&oloq ?%If. 1993. pp. 265-269 C 1 9 0 by t & ~ s a q a y O f Amma

hadkarn~ ~ n d L1)ngtno !Q90) and mtcrob~al acti\~t~c's of fallen eptph>tes re!at~\c tu I~ght :cgitne n u t

-z c

(vancc and X~dkornt iQc39,. leading to &&rent rates forest undmtory. hereafter "shade." \ s. ppt . rb, at- of decornpclsrtion and nutrient release (Sadkarnr and tachment to fallen branch. cc) ph>slcal Jirnrns~onb dl'

' , Ualelson : 39 1 \ Some of the 9tructural and ph>sio- the "clump" (defined hare ds a cofTtiguous tp~ph? tc Iogrcai ?hturc's that permtt epiphjtrs to t h r~ \ e In the mat that fa& from the canop)). and (d) the number ot'

. zanop) are ~ ~ n t ur ver) differrnt from. those on rhe epiphytes in the clump. forest tloor In fact. the \. ast majorit) of tlpiph) tes are ohliy~tc. 1.e.. occur onl? In the canopy (Kress 1986). .\fute~luls und .\fethds

The basis t ; ~ this c\cluslr lt? is not known. Sittd!. arcs. Fieldwork uas conducted from 12 \la) The ph>,tcsl mu\ emenr of tivf epiptr)tes from the 1989 to I March 199 t In the hfonte~erde Cloud Forest

canop? to the forest tlmr is a f t e q u e ~ event In epiphyte Reserve (MVCFR). a bwer montane mast forest In communiti'bs. Li\e cpiphptm fall to the &rest floor Costa Rica (10018' N. 84*48 W). The stud) area icl- because they are disl&#ed b) wind or antmals or be- evation: 1480 m) was in Leeward Cloud Forest (Law- cause .branches and t e s break and Pall ((Strong 1977). ton and Drqer 1980). The annual gross precipitation Some epiphy~es with m y devcbped root systems is 2000 mm. but actual wet deposition is much higher (e.g.. tsnk bromcflads>. teed to fall as indit iduab. because of frequent wind-driven mist and f q (Lawton Howvtr. live epiphyte m the form of contiguous mats, and Dryer 1980). During the dry-wind) season (No- connected by utterwoven root systems and a layer of vern&r-April) much of the area intempts clouds borne crown humus (Jenik 1973). often fall jntact. as on the strong northeast trade winds, resulting in a par- "clumps." The continued association of individual ept- trcularly species-rich cioud forest *ith complex struc- .phyt& with their original canopy organic material may ture (Hartshorn 1983). affect the survival of these individuab. The fate of an The Monteverde epiphte flora is e~treyel) di\ e r x epiphyte fatting 8s pan of an infact mat. in contrast to and abunbont (Nadbmi 1984. 1986). Branch surfaces falling iMivi&al, may differ because roots in the crown interior of nafrly all mature trees support i m W in m s may bc Lm disturbed than the un- epiphytcs(brJi0phyt~ herbs, woody shrubs. and heml- proTectcd mots of individtid plants. .4llw. the sponge- epiphytes) in i n t m o v m s ' ~ t - h u m u s mats up to 25 tikt ewts retain considcwbk amounts of water in the em thick. Epiphyte dry mass falh from the canop) absnrct of dryin8 cd i t i ans . which affirts the water ttrro@(wt the yerr at a mean rate of 50 g.m : )r '

statusofthe planu and conditions forassociated patho- (NadSunri and Matelson 1992). Eptphj tes fall in a r a- wns and mutuafists. riety of fotms. from individual plant pans to large mats

AnccdoW observations of hlkn epiphytes include that cover whole b r a n c h The mean standing crop of a range of responses: 1oqw epiph- kn ish within falkn epiphytic maUri.1 on the ground IS 35 g rn' weeks, whik others persist and even thrive fot months (Ncadkorni and Matchon 1992). to even ).ern (N. M. N a d b i T. j. Matelson. a d A. .Uah&. A ?-ha study area was established wlthin Pou~ds. penonai obsen~tion). Apl)Pnntly. them are the 10-ha Res~amh Ares of the MVCFR. It encom- diverse factors that dlow or tirnit the survival of epi- p.& a Variety of elopes (W to 2096) and areas of phym after thcy land on the fdbmt h r . If we could etOSCd canopy and &aps. W a n tree diameter at breast

