A study on the distribution of vascular epiphytes in a secondary cloud forest, Central Cordillera, Colombia.

Maaike Bader

A study on the distribution of vascular epiphytes in a secondary cloud forest, Central Cordillera, Colombia.

Oktober 1999

Thesis tropical nature management (H300-762) Maaike Bader (Wageningen University)

Main tutor: Drs. Frans van Dunné (Hugo de Vries Laboratory, University of Amsterdam)

Other tutors: Prof. Dr. Antoine M. Cleef (Hugo de Vries Laboratory, UvA & Vertebrate Ecology & Tropical Nature Management, Wageningen University) Dr. Pieter Ketner (Vertebrate Ecology & Tropical Nature Management, Wageningen University) John Stuiver (Laboratory of Geographical Information Science and Remote Sensing, Wageningen University)

Internal Report no. 326 Wageningen University and Research Centre (Formerly ‘Wageningen Agricultural University)’

THE DATA IN THIS REPORT ARE MEANT FOR INTERNAL USE ONLY. NO COPYING PERMITTED WITHOUT PERMISSION FROM THE AUTHOR OR TUTOR(S).

Contents

`CONTENTS...... 1

PREFACE...... 3

ABSTRACT ...... 4

SAMENVATTING...... 5

RESUMEN...... 6

1 EPIPHYTISM...... 7

1.1 DEFINITION ...... 7 1.2 ECOLOGY AND EVOLUTION ...... 7 1.3 DISTRIBUTION AND TAXONOMY ...... 10 1.4 BROMELIACEAE ...... 11 1.5 ORCHIDACEAE ...... 13 1.6 LORANTHACEAE ...... 14 2 INTRODUCTION TO THE STUDY ...... 18

3 STUDY AREA ...... 22

4 METHOD...... 25

4.1 FIELDWORK ...... 25 4.2 DATA ANALYSIS ...... 26 4.2.1 GIS ...... 26 GIS pre-processing ...... 27 GIS-analysis ...... 29 4.2.2 Spatial point pattern ...... 29 4.2.3 Climatic data ...... 30 4.2.4 Height distribution ...... 30 4.2.5 Other environmental factors ...... 31 4.2.6 Plant appearance ...... 31 5 RESULTS...... 32

5.1 CLIMATE ...... 32 5.2 EPIPHYTE SPECIES ...... 35 Bromeliaceae ...... 35 Orchidaceae ...... 35 Loranthaceae ...... 36 5.3 EPIPHYTE ABUNDANCE ...... 36 5.4 HEIGHT DISTRIBUTION ...... 38 5.5 SPATIAL POINT PATTERN ...... 40 5.6 PHOROPHYTES ...... 40 5.7 PLOTS ...... 42 5.8 GROWING SITES ...... 42 5.9 PLANT APPEARANCE ...... 43 6 DISCUSSION ...... 45

6.1 CLIMATE ...... 45 6.2 EPIPHYTE SPECIES AND ABUNDANCE ...... 45

1 6.3 POPULATION STRUCTURE ...... 46 6.4 HEIGHT DISTRIBUTION ...... 48 Height of the epiphytes ...... 48 Ecological equivalence and coexistence ...... 49 Defining the vertical position ...... 51 6.5 SPATIAL PATTERN ...... 51 Clustering of the epiphytes ...... 51 Describing spatial patterns ...... 52 6.6 PHOROPHYTES ...... 53 6.7 PLOTS ...... 54 6.8 GROWING SITES ...... 55 6.9 PLANT APPEARANCE ...... 56 6.10 GIS ...... 57 7 CONCLUSION ...... 59

REFERENCES ...... 60

APPENDIX I : EVALUATION OF SOME METHODS...... 68 Field methods ...... 68 Analysis ...... 69 APPENDIX II-1: MAPS OF THE PLOTS: SOME GRAPHICS ...... 71

APPENDIX III-1: HEIGHT DISTRIBUTION OF ALL EPIPHYTES...... 83

APPENDIX IV : DIFFERENT HEIGHT MEASURES PER PLOT ...... 90

APPENDIX V : DIFFERENT HEIGHT MEASURES PER SPECIES...... 91

APPENDIX VI-1: L 2-GRAPHS ...... 92

APPENDIX VII-1 : DISTRIBUTION ON PHOROPHYTES...... 108

APPENDIX VIII: CRYPTOGAMS...... 110

2 Preface

This is a report of a engineers thesis carried out for the group Vertebrate Ecology & Tropical Nature Management of Wageningen University and Research Centre (formerly Wageningen Agricultural University), in cooperation with the Hugo de Vries Laboratory of the University of Amsterdam, and the Biology Department of the Universidad de Antioquia, Medellín, Colombia. Fieldwork in Colombia was carried out from August to December 1998, analysis in Wageningen from January to June 1999.

This report covers the scientific side of my thesis. It does not and cannot include the other aspects of my working and living in Colombia, or the many things that I have learned there and back here in Holland in the past year. It can, and does include, however, many thanks to all the people that have made doing this thesis such a pleasant and useful experience. Muchas gracias a: ☺ la gente de Santa Rosa de Cabal, por ser un pueblo tan agredable. ☺ Alex Ramirez y Germán Vargas B. por su bien companía y ayudo en el trabajo de campo. ☺ Juan Diego Alvarez G. por su amistad y el uso de su computador, sin aquel no hubo habido datos climáticos. ☺ Miriam Herrera y su familia, por el uso de su e-mail y el aguapanela. ☺ Veronica Mora G. por sus introducciónes en la vida Colombiana. ☺ Alex, Natalia, Gustavo y Frans, por incluirme en ‘la familia’. ☺ Walter, Efrain, Leo, Mancho, Alex, Fido, Alejandro, por ser amigos. ☺ todas las familias Colombianas donde me senti como en la casa. ☺ Frans van Dunné voor de prima begeleiding in Colombia en in Nederland. ☺ mijn begeleiders in Nederland, Antoine Cleef, Pieter Ketner en John Stuiver, voor hun interesse en steun. ☺ mijn familie, huisgenoten en vrienden in Nederland voor vanalles.

Dit onderzoek is mogelijk gemaakt door de financiele ondersteuning van:
tropen subsidie van de Landbouw Universiteit Wageningen
de Stichting Wageningen Universiteits Fonds
de Alberta Mennega Stichting, Odijk
stichting FONA, Fonds voor Onderzoek ten behoeve van het Natuurbehoud, IBN- DLO, Wageningen.

