Table Of ContentFungal Diversity
Fungal succession on fronds of Phoenix hanceana in Hong Kong
Yanna, W.H. Ho* and Kevin D. Hyde
Centre for Research in Fungal Diversity, Department of Ecology and Biodiversity, The
University of Hong Kong, Pokfulam Road, Hong Kong SAR; e-mail: [email protected]
Yanna, Ho, W.H. and Hyde, K.D. (2002). Fungal succession on fronds of Phoenix hanceana in
Hong Kong. In: Fungal Succession (eds. K.D. Hyde and E.B.G. Jones). Fungal Diversity 10:
185-211.
Seventy-three fungal taxa were identified during the decomposition process of frond baits of
Phoenix hanceana, comprising leaves, rachis-tips, mid-rachides and rachis-bases. Pioneer,
mature and impoverished communities were observed in sequence on the frond baits. Fungal
communities on different frond parts reached pioneer, mature and impoverished communities
at different rates. Fungal communities on leaves and rachis-tips matured more slowly than
other parts, but became impoverished rapidly thereafter, and samples were completely decayed
at month 13. On the contrary, fungal communities on mid-rachides and rachis-bases matured
earlier at month 1,but became impoverished at month 13.Naturally occurring fronds were also
examined at the same time. Only half of the fungi were common to baits and naturally
occurring fronds. Thus, examination of both frond baits at different stages of decomposition
and naturally occurring fronds isrecommended to obtain abetter estimation of biodiversity.
Key words: fungal distribution, fungal ecology, palm, plant decomposition.
Introduction
Succession has been defined as "the sequential occupation of the same
site by thalli (normally mycelia) either of different fungi, or of different
associations of fungi" (Rayner and Todd, 1979).
There have been numerous studies on substratum succession involving a
variety of substrata, for example, cellulose film (Tribe, 1957, 1961), plant litter
(Webster, 1956; Tokumasu, 1998) and wool (Ghawana et al., 1997). There
have also been several studies of succession of fungi on degrading cellulosic
substrates (Kuester, 1979; Gorska, 1982)
In succession, biotic communities change over time and the complete
sequence of change is called a sere. Seres are made up of recognizable units
(seral stages) (Luczkovich and Know1es, 2000). In general, fungal
communities go through the following three stages (Dix and Webster, 1985;
Gessner et al., 1993):
•Corresponding author: W.H. Ho; email: [email protected]
185
Pioneer community
This community consists of pioneer species which have low percentages
of abundance (Dix and Webster, 1985; Gessner et al., 1993). Pioneer species
tend to be fast growing, short-lived, and capable of rapid and wide dispersal
(Luczkovich and Knowles, 2000). This community type usually has low
species diversity, while a few species have high abundance (Dix and Webster,
1985; Gessner et al., 1993).
Mature community
The species diversity in mature communities is high and has peaked,
while a number of species occur with a low percentages of abundance.
However, several species may have a high level of abundance. The dominant
species have extremely high levels of abundance. During the later stages of the
mature community, the number of dominant species declines, but species
diversity is still high (Dix and Webster, 1985; Gessner et al., 1993).
The highest species diversity is likely to correspond with the highest
rates of decomposition because greater genetic diversity is likely to correspond
with greater enzyme diversity. There is also a greater likelihood that
mutualistic associations and synergistic interactions can develop that can
promote decay (Dix and Webster, 1985). Biirlocher and Kendrick (1974) found
that five aquatic hyphomycete species growing together decomposed leaves
faster than a single species.
Impoverished community
The species diversity declines towards an impoverished community. The
community is dominated by a few species with extrememly high levels of
abundance (Dix and Webster, 1985; Gessner et al., 1993). These dominant
species tend to be persistent and longer-lived species (Luczkovich and
Knowles, 2000). However, there are still some species with low levels of
abundance. The community will be in climax when it is dominated by one or
two highly antagonistic species (Dix and Webster, 1985).
The present study was initiated to investigate the sequential occurrence
of sporulating fungi on frond baits of Phoenix hanceana, and also to address
the question, "Where are the undescribed fungi?", with the following
objectives:
1. To investigate the fungal communities occurring on palm fronds during
different stages of decay on different frond parts until complete
decomposition.
2. To compare fungal communities from the succession study and with those
of naturally occurring samples.