or die on the height (dbh) for W g > 49 ~m #$a ~ ~ 5 5 . 5 cm: mean

mrvival OR the contat

\

. t r , ~3 gL.;: - &%r\?glil;+

* - and a Ionget of 12 ~ndicatcd that a plant remained al:ve at [tie end of the stud?. Clump iongeclt) (as op- posed to longevity of individual plants) was defined as the average longevit) of a11 plants within a clump. .%nalyses are complicated by two levels of spatla1 as- sociation, wlthln clumps and within plots. which are addressed in the results. h d i v i d ~ l plant longev~t?;. which was not normally didributed. was analyzed w~th non-parametric-tests. Clu&b longevity. u hich was nor-

R ~ ~ ~ ( ~ & 8 := C d -;* : - &Q '- . - rr:T+$ :..;Ty,J :- 1, - f k the first year only 2% of ;heeplants

remained alive, and by the end of themdy (2 1 mo). only 7% had survive3 fFig. I). The brahches to which

- dumps had been originally attached were intact. but had deteriorated. Of the cases in which the clumps were unattached to branches. some clumps had disappeared. whlle for others. lumps of dead organic matter knit

-8% * oj f o g ~ h e with remains &the inat were detectable 8@8p, " on the %rest flbor.

f the fol- All plant categories exhibited similar rates of mor- ntsX tality. Discounting spatiaI &&ciation. there were no , Er- sipifkant d iLmces in longevity lHRong the-eight plant (40). categoties (KNshl-Wallis test, P < .07). Plant cate-

ts, gsfics wen dispersed acrois %zkkps and pfats, making n- it Ins likely that a s@dal -iaoion would obscure a .a real pi& category ditftrenco' Witangevfty.

In contrast, there was a dgni-nt plot @kt on lon- cm3 (mean = 2880 cqJ), and the number of individual gevity - -Was Wt, P .< .001F The two gap

f & f ~ j l: * . plants per clump (we could not distitkpish bet& ploL hab'&wih@flb tmt& thltklhe ttwe%trade plots.

-" * rarnhs and genets) raw between,I and 9 plants (mean Clump lo&~rhoWdtJirnithr st r'effects (Fig. FP,*i*

= 4.5 plants). 1 .- 2. kNUV94. fi, , = 5.09, P < :W: S b d e plots had -fv "' BP'd~ach of!he 223 piants war examihed with minim1 lorn kwt#wi* thin ~ ~ ~ * w @ Y S T A T a posteriori *"ntp %ndlingDt near-inonthly ihtervais'during the first ye& .*Hypo€lk&sw pf&edm, h & m ~ * u i O( two shade *-'= (43.97, 13t',159,191,216,'246,ZiS,307,333daf~ p l~da~twagrppto t s ,F , , , ~*M.11;P< .001).

placement) and agaih dear thi end of the second yeaid Thm virbrs & cfkt sf 6piPbfle .attachment to (day 637). One person monitor& the clumps for the branches cm chmp longevity (t telt, P C .35), and no entire study. Some of the leaf litter that accumutated significant regiwions of W p lon 'wty on clump

-n& .u mi@- on clumps was unavajdlbly dburbed at each inven-. volume fiJ %- O.04,P < .I@ ~r n~mbct'of plants per

tory in order to pleat status. Each plarlt was clump (r"*i. 0 .01 ,~@*&) . ;~1~ f? ' t ' ?&3~ -re*> *&n score& as live or dead at each inuentory, Plant deadr W- . * ~ i * yak + . c ~ ~ ~ @ B ^ j ~ s r i : .

was ind i caa by bMrre; krsfl& kaves, f r ~ a 2 Dwi@&X%@%% *fit ?9 EEf& &%z&s< -TF.~=S tation, and shrivelling OT stems of rhi-es. '.& Qi h vadcity of faerors migtneausd&# epiphy tes to die 3 ~ % % f Fmqmr-* 8 %. ,- Longevity was dedried as the dine (ih days) between aRer falling to*s'~und. Fint, epiphytes may die due

day I and the last sampling day a plant was recorded to dimi&sIted photo3ynthtsis caused try environmen- '&:+ &*Tt~aive placemint otr f m t &oos. For purposcs tal d i h n c e s bct%~mh canopy and fotest floor-es- z'm3 XI analm. t o n p i t y was defined tilo time interval p&i&iy light and fiolstufe mgimcsand air movement.

