4 2W 0.27 (43 ) 0 .75 (129) 0.02 (3) 0.02 (3) 0.13 (21) 0.30 (48) 0.54 (86) 0.01 (2) 0.17 (27) 0.16 (26) 0.06 (10) 0.04 (6) 0.07 (11) 0.03 (4 )- 0.36 (58) 0.03 (4) 0.01 (2) 0.03 (4) 0.01 (1) 0.01 (2) 0.01 (1 )- 0.03 (4) 0.01 (2) 0.04 (6) 0.11 (18 ) 0 .12 (21) 0.36 (57) 0.73 (116) ------0 .03 (4 )- - - 23 0.88 0.01 (2) 0.02 (3) 0.02 (3) 0.01 (2) 0.01 (2) 0.04 (7) 0.02 (4) 0.02 (3) 0.05 (9) 0.02 (3) 0.02 (4) 0.01 (1) 0.01 (1) 0.01 (1) 0.15 (25) 0.02 (4) 0.22 (36) ------) 1 22 4 1 (24 ) 7 6

0.80 4 . 8 (

t .

3 1R b 1 Rc 0 1 S 5 . 0.20 (26) 0.01 (1) 0.01 (1) 0.01 (1) 0.02 (3) 0.01 (1) 0.01 (1) 0.02 (2) 0.32 (41) 0.01 (1 ) 0 .02 (3) 0.32 (41 ) 0 .02 (3) 0.02 (2) 0.01 (1 ) 0 .01 (1 ) 0.03 (4) 0.02 (2) 0.09 (12 ) 0 .11 (18) 0.05 (6) 0.04 (5 ) 0 .01 (2 ) 0.05 (6) 0.02 (2 ) 0 .01 (1) 0.1 9 1 0.88 (112) 2.30 (295 ) 0 .84 (138 ) 3 .56 (569) ------21 (10 ) (11 ) 0.79

1Ra 0.01 (1) 0.02 (2) 0.05 (7) 0.12 (16) 0.01 (1) 0.02 (2) 0.65 (86) 0.15 (20) 0.18 (24) 0.02 (2) 0.01 (1) 0.01 (1) 0.06 (8) 0.01 (1) 0.05 (6) 0.03 (4) 0.01 (1) 0.01 (1) 0.02 (3) 0.0 8 0.0 8 1.58 (208) シ シ シ シ シ シ シ シ シ シ シ リ シ シ エ ゾ カ タ ビ ロ オ サ ム シ ヤ コ ン オ サ ム Japanese name ケゴモクムシ ヒメケゴモクムシ オ オ ク ロ ナ ガ オ サ ム シ マ イ マ イ カ ブ ケウスゴモクムシ ナ ガ ヒ ョ ウ タ ン ゴ ミ ム オ オキ ゴ ン ミ ナ ム ガ シ ゴ ミ ム シ キ ア シ ヌ レ チ ゴ ミ ム シ ト ッ ク リ ナ ガ ゴ ミ ム シ オオホシボシゴミムシ オオズケゴモクム コゴモクムシ ア シ ミ ゾ ナ ガ ゴ ミ ム シ オ オ ナ ガ ゴ ミ ム シ オ オコ ク ガ ロ シ ナ ラ ガ ナ ゴ ガ ミ ゴ ム ミ シ ム シ ア オ グ ロ ヒ ラ タ ゴ ミ ム オオクロツヤヒラタゴミムシ セ ア カマルガタツヤヒラタゴミム ヒ ラ タ ゴ ミ ム シ キアシツヤヒラタゴミムシ ヒメツヤマルガタゴミムシ ニセマルガタゴミムシ コマルガタゴミムシ ナガマルガタゴミムシ オオマルガタゴミムシ オオゴモクム ウスアカクロゴモクム ゴミムシ ホシボシゴミムシ クロゴモクム ニセクロゴモクム ヒラタゴモクムシ チョウセンゴモクムシ アカアシマルガタゴモクム ゴモクムシ属spp. オオスナハラゴミムシ スジアオゴミムシ チビアオゴミムシ ニセコガシラアオゴミムシ アオゴミムシ クビボソゴミムシ アトワアオゴミム オオアトボシアオゴミムシ キボシアオゴミム オオホソクビゴミムシ ミイデラゴミムシ アトボシアオゴミムシ ヒメキベリアオゴミム ) 1-λ (

s

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.

