Iwatsuki, Kunio

Ueno, Shunichi

English

Kyoto University Research Information Repository

RIGHT:URL:CITATION:AUTHOR(S):ISSUE DATE:TITLE:The Green Plants growing inAkiyoshi-dô Cave, SouthwesternJapanIwatsuki, Kunio; Ueno, ShunichiIwatsuki, Kunio ...[et al]. The Green Plants growing in Akiyoshi-dô Cave, Southwestern Japan. Memoirs of the College ofScience, University of Kyoto. Series B 1959, 26(3): 315-3221959-11-15http://hdl.handle.net/2433/258582MEMOIRS OF ME COLLEGE OF SCIENCE,             Vol. XXVI, No. 3, ArticleU !VERS!TY OF 1<yoTo, SERXES B,11 (Biology), 1959         The Green Plants growing iA Akiyoshi-d6 Cave,                           Southwestern Japarf)                                   By                            Kunie IwATSUKI             Betanical Institute, College of Science, University ef Kyoto                                   and                                         t                            Shun-Ichi UENo             Zooiogical Institute, College ef Science, University of Kyoto                         (Received September 25, 1959)    Akiyoshi-dai is the most extensive karstic plateau in the Japanese Islands. Itoccupies the northeastern half of the Akiyoshi lirnestone area and is excavated bymany caves and potholes, among which is found the vastest one of the Japaneselimestone caves. It is called either "Akiyoshi-d6" or "ShGh6-d6". Besides theremarkable development in scale, this cavern is bestowed with a variety of caveformations. It has long been commercialized, and is so well known in Japan thatthe name "Shah6-d6" attalns to have become a substitute of `sh6nya-d6' that means`limestone caves' in Japanese.    On his collecting trip in the Far East made in 1925, the Iate Prof. F. SiLvEsTRihappened to visit the cavern, which was then called "Taki-aRa", and investigatedthe cave aRlmals for the first time. A new troglophilous opilionine was thendescribed from his collection2). Two years later of SmvEsTRi's visit, Prof. M. UENoinvestigated the aquatic fauna of the same cavern, finding three species of cave-dwelling crustaceans3). Since that time, however, no successor had appeared tiii thetimes just before the outbreak of the World War II, when three biologists`) workedindependently en the cave fauna.    Aftex the War, the researches for cave animals have rapid}y progfessed in Japan,and the animals inhabiting Akiyoshi-d6 Cave have been investigated repeatedly.Considerable efforts have been directed by UENo, one of the authors, to clarify thefauna. Systematic surveys were also carried out in 1956 and 1957 by the Spelaeo-Iogical Society of Japan. The rnore the knowledges have become enlarged, however,    1) Contribution No. 27 from the $pelaeelogical Seciety of Japan.    2) Strisiivea cavicola RoEwER, 1927, p. 197.    3) UENo, M., 2927.    4) Dr. T. ffABE, Messrs. K. ToRxr and Y. kcEDA.  316 Kunio IwATsm<I and Shun-Ichi (JENo  the more the investigators have been puzzled with the excessive abundance of  trogloxenes found in Akiyoshi-d6 Cave. The matter is apparent on the lists of  animals obtained in the cavern, compiled by two different authors5). Yet, the actual  number of the species is much larger than those appeared on these lists concerning  the trog}oxenous animals hitherto found in Akiyoshi-d6 Cave. According to the  present authors' own knowledges, they are so numerous in the cavern as to be  impossible evell to compile a tentative list of them. It is obvious that such a  pheRomenoR could not be resuited from one or two simple causes. It may have  arisen from a co-operation of some peculiar environmental factors, e.g., th`3t the  cavern has long been illuminated for tourists, that it has a large entrance, through  which the sunlight penetrates into the cavern to a considerable extent, that there  are many potholes connecting the cavem with the karstic surface, and that the  strearn which runs threugh the cavern is not only the underground water of phreatic  zone but is an assemblage of the surface waters. There is one more remarkable  factor in the cavern, which seems to play an attractor for epigean animals. It is  the presence of green plants.      Naturally, no chlorophy}l-bearing plant grews in the totai darkness within caves.  Fungi are frequently feund in the depths, growing on rotten boards or logs, and  furnish nutriment te springtails and sflails. They are, hewever, not identified as  yet. The subject of the present paper is to show the presence in Akiyoshi-d6 Cave  of the colonies of greeR piants under natural and artificial li.crhts. Such an attempt  may be of sorne value for the future stu(lies on the speo-eco}ogy in Åíhe cavern.                    