186
Fungal Diversity
Materials and methods
Study sites
Hong Kong SAR (22°N 114°E) is located at the south-eastern coast of
China, east of Guang Dong Province, some 100 km (1° latitude) south of the
Tropic of Cancer. The study site was located in Tai Mo Shan (22°25'N
114°05'E) at around 600 m attitude. The climate in Hong Kong SAR is
subtropical, tending towards temperate for nearly half of the year (Dudgeon
1994). During April to September, there is a wet and hot season, due to the
prevalent south-western monsoon, and during October to the following March,
there is a dry and cooler season due to the prevalent north-eastern monsoon
(Dudgeon 1994). In general, January and August are the driest and wettest
months respectively. The mean daily temperature ranges from 15.8 C in
January to 28.8 C in July. It is not uncommon for temperatures to drop below
10 C during January and February (Dudgeon 1994).
Sample collection
Samples ofsuccession stuay
Twelve Phoenix hanceana trees that were higher than 3 m and bearing
more than 30 green, mature fronds were selected in a forest at Twisk, Tai Mo
Shan, Hong Kong SAR on 16 July 1998. Ten random palm trees were used in
this experiment and the remaining two trees were set as backup. Eleven green
and mature fronds were cut from each of the ten individual palm trees. One of
each of the eleven fronds was randomly collected at day O. The other fronds
were tied by nylon string to the host to prevent the fronds being removed. The
position and location of the experimental fronds (frond baits) were similar to
the adjacent naturally fallen fronds on the ground. At each sampling time, one
decaying frond bait was randomly collected from each selected palm tree. It
was planned to collect decaying fronds at week 1,months 1,2,4,6, 12, 18,24,
30 and 36. However, at month 13, leaves and rachis-tips were found
completely decayed and at month 18, mid-rachides and rachis-bases were
completely decayed. Therefore, frond baits were only collected on 16 July
1998 (day 0),23 July 1998 (week 1), 17August 1998 (month 1), 19 September
1998 (month 2), 17November 1998 (month 4),21 January 1999 (month 6) and
8 September 1999 (month 13). Collection of frond baits was more frequent at
the early part of this study because fungal communities on palm (Livistona
chinensis) were recorded to change rapidly at the earlier stages of decay
(Yanna et al., 2001b) and a dramatic increase of activities of saprobic fungi
was also observed on newly dead leaves of the monocotyledon, Pisum sp.
(Dickinson, 1967).
187
Ten samples were retrieved at each sampling time. Thirty centimeter
long tip, middle and basal parts of rachis and a ten pieces of leaves were cut
and placed individually in separate snap-locked plastic bags in the forest and
brought back to the laboratory. Sterile moist tissue was added in the plastic
bags to create a damp chamber within the bags. All samples were examined
under a microscope within one month, except for the samples collected at day
O.In the latter case, microscopic examination was completed within 2 days in
order to prevent growth of fungi that were not sporulating on the living fronds
when they were cut. Squash mounts of sporulating fungi were made in water
for examination with differential interference contrast microscopy. Fungi were
isolated by staff of The University of Hong Kong Culture Collection (HKUCC)
and the cultures are cryo-preserved at -140 C in HKUCC. Palm samples were
also air-dried in an oven at 35-40 C and deposited in the University of Hong
Kong Herbarium [HKU(M)]. Details of the fungi (specimens and cultures) are
stored in the databases of HKUCC and HKU(M).
Naturally occurring samples
During the experimental period, naturally occurring fronds of Phoenix
hanceana were collected on 17 August 1998, 21 January 1999 and 8
September 1999 for comparison with the frond baits. At each sampling time, a
frond which had been decaying for a long time (later stages of decay) and a
frond which was recently dead (the early stages of decay) were collected from
each palm tree selected for the successional study. Samples were examined and
stored as described for the frond baits.
Statistical analysis and simple calculation
A 3-dimensional correspondence analysis was performed to examine the
differences in fungal communities at different times of decay. The fungi
recorded on the palm frond parts were also compared with those from naturally
occurring samples by correspondence analysis (Booth and Kenkel, 1986;
Anonymous, 1995).
The fungi found in this study are presented in terms of percentage
abundance. Fungal taxa with a percentage abundance equal to or higher than
ten are regarded as dominant species. These fungal taxa are plotted to illustrate
changes in the dominant species throughout the experimental period. Shannon
indices (H') are used to express species diversity of a community (Shannon
and Weaver, 1949), whereas species area curves are used to determine the
adequacy of the sampling size.
Percentage abundance = occurrence of taxon A x 100%
of taxon A occurrence of all taxa
188
Fungal Diversity
Shannon index (H') = -L Pilog2Pi
where Pi is the probability of finding each taxon in a collection
Results
Determination of adequacy of sampling size
The species area curves for each frond part almost reached asymptote
because the slopes of the curves were declining with the increase number of
sample and at about 10samples the slopes were near zero (Figs. 1-7). Although
the curve did not completely level off, the number of samples was large
enough to obtain highly representative results.