Tota

Specie sp p Total no. of specie Species diversity index R: reed community, W: woodland, G: the grass, B: bare ground Campalita chinense Carabus yaconinus H. vicarius H. jureceki Leptocarabus kumagaii Damaster blaptoide s H. griseus Scarites terricola magnus Pterostichus versicolo Archipatrobus flavipes P. haptoderoides A. sadoensis H. eous H. tridens P. sulcitarsis P. eschscholtzii P. prolongatus P. microcephalus Agonum chalcomus Dolichus halensis S. arcuaticollis S. callitheres Amara congrua A. nipponica A. simplicidens A. macronota A. gigantea Harpalus capito H. sinicus Synuchus nitidus Anisodactylus signatus A. punctatipennis H. niigatanus H. simplicidens H. platynotus H. crates Diplocheila zeelandica Haplochlaenius costiger H. tinctulus Harpalus Eochlaenius suvorov C. kurosawai Chlaenius pallipes Galerita orientalis C. virgulifer C. micans C. posticalis Brachinus scotomedes Pheropsophus jessoensi s C. naeviger C. inops December, 2008. Total number of individuals caught at each sub- site is shown in parentheses. Table １ Mean number of individual ground beetles caught per trap at each of 12 sub-site in Sites 1-4, in the riverbed of the Yodo River, central Japan from April-

― 92 ― Species diversity of ground beetle assemblages in the distinctive landscapes

Site 3（3.48）and Site 4（2.37）, and lowest at Site 1 contrast D. halensis and C. posticalis were dominant （1.51）. Among the 12 sub-sites, density was highest at at all three sub-sites of Site 1, with the latter species 4B（7.31）and the lowest at 4W（0.12）. It should be being the most dominant at 1Rb and 1Rc. noted that Site 2 had the highest species richness and Fig. 2 shows the percentage of individuals of nine abundance of ground beetles, and Site 4 included sub- dominant genera, Archipatrobus, Lesticus, Pterostichus, sites with assemblages of both the highest and the Dolichus, Synuchus, Amara, Harpalus, Chlaenius and lowest densities. Pheropsophus, which were captured at more than Species diversity（ 1−λ ）was the highest at Site 2 six sub-sites in this study. Percentages of Dolichus, （0.94）, followed by Site 4（0.90）and Site 1（0.87）, and Synuchus（Sub-site 1Ra）, Amara（1Ra and 1Rb）and the lowest at Site 3（0.77）（Table 1）. In most sub-sites Chlaenius（1Rb and 1Rc）species were especially high species diversity was more than 0.8 with the highest at at Site 1, compared with the other sub-sites. At Site 4W and 4G（0.92）, and the lowest at 3G（0.66）. 2, percentages of Pterostichus（2W and 2G）, Chlaenius Table 2 shows the dominant species in the （2W）and Harpalus（2G）species were high. Ground whole sites and each of the four sites in the Yodo beetle assemblages of Site 3 were characterized by the River. Dominant species from the whole sites were abundance of Pterostichus and Pheropsophus species at Pheropsophus jessoensis, Pterostichus prolongatus, P. all the 3 sub-sites, with a high percentage of Chlaenius eschscholtzii, Dolichus halensis and Chlaenius pallipes in species at 3W. At Site 4, Harpalus and Chlaenius species descending order, which numbered 3,192 individuals were predominant at all 4 sub-sites, and the abundance and accounted for 56.8 % of the total individuals of Pterostichus, Pheropsophus and Archipatrobus was also captured in this study. Four of the five species, P. high at 4R, 4G and 4B, 4W and 4G, and 4G and 4B, jessoensis, P. prolongatus, D. halensis and C. pallipes were respectively. recorded from all the four sites, and P. eschscholtzii was Table 4 shows the number of individuals of the found at all the sites except for Site 1（Table 1, 2）. ground beetle species unique to a particular site However, at Site 1, D. halensis was the only dominant （“unique species”）in this study. The number of species included in the five dominant species in the unique species was highest at Site 1（4 species）, whole sites（Table 2）. followed by Site 2 and 4（3）, and no unique species Table 3 shows five dominant species at each of the were recorded from Site 3（Table 4）. At Site 1, the 12 sub-sites. At six sub-sites, 2W, 2G, 3R, 3W, 3G, and unique species were Synuchus callitheres, Harpalus 4B, more than two dominant species were common vicarious, Galerita orientalis and Brachinus scotomedes, and to the whole sites. In particular P. jessoensis and P. the total number of individuals of the four species was prolongatus, which were the first and the second most as high as 62. dominant in the whole sites, dominated at seven The quotient of similarity（Qs）was high between and six sub-sites, respectively, although only a few 1Rb and 1Rc, 2W and 2G, 2W and 3W, 2G, 3G and 4B, individuals were captured at Site 1（Table 1）. In 4R and 4G, and 4G and 4B（higher than 0.7）, while it