% @ red lant was $een dive, wi* time inteival being an Water and nutrient inputs may &*r because fallen 1. tnwIriswtegtr f&m 1 to 12, rcllnser\ting t6e day of plaetwmt epiphytes receive primarily throughfall, which is de-

m d tha 1 1 subsequenoansuses. Thus, longevitits from posited ia w &OW t h ~ in mist or w. throughfall ofoc''~t~@ $to 1 O ~ ~ m o n t h l ) c ~ ~ I i t y durbgthe first year, chemist* is often atterrd bqr contact with the canopy

a longevity'of 1 1 rkflicctedidttl a n d year mbrtality, (Yitousek end Sanford 1986, Veneklas irnd Van Ek

3 X ' . . NOTES .I>D COUMEhTS 4t>it1 \ -; \ ,J P . : 92&:-...:

1 1 I * . . i:' t ' C k

, s t . ' . < - - 9 , SUN conditions overhead. and are then subject to cond~t~ons

. . N -7 that might cause them to die rapidly. relattve to the rates of thox deposited in gaps, Environmtaf con- ditions (especially light and tent perature regimes) in gaps are more canopy-like than closed-canopy forest floor. thusdlowinp fdlen e h z in gaps to survive "Iy longer than in deeper shade.

Other studies have shown that epiphktes can con- Hibutt! app&i&ly to biorbass and nutrient Inputs to the forest f f4 r tVuneklaas 199 1 )-up to 10% of total deposition ira fi&e titter dt our site (Nadkarnl and Ma- elson 109"2).".&fois nuaidnts * epiphytes can be re- leased through decom&. hwever. the live plants must dte. Thus. fallen epiphytic material probably af- fects nutrient cyclis differently lirrtn litterfall from ter- restrially .rooted plants, whose nutrients can be min- eralized faster because that material is already dead

npvity of (Vitousek and Sanford 1986). f& &&n live epiphytes. T*,; ,s then, there is a potential lag time-in nutrient release

. via mineralization. In forests with well-developed can- opy communities, epiphytes can profoundly affett both the amounts of nutrient storage and the timing of nu-

asshown thal the rate of nutrient release blomass varies with microhabitat. Fur-

w * i # u r e . subst~@~anoisture content. and w@ting/drying ther investWptions should pursue thc spatial and tem- -a"; tg$&$#ycks are pea- in the canopy than on thi: forest floor jpqdistribution of Wen epiphytes at the species level B S ~ J ~ 4. f. Matelson, S. Bowann, and N. M, Nadkami, 'in relation to microhabitat characteristics in order to a 511;*3 &npublished data). The meet striking micrwnvimn- &~&*$otb the rob o6f epiph* at an ecosystem

mental difference is the lack of extmmely dry periods level as we!!&$ fw i p w & b p h t ~ ~ h q i s m s that foster 1 7 1 . .

.rrct S* rsdiln the f w ~ floor during the dry and windy-misty , epiphygs~,, ,, %.- 1; <7-?ts>b .-

rrq QW -sons, which creates* more c~nqtmtly wet environ- , .?,.&-' > v p ,. '%+t - '

ongverde Cloud nt for fallen epiphytes than for,gmo@y + % c ~ ~ g * e n k : 'a"**$' ere such "dry-downs" occur. - Forest Reqrve and the '% ience Center. Re-

B ~ r i wq d !Second, biotic factors may distinguish the canopy Search was supported by NSF &ts BSR 86-14935 w w r q &am the famt Boor. including d i f fmnw in patho- and 89- 1W.N. the Whitehall Foundation. and the Na-

mt- htrbivorep, and symbionts. Oved l &~si ty of tional Geographic Society. Helpful reviews of earlier .f ' 3 ~ . *vertebrates is lower in the Monteverdg canopy @an drafts were provided by D. Schaefer, S. Kinsman, Deb-

w: t ~ = - the forest floor, &prtajn @,&a are virtuaUyabscnt orah Clark, D. &win& and D. Hicks. on trrr j39 the canopy (Nadkami and Lonuno 1990). - '