October 1999. Maaike Bader.

3 Abstract Epiphytes are an important aspect of tropical montane rain forests. Most of the primary montane rain forests have disappeared, and regrowing forests are important for the preservation of biodiversity. To be able to recolonize secondary forests and add their typical presence to these forests, epiphytes need a seed-supply and suitable growing sites. The spatial distribution of angiosperm epiphytes in a secondary upper montane forest was studied, in relation to forest structure dependent variables and the distance to possible seed sources. The methods used were mostly explorative, with an emphasis on the search for new methods for describing epiphyte distribution. Instead of using tree- zonations, like many authors have done, epiphytes, phorophytes and undergrowth were positioned in a three dimensional co-ordinate system. A GIS (Geografical Information System) was used to analyze spatial relationships. Growing site variables were related to epiphyte occurrence and morphology. Air humidity was highest, with smallest variation, close to the ground. Light levels were lowest here, and the temperature slightly lower than higher up. Three epiphyte families were found; Bromeliaceae, Orchidaceae and Loranthaceae. Diversity was rather low, but the number of individuals was high compared to other studies. There was a clear optimum height for epiphyte occurrence, which differed between families, but not convincingly between bromeliad species. No host specificity was observed, except for the absence of Loranthaceae on Clethra sp. None of the tested plot variables were significantly correlated to the number of species per plot, but a weak relation exists between basal area and epiphyte number. On this scale big differences in seed-supply are unlikely. Adult epiphytes grew on bigger branches than juveniles. Forks and the topside of branches were no popular growing sites. Plant color of Racinaea tetrantha was related to height above the ground. Differentiation of the substrate by families may reflect a weak habitat differentiation. Bromeliad species do not seem to differ in their ecological preferences. Co-habitation of these species could be explained by the high abundance of substrate, making competition for space unimportant. Different life-strategies may strongly influence the rate and patterns of dispersal of different epiphyte-species. Some patterns in the distribution of epiphytes have been detected in this explorative study, but a more detailed, preferably experimental research would be necessary to get insight into the mechanisms underlying these patterns. Describing spatial epiphyte distributions remains a challenge, and GIS is a promising tool in developing a good method.

4 Samenvatting Epifyten zijn planten die op andere planten groeien, meestal op bomen. Epifyten vormen een belangrijke component van tropische bergbossen. De primaire bergbossen zijn grotendeels verdwenen, en secundaire bossen vormen nu belangrijke elementen voor het behoud van de biodiversiteit. Om hergroeiende bossen te kunnen koloniseren, en hun typische aanwezigheid aan deze bossen toe te kunnen voegen, hebben epifyten een aanvoer van zaden en geschikte vestigingsplaatsen nodig. In dit onderzoek is de ruimtelijke verspreiding van epifytische bloemplanten in een secundair hoog montaan bos onderzocht, in relatie tot bos struktuur-afhankelijke variabelen en de afstand tot mogelijke zaadbronnen. De gebruikte methoden waren voornamelijk exploratief, met de nadruk op het zoeken naar nieuwe methoden voor het beschrijven van epifyten verspreiding. In plaats van een beschrijving naar ‘boom-zone’, zoals veel auteurs dat gedaan hebben, zijn epifyten, bomen en struiklaag beschreven in een 3-dimensionaal co-ordinaten stelsel. Voor de analyse van ruimtelijke relaties is gebruik gemaakt van een GIS (Geografisch Informatie Systeem). Het voorkomen en het uiterlijk van de epifyten zijn gerelateerd aan verschillende standplaatsfactoren. De luchtvochtigheid was het hoogst, met de minste variatie, dicht bij de grond. Lichtsterkte was hier het laagst en de temperatuur was iets lager dan hoger in de vegetatie. De gevonden epifyten behoorden tot drie families: Bromeliaceae, Orchidaceae en Loranthaceae. De diversiteit was vrij laag, maar de hoeveelheid individuen per soort was hoog vergeleken met andere onderzoeken. Er was een duidelijke optimum hoogte voor het voorkomen van epifyten, welke verschilde tussen de families, maar niet overtuigend tussen verschillende bromelia soorten. Er is geen gastheer-specificiteit waargenomen, behalve de afwezigheid van Loranthaceae op Clethra sp. Geen van de geteste perceel-variabelen was significant gecorreleerd met het aantal epifyten per plot, maar er was wel een zwakke relatie tussen de ‘basal area’ en het aantal epifyten. Op deze schaal zijn grote verschillen in de aanvoer van zaden onwaarschijnlijk. Volwassen epifyten groeiden op dikkere takken dan jongere. Vertakkingen en de bovenkant van de takken waren geen drukbezette groeiplaatsen. De plant-kleur van Racinaea tetrantha was gecorreleerd met hoogte boven de grond. De verdeling van het substraat door de families zou een reflectie kunnen zijn van een zwakke habitat differentiatie. Bromelia soorten lijken niet te verschillen wat betreft hun ecologische voorkeuren. Co-habitatie van deze soorten zou verklaard kunnen worden door de grote hoeveelheid beschikbaar substraat, waardoor er weinig concurrentie om plaats zal optreden. Verschillende levensstrategieën zouden een sterke invloed kunnen hebben op de snelheid en het patroon van de verspreiding van verschillende epifyten soorten. Er zijn in dit onderzoek een aantal patronen gesignaleerd in de verspreiding van epifyten, maar voor een beter inzicht in de mechanismen die deze patronen veroorzaken, zou een meer gedetailleerd, liefst experimenteel onderzoek nodig zijn. Het beschrijven van de verspreiding van epifyten blijft een uitdaging, en GIS is een veelbelovend gereedschap voor het ontwikkelen van een goede methode.