Table ２ Five dominant ground beetles in decreasing order and their mean number of individuals caught per trap at each of 4 sites, St. 1-4, in the riverbed of the Yodo River. Total number of individuals caught at each site is shown in parentheses. Whole Order St. 1St. 2St. 3St. 4 sites Chlaenius posticalis Pterostichus versicolor Pheropsophus jessoensis Pheropsophus jessoensis Pheropsophus jessoensis 1 0.38 (159) 0.62 (207) 1.17 (601) 0.40 (276) 0.53 (1034) Dolichus halensis Pterostichus prolongatus Pterostichus prolongatus Pterostichus eschscholtzii Pterostichus prolongatus 2 0.32 (136) 0.54 (180) 1.02 (527) 0.30 (209) 0.46 (903) Amara gigantea Chlaenius pallipes Pterostichus eschscholtzii Pterostichus prolongatus Pterostichus eschscholtzii 3 0.16 (68) 0.54 (179) 0.48 (247) 0.28 (193) 0.26 (506) Chlaenius kurosawai Carabus yaconinus Chlaenius pallipes Harpalus eous Dolichus halensis 4 0.13 (55) 0.52 (172) 0.30 (152) 0.20 (141) 0.20 (394) Carabus yaconinus Pheropsophus jessoensis Lesticus magnus Chlaenius posticalis Chlaenius pallipes 5 0.09 (38) 0.45 (151) 0.08 (39) 0.20 (139) 0.18 (355) Total 1.08 (456) 2.68 (889) 3.04 (1566) 1.39 (958) 1.63 (3192) Percentage1) 71.14 57.17 87.4458.5956.78 １）Percentage of the 5 dominant to all the species caught at each site in the total number of individuals.

― 93 ― Fujisawa et al.

Table ３ Five dominant ground beetles in decreasing order and their mean number of individuals caught per trap at each of 12 sub-sites in the riverbed of the Yodo River. Total number of individuals caught at each sub-site is shown in parentheses. St. 1 Order 1Ra 1Rb 1Rc Dolichus halensis Chlaenius posticalis Chlaenius posticalis 1 0.65 (89) 0.88 (115) 0.22 (34) Amara gigantea Dolichus halensis Chlaenius kurosawai 2 0.18 (25) 0.32 (40) 0.15 (24) Synuchus callitheres Amara gigantea Galerita orientalis 3 0.15 (20) 0.32 (34) 0.11 (16) Synuchus arcuaticollis Carabus yaconinus Dolichus halensis 4 0.12 (16) 0.20 (26) 0.05 (10) Chlaenius posticalis Chlaenius kurosawai Synuchus arcuaticollis 5 0.08 (10) 0.19 (25) 0.04 (7) Total 1.19 (157) 1.49 (244)0.74 ( 95) Percentage1) 75.48 82.71 68.84

St. 2 Order 2W 2G Chlaenius pallipes Pterostichus prolongatus 1 0.73 (116) 0.90 (154) Pterostichus versicolor Carabus yaconinus 2 0.54 (86) 0.75 (129) Anisodactylus sadoensis Pterostichus versicolor 3 0.36 (58) 0.70 (121) Pheropsophus jessoensis Pheropsophus jessoensis 4 0.36 (57) 0.55 (94) Archipatrobus flavipes Dolichus halensis 5 0.30 (48) 0.51 (88) Total 2.28 (365) 3.41 (586) Percentage1) 64.15 59.43

St. 3 Order 3R 3W 3G Pterostichus prolongatus Chlaenius pallipes Pheropsophus jessoensis 1 1.23 (219) 0.69 (123) 2.94 (468) Pterostichus eschscholtzii Pterostichus prolongatus Pterostichus prolongatus 2 0.84 (149) 0.51 (90) 1.37 (218) Pheropsophus jessoensis Pheropsophus jessoensis Pterostichus fortis 3 0.55 (94) 0.20 (35) 0.46 (73) Synuchus nitidus Pterostichus fortis Chlaenius pallipes 4 0.11 (19) 0.14 (25) 0.16 (26) Amara macronota Harpalus capito Archipatrobus flavipes 5 0.06 (11) 0.10 (18) 0.13 (20) Total 2.76 (492) 1.83 (291)4.52 (805) Percentage1) 93.01 80.17 89.94