Literanm Cited :- : ' * - q*"~f~h ee> Third, accumulation of leaf litter on top of fallen n . 7@ aW&@*/bjphytes may encourage their death on the forest floor. Ackennm. 3, D.. and f. C. Menutvo.. 1990. Short- and , . Gaf litter accumulation blo& insolah@, chaw the ~0ng-telTIY littiitations to fruit pmductibe nopid Ot-

chid. Ecology 71:263-272. +- moisture regime, and may influence herbivore@ and Bmrinta H, 1990. vuulN e*phytctytct Csmbndp Uni- pathogens. Rates of litter accumulation &Ref bct.yeen vmiw.Rcs), fim

alb .sn as Inopy an$ fomttfloor, 4s to high- wind in the can- Chacon, D., and J. Duval, 1963. Variations mimclima- ?wfas srtj Y ~ P Y and the non-conti$uous surface atcp of canopy tiques verticalcs et saiyni* dans fa for& umpervirente - n ~ 4 m ~ f e u b s t r a t e s (Nadkami and Matelson 1991). de Basse CBte d'Ivoirr. Annales facultC Sciences. Dakar 8:

89-155. " * -m -%mi% Although little is known about the Spatiel dktribu- u. L., a d N. F-. 1 9 ~ . Pbt@ynlhetic l l f i t *~r%*s.a: tion of fallen e p i p b w ~ u o h f- epiphytic material enviroprp*nts in a IOWIUKJ tropicai rain f i t in costa ir%;ri+F -& is deposited in gaps, as it "rides down" large branch- Rica. Journal of Ecology 72553-564. -li;s a; :%s, and treefalls (Nadkami and Matelson 1992). Epiphym Ha*$horn- G. S. 1983. I'bM. 1&157 In D. H.

J a n z ~ , editor Costa Rican natural history. Un~vtrsity of u i i i y u o w Wl in a centinvl ~ ~ D S F ig Wl6r a m o w . . pm; Cbiop, UU C

rqcsne s !aching the forest flwr oa amaUer branches at as h- w, 1. 1933. tnn. 8. Stiit-toots .5 3 a* dv@ud epiphyr- ~$atter@$gi$w&rdased-canopy and aUd ed8ptuims. Rrrlii 45:2j0-2641- ;p ...$

:n -&* - v r , -su& ~ ~ ~ a I J X F ~ Y r -F+ **o$~<- "'I -- - -9

t

(, hOTES 4ND COMMENTS 2 69

Kress. W J. 1986. The s)stemattc distnbutlon of \.ascular species n~hness m the tropics wtthout animals. Journal of cprph!tes. an update. Selbyana 9.2-22. Brogeography 4:2 15-2 18.

Lawton. R. 0.. and V. J. Dr)er. 1980. The wgetatlon of SYSTAT. 1984. SYSTAT. The system forstatlstlcs. Volume the Monrcs+e& Cloud Fomt Reserve. Brenesia 18:101- 2. Number 2. SYSTAT. Inc., Evanston. Illino~s. USA. 116. Vance. E.. and N. M. Nadkam~. 1989. 'U~crob~al b~omass dkarni. N. 34. 1984. Epcphtte biomass andnutrient cap and actrvrty in canopy organic matter and the forest floor tal of a neotrop~cal elfin forest. B~otroptca 16.219-256. of a troptcal cloud forest. Soil Biology and Biochem~stry

. 1986. An ecolopcal overvlew and checklist of \as- 22:677-684. r ep~ph! tcs rn the Monteverde Cloud Forest Reserve, Veneklaas. E. 1991. Lltterfall and nutnent fluxes In two a R~ca. Brenesta 24:55-62. tropical montane rain forests. Colombia. Journal of Trop mi. N. M . and J. T. Longlno. 1990. Mncroinverte- #a4 Ecology 7:319-335.

ommunttles in canopy and forest floor organ:^ matter Veneklaas. E.. and R. Van Ek. 1990. Ramfall interception

ontane cloud forest. Costa Rica. Brotropica 22:286 In two tropical montane rain forests. Colombia. Hydrolog- ical Proces~s 4:3 1 1-326.

. M.. and T. J. Matelson. 1991. L~tter dynamics Vttouxk. P., and R. Sanford. Jr. 1986. Nutnent cycling In canopy ofa neoiropicsl cloud forest. Montever- motst tropical fomt. Annwt Review of Ecology and Sys- Rica. Ecolay 72:849-860. temattcs I7: 137-167.

d i.- J. Matelson. 1992. Biomass and of epiphyte litterfall in a neotropical .Uanuscript receit.ed 7 October 1991:

sta Rica. Biotropica 2424-30. rewsed 20 March 1992;

Epiphyte loads, tree falls. and perennial accepted 27 .4prd 1992.

a mechanism for maintaining higher tree