Colonisation patterns on different frond parts
Correspondence analyses of fungal communities at different times
throughout the decay process are presented in Figs. 8-15. Shannon indices for
different frond parts are plotted in Fig. 16 to illustrate changes of fungal
diversity throughout the study period. Dominant species at different stages of
decay are given in Figs. 17-20. The percentages of abundance for each species
are listed in Table 1.
The values of Shannon index increased from 1.4-2 at the beginning of the
study and reached peaks of about 3.7-4.1 at 120-200 days (Fig. 16). Fungal
communities on leaves peaked first (at about 120 days) and were followed by
rachis-tips (at about 150 days), and mid-rachides and rachis-bases (at about
200 days). Fungal diversity subsequently gradually declined. The changes of
fungal communities on different frond parts were as follows.
Leaves
There were 44 fungal taxa found on the palm leaves over the
experimental period, while three-dimensional correspondence analysis of
fungal communities showed that there were at least three distinct communities
(day 0, week I-month 1, months 2-6) (Figs. 8, 9). The fungal community
composition was distinct at each stage of succession, while dominant species at
each sampling time were distinct (Fig. 17, Table 1).
Actinopelte sp., Asterina clasterosporium, Everhartia phoenicis,
Graphiola sp., and an unidentified discomycete were recorded on green leaves
at day O. Everhartia phoenicis was associated with yellow spots on leaves
(Yanna et al., 2000), while Graphiola sp. was associated with brown spots.
Fruiting bodies of Actinopelte sp., Asterina clasterosporium, and the
unidentified discomycete, were formed on thin mycelial mats on the leaf
189
Table 1.Percentage of abundance of fungi found on samples of Phoenix hanceana during succession process in Hong Kong SAR (10 sub
samples per sampling time).
III I
Spe93m6r535m331mmm628811111ct3120251i3rrrrres4r231r2r9rr11bbbbb302755 826rr81rr32411r1ttttt914 49634m51wmmm8r31m1m3t210eooooroennnnnk2811trtttthhhhbh29414612764514 23 d33a33y344027 4433 3333366661133332813 753 5100 3336 3 5 615 47 5 3
ActinopeACltsehKtae.erBBDCsitpelnor.e.lyaptnHprsBnatiyoocneCndllpraiatieiahrfCas.ait)oahenrslorbiPhetaonuaeosgxnempkuiartoiabodfnFrrlinaleicirygucgl.alemaaannwPsaICaieccsSenrlhSCD.aazin.vn.HPaGaeaoHpicuortetsaoughyuzghlla.Hohe&rsseoi&psal1o.f*-urJsaeicfohbrmruinsneBisSopAheoendraatiijrpneorKd&.&iDumR.KJe.H.LiCDta.ysa.rmdmeeHacpayoedsepMo&raiutsEmu.MsBh..a.GJ.n.tWeJnoinnnagetfsu.mAHstarorksnp.haeriella nypae K.D. Hyde CCCCC*Ciyyyyo11rlllld3ciii=innnniinnddddlaoerrrretoooaoravccccilllcelaaaahsidddd;nuiiiitmuuueretlmmmrlma=peradqsbaleciurcmaloahieinpsicgsqiaRoal-uritlnaeiiaeupmsnsmsseb;eJCpe.tErlamMol(.itBuuroTsmar=tag.&yaml&noird,-rachides; rb = rachis-bases.