St. 4 Order 4R 4W 4G 4B Chlaenius kurosawai Archipatrobus flavipes Pheropsophus jessoensis Pheropsophus jessoensis 1 0.26 (43) 0.02 (4) 0.21 (36) 1.36 (240) Pterostichus prolongatus Harpalus tinctulus Archipatrobus flavipes Pterostichus fortis 2 0.19 (32) 0.02 (3) 0.10 (18) 1.17 (207) Harpalus capito Chlaenius pallipes Chlaenius kurosawai Pterostichus prolongatus 3 0.14 (24) 0.02 (3) 0.09 (15) 0.90 (159) Synuchus arcuaticollis Synuchus arcuaticollis Chlaenius posticalis Harpalus eous 4 0.04 (7) 0.01 (2) 0.09 (15) 0.73 (129) Chlaenius posticalis Harpalus capito Chlaenius micans Dolichus halensis 0.04 (7) 0.01 (2) 0.09 (15) 0.70 (124) 5 Chlaenius kurosawai 0.01 (2) Total 0.65 (113) 0.10 (16)0.58 (99) 4.85 (859) Percentage1) 84.33 80.00 53.51 66.38 １）Percentage of the 5 dominant to all the species caught at each site in the total number of individuals. R: reed community, W: woodland, G: the grass, B: bare ground

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Fig. 2 The percentage of individuals of nine dominant ground beetle genera（collected at more than 6 sub-sites）, Archipatrobus, Lesticus, Pterostichus, Dolichus, Synuchus, Amara, Harpalus, Chlaenius and Pheropsophus at 12 sub-sites, in the Yodo River, central Japan, in 2008.

Table ４ Total number of individuals and species of ground beetles caught atan only site in this study. St. 1St. 2St. 3St. 4 Species Total 1Ra 1Rb 1Rc 2W 2G 3R 3W 3G 4R 4W 4G 4B Pterostichus haptoderoides ----1------1 Synuchus callitheres 20 ------20 Agonum chalcomus ------1 1 Amara simplicidens ------1 -- 1 Anisodactylus punctatipennis ---41------5 Harpalus vicarius -1------1 H. platynotus ----3------3 Chlaenius inops ------1 1 Galerita orientalis 11416------31 Brachinus scotomedes 352------10 24 20 18 45 0000102 Total no. of individuals 74 62 9 0 3 Total no. of species richness 33213000 0102 10 4 3 0 3

was low between each of Sub-sites 1Ra, 1Rb and 1Rc （Ministry of Environment, 2007）and Osaka Prefecture and most of other sub-sites（lower than 0.6）（Table 5）. （Osaka Prefecture, 2000b）were found at Site 2 and As for a cluster analysis with the Pianka’s α , ground 3. However, other red list species previously recorded beetle assemblages at 12 sub-sites were grouped into from the Yodo River, such as Carabus tuberculosus, three clusters, consisting of all the three sub-sites at Chlaenius pericallus, Ch. spoliatus, etc., could not be found Site 1, Sub-sites 4R and 4W, and the remaining seven in this study. Comparing the ground beetle fauna of the sub-sites, at a level between 0.3 and 0.4 in the index Yodo River（this study）with that of the Yamato River （Fig. 3）. （Lee and Ishii, 2010）, which runs through southern Osaka Prefecture, the number of species recorded was Discussion similar, and 39 species were common between the two areas with P. jessoensis, P. eschscholtzii, and D. halensis In this study, 51 species of ground beetles, which dominating in both rivers. Since more than 40 species represented 24.1% of those recorded from northern and have been recorded from other river studies（Ishii et central Osaka Prefecture（Osaka Prefecture 2000a）, al., 1996；Ishitani et al., 1997；Hiramatsu, 2007）, it is were found in the riverbed of the Yodo River. It should possible that riverbeds represent an important habitat be noted that a total of 11 individuals of a species, for ground beetles. Eochlaenius suvorovi, listed in the Red Data List of Japan It is notable that both species richness and species

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diversity of ground beetle assemblage were the highest jessoensis, P. prolongatus, P. eschscholtzii, D. halensis and C. at Site 2 near the confluence of the Akuta River, which Pallipes, in decreasing order. In particular, P. jessoensis rises in the Hokusetsu mountainous region and flows and P. prolongatus were the dominant species in the through rural areas. Previous studies have shown that riverbed of the Yodo River and in most sub-sites：P. the species diversity of ground beetle assemblages jessoensis was recorded from eight sub-sites and was in the grass and forest are higher in rural areas than dominant at seven sub-sites, and P. prolongatus was in urban and suburban areas（Niemelä et al., 2002； recorded from 10 sub-sites and dominant at six sub- Ishitani et al., 2003；Hartley et al., 2007；Niemelä sites. Out of the five dominant ground beetles, three and Kotze, 2009）. At the Akuta River, rising waters species, P. jessoensis, P. prolongatus and P. eschscholtzii, every summer（Ministry of Land, Infrastructure and are known to be hygrophilous（Nakane et al., 1963； Transport, Japan, 2002）may lead to ground beetles Habu and Sadanaga, 1965；Ueno et al., 1985）. However, being carried from the rural area of the Akuta River P. jessoensis was captured not only in riverbeds（Ishitani, and then concentrated at the confluence. 1996；Ishii et al. 1996；Lee and Ishii, 2010）, but in Dominant species in the whole sites were P. other environments such as cultivated fields（Togashi