EnvlrenmeRtal Cenditioms in tke Cavern     In Akiyoshi-d6 Cave, the cave walls on which the plants are found are corr]posed  of limestone at every station. This is rather exceptional, becatise, ln Japan, massive  limestones are usu.ftl}y interbedded with the other rocks (e.g. chert), which are' frequent}y exposed on cave walls. It is, however, diMcult to censider the vegetation  to be restricted to llmestone. Several papers have hitherto been appeared dealing  with the Japanese limestone plants, coming usual}y to a result that the so-called  limestone plants are reaily not alkali-philous but merely resistib!e to drought. Owing  to the humid climate, genuine limestone fiora is not so prominent in Japaxx as ln  Europe.     The climatic conditions inside the cavern are, of course, greatly different from  those of the outside. The hurriidity of the air is extremely high, above 90 per cent  even at the twilj.ght zone (IsmKA.wA., 1957, p. 32). The temperature is net enly  low (be]ow 160C), but always low. There is no current of the air in many places  in the cave. Further, they are remarl<ably constant, especial}y in the depth. Such  a peculiar environment allows only some particular species of p}ants to grow in  the cave.     5) ToRII, l956, pp. 423-424; Is}iu<AwA, 1957, p. 33.The Green Plants growing iR Akiyoshi-d6 Cave rnFig. 1. Sketch map of Akiyoshi-d6 Cave (adepted frem ETo, partly modified by YAMAuTi, 1957) ; the numbers 1-15 indicate the stations  investigated (cf. pp. 318-319).317318 Kunio IwATsuKi and Shun-Ichi UENo    Beyond these features, extreme shortage of light gives an important and vitaleffect on the fermation of fiora. Artificial lights introduced in the cave are notcomparable with the natural daylight in their eficiency, i.e. in the intensity andthe quantity of light, in the wave-lengths, in the duration of illumination, and soon. There are tvv'o kinds of vegetations in Akiyoshi-d6 Cave:that growing at thetwilight zone under the faint daylight and that growing under the artificial lightsinstalled Åíor tourists. The latter is usually small and stunted, but sometimes attainsto a fuil growth or makes thiclc carpets. Successive data are unfortunately notavailable for the formation of such vegetations. However, it may not be uselessto give here a brief history of the installation of electric lights.    The first attempt to illuminate the cavern was made in October, 1925, withthe installation of incandescent electric lamps. Since then, the illumiRation of thissort has been increased and improved. It makes a main source of light even atpresent. IR December, 1956, several fiuoresceRt lamps were installed in companywith the establishment of a lift. The Iight thrown from these lampsis, however, sofaint that no vegetatioR can usually be detected around thern. More receRtly, inJuly of l957, a dozen of mercury lamps were provided at She important places.The cavern is now equipped with three kinds of artificial lights, of which the effectsupon the development of vegetation will be given on the following pages.                         Green ?lants in tke Cavern    The plants inhabiting Akiyoshi-d6 Cave were co}lected by the authors duringtheir recent trip made ig june and July, 1959. They are listed below according torespective stations. All the specimens examined are preserved in the herbariumof the University of Kyoto.    Station 1. 'Threshold (daylight).       Several species of ferns and bryophytes. Lichens and c}imbing seed plants are also       seen.    Station 2. Rol<ujiz6 (incandescent lamp, mercury lamp and faint glimmer of the daylight).       Pteris mttttifida PolR. 4572S)       }IyPode•matittm fauriei (KoDAMA) TAGAwA 4570       Cyrtomittm fortunei }. SM. 4571       AsPlenium varians WALL. 4573       BrachNtheciu?n buckana,ni <Hooi<.) 3AEG. 4569       Fissideiis nagasakim4s BEscH. 4568       Algae    Station 3. NagafuÅëhi (incandescent lamp).       Algae    Station 4. Hyakumaizara (mercury lamp).       Algae    Station 5. Hironiwa (incandescent larnp).       Algae    6) The numbers on this list indicate iwATsuKr's field numbers of the specimens.                   The Green Plants growing in Akiyoshi-d6 Cave 319    Statien 6. I<abocba-iwa (incandescent lamp).       Cyrtornium fertzenei J. SM. 4575       Fisstdens nagasaki?tus BEsci{. 4574       Algae    Station 7. Chirimen-iwa (mercury lamp).       Algae    Station 8. Chimachida (incandescent lamp).       Pteris ?meltifida Pom. 4578       AsPle?zitt?n sareiii Hooi<. 4577       Rgtyncestegktm sp.7) 4576       Algae    Station 9. I<asazukushi (merÅëury lamp).       Algae    Station 10. Karataki (incandescent lamp).       Algae    Station 11. Senj6jiki (mercury lamp).       Algae    Station 12. Iwayakannon (incandescent lamp).       Fissidens nagasakinus BEsc!{. 