Colonization of Stripped Branch Surfaces by Epiphytes in a Lower Montane Cloud Forest, Monteverde, Costa Rica Author(s): Nalini M. Nadkarni Source: Biotropica, Vol. 32, No. 2 (Jun., 2000), pp. 358-363 Published by: The Association for Tropical Biology and Conservation Stable URL: http://www.jstor.org/stable/2663865 Accessed: 04-05-2015 04:25 UTC Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at http://www.jstor.org/page/ info/about/policies/terms.jsp JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. The Association for Tropical Biology and Conservation is collaborating with JSTOR to digitize, preserve and extend access to Biotropica. http://www.jstor.org This content downloaded from 155.97.178.73 on Mon, 04 May 2015 04:25:12 UTC All use subject to JSTOR Terms and Conditions 358 Nadkarni SHARP, R. E., AND J. S. BOYER. 1986. Photosynthesisat low waterpotentials in sunflower:lack of photoinhibitory effects.Plant Physiol.82: 90-95. ToMA,T., P. MATIUS, Y. HASTANIAH, KIYONO, R. WATANABE, AND Y. OKIMORI. 2000. Dynamicsof burnedlowland dipterocarpforest stands in Bukit Soeharto,East Kalimantan.In E. Guhardja,M. Fatawi,M. Sutisna,T. Mori, and S. Ohta (Eds.). EcologicalStudies 140, Rainforestecosystems of East Kalimantan:El Ninio,drought, fireand human impacts,pp. 107-119. Springer-Verlag,Tokyo, Tokyo, Japan. VON CAEMMERER, S, AND G. D. FARQUHAR. 1981. Some relationshipsbetween the biochemistryof photosynthesisand the gas exchangeof leaves.Planta 153: 376-387. Vos, J., AND P. J. OYARZUN. 1987. Photosynthesisand stomatalconductance of potato leaves-effectsof leaf age, irradiance,and leafwater potential. Photosynth. Res. 11: 253-264. WONG, S.-C., I. R. COWAN, AND G. D. FARQUHAR. 1985. Leaf conductancein relationto rateof CO2 assimilation. III. Influencesof waterstress and photoinhibition.Plant Physiol.78: 830-834. Atsushi Ishida Forest EnvironmentDivision Forestryand Forest Products Research Institute(FFPRI) P.O. Box 16, Tsukuba NorinDanchi, Ibaraki305-8687, Japan. Takeshi Toma Tropical Rain Forest Research Center MulawarmanUniversity P.O. Box 1165, Samarinda 75117, East Kalimantan,Indonesia. Shigeta Mori Tohoku Research Center Forestryand Forest Products Research Institute(FFPRI) Morioka,Iwate 020-0123, Japan and Marjenah Tropical Rain Forest Research Center MulawarmanUniversity P.O. Box 1165, Samarinda 75117, East Kalimantan,Indonesia BIOTROPICA 32(2): 358-363 2000 Colonizationof StrippedBranch Surfaces by Epiphytesin a Lower MontaneCloud Forest,Monteverde, Costa Rica1 Keywords: cloudforest;colonization; Costa Rica; epiphyte;Monteverde; secondary succession. EPIPHYTES GROW ON SUBSTRATES THAT ARE DIVERSE AND EPHEMERAL. Canopy-dwellingplant communities are subject to disturbancessuch as wind, animal movements,waterlogging and subsequentsloughing, branchbreakage, and treefalls.These perturbationsresult in theirultimate death and decompositionon the forestfloor (Matelson et al. 1993). The rate of loss and replacementfor epiphyte communities in forestcanopies is unknownbecause the lengthof most studieshas been shortrelative to the timescale needed to monitorepiphyte colonization and growth. Some forestmanagement practices (e.g., epiphytic-moss harvesting for the floraltrade in the Pacific Northwestof NorthAmerica) and researchactivities (e.g., climbinginto treesand knockingepiphytes off) cause apparentshort- and long-termchanges in epiphytecommunities. Although moss collectors and researchersoften try to minimizedamage to the communitiesthey are harvestingor studying,the potentialfor their activities to affectcanopy plant communitieshas not been investigatedquantitatively. Littlehas been documentedon the amountof time and conditionsrequired for epiphyte communities to regeneratefollowing disturbances. Understanding epiphyte community dynamics under natural con- 1 Received8 July1998; revisionaccepted 1 February1999. This content downloaded from 155.97.178.73 on Mon, 04 May 2015 04:25:12 UTC All use subject to JSTOR Terms and Conditions Notes 359 ditionsmay help mitigatepotential negative effects of humanactivities and contributeto our understand- ing of community succession. Althoughthe communitycomposition and abundanceof epiphytecommunities at singlepoints in time have been documentedin numeroustropical and temperateforests (Oliver 1930, McCarthyet al. 1986, Peck et al. 1995), the dynamicsof epiphytecommunities has been studiedonly rarelyand indirectly.Successional patterns of epiphytecommunities in temperateforests have been inferredby usingchronosequences of foreststands (Dudgeon 1923), toposequencesof treebranches (Stone 1989), or by aging the