Table ５ The quotient of similarity（QS; figures lower left from the diagonal）and number of common species among the ground beetle assemblages（figures upper right）at 12 sub-sites, in the riverbed of the Yodo River, central Japan. Shaded numbers represent. Site 1 Site 2 Site 3 Site 4 1Ra 1Rb 1Rc 2W 2G 3R 3W 3G 4R 4W 4G 4B 1Ra -131311149111012612 10 Site 1 1Rb 0.60 -17141611121010510 10 1Rc 0.59 0.76 -141710131111611 10 2W 0.46 0.57 0.56 -241117171251219 Site 2 2G 0.47 0.52 0.55 0.73 -14182413717 25 3R 0.47 0.56 0.50 0.50 0.50- 13 13 10 71314 Site 3 3W 0.52 0.56 0.59 0.71 0.60 0.68- 15 11 71315 3G 0.43 0.42 0.45 0.64 0.74 0.60 0.64 -1161621 4R 0.63 0.51 0.55 0.55 0.460.59 0.58 0.51 -714 12 4W 0.39 0.31 0.36 0.27 0.29 0.520.45 0.33 0.52- 86 Site 4 4G 0.57 0.47 0.50 0.50 0.57 0.68 0.62 0.68 0.74 0.52 -18 4B 0.39 0.38 0.38 0.67 0.720.60 0.59 0.75 0.510.30 0.71- R: reed community, W: woods, G: the grass, B: bare ground

Fig. 3 Cluster analysis dendrogram（using Pianka’sα Index）showing differences in ground beetle assemblage structure at 12 sub-sites, in the Yodo River, central Japan, in 2008.

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and Kitajima, 1993；Ishitani, 1996）, paddy fields（Habu reported that overwintering adults were found inside and Sadanaga, 1965；Yahiro et al., 1992；Lee et al., rotten wood on the major bed and the shoulder of 2008；Lee and Ishii 2009）and city parks（Lee and terraces between the major and minor beds in the Ishii, 2009）. Also, P. prolongatus were found in paddy Kizu River, a branch of the Yodo River. This species fields（Yahiroet al., 1992；Lee et al. 2008；Lee and Ishii is considered to be distributed everywhere in the 2009）, forests（Togashi and Sugie, 1994；Hori, 2003）, riverbed of the Yodo River. Amara gigantea, which wetlands（Kimoto and Yasuda 1995）and city parks had the highest number caught at Site 1 among the （Lee and Ishii, 2009）, as well as in riverbeds（Ishii et four sites, has been recorded from a gravel riverbed al., 1996；Ishitani et al., 1997；Lee and Ishii, 2010）. In （Togashi, 1986）, riverbeds（Ishii et al., 1996；Ishitani et contrast, there have been few records of P. prolongatus al., 1997；Hiramatsu, 2007；Lee and Ishii, 2009, 2010） in woodlands. Nevertheless, the results of this study and a crop field（Ishitani, 1996）. Lee and Ishii（2009, show that ground beetle assemblages in most parts of 2010）reported that many individuals of this species riverbeds of the Yodo River are characterized by the were caught at riverbeds where the reed, P. karka, was dominance of eurytopic hygrophilous species. dominant, indicating that it could be regarded as a The results of cluster analysis showed that ground grassland species. Thus, the ground beetle assemblage beetle assemblages of all the three sub-sites at Site 1 of Site 1 was mainly composed of grassland species were different from those of other sub-sites（Table with a few individuals of hygrophilous species. 5, Fig. 3）. Although assemblages of 4R and 4W were As a result of the river regulation works in the Yodo also different from those of other sub-sites（Fig. 3）, River since 1971, the ground water level has decreased this may be due to the lowest species richness and and major beds have been dried at Udono（Site 1）, and abundance of ground beetles（Table 1）with few reed communities have been replaced by terrestrial dominant species common to the whole study sites plants such as S. canadensis and H. japonicus（Koyama, （Table 3）. The grass was mown three times during 1999；Aya, 2004；Nishino, 2009）. Previous work has the active season of ground beetles at the two sub- shown that ground beetle assemblages are sensitive to sites. Earlier studies have shown that species diversity changes in river conditions（Togashi, 1986；Gerisch of ground beetle assemblages is low with dominated by et al., 2006；Lee and Ishii, 2010）. Thus, the recent habitat generalists and open habitat species in highly river regulation in the Yodo River may have caused disturbed grassland areas（e.g. Davis, 1982；Koivula a decrease in hygrophilous species and increase in et al., 2005；Hartley et al., 2007）. So it is possible that species that prefer drier grassland habitats, especially lower abundance at the two sub-sites may be caused at Site 1. Further, control burning of the huge reed by the high level of local disturbance in the riverbed community at Site 1 occurred every February, when grass from frequent mowing. most ground beetles hibernate under the ground. It On the other hand, unique species were most is known that fire can influence terrestrial abundant and few dominant species were common including ground beetles（Touyama et al., 1989; to the whole sites, with the exception of D. halensis at Touyama, 1999）. It is possible that the unique ground Site 1（Table 2-4）. At Site 1, four species, C. posticalis, beetle assemblage at Site 1, where it was proved in this Amara gigantea, C. kurosawai and C. yaconinus, instead study that an abundance of grassland species was high proved to be dominant（Table 2）. Among the four but that of hygrophilous low, is related with the two species, two Chlaenius species, C. posticalis and C. factors of aridification and fire events in the riverbed. kurosawai, were dominant at 1Rb, 1Rc and 4R, although both species were caught in the whole study sites Acknowledgements （Table 1）. Chlaenius posticalis has been recorded from various types of habitats including riverbeds（Ishii The authors are grateful to Dr. T. Hirowatari and et al., 1996；Ishitani et al. 1997；Lee and Ishii, 2009, N. Hirai of Osaka Prefecture University and Dr. M. 2010）and agricultural landscapes consisting of paddy Ishitani of Osaka Sangyo University for their useful fields, pastures, orchards and coppice（Kagawa et advice on the present study. Thanks are also due to al., 2008）. Kagawa et al.（2008）pointed out that C. our laboratory members for their kind co-operation and posticalis preferred dried grassland conditions, and assistance. This study was allowed by the Yodogawa Inoue（1953）mentioned that it does not prefer River Office（Kinki Regional Development Bureau, wetland habitats. For C. kurosawai, Yamazaki（1999） Ministry of Land, Infrastructure and Transport）