4579       Algae    Station 13. Sarusuberi (incandescent lamp).       Pteris ?nttltiptda Po!R. 4583       Cyrtomitem fortscnei I. SM. 4582       AsPlenium saretii HooK. 4584       Bracltytlteciui•n buchanani (MooK.) JAEG. 4580       Fisside?ts nagasakintes BEscH. 4581       Algae    Station 14. Eastern foot ef Senj5jiki (mercury lamp).       Algae    Station 15. Lift (fluorescent lamp).       Algae    These plants were, no doubt, introduced into the cave after the artificial illumlna-tions were installed. Their spores might have been swept in with the streams orbrought in by hurnan agencies, and might have sett}ed there. They are usuallydifferen't from the normal ones due to the peculiar environmental conditions. Theyare small and stunted in many cases, and are always sterile. These worse con-ditions make the identification much diMcult.    Seed Plants : -Seed plants are found only at the threshold and wholly unknownat the dark zone. This straRge phenomenon may be attributed to various causes:that the spores of mosses aRd ferns might have larger abilities of dispersion thanthe seeds of spermatophytes; that all the seed plants hitherto introduced lnto thecave might not be able to grow, because the minimttm quantity of their lightrequiyement exceeded the given light; that the seeds carried in might have missed    7) Refer to the paragraph of the bryophytes.320 Kunio IwATsvKi and Shun-Ichi UENotheir chance, for some reason, to germinate normally ; or that some of the climaticor the other factors might have been unsuitable fer the survival of them. Any ofthese explanations, however, seems not te be satisfactory. To analyse the problem,2t may be helpful to know what species of seed plants would settle down for thefirst and what species would follow the pioneer.    PteridoPhytes:-No fern allies were collected. All the pteridophytes growingin the cavem are leptosporangiate ferns, as seen below :   Pteris m"ltifida PoiR.    Hypodematiuwt fauriei (KoDAMA) TAGAwA.    Cyrtomium fortunei j. SM.    AsPlenium sarelii ffooi<.    A. varians WALL.    Of these species, HyPodematiptm fa"riei was found only on the walls near theentrance, where there reached the faint glirnmer of the daylight. This species iswideiy spread over the warrn regions of Japan and Korea, and is usually knowngrowing on dry limestone outcrops exposed to the sun. It is also taken on thecliffs in front of the entrance of Akiyoshi-d6 Cave. At the present 1{nowledge ofthe atithors, it is diMcult to understandl why the species c.an not penetrate into thedepth of the cave.    In the epigean habitats around the entrance, the gemis Cptrtomium is representedby two species, including two varieties, i.e. C. faicatum, C. fortttMei var. foTtunei,C. forlanei. var. clivicolzam and C. fortunei var. intermedium. The cave specimensof Cyrtomium are easily ideatified as C. fortunei, because, in those specimens, themargin of pinnae is dentate near the apex. Cioser determinatioR is, bowever,impossible, as the plants are stunted and reasonably sterile. All tlte species belong-ing to the genus Cptrtomium are known to be of apogamous reproduction. Thisseems to be advantageous to the subterranean dispersal. C. fortunei is the mostdominant species in the cavem and is always in good conditiofi.    BryoPh),tes:-Hepaticae was entirely absent at the dark zone and was foundonly at the threshold. Three species of mosses were known in the depth. Theywere identified through the courtesy of Mr. T. NA.i<A.JiMA as listed below :    Fissidens ?tagasakintts BEsca.    Brachythecium buchanani {Hooi<.) JA.Ec..    Rlzynchostegittm pailidifoiium (MITT.) JAEG.?    Mr. NAi<A.JiMA kindly gave the authors a note on the third species, in which liestated as follows : The Akiyoshi-d6 specimen resembles the members of Ezerh-ynchitefnin its general aspect and in the presence ef small projections at the apices of costae,but is different from the latter in the shape of areolation and in the form of theapices of ieaves. It agrees with characteristics of R}iyncltostegium in some im-portant features, and seems to be a variant of R. pallidifoliz{m, which has sufferedfrom the influence of pecu}iar cave environment.The Green Plants growing in Akiyoshi-d6 Cave 321    Contfary to the supposition widely prevalent, rnosses are not so common in thecavern as ferns, especially as the prothallia of the latter. The commonest amongthe cited three species is Fissidens nagasakintts, which is usually growing on thewet cave walls fed by trickling water and forms at the station 12 a considerablythick carpet.    