5 Resumen Epífitas son plantas que crecen sobre otras plantas, por lo general en árboles. Las epífitas son un componente importante de la vegetación en bosques montanos tropicales. Muchos de los bosques primarios de este tipo han desparecido y los bosques secundarios desempeñan una functión importante en la preservación de la biodiversidad. Para poder recolonizar bosques secundarios, las epífitas necesitan una fuente de semillas cercana y sitios apropiados para establecerse. En esta investigación se estudió la distribución de las epífitas vasculares en un bosque alto montano secundario, en relación con factores dependientes de la estructura del bosque, y con la distancia de las fuentes de semillas. Se utilizaron métodos sobretodo explorativos, con énfasis a buscar nuevas formas de describrir la distribución de epífitas. En lugar de una zonificación de los árboles, como empleado por muchos autores, se pusieron las epífitas, los árboles y los arbustos en un sistema de coordenadas en tres dimensiones. Se utilizó un SIG (Sistema de Información Geográfica) para estudiar las relaciones espaciales. Factores ambientales locales fueron relacionados a la presencia y la morfología de las epífitas. Cerca del suelo la humedad del aire fué más alta, con menos variación, que más arriba. La luz y la temperaturas fueron también más bajas. Se encontraron epífitas de tres familias: Bromeliaceae, Orchidaceae y Loranthaceae. En comparación a otros estudios, no habian muchas especies, pero sí muchos individuos de cada especie. Habia una clara altura óptima donde había más epífitas, con diferencia entre familias, pero no entre especies de bromelias. No se observó especificidad de hospedero, fuera de la ausencia de Loranthaceae en Clethra sp. Las cualidades de las parcelas probadas no pudieron explicar las diferentes cantidades de epífitas entre parcelas, pero sí había una relación débil entre el área basal y el número de epífitas. A esta escala, grandes diferencias en el abastecimiento de semillas no son probables. Las epífitas adultas se encontraron en ramas más gruesas que las epífitas juveniles. No se encontraron muchas epífitas en bifurcaciones, ni encima de las ramas. El color de Racinaea tetrantha estaba relacionado con la altura sobre el suelo. La diferenciación del sustrato por las familias, podria reflejar una diferenciación de habitats. Parece que las especies de bromelias no difieren mucho en sus preferéncias ecológicas. La co-habitación de estas especies se podría explicar por la alta cantidad de sustrato, por lo cual competencia por espacio no será importante. Strategias de vida diferentes podrían influir fuertemente en la velocidad y el patrón de distribución de las diferentes especies de epífitas. Se encontraron algunos patrones en la distribución de epífitas en esta investigación explorativa. Pero un estudio mas detallado, preferiblemente experimental, sería necesario para conocer los mecanismos que causan estos patrones. Describir la distribución espacial de epífitas seguirá siendo un reto, y los SIG son un instrumento prometedor para el desarollo de un método eficaz.

6 1 Epiphytism

1.1 Definition The first recorded comment on epiphytes a is credited to Columbus (ca. 1492), who wrote that tropical trees “have a great variety of branches and leaves, all of them growing from a single root” (Gessner 1956, in Benzing 1990). A more recent text by Goebel (1889) is still accurate for the general opinion about epiphytes today: ‘ A …symbiosis (of several plants) occurs in the most varied arrangements, it is at the most extreme in those plants, which have settled on the surface of others, without finding here anything but a profitable growing site. The epiphytes do not take nutrients from the plants on which they grow (apart maybe from decomposition products of the outer bark), they are also not restricted to certain plant forms.’ b

Many similar definitions for true epiphytes or holo-epiphytes have been formulated: Madison (1977): ‘… those species which normally germinate on the surface of another living plant and pass the entire life cycle without becoming connected to the ground.’ Kress (1989): ‘… those plants that normally spend their entire lifecycle perched on another plant and receive all mineral nutrients from non-terrestrial sources.’

In this report the term epiphyte will be used to denote vascular epiphytes in particular.

1.2 Ecology and evolution Epiphytes have found a clever way of escaping the dark circumstances of the forest understory, without having to invest in expensive structures to rise towards the sun. This is, at least, one scenario of how epiphytism evolved: rainforest understory species working their way up to the crowns, getting more and more adapted to the xeric circumstances that dominate up there (Schimper 1888). It has also been argued that epiphytes may have colonized the forest canopy arriving from a xeric environment, pre- adapted to that aspect of canopy-life (e.g. Pittendrigh 1948). Most probably both these pathways have been followed by different epiphyte species (Benzing 1989a). The canopy habitat imposes some typical stresses on plant life, most importantly drought and limited nutrient availability. Both these factors are more pronounced in some environments than in others. In tropical montane cloud forests the cool and always moist a meaning vascular plants as epiphytes, though the definitions could apply to lower plants as epiphytes, a widespread phenomenon, aswell. Epiphytism is also known in aquatic systems, where algae grow on each other as on any substrate (Lüttge 1989, 1997),but this type of epiphytism is not relevant to the subject of this report. And will not be further discussed. b “Ein … Zusammenleben (verschiedener Pflanzen) findet in der verschiedensten Abstufung statt, es ist am äusserlichsten bei denjenigen Pflanzen, welche sich auf der Oberfläche anderer angesiedelt haben, ohne auf denselben etwas anderes zu finden, als einen günstigen Standort. Die Epiphyten entnehmen den Pflanzen, auf denen sie wachsen, kein Stoffe (abgesehen allenfalls von Verwitterungsprodukten der äusseren toten Rindenschichten), sie sind auch nicht an bestimmte Planzenformen gebunden.”

7 climate favors a higher diversity and biomass of epiphytes than is found in hot tropical lowlands forests (Madison 1977, Sugden & Robins 1979, Lüttge 1989). However, even in (semi-) deserts epiphytes can be abundant, and even in moist montane forests many epiphytes show xeromorphic adaptations.