underlyingbranches in temperateforests through counting annual rings(Pike 1978). The generalpattern of epiphytesuccession on temperatetrees is thatearly colonizers are poikilohydric mosses and crustoseor fruticoselichens. These die in place and a layerof dead organicmatter accu- mulates,which serves as substratefor the fewvascular epiphytes that occur in temperateforests (Benz- ing 1995). The dynamicsof epiphytecommunities in tropicalforest ecosystems, however, is largelyunknown due to thehigh diversity of epiphytesand theinability to determinereliably the age ofepiphyte substrates. Studieshave been based eitheron communitiesexisting at a singlepoint in time (Yeaton& Gladstone 1982) or anecdotaldata. Observationsfrom tropical dry forests, for example, indicate that lichen colo- nizationof verticaltree trunks is extremelyslow, with areasscrubbed clean remainingvirtually bare 15 yearslater (D. Janzen,pers. comm.). In vegetationsuch as tropicalmontane cloud forests,in which epiphytesare highlydiverse and abundant,recovery from small-scale disturbance would be expectedto be veryrapid. With nearlyevery availablebranch and bole coveredwith diverseepiphytes, one would expectthat canopy communities on exposedbranch surfaces resulting from within-canopy disturbances in theseforests would be recolo- nized withina veryshort period. In this note, I reporton a decade of monitoringthe amount,com- position,and locationof epiphytecover following experimental stripping of largebranches on mature treesin Monteverde,Costa Rica. This is partof a landscape-levelstudy on theecological roles of epiphytes in tropicalcloud forests(Nadkarni et al. 1995, 2000). Fieldworkwas conductedfrom May 1987 to March 1997 in the MonteverdeCloud ForestReserve, a lowermontane moist forest in Costa Rica (10?18'N, 84?48'W). Annual grossprecipitation is ca 2200 mm, but actual wet depositionis much higherbecause of frequentwind-driven mist and fog (Clark 1994). The studyarea is in tropicallower montane wet forest(1550 m elev.) in LeewardCove Forest (Lawton & Dryer 1980), with a brokencanopy 12-25 m in heightand a densityof ca 150 trees/ha (>10 cm DBH; Nadkarniet al. 1995). The Monteverdeepiphyte flora is extremelydiverse and abundant (Nadkarni 1984, Ingram & Nadkarni 1993). Branch surfacesin the crown interiorof nearlyall maturetrees support epiphytes (bryophytes,herbs, woody shrubs,and hemi-epiphytes)in interwovenroot-humus mats up to 25 cm thick.The greatestaccumulations of humus are foundon junctionsof largebranches. Outer branches and branchtips are partiallyto completelycovered with bryophytesand small xerophyticherbaceous plants,with verylittle or no accumulatedhumus (Nadkarniet al. 2000). Relativeto the forestfloor, the upper treecanopy experiencesmore wind (Lawton 1982), more frequentmist deposition (Clark, Nadkarni,Schaeffer, and Ghulz 1998), higherair temperaturemaxima, and more frequentwetting/ dryingcycles (Bohlman et al. 1995). At thissite, epiphytes fall from the canopythroughout the yearat a mean rateof 50-g drywt/m2/ yr in a varietyof forms,from individual plant partsto largemats thatcover whole branches(Nadkarni & Matelson 1992). When climbingin the canopy,one frequentlyencounters patches of exposedbark resultingfrom individual plants and whole mats sloughingoff branches. These "epislides"are apparent in all areasof the canopy.Exposed areason branchtips and branchlocations in the outercanopy appear to be relatedto bird foragingand movement;exposed areas on innerbranch locations appear to be relatedto large,mature epiphyte mats fallingoff due to theirown weight,or due to large arboreal mammalsunintentionally knocking them off (e.g., howler monkeys, tayras) or pullingthem off as they foragefor invertebrates in bromeliads(white-faced capuchins). In April 1987, my researchteam establisheda 4-ha intensiveresearch plot. We riggedca 35 trees fromthe most common familiesof treesin this forestwith mountain-climbingequipment, following Perry(1978). To sample the originalepiphyte community, we chose a randomsubset of all accessible branchesin fiveof the treeswe climbed (Table 1). All live and dead epiphyticmaterial was cut and This content downloaded from 155.97.178.73 on Mon, 04 May 2015 04:25:12 UTC All use subject to JSTOR Terms and Conditions 360 Nadkarni TABLE 1. Identityof host tree and numberof cylindrats sampledfor which original and recolonizingepiphyte communities weremonitored from 1987 to 1997 in Monteverde,Costa Rica. NS = notsampled due to treeor branchloss duringthe 10 yearsof the monitoring period. Numberof Numberof cylindratsfor cylindratsfor Tree original recolonizing Number