1022 REVISTA DE BIOLOGIA TROPICAL TABLE 1 Percent of LifeZones wherespecies offive bromeliad genera were expected(according to the Holdridge Life Zone System) but were not found. Genus Mean Standard Maximum Minimum Sample size* deviation Tillandsia 47 17 85 17 31 Vriesea 51 15 75 14 24 Aechmea 51 9 67 36 12 Catopsis 47 13 64 29 6 Guzmania 47 17 82 12 22 * Sample size in number of species. 1988). The number of specimens per Life Zone DISCUSSION were tabulated by species and distribution maps were copied to smaller and simplified maps for Biogeographic studies based on herbarium visual examination. To assess agreement records are subject to collection bias. In this between the Holdridge Life Zone System and case, however, the extensive Costa Rican road bromeliad occurrence, the percent of zones system has made all of the Life Zones where each species was expected but has not accessible to coHectors and an examinatíon of been collected was calculated. A species is Fig. 34 suggests that we have a reliable view of expected to occur in life zone "B" if it occurs in bromeliad occurrence across the country. zones "A" and "C" that are immediate to it in The greater number of records for montane the Holdridge classification, because zone "B" habitats, previously noted by Gómez (1986) can is expected to have intermediate characteristics. be explained by the need for moisture al.1d light Here only the genus means (and related that is common in epiphytic bromeliads (Picado summary statistics) of those percents are 1911, 1913, Benzing 1994). Relatively low presented (detailed species tables are available diversity in NW Costa Rica was reported earlier from the authors). by Burt-Utley and Utley (1975), and attributed to the prolonged dry season there. Moisture RESULTS supply strongly influences the distribution of Bromeliaceae in broad (regional) and finer A total of 715 valid records spanning almost (local) scales (Gómez 1986, Brown 1990, a century were found (Fígs. 1-34). Most records Gómez and Winkler 1991, Benzing 1994). of Costa Rícan epiphytic bromeliads are from Sorne Vriesea are known to require high the mid-altitudes along the mountainous humidity, low líght levels and thin phorophyte backbone of the country (Fig.3 4). When branches (Brown 1990, Fontoura 1995) which numbers of records are pooled for genera agrees with the over-representation of the genus (because not enough data are available for in moist Costa Rican highlands (the same may individual species) Vríesea and Guzmania are apply to Guzmania). more frequent in moist highlands (Fig. 33), The need for high humidity characterizes Tillandsia and Catopsis peak at varíous many species of Ti llandsia, but this altitudes (Fig. 33) and Aechmea most often ecophysiologically diverse genus has species inhabits moist lowland habitats (Hg. 33). with very contrasting habitat requirements The percents of Life Zones where each (García-Franco and Peters 1987, Brown 1990) species was expected (see Materials and which may explain why abundance varied Methods) but has not been recorded had a mean greatly with Life Zone in this study. Finally, the of 50 % (Table 1), that is, there are no records apparent exclusion