One such an adaptation is water-storage in succulent tissue, which is a nearly universal trait in vascular epiphytes (Madison 1977). Also a big proportion (over 50%) of epiphyte species is said to have a CAM photosynthesis, allowing the stomata to stay closed during the day, thus reducing water-loss (Lüttge 1997). The possibility to take up water directly from rain or mist through aerial roots or leaf-trichomes, is another adaptation for survival in xeric habitats that is found in many epiphytes, e.g. many Orchidaceae and Araceae (aerial roots) and Bromeliaceae (leaf-trichomes)(Goebel 1889, Benzing 1986). Nutrient availability can be higher in canopy-soils than in the ground beneath (Benzing 1990), but the surface of canopy-soil on branches is generally small, and many epiphytes are independent of this nutrient-source. Instead they may accumulate their own humus in basket-like structures formed by negatively geotropic roots. This phenomenon is found in various epiphytes, like several Orchidaceae and Anthurium (Araceae) (Madison 1977). Humus and water can also be accumulated in leaf- structures, like the tanks of many Bromeliaceae. While carnivory is underrepresented in epiphytes (Benzing 1989b, 1995), associations with fauna are not uncommon. Bromeliad-tanks may contain numerous invertebrate- species, some endemic to bromeliads, and may even provide a habitat for frogs. These animals can be useful in the digestion of the organic matter in the tank, releasing nutrients in a form that the plant can take up (Benzing 1989, 1990). A special form of animal-epiphyte relation that has received a lot of attention is the association between epiphytes and ants. Two types of epiphytes are fed through such associations: ant-nest epiphytes and ant-garden epiphytes (Benzing 1989). Ant-nest epiphytes provide housing for ants in hollow cavities in their vegetative parts. The ants’ secretions in the hollows feed the epiphyte, and the ants may also protect the epiphyte from herbivores (Huxley 1980). Ant gardens are arboreal antnests with a typical community of epiphytes rooting in the nest-carton. The plants provide structural strength to the nest and food-rewards to the ants, while the ants benefit the epiphytes by providing a rich rooting-medium, by protection against herbivores and by dispersal of seeds (Ule 1902, Kleinfeldt 1978, Madison 1979, Davidson 1988, Davidson & Epstein 1989, Mora 1999). Another prerequisite to living epiphytically, is the ability to attach to the phorophyte (host tree). In over 99% of vascular epiphyte genera species have part of their roots arising from the stem rather than the primary root. Usually these adventitious roots are used for adhesion to the bark of the phorophyte. They also allow for clonal reproduction by fragmentation of the plant, since every portion can have its own roots. Another common feature in epiphytes that can be advantageous for attachment, are pendulous shoots.

8 With shoots hanging down on both sides of a branch, an epiphyte is less likely to be blown or knocked off than an upright plant might be (Madison 1977). An advantage at high positions may be the enhanced dispersability of wind borne seeds. This might have been a selection pressure favoring epiphytism especially in wind- dispersed species: 84% of all epiphyte species are dispersed by wind, in contrast to terrestrial tropical rain forest species (fig. 1). The remaining 16% have fleshy fruits and are dispersed by animals. Seeds are generally rather small (<1 mm long). This may have three advantages compared to bigger seeds: more seeds can be produced at the same cost, enhancing the chance of some reaching suitable growing sites; small seeds can easier get attached to bark surfaces, even on relatively smooth surfaces, e.g. in little fissures; and small seeds are easier wetted, because of their bigger surface to volume ratio Figure 1 Epiphyte seeds. 1: Hymenopogon brasiliensis , 2: (Madison 1977). Cosmibuena sp. (Rubiaceae), 3: Hillia sp. aff. brasiliensis (Rubiaceae), 4: Rhododendron pendulum (Ericaceae), 5: Dischidia imbricata (Asclepiadaceae), 6: Dischidia rafflesiana , 7: Aeschynanthus leucalatus var. sikkimensis (Gesneriaceae), 8: Several levels of Catopsis sp. (Bromeliaceae), 9: Tillandsia vestita epiphytism can be (Bromeliaceae). From Schimper (1888). distinguished. Hemi- epiphytes are distinguished from true epiphytes, because they are epiphytic only part of their lives. They either germinate in the ground, growing up like vines and losing their connection with the soil once they settle in the canopy (secondary hemi-epiphytes), or they start of as epiphytes, sending out aerial roots towards the soil (primary hemi- epiphytes). In casual epiphytes some individuals in a population function as true epiphytes, while other grow terrestrially. These are distinguished from accidental

9 epiphytes, species without special adaptations to epiphytic life that can occasionally be found growing in soil-pockets on trees or on rotting stumps (Madison 1977). Semi- epiphytic climbers are vines that are rooted in the soil, but which climb with adventitious roots that also function in uptake of water and nutrients (Kress 1989).

1.3 Distribution and taxonomy Within non-vascular plant groups like algae, mosses and lichens epiphytism has a very wide geographical range, but vascular epiphytes are mostly restricted to the tropics (Johansson 1974, Benzing 1995, Lüttge 1989 & 1997) and southern hemisphere temperate forests (Schimper 1888, Dickinson et al . 1993). Diversity and abundance of vascular epiphytes is greatest in the neotropics, where, according to an estimation of Madison (1977), 15510 species have been recorded as epiphytes, compared to 12560 in all of the paleotropics (Sugden & Robins 1979).

The epiphytic lifestyle has developed in no less than 84 families of vascular plants (Kress 1989). The following numbers are those found by Kress (1989), whose counts include true epiphytes, hemi-epiphytes, casual epiphytes and some semi-epiphytic climbers, but no accidental epiphytes. The exact number of epiphyte-species in the world is still unknown, and change with every new publication on the subject (Schimper 1888, Richards 1952, Madison 1977, Kress 1989). Approximately ten percent of all vascular plant species are epiphytic. 23466 species in 879 genera have been recorded, most of which are angiosperms (20863 species in 784 genera). Although many families contain at least one epiphyte, only 32 seed-plant families have 5 or more epiphytic species (Gentry & Dodson 1987) and only 16 have more than 50 (Kress 1989). The family Orchidaceae contains by far the most epiphytic species of all plant species (ca. 13951 in 440 genera). This is 73% of all Orchid species and 60% of all epiphytic species. Second biggest are the Araceae, with 1349 species in 13 genera. The Bromeliaceae, which are originally restricted to the Neotropics, come third with 1145 species in 27 genera. All three of these biggest families are monocotyledons. Other angiosperm families that contain many epiphytes are, in descending order, the Piperaceae, Ericaceae, Melastomataceae, Gesneriaceae, Moraceae, Rubiaceae and Cactaceae (Kress 1989). Species from the Loranthaceae and Viscaceae were excluded from these counts. These are all epiphytic parasites (together ca. 1315 species (Reid et al. 1995)).

The epiphytes encountered in this research belong to three different families: Bromeliaceae, Orchidaceae and Loranthaceae. The growth habits of these three families are quite different. The following three paragraphs give a general description of epiphytic life in these different families. No hemi-epiphytes or semi-epiphytic climbers were encountered in the study area, so these will not be further discussed.