ThaloP hptes : -ln this paper, the coymophytes are mainly dealt with, Åíor theauthors' present interest is focused to the effect of artificial illumination$ upon theformation of green vegetations. Some algae were col}ected aro"nd the electric}amps but yet undetermined. As regards the cave flora of lower plants, especiallyof fungi which can survive in the total darkness, close investigations shou}d berequired by the botanists of that field. Such troglobiontic plants must have directrelation$ with troglobiontic anima}s from the ecologica} point of view.                 Animals depending on the Introduced Flora    Up to the recent times, nothing has been rr}ade to clarify the relations betweenthe cave-dwelling animals and the iRtroduced plants. The effect of iliuminationsupon the trog}obiontic animals has been observed only from its destructive aspect.This is terribly true regarding many groups of cave animals. Troglobiontic beetlesof the subfamily Trechinae, for example, are rapidly destroyed by the installationof artificial lights. Tltere is, however, a few groups of animals, which do not sufferfrom the effect of artificial lights but can survive noymally tal<ing the introducedp}ants as their nutriment. Unfoytunately, the accurate data are inadequate to showthe phenomenon in relief. The authors will give here an example of such a case.    At the station 13, many individuals of a minute trogloblontic snail, Caversc-acmeila kuzuue•nsis (SuzuKD, are Åíound on the wet staiagmitic wall (HAsE, 1942,pp. 28-29). TroglobiontiÅë as it is, this species can safely survive under the arti-ficial iight among the introduced vegetations. It usually feeds on algae, wliich hasbeen found from its alimentary canal.    Further, a troglophilous fiy, Exechia sp. is usually found at the station 2, anda harpacticoid copepod, BryocamPtus asclto}ekei (ScHMEiL) is taken at the station l2in the carpet of F•issidens nagasafeinecs.                                  Summary    The occurrence of green piants is reported from the dark zone of Akiyoshi-dbCave. Total eight species of cormophytes are found under the artificial illuminationsinstalled fer tourists. Five of them are leptosporangiate ferns and the other threeare mosses. Of these species, Cyrtomium fortunei and Fi.ss•idens nagasakinus aredominant aiad sometimes attain to a full grewth. The establishment of thesevegetations seems to have ecological significance to the biospeology. Severalexamples are given towards the relations between the introduced plaRts and thecave animals.322 Kunio lwATsuKi and Shun-Ichi UENo    In closing, the authors wish to express their hearty thanks to tke authoritiesof the town of Shtih6-ch6, to Mr. Ichiro ETo and his staff of Akiyoshi-dai ScienceMuseum as well as to Mr. Seiu bBA and his family. Their kind aid renderedduring the trip enabled the authors to make full iRvestigations possible. Theauthors' deep gratitude is also due to Mr. Tokuichiro NAKAJiMA of Kishiwada HighSchool, who kindly takes labour of identifying the specimens of mosses.Literature citeGC!iAppvls, P. A., l958. Mission franco-japonaise dans les grottes du Japon. Karpacticoides       de la grotte dite Akiyoshi-do. Notes Biosp6ol., 13 : 71-83.HABE, T., 1941. Spiders fouRd in Japanese caves. AÅëta Arachnol., 6: 212-113. (In Japanese.)---  1942. 0n the recent specimen of Palttdinella <Cavernacmella new subgen.) leu2t(t{ensis,       with a list oÅí known species of the Japanese cavernicolous melluscs. Venus, Mukai-       sima, 12 : 28-32.IsHIKAwA, J., 1957. The limestone caves and their faunae on the Akiyeshi ?lateau, Yama-       guchi Prefecture. Bull. Kochi Woraen's Univ., 5, (Nat. Sci.): 31-44. (In Japanese,       with English resume.)KAMITA, T., 1957. Ecological notes on the freshwater shrimps and prawns of Japan. 2. 0n       the shrimp, Neocaridlna denticulata (DE HAAN). Zool. Mag., Tokyo, 66: 240-244.       (In Japanese, with English r6sume.)RoEwER, C. F., 1927. 0stasiatische Opiliones, vgn Kerrn Prof. F. SiLvEsTRI im Jahre 1925       erbeutet. Boll. Lab. Zool. Portici, 2e:191-210.Suzum, S., 1940. Strisigvea cavicola, ein interessanter H6hlen-Opilionid aus Akiyosi und       RyugadO ff6hlen. Zoel. Mag., Tokyo, 52:482-487. (In Japanese.)ToRrr, H., 1953. A catalogue oÅí caves in Japan. Saitama Univ. Stud. Educ. Dep., 2: 49-56.       (In Japanese.)      l956. H6hlen in Yamaguchi Prafektur und ihre Faunen (Die Berichte der speltiobio-       logischen Expeditionen Vil). Bull. biogeogr. Soc. Japan, 16-19 (for l955) (Recent       Conceptions oÅí Japanese Fauna): 418-426.UENo, M., 1927. Notes on some subterranean isopods and amphipods oi Japan. Mem. Coll.       $ci. Kyoto Imp. Univ., (B), 3: 355-368.

The Green Plants growing in Akiyoshi-dô Cave, Southwestern Japan

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The Green Plants growing in Akiyoshi-dô Cave, Southwestern Japan

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