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and supported in part by the Japan Society for the Nature Conservation Committee of Entomological Promotion of Science（Grant-in-Aid for Scientific Society of Japan.（in Japanese） Research 20510217）. Ishitani, M.（1996）Ecological studies on ground beetles（Coleoptera：Carabidae, Brachinidae）as References environmental indicator. Misc. Rep. Hiwa Mus. nat. Hist. 34：110pp.（in Japanese） Aya, S.（2004）Recent Changes of Ecological Ishitani, M.（2003）Bioenvironmental evaluation Environment in Yodo River. Journal of Urban Living technique by ground beetles. In“ Wildlife conserving and Health Association, 48：334 − 340.（in Japanese） technique”（Sato, S. and Niisato, T. eds）pp. 171 − Davis, B. N. K.（1982）Habitat diversity and 185. Kaiyu-sha, Tokyo.（in Japanese）. invertebrates in urban areas. In“Urban Ecology. Ishitani, M.（2010）Evaluating ground beetles as The Second European Ecological Symposium Berlin indicator species to assess the environments. Jpn. 1980”（Bornkamm, R. Lee, J. A. and Seaward, M. R. J. Environ. Entomol. Zool. 21：73 − 83.（in Japanese D., eds）, pp. 49− 64, Blackwell, London with an English summary） Follner, K., Hofacker, A., Glaeser, J., Dziock, F., Gerisch, Ishitani, M., Tukamoto, T., Ikeda, K., Yamakawa, K. and F. F., Ilg, C., Schanowski, A., Scholz, M. and Henle, Yano, K.,（1997）Fauknal and biological studies K.（2010）Accurate environmental bioindication in of ground beetles（Coleoptera；Carabidae and floodplains in spite of an extreme flood event.River. Brachinidae）（1）Species compositions on the Res. Applic. 26：877 − 886. banks of the same river system. Jpn. J. Ent. 65：704 Gerisch, M., Schanowski, A., Figura, W., Gerken, − 720. B., Dziock, F. and Henle, K.（2006）Carabid Ishitani, M., Kotze, D. J., Niemelä, J.（2003）Change in beetles（Coleoptera, Carabidae）as indicators of Carabid beetle assemblages across an urban-rural hydrological site conditions in floodplain grasslands. gradient in Japan. Ecograpy 26：481 − 489. Internat. Rev. Hydrobiol. 91：326 − 340. Kagawa, Y., Ito, N. and Maeto, K.（2008）Species Habu, A. and Sadanaga, K.（1965）Illustrations for composition of ground beetles（Coleoptera： identification of larvae of the Carabidae found in Carabidae and Brachinidae）in an agricultural cultivated fields and paddy-fields（III）. Bull. Nat. landscape consisting of a mosaic of vegetations Ins. Agr. Sci. C 19：81 − 216.（in Japanese with an types. Jpn. J. Ent. 11：75 − 84.（in Japanese with English summary） an English summary） Hartley, D. J., Koivula, M. J., Spence, J. R., Pelletier, Kimoto, S. and N. Yasuda（1995）Ground-Surface R., and Ball, G. E.（2007）Effects of urbanization Carabids of Hokkaido. Tokai Daigaku Shuppankai, on ground beetle assemblages（Coleoptera, Tokyo.（in Japanese） Carabidae）of grassland habitats in western Koivula, M., Kotze, D. J., & Salokannel, J.（2005）. Canada. Ecography 30：673 − 684. Beetles（Coleoptera）in central reservations of Hiramatsu, S.（2007）Species composition of Carabid three highway roads around the city of Helsinki, beetles（Coleoptera, Carabidae and Brachinidae） Finland. Annales Zoologici Fennici 42：615 − 626. on a riverbank of the Tedori river. Biogeography 9： Koyama, H.（1988）Conservation of phragmites 31 − 40. communities at Udono. KONC 15：13 − 18.（in Hori, S.（2003）The characteristic of Carabid beetles Japanese） community in isolated forest. Bull. Hist. Muse. Koyama, H.（1999）Conservation strategies for Hokkaido 31：15 − 28.（in Japanese） phragmites communities at Udono, The Yodo Inoue, H.（1953）The life history of Chlaenius posticalis River. KONC 21：207 − 216.（in Japanese） in Hokkaido. Sinkonchu 6（13）：43 − 44.（in Lee, C. M., Nagai, Y., Hirowatari, T., Ishitani, M. and Ishii, Japanese） M.（2008）Change in structure of ground-beetle Ishii, M., Hirowatari, T., Yasuda, T. and Miyake, assemblage on levee of paddy field after the paddy H.（1996）Species diversity of ground beetles in reclamation in southern Osaka, central Japan. the the Rverbed of the Yamato River. Jpn.J. Environ. nature and 43：6 − 10.（in Japanese） Entomol. Zool. 8：1 − 12. Lee, C. M. and Ishii, M.（2009）Species diversity of Ishii, M., Goukon, K. and Yata, O.（2002）The ground beetles assemblages at urban greeneries important regions to conserve diversity. The in southern Osaka, central Japan. Jpn. J. Environ.