10 1.4 Bromeliaceae The Bromeliaceae are a very divers family. In size they range from Tillandsia bryoides , tiny and moss-like, to Puya raimondii , with inflorescences up to 6 meter tall (Smith & Downs 1974). Habitats in which bromeliads are found range from virtually rainless deserts to rain and mist forests and from sea level to nearly 4500 meter. About half of all Bromeliaceae species are epiphytes. An important problem to be overcome by epiphytes is how to acquire water and nutrients in the tree canopies, away from the common source for terrestrial plants: the soil. In terrestrial bromeliads some traits are found that could serve as a pre-adaptations to solving this problem. Pittendrigh (1948) has made a division of Bromeliaceae into four ecological types, which is now widely used (Smith 1989, Lüttge 1997). The classification is based on the mode of nutrient and water acquisition, and shows an increasing level of (pre-)adaptation to epiphytism: Type I: Soil-Root. Terrestrial species with a normal root system for taking up water and nutrients. These species do not form tanks. Foliar scales are unspecialized and non- absorbent. Species are often highly xeromorphic and may be densely covered by scales, which appear to serve for reflection of light and minimizing water loss. Type II: Tank-Root. Species in this group do form tanks: the rosette arrangement of their leaves collects rainwater and detritus at the leaf bases. Scales on the leaves only make a minor contribution to water and nutrient uptake, but stem-based ‘tank-roots’ grow between the leaves and exploit the resources in the tank. Soil-roots also take up water and nutrients from the soil. Most species of this type are terrestrial, but some can grow epiphytically as well, e.g. Streptocalyx angustifolius Beer and Aechmea brevicollis L.B. Smith, growing in the ‘soils’ of Amazonian ant gardens (pers. obs.). Type III: Tank-Absorbing Trichome. Epiphytic species that form tanks, generally more developed ones than those of tank-root types, that can collect considerable amounts of water and detritus. The roots usually have a mechanical function only. Water and nutrients are absorbed from the tank by means of foliar scales, which are especially abundant at the leaf base. Type IV: Atmospheric-Absorbing Trichome. Epiphytic species with tanks being poorly developed or lacking. The entire leaf surface is covered with highly specialized scales, that absorb water and nutrients from rain, mist and dust in the atmosphere. Roots serve for attachment only. An extreme atmospheric form is the most widespread of all Bromeliaceae: Tillandsia usneoides (sometimes called ‘Spanish Moss’ or ‘Old Man’s Beard’), which in its mature form lacks roots and a tank completely and can cover trees with veils of its finely dissected strands.

The foliar scales mentioned above are epidermal structures (trichomes) with varying functionality and complexity in different species. In most epiphytic bromeliads they have taken over the function of the roots by becoming absorbing structures. The trichomes can take up water, and mineral nutrients as well as amino acids (Picado 1913, Benzing 1970, in Smith & Downs 1974). In high densities the scales give the leaves a greyish appearance and are effective in reflecting radiation, thus protecting the leaves from photo-damage and overheating. The highest development of scales is found in the genus Tillandsia (Smith & Downs 1974).

11 Although they are crucial for water uptake, the scales also impair CO2-uptake when wet. Therefor species with very high trichome densities on the entire leaves are best adapted to drier or more exposed habitats (Mez 1904, Benzing & Renfrow 1971, Martin et al . 1981, in Smith 1989). Schimper (1888) describes the occurrence of ‘green Bromeliaceae’ in the shaded circumstances of rain forest tree trunks, while on the outer twigs he finds ‘the same grey Tillandsias (…) that the stem and branches of savanna-trees are overgrown with’.

Some other adaptations are also related to the habitat of the species. Pittendrigh (1948) divides the Trinidad bromeliads into three groups based on their vertical stratification within the forest: an exposure group, a sun group and a shade-tolerant group. More than half of the exposure species are type IV Tillandsias , with a CAM metabolism and a relatively dense covering of scales. The sun group requires a high humidity but is not shade tolerant. These are mostly C3 plants. Tillandsias in this group are broad-leafed type III epiphytes. The shade tolerant group contains only type III C3 species (incl. Tillandsias ) with broad relatively thin leaves (Smith 1989). The shape of bromeliad tanks, or phytotelma, also shows a relationship with the abiotic circumstances at growing sites. Species growing in shady and humid environments tend to produce open shallow tanks, suited to intercept as much light as possible. In more exposed and drier environments species with tanks tend to have a narrow tubular shape, which minimizes water loss by evaporation and damage by direct radiation at midday (Benzing 1990). Figure 2 demonstrates this phenomenon. Broad-leafed open species are found mostly at sheltered ridges, which have a denser canopy and higher supply of moisture. The leeward slopes are relatively cloud free and rather open. Species here are heliophilic (Guzmannia monostachia ), Figure 2 Bromeliad species with different shapes in semibulbous ( Vriesia heterandra ) or different habitats in a cloud forest. (from Sugden 1988) succulent ( Tillandsia bulbosa ). The windward slopes receive a lot of rain, but also desiccating winds. The

12 species mostly found ( Guzmannia cylindrica ) here has its big tank volume well protected by upright rigid leaves (Sugden 1981). Differences in tank shape do not only exist between species, but even within populations there can be a certain plasticity with regard to tank shape in relation to the local climate (Benzing 1990). Within populations there can also be considerable differences in leaf-color. Species often have typical pigmentation patterns, but cyanic (red) pigmentation is also known to appear under high levels of radiation in many bromeliad species, particularly at high altitudes. Such coloration can fade again when conditions become more shaded (Smith & Downs 1974, Benzing & Friedman 1981a). In other plant groups coloration upon exposure is considered protective, protecting the photosynthetic tissue against excessive radiation (Caldwell 1971, in Benzing & Friedman 1981a).

The seeds of epiphytic Bromeliads are dispersed by wind or by birds. The Bromeliaceae are taxonomically divided into three subfamilies (Smith & Downs 1974, 1977, 1979). The Pitcairnioideae (16 genera, 731 species) are terrestrial species with winged, wind-dispersed seeds. The Tillandsioideae (6 genera, 800 species) are generally epiphytic species with plumed, wind-dispersed seeds. The fruits of species belonging to the Bromelioideae (27 genera, 557 species) are berry-like and are mostly dispersed by birds. Roughly half of the Bromelioideae are terrestrial and half are epiphytic. Seed dispersal by birds has probably helped the Bromelioideae to be the most widely distributed subfamily in the rainforests of the amazon basin. The Tillandsioideae however have the widest geographical range per individual genus, probably thanks to the wide range of environments different species within a genus can occupy, in combination with the effective wind-dispersal of the seeds (Smith 1989). The plumose seeds of the Tillandsioideae are not only suited for flying, but also serve very well for attachment. Especially in moist conditions the big surface-area of the plumes help to easily stick the seed to tree bark or other surfaces (Beccari, in Goebel 1889).