of most Aechmea from for most species in about half the Life Zones open habítats (Brown 1990) is also consistent where they should occur according to the with our results, except for specíes such as Holdridge classification. Aechmea mexicana. Rivas el al: Distribution of Costa Rican epiphytic bromeliads 1023 2 � TROPICAL T1LLANDS/A COSTA TROPICAL-PREMONTANE • A E PREMONTANE • T/LLANDS/A ADPRESSA MONTANE e TlLLA NDS/A A NCEPS PARAMO O TlLLANDS/A BALB/SIANA • T/LLAN DS/A BUTZII • TlLLANDS/A FASC/CULATA • T/LLANDSIA BRACHYCAULOS • TlLLANDS/A FES TUCO/DES e e T/LLANDSIA EXCELSA TlLLANDS/A F/LlFOLlA TlLLANDS/A FLEXUOSA O T/LLANDS/A /NS/GNlS 6 • TlLLANDS/A BULBOSA • TlLLANDS/A JUNCEA • TlLLANDS/A CAPUT-MEDUSAE • TlLLANDS/A LE/BOLDIANA e TlLLANDS/AMONADELPHA e TlLLANDS/A COMPLANATA o TlLLANDS/A MULTlCAULlS o TlLLANDS/A CONTORTA Figs_ 1-6. Costa Rica: GeneralLife Zones (1) and localities where several species ofTillandsia havebeenc ollected (2-6).ln this andfollowing figures asterisks indicate data fromthe literature (see main text). 1024 REVISTA DE BIOLOGÍA TROPICAL 8 • TlLLANDSIA PAUClFOUA • TILLANDSIA SCHIEDIANA • TlLLANDSIA PRUINOSA TILLANDSIA SINGULARIS IJ TlLLANDSIA PUNCTULATA • IJ TILLANDSIA SPICULOSA O TlLLANDSIA ROTHSCHUHIANA O TlLI:ANDSIA SUBULlFERA 10 • TlLLANDSIA USNEOIDES • AECHMEAANGUSTlFOUA • TlLLANDSIA UTRlCULATA • AECHMEABRACTEATA IJ TlLLANDSIA VENUSTA IJ AECHMEA DACTYLlNA O TlLLANDSIA COMPRESSA O AECHMEA MAGDALENAE • AECHMEA PUBESCENS • AECHMEA MARIAE-REGINAE • AECHMEA TlLLANDSIOIDES • AECHMEA MEXICANA IJ AECHMEA TONDUZlI e AECHMEA NUDlCAUUS O AECHMEA VElTCHII o AECHMEAPlmERI Figs. 7-12. LocaIities where several species oC Tillandsia andAechmea have been collected. - 1026 REVISTA DE BIOLOGÍA TROPICAL 20 III GUZMANlA PLlCATlFOLlA 111 GUZMANlA MUSA/CA GUZMANlA SANGUINEA • GUZMANlA NlCARAGUENS/S • iJ GUZMAN/A OBTUS/LOBA ¡;¡ GUZMANlA SCI-IERZERIANA O GUZMANlA PATULA O GUZMANlA SPECTABIUS 21 11 GUZMANIA STENOSTACHYA • GUZMANIA SUBCORYMBOSA l!II VRIESEA ACUMINATA • VRlESEA APICULATA ¡;¡ GUZMANIA ZAI-INIJ e VR/ESEA ATTENUATA o VRlESEA BICOLOR 11 VRIESEA COMATA iII VRIESEA GRAMINlFOLlA VRIESEA CI-IONTALENS/S • • VRIESEA GREENBERGI/ e VRIESEA DIFFUSA !J VRIESEA I-IEUCONlOIDES o VRIESEA GLAD/OLlFLORA e VI�/ESEAHYGROMETRI CA Figs.l9-24. Localities where severa! species of Guzmania and Vriesea have been collected. - 1027 IUvaset al: Distributionof Costa Rican epiphytic bromeliads 26 ID VRIESEA INCURVA 111 VRIESEA LEPTOPODA iD VRlESEA KATHYAE iD VRIESEA LEUCOPHYLLA e VRIESEA KUPPERIANA e VRIESEA LYMAN-SMITHI/ o VRIESEA LAnSSIMA o VRIESEA MARNIER-LAPOSTOLLEI 18 VRIESEA PEDlCELLATA 11 VRIESEA MONSTRUM VRIESEA PlmERI • VRIESEA NEPHROLEPIS e VRIESEA SANGUINOLENTA e VRlESEA NOTATA VRIESEA SUBSECUNDA o VRIESEA ORORIENSIS 30 lIi VRiESEA VIRIDlS III! VRIESEA TONDUZlANA • VRIESEA VITTATA iD VRIESEA TRIFLORA e VRIESEA WERCKLEANA e VRIESEA UMBROSA o VRIESEA WlLLlAMSII o VRIESEA VIRIDIFLORA Figs. 25-30. Localities where severa! species of Vriesea have been collected. 1028 REVISTA DE BIOLOGÍA TROPICAL Figs. 31-32. Additionallocalities where several species of Vriesea have been collected (al1 from the literature). Aechmea 1 castelnavii, 2 penduliflora; Catopsis 3 mutans, 4 werkleana. 