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Entomol. Zool. 20：47 − 58.（in Japanese with an groups of equal amplitude in plant sociology based English summary） on similarity of species content and its application Lee, C. M. and Ishii, M.（2010）Species diversity of to analysis of the vegetation on Danish commons. ground beetle assemblages in the riverbed of the Biol. Skr. K. Danske Vidensk. Selsk. 5：1 − 34. Yamato River. Jpn.J. Environ. Entomol. Zool. 21：15 Togashi, I.（1986）Ground beetles inhabiting a dry − 28.（in Japanese with an English summary） riverbed situated in the middle reaches of the Luff, M. L.（1987）Biology of polyphagous ground Saigawa, Kanazawa, Ishikawa Prefecture. Bull. beetles in agriculture. Agricultural Zoology Reviews 2： Japan Sea Res. Inst. Kanazawa Univ. 18：37 − 42.（in 237 − 278. Japanese） Lövei, G. L. and Sunderland K. D.（1996）Ecology Togashi, I and Kitajima, H.（1993）Ground beetles and behavior of ground beetles（Coleoptera： （Coleoptera）caught by pitfall traps in an Carabidae）. Annu. Rev. Entomol. 41：231 − 256. onion patch of the experiment farm of Ishikawa Ministry of Land, Infrastructure and Transport, Japan Agricultural College, Ishikawa Prefecture. Proc. Pl. （2002）Water information system. http://www1. Prot. Hokuriku 41：97 − 99.（in Japanese） river.go.jp/（accessed on 7 March 2012）. Togashi, I. and Sugie, Y.（1994）Epigaeic ground Ministry of Environment, Japan（2007）Listed species beetles caught by unbaited pitfall traps in of Red Data. http://www.biodic.go.jp/rdb/rdb_ Kawachimura, Ishikawa Prefecture, in 1989. Jpn. J. f.html（accessed on 7 March 2012） Environ. Ent. Zool. 6：27 − 30.（in Japanese with an Nakane, T., Ohbayash, K., Nomura, S. and Kurosawa, English summary） Y.（1963）Iconographia Insectorum Japonicorum Touyama, Y., Nakagoshi, N. and Takahashi, F.（1989） Colore natural Edita, Vol. 2. Hokuryukan, Tokyo.（in The dynamics of the terrestrial Japanese） community and vegetation recovery at post-fire Niemelä, J., Kotze, D. J., Venn, S., Penev, L., Stoyanov, I., stands. Jpn. J. Ecol. 39：107 − 119.（in Japanese Spence, J., Hartley, D. and Oca E. D.（2002）Carabid with an English summary） beetle assemblages（Coleoptera, Carabidae）across Touyama, Y.（1999）Ecological effect of reforestation urban-rural gradients: an international comparison. on the postfire succession of Carabid fauna. Landscape Ecology 17：387 − 401. Edaphologia 62：1 − 9. Niemelä, J, and Kotze, D. J.（2009）Carabid beetle Ueno, S., Kurosawa, Y. and Sato, M.（1985）The assemblages along urban to rural gradients: A Coleoptera of Japan in Color, 2. Hoikusya. Tokyo. review. Landscape and Urban Planning 92：65 − 71. Yahiro, K., Fujimoto, T. Tokuda, M. and Yano, K.（1992） Nishino, M.（2009）Recover the past landscape of Lake Species composition and seasonal abundance of Biwa and Yodo River. Sunrise publishing, Shiga.（in ground beetles（Coleoptera）in paddy fields.Jpn. J. Japanese） Ent. 60：805 − 813. Osaka prefecture（2000a）The list of wildlife in Osaka. Yasui, M., Shiyake, S. and Beetle Team of Yodogawa Osaka Prefecture. Osaka.（in Japanese） River Research Group（Project Y2, Osaka Osaka prefecture（2000b）The important wildlife to Museum of Natural History）（2011）Fauna and conserve in Osaka Prefecture. Osaka Prefecture. distribution of the bembidiine ground beetles Osaka.（in Japanese） （Coleoptera：Carabidae）in the investigated areas Pianka, E. R.（1973）The structure of lizard of the Yodogawa River system, central Japan. Bull. community. Ann. Rev. Ecol. Syst. 4：53 − 74. Osaka Mus. Nat. Hist. 65：39 − 76.（in Japanese Raino, J. and Niemelä, J.（2003）Ground beetles with an English summary） （Coleoptera：Carabidae）as bioindicators. Yamazaki, K., Sugiura, S. and Kawamura, K.（1999） Biodiversity and Conservation 12：487 − 506. Overwintering ground beetles assemblages along Simpson, E. H.（1949）Measurement of species the Kizu river, Kyoto. Entomological Science 2：33 diversity. Nature. 163：688. − 40. Sφrensen, T. A.（1948）A method of establishing