Many Bromeliad-species have a very low growth rate, especially the extreme atmospheric CAM types. Some species have a distinct juvenile stage, characterized e.g. by a different leaf-shape or by a high trichome-density in species that are tank-types as adult. Other species only have a minimum size for flowering. Many species propagate vegetatively by forming clones. In some- species (e.g. Ananas comosus ), the side-shoots are only formed after the mother-plant has flowered, while in many others they are formed before and may have grown to considerable size before the primary shoot starts flowering. The primary shoot usually flowers only once. After fruiting it may die back or stay alive another couple of years as an extra photosynthetic leaf- surface for the side-shoots (e.g. Ananas comosus ) (Smith & Downs 1974).

1.5 Orchidaceae The Orchidaceae are a very big and variable family, containing more epiphytes than any other family (Madison 1977, Kress 1989). The epiphytic species are restricted to the tropics, but the family occurs all over the world, except for the very cold regions. The greatest biomass and diversity of Orchids occurs in the Neotropics.

13 Epiphytic orchids usually have more or less succulent leaves and/or stems, containing special water-storing tissue. Most of them also have 'pseudobulbs': short, thick bulb- shaped stems for storage of water and carbohydrates. Another adaptation that can help epiphytic orchids to conserve water, is the possibility of most species to shed their leaves during dry spells (Goh & Kluge 1989). Epiphytic orchids can have two kinds of roots, both secondary roots. Substrate roots enter the substrate and take up water and nutrients (in humus-epiphytes), while aerial roots serve for attachment to the tree or hang freely in the air. Aerial roots are covered by a velamen; a spongy tissue of dead cells that serves for uptake of water and dissolved nutrients and for protection against desiccation (Benzing 1986). Terrestrial orchid roots also often have a velamen, but here it is less pronounced, indicating that it provides additional advantage for epiphytic life. In fact some other epiphytes also have a velamen (certain Araceae and Liliaceae). The roots often contain chloroplasts, and they can perform photosynthesis. In some epiphytic species, the leafless orchids, the roots have totally taken over all vegetative functions, and leaves and stems are rudimentary (Schimper 1888). Other species have special aerial roots that grow negatively geotropically, the upward pointing roots forming humus-collecting 'baskets' (Goh & Kluge 1989). Orchid flowers are often highly specialized to attract specific pollinators. Deception by mimicking brood sites or fertile females of the pollinator species, attracting female and male insects respectively, are well known examples. Food-deception, mimicking pollinator food resources or looking like promising food plants in general, without actually giving any food-reward, also occurs. These deceptions can be brought about by visual, tactile and olfactory stimuli. Another highly specialized strategy is that of certain neotropical orchids that are pollinated by male euglossine bees. The flowers of these species attract and reward these bees with fragrances, which the bees collect and store in special structures, possibly converting them into sex pheromones (Ackerman 1986). The seeds of the Orchidaceae are extremely small 'dust-seeds', of which one capsule may contain millions. To survive as seedlings, an association with mycorrhiza is necessary, which provides the seedling with consumable organic nutrition (Benzing 1981a). These mycorrhiza accompany epiphytic orchids as adults as well, at least in some species, and many aspects of canopy orchid biology have been related to this association (Benzing & Friedman 1981b).

1.6 Loranthaceae A very distinct group of epiphytes is that of the mistletoes. The mistletoes are often not considered real epiphytes (Goebel 1889, in Went 1940, Madison 1977, Lüttge 1989 & 1997), because they are true parasites on their host trees. This means that they do actually have a vascular connection to the soil, through the host xylem (Madison 1977). However, in this study a wider interpretation of the term epiphyte is preferred: plants growing on other plants, with a distinction between parasitic and non-parasitic epiphytes.

14 ‘Mistletoe’ is the commonly used name for a group of shrubby epiphytic parasites (or parasitic epiphytes) belonging to the order Santalales. There are about 1400 species, mostly in the families Loranthaceae (ca. 950 species and 65 genera) and Viscaceae (ca. 365 species). Mistletoes occur ubiquitously in forests, woodlands and shrublands in temperate and tropical areas, and dry and wet conditions, on all continents except Antarctica (Reid et al. 1995). The Loranthaceae are best developed in the tropics and the southern hemisphere, while the Viscaceae have a more northern distribution, plus a centre in the Pacific basin. Viscum album (Viscaceae) and Loranthus europaeus (Loranthaceae) are the only mistletoes of Europe (Calder 1983). A special type of mistletoes is that of the dwarf mistletoes, which typically cause the production of so-called witches’ brooms; dense masses of distorted host branches. No Loranthaceae belong to this group of heterotrophic parasites. They were not encountered in the study area and will not be further discussed here.

The seeds of most mistletoes (all Loranthaceae and most Viscaceae) are dispersed by frugivorous birds. The seed is surrounded by a pseudoberry that is nutritive for birds and usually viscous. The birds regurgitate or defecate the seeds and wipe them onto branches, where the remains of the sticky fruitpulp glue them to the bark. Many specialized mistletoe birds have special adaptations in the inner tract to avoid damage to the mistletoe seeds, but seeds can be damaged by passage through other types of birds (Liddy 1983, Godschalk 1983). Mistletoe seeds may germinate directly after release from the fruit, if the conditions are right. Unlike all other groups of plants, many mistletoe species have seeds that can germinate in dry air. Others require humid air or water. Light positively influences germination and enhances embryo elongation. The optimum temperature for germination depends on the habitat preference of the species (Lamont 1983).

After a brief free-living phase the seedling infects the host, after which it is dependent on the host. The radicle develops into the penetration organ. After making contact with the branch, the tip thickens into a club-shaped holdfast. Through a combination of enzymatic digestion and mechanical pressure mistletoe tissue enters the host bark and cortex When the host vascular cambium is reached, the mistletoes forms a cambium itself and starts growing along with the host tissue and a direct xylem to xylem contact is established (Sallé 1983, Reid et al . 1995, Lüttge 1997).

The holdfast and penetration structure together are called the haustorium (Goebel 1889). The haustorium serves for anchoring the mistletoe to the host and for tapping water and nutrients from the host. Usually the integrated mistletoe tissue causes thickening of the host branch. A haustorium can be restricted to one ball like attachment, the primary haustorium, but many species develop secondary haustoria. These may develop from external root-like runners that establish new connections with other parts of the host or neighboring trees. These runners also give rise to new aerial shoots.