Tab934332m335638ml1e9rr1239363r186r9113b9cb590onIrr1Ittt7inu223mmrmm13mmwmr6rr1et6tt8t5deoorroooe.nnnnnkrm1rtttttbhhb4hhhr12461Ir1Ib9 5I 8 d77ay101 5 613 8 393 3104 9 2 3 33 25 25
DiaporHthuDegihcpetysDhooiFSccehritnnEoyaicohcneWYlsildtas.paoai.ornBm&,rPn.mieauaEKlteKami..ncn&DekicnsK.eopdtrneo.HrDti.rr)u&yo.amdisHdeBHeReorhysi.lpaFad.-htl.eJVeoHeCe.coGnGhali.s..c-otJiahRcef,ociaehload.)aKrt.D.mHryrdbe I EDniYcdtaoynconacalhy,axeKtac.Din.csitHmuysp&dlePeDGxKeor&t.camD(hpSGi.hn.oiHgHohoyluaedglelhase-psli.k&e species DDDEEDDFGvxiiiaiil1ncdpsiesso3ctereylcyocohrmmioltcamaaiasooctrdpiyssctlsipopiaccpuaorhveiomuiatrauremipeaumrhmvsioapapes.seetniotlfilrecovcaagaeirnskamrlaiainitimussY(mi(MacCM(noM.onNBlharaaa.da,stgaskEAWualRsplrih.tasHr.j)o)&.o&RHtS,..eo.J. 20
Species
Tab44m434555mmmm573388338385111l0419errrrr646rrr18rr311bbbbb41co3Irr3rrIrI4nIIttttttin9mm6rmwmm1mut0eeoorooodennnnn.krttttthhbhhh14261I day 03 3 19 8 7 339 33 44 '74 52 53 222 11
GuignaSruPdObihraxBaoymrmHdHomo.aoeatamlrhpnksieoosnp)tke.rwpsiScsPaaihalear'ienviacauz.gilgalKmKoobm.a.M(DDoScys.roy.caondeHHtts.ra)yRiyKgcddCPhnne.ePDeau.oteld&.ras.Sitp(HauBEeltsyPs.eot&tBdohrrtekino.o(oGMP.mmpe.a&saaniutJtszooob.srsnlut.pp&esoasrlSmaJa.aEcPrc.bau.ep)TmruaklyeaSll(soeCtpeyrooy,iSoraaykeSrdeat).eSsceh&.poeePdm.oPanSkhiyoeodirmd.ea&s sCpP..rEe.usBsabe. LMLMPNPPaihehe1eonsracolno3iiatemocorcnoodiadaaosnirippgcipphalrtcooyuaahndstpeaamirhaemiippitanuoiaunumpnttutrhsdseemiesaundoinpsamibntiaeorSailsommp(mSSeoiCcg(ayaiWdoo.mdeelr.aduaslaeP(lPlr.Gs(.aS)Sto.ay)hHedeG.u&.))grihfef.s
Species
Tabm795m42543398mm3653333521l1errrr51r157rrr31bbbb91co3nIrr627Ir4Ir5I3ttttt4in466wmu36mmmmmr22r633222331tt125e51erooooodennnnn.krm21tttttbhhhhh53r12146I2r35b5 7I 3 day 0 9 6 93 310 448 5 63 44 212 2 33
PTuhMboam.Bkaih.atyoESTaspsplhlEoIpoooisl.srrzlpiaeidestCreemslolsmalapeRi.eale(lVofaCfeuor&srtPaSPhidcehdyoRiarBaoelle)ylalmi.notHbCuProosemeY.o.pmpMntoeo.shSMygri.p.ucesmh.eftKto.vasoJaRiralnruararak,c.stvmehh&Jamreie.rcciDra.itahGniir.luliic.omiTmTR(arSe.urioPtd.amrAge(itauEeat.prrmh.sr(lAroSjtMeaara&nscercbhtroie.ceHc)rlarulyu)dil,shaoiBnitud.mcCo.rofokSeuVtt.oGn. RSSPSVTSeptprohoi1Sliooluolecb3aurrsmnheritisodteodlooollsedepaelrpssaeylsmmolriasamriiR&euluablimmplaloavMurmansheitopamnuy(clerPuldu.aazd)teircianuaarvrVssneinu.sc)uarpSuulm(BoeelSEmarin.faClattelucaRi.resm(tiS.MfSa&aueactc(ctEPo.)vneGceaMkrrh)v..B)ie.
Species
Leaf <> Rachis-tip o Mid-rachis l> Rachis-base x
4.5 -
~ 4- a ~
..8D ~ - •• ---
;j >r<o3.53 -.- B--,go -.-- .a._..--~-------a----~- - ----""'(r - -'LT- - '0
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8 0 1~ , /'
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2 4 6 8 10
1. Day 0
Number of samples
U•;;..>.j•D..•.4.-•...•.~c....... .:aa8•;r.x.))8;o.j~:.j4-brr0;oo~Jcj)8 -1142602--'--
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r .~.-1:i -• -.r--~------- ..-~- -
O .__ ~ __' . ' - - -- - - --A - - - -=_-.:6-- ----~-----' .-
2.Week1 __ "-<>2 4xA -_.--- 6 -8 --T--~~ 10
Number of samples
25 -
•..
15 20 -
8 ~
;j
ro
~ :: 15
a) ro _ •••_• ~. rr
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U •,,'"..I,t- .".'""!( - - ••.- -'"" - -",. - -- - --"- - -
o
2 4 6 8 10
3. Month 1
Number of samples
Figs. 1-3. Species area curves for fungi collected on Phoenix hanceana frond baits at different
stages of succession.
194