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大阪府北部を流れる淀川の特徴的な景観における地表性甲虫群集の種多様性

藤澤貴弘・李 哲敏１）・石井 実

大阪府立大学大学院生命環境科学研究科 １）現在，韓国国立森林科学院

大阪府を流れる淀川には，鵜殿のヨシ原や城北のワンド群のような特徴的な景観が存在する．これらの景観における 地表性甲虫（オサムシ科）の相の特徴や群集の種多様性を明らかにするために，淀川河川敷に 4 ヶ所の調査地を設定し， 各調査地の 2 ～ 4 地点，合計 12 地点において，2008 年 4 月から 12 月に各月 2 回，各回 1 週間ずつ，無餌ピットフォー ルトラップを用いた調査を行った．その結果，全調査地で 51 種 5,622 個体の地表性甲虫が捕獲された．全調査地の上位 種はミイデラゴミムシ，オオクロナガゴミムシ，オオナガゴミムシ，セアカヒラタゴミムシ，アオゴミムシであり，こ れら 5 種で全捕獲個体数の 56.8％を占めた．中でも，好湿性として知られる前 3 種は大部分の地点から記録され，淀川 の河川敷を特徴づける種と考えられる．しかし，鵜殿では上位 4 種が全調査地の上位種と異なっており，重複度指数α に基づくクラスター分析の結果，鵜殿の調査地の 3 地点が独立したクラスターを形成した．その要因として，鵜殿のヨ シ原の乾燥化による好湿性種の減少が考えられる．

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