15 Alternatively the mistletoe tissue may ramify underneath the bark, occasionally penetrating the xylem again and growing new aerial shoots through the bark. These secondary haustoria are especially rewarding in dry environments, where extra contact with the host will facilitate water uptake. Host generalists in tropical rainforests also often have external runners going through the canopy, infecting multiple hosts. In unstable environments, e.g. short lived hosts or fire prone vegetations, mistletoe species are more likely to have simple ball shaped haustoria, because the uncertainty about the future favors quick sexual reproduction rather than investment in vegetative extensions (Reid et al . 1995).

All Loranthaceae are more or less autotrophic parasites, fixing their own carbon. Although they have high chlorophyll concentrations and only tap the host xylem stream, research has shown them to be partly heterotrophic as well. Estimates for the contribution of carbon from organic compounds dissolved in host xylem water to the carbon content of various mistletoes range from 20 to 67% (Reid et al . 1995).

Mistletoe transpiration rates can be 1.5 to 10 times those of their hosts (Fischer 1983, Ullman et al . 1985, in Reid et al . 1995). Their leaves have indeed been shown to have a more negative leaf-water potential and a higher conductance for water vapor than the leaves of their hosts (Schultze et al . 1984, in Lüttge 1997). This is a necessary adaptation of the mistletoes to draw the xylem waterstream towards themselves. As mistletoes generally have similar or lower carbon assimilation rates than their hosts, such a high water use implies a very low water use efficiency. An advantage of such a high transpiration is the higher supply of nitrogen and carbon with the high amount of water coming through. Nitrogen is regarded as the macronutrient most limiting to mistletoe growth, and heterotrophic carbon gain can lower the need for nitrogen. If the mistletoe assimilates less carbon through photosynthesis, less nitrogen is needed, because the photosynthetic apparatus is the main user of nitrogen (Reid et al . 1995) .

Host specificity varies between mistletoe species, possibly as an evolutionary result of the likelihood of meeting hosts species (Atsatt 1983). Populations in forests with low tree species dominance, such as tropical rain forests, are likely to become generalists, because seed dispersal is not specific enough to have a high proportion of seeds delivered to a particular species of tree. However, in habitats with one or few dominant species, such as dry open forests, mistletoes are most likely to adapt to the tree species present, possibly leaving the population less fit to use other trees as hosts (Barlow 1981, in Reid et al . 1995). Some ecological factors could explain host specificity of mistletoes. Tree species that maintain a very low water potential will not a very suitable mistletoe-host. However, some mistletoe species can even grow on mangroves, which are salt loaded and thus have quite a low water potential (Lüttge 1997). Also the behavior of the birds that

16 disperse the seeds can influence the distribution of mistletoes, because they may prefer shrubs or trees of particular species or size (Godschalk 1983). Several incompatibility mechanisms could prevent mistletoes from establishing or reproducing on certain hosts. These might operate at the penetration stage or the parasite might die afterwards but the precise mechanisms of incompatibility and the biochemistry of mistletoe-host recognition are yet greatly unknown. Chemical cues from the host seem to be necessary for holdfast development at least in some species (Dawson and Ehrlinger 1991, in Reid et al . 1995). Some interesting observations have been made with regard to host-respons to mistletoes, like an apparent resistance of some hosts to mistletoe infection when it already houses one (Hoffman et al . 1986, in Reid et al . 1995), or to infection by a dwarf mistletoe species other than the one already present (Hawksworth 1983).

17 2 Introduction to the study

The area of primary montane rain forest in Colombia has been greatly reduced this century by various human activities (Cavalier 1995), a trend that is still being continued for montane cloud forests a worldwide (Hamilton et al . 1995). In Colombia, nearly all of the upper montane mist forest has at some time been cut for charcoal production or cleared to make room for agriculture: potato production and grazing of cattle (fig. 3).

Figure 3 Potato fields and grazing in a large gap in the upper montane forest. Surrounding forests are secondary growth in this case.

If the land is left alone after having been cleared and used, shrubs and trees will soon grow again, initiating a secondary succession with unknown outcome. Kapelle (1995) estimates that floristic recovery of a montane Quercus forest in Costa Rica will take about 65 years, but for the Colombian situation and forest type it is not known if and on what timescale a forest like the primary mossy forest will develop again.

The abundance of epiphytic growth is an important feature in montane forests, the biomass amounting to 12 tons per hectare (Veneklaas, 1990). The diversity and abundance of epiphytic growth is also one of the features said to distinguish mature neotropical forests from late-secondary stages (Hartshorn 1980). Understanding the a These forest can also be called upper montane mist, cloud or rain forest, all referring to the same phenomenon, the frequent occurence of mist (which are called clouds when one is not

18 mechanisms of recolonization of secondary forests by epiphytes is therefor crucial for truly understanding forest regeneration, but this has so far received little attention in regeneration research (Finnegan 1996). A first step towards understanding these mechanisms is knowing which are the main factors determining patterns of epiphyte occurrence. Such patterns can be studied from a continent level to a branch level, depending on the questions to be answered. In the case of forest regeneration, a regional or forest level would be relevant. Regionally the landscape, including differences in local climate and geomorphology and the position of forest remnants (Williams-Linera et al. 1995, Hietz-Seifert et al. 1996, Guevara et al. 1998), is probably the most important factor. On a forest level the age and structure of the forest are more important variables, as is the presence and species composition of a propagule source.