5 Guzmania milis; Tillandsia 6 abdita. 7 biflora, 8 cal/lif/ora. 9 lampropoda. 10 longifolia, 11 makoyana, 12 oerstediana, 13 tricolor; Vriesea 14ampla, 15 bala/lophora, 16 brunei, 17 burgeri, 18 picla, 19 ringens, 20 stenophyla. - 1030 REVISTADE BIOLOGíA TROPICAL , . ' " . ... , " · . .. :·A : .. " I •.. :t 0 • .. .. .� ... " .� :� • l. l· • , .. t; ... .-: .. : :. ". r .. .. ·-" �V...·,.,: .. ;- 0. ' .. :.\. .� ., -. I. .. ' .. ' :. '. \ ., . - Fig. 34. Sununary of CostaRican bromeliad locaIityrecords considered intbis study. Rivaset al: Distribution of Costa Riean epiphytic bromeliads 1031 cuales se les esperaba según la clasificación de Holdridge. Individual species were absent in about half Se presenta la hipótesis de que el sistema falló porque la of the expected Life Zones: light, humidity and distribución de las brolilelias epifitas depende de las interacciones entre factores, más que de humedad, luz o temperature, i. e. the factors used by the temperatura individualmente. Holdridge life System:, faíl to fully predict bromeliad occurrence. Assuming that sampling REFERENCES is consistent across Life Zones, this study Benzing, D.H. 1994. How much is known about rejects the hypothesis proposed by Burt-Utley Bromeliaceae in 19947 Selbyana 15: 1-7. and Utley (1975), even for Vriesea, which in BrowIi, AD. 1990. Elepifitismo en las selvas montanas del their opinion followed the Life Zone Parque Nacional "El Rey", Argentina: Composición ' classification System closely (Burt-Utley and florística y patrón de distribución. Rev. Biol. Trop. 38: 155-166. Utley 1975). Burt-Utley, K. & J.F. Utley. (1975). Supplementary notes: G6mez (1989) stated that Holdridge's Life Phytogeography, physiological ecology and the Costa Zone Ecology map of Costa Rica was not Rican genera of Bromeliaceae. Historia Natural Costa Rica 1: 9-29. intended to be a vegetation map but this fact Fontoura, T. 1995. Distribution pattems of five does not justify the System' s failure because Bromeliaceae genera in Atlantic rainforest, Rio de bromeliads are known to depend on JaneiroState, Brazil. Selbyana 16: 79-93. environmental factors considered by the system García-Franco, J.G. & C.M. Peters. 1987. Patrón espacial y abundancia de Tillandsia spp. a través de un gradiente (Burt-Utley and Utley 1975). Future workers altitudinal en los altos de Chiapas, México. Brenesia 27: may test the hypothesis that epiphytic 35-45. bromeliad distribution reflects factor Gómez, M.A. & S. Winkler. 1991. Bromelias en manglares interactions rather than humidity, light or del Pacifico de Guatemala. Rev. Biol. Trop. 39: 207- 214. temperature individually. Gómez P., L.D. 1986. Vegetación de Costa Rica. Apuntes para una biogeografía costarricense, p. 1-328. In L.D. ACKNOWLEDGMENTS Gómez P. (ed.). Vegetación y clima de Costa Rica, vol. 1. Universidad Estatal a Distancia, San José, Costa Rica. Gómez P., L.D. 1989. Costa Rica, p. 305-308. In D.G. This project was financed by Centro de Campbell & D. Hammond (eds.). Floristic inventory of Investigaci6n General, UNED. We thank tropical countries. NY Botanical Gardens, New York. Mariela Bermúdez, Luis D. G6mez and B. Herrera, S.W.