In upper montane forests mosses are the main component of the epiphytic vegetation. They cover trees as well as the forest floor with thick layers. Wolf (1993) describes the epiphytic vegetation of primary montane forests near the location of the study presented here. Wolf’s study was focussed on cryptogams, but vascular epiphytes are also included in the vegetation descriptions. In the lower strata angiosperm epiphytes hardly occur, but in the canopy at least 23 species were found. The distribution of vascular epiphytes in relation to their environment has been the subject of a growing number of studies (e.g. Went 1940, Pittendrigh 1948, Johansson 1974, Sugden & Robins 1979, Sugden 1981, Yeaton & Gladstone 1982, Bennett 1986, 1987, Catling & Lefkovitch 1989, ter Steege and Cornelissen 1989, Bøgh 1992, Migenis & Ackerman 1993, Dickinson et al . 1993, Sterna 1994, Kernan and Fowler 1995, Hietz & Hietz-Seifert 1995a+b, Fischer & Araujo 1995, Freiberg 1996a, Rudolph et al . 1998). Thanks to new or re-discovered possibilities for canopy access (Perry & Williams 1981, Whitacre 1981, Moffet & Lowman 1995) and the recent interest for rainforest diversity and canopy diversity in particular (e.g. Lowman & Nadkarni 1995), the number of epiphyte studies has increased rapidly, especially in the past 20 years (Hietz & Hietz- Seifert 1995a). The main topics for ecological research, excluding ecophysiological topics, have been distribution in different climates, over altitudinal gradient, in different forest types or on different tree-species, within forests or trees, on branches…studies on many different levels. Throughout these studies the main limiting factors for epiphytes, light, water and nutrients, play an important role, be it explicitly or in the background. The relative importance of these factors has never been established however, as they are all strongly related. Height above the ground and altitude above sea-level, for instance, are parameters always found to be important for epiphyte occurrence (e.g. Wolf 1993, Hietz & Hietz-Seifert 1995a). Both are complex factors, and the proximate factors, those environmental circumstances that are of direct influence to the epiphytes, are difficult to distinguish.

inside them) and precipitation. Another name sometimes used is upper tropical montane forest (Wolf 1993)

19 Going from the top of the canopy down to the forest floor, several climatological factors change. Generally air humidity increases and wind speed, average temperature, temperature and humidity oscillations, vapor pressure deficit, amount of light, and the red-far red ratio decrease (Parker 1995). Furthermore the supply of nutrients in stemflow and throughfall water and the amount of falling and accumulated detritus will be different in lower forest strata than high in the canopy. This not only depends on the amount of leaching and dying tree-biomass supplying these regions from above (Reiners & Olson 1984), but also on the leaching from and uptake by other epiphytes (Nadkarni 1986, Lüttge 1989, Veneklaas 1990, Awasthi et al . 1995). Variations in the amount of available branches and their size, roughness and inclination may further influence the amount and species of epiphytes that grow in a given part of the forest (Ter Steege & Cornelissen 1989, Kernan & Fowler 1995). Johansson (1974) distinguished five zones in a tree, dividing the tree into stembase, stem and three zones of equal length inside the crown (fig. 4). He lists 5 similar subdivisions of trees used by different authors, and since Johansson others have used his zonation with small Figure 4 Zones according to Johansson applied to different tree alterations (e.g. ter types. Zonation reflects tree structure, not height above the ground, and not characteristics of single branches. Zones 3 to 5 form Steege & hemispheres in the canopy of the phorophyte (from Nieder & Zotz Cornelissen 1989, 1998). Wolf 1993, Freiberg 1996b). All these tree-zonations are based on tree-architecture, and not on height from the ground (Nieder & Zotz 1998).The ecological characteristics presumed to distinguish the zones are mostly the same as those related to height in a forest. Johansson (1974) discusses the theoretical gradients going from the inner crown towards the tips of big branches: humidity, nutrients, humus deposits and bark roughness decrease and temperature, light and wind velocity increase. Freiberg (1996) verified these microclimatic gradients within an emergent canopy tree.

Height above sea level is another complex factor that strongly influences the occurrence of epiphytes. At higher altitudes the climate is generally cooler and air-humidity

20 increases (Wolf 1993). Forests change in structure and tree species composition at increasing altitude, providing different quantities and qualities of substrate to epiphytes. These differences in structure do not only occur between different altitudes, but also between different forests at the same altitude. Secondary forests can provide a wide range of forest structures, depending on their age, position and history. Such forests can be very suitable for studying the influence of the above-mentioned environmental factors on epiphytes, independent of altitude. However, when forests of different ages are compared, the difference can also be due to the varying amount of time that has been available for recolonization and growth. For studying environmental influences this problem can be overcome by comparing different types of even aged secondary vegetation.

Apart from the growing conditions the supply of propagules is an important factor determining the distribution of epiphytes. When species seem ecologically equal, it may in fact be the most important factor (Benzing 1981b, Yeaton & Gladstone 1982). Obviously epiphytes do not have a seedbank in the soil, so in regrowing forests the first epiphytes must arrive from the surrounding vegetation. Remnant forest fragments, even single trees, can be an important reservoir for epiphyte diversity and a source for seeds in regrowing forest. Isolated remnants in Mexico have been shown to have a high epiphytic species richness, similar to that of trees in undisturbed forests (Hietz-Seifert et al . 1996), and to contain in part species that occur also in undisturbed forests (Williams- Linera et al. 1995).

Barkman (1958) summarizes the factors that are important for epiphyte establishment as follows: “1. accessibility (can diaspores of the species reach the locality?), 2. priority (is the habitat already occupied by other species?), 3. environment (does it enable the species to germinate and grow?), 4. competition (can the species withstand competition of other species already present or coming shortly afterwards?).” For vascular epiphytes the first and third factor are the most important, factor 2 and 4 applying mostly to mat- forming bryophytes (Barkman 1958, Wolf 1993). In the present study the spatial distribution of angiosperm epiphytes was studied, in an attempt to quantify ‘accessibility’ and ‘environment’ in an open, heterogenous secondary upper montane forest. The study was also an exploration of methods for quantitatively describing epiphyte distributions. An additional research objective was to study the relation between bromeliad morphology and some environmental factors. Possible relations between environment and bromeliad color and shape, as described in chapter 1.4, were investigated for the species in the study area.

21 3 Study area

The study area is situated at 3000 meters above sea level at the west side of the Cordillera Central, near the town Santa Rosa de Cabal in the province Risaralda, Colombia (ca. N 04 50'17'', W 75 30'14'') (fig. 5). The study site is situated close to the Parque Nacional Los Nevados, containing several more or less dormant, snow-capped volcanoes, some over 5000 meter in height. Soils in the area are of volcanic origin. The climate at 3000 m is moist and cool, but temperatures rarely, if ever, drop below zero. Wolf (1993) has recorded relative air humidity being close to 95% most of the Figure 5 Position of study area: Santa time, with temperatures between 5 and 10 Rosa de Cabal, Central Cordillera, °C. Usually clouds move upwards from the Colombia. valley in the morning, causing rain early in the afternoon. Sunny periods usually occur in the morning and later in the afternoon, after the clouds have moved away again (pers. obs.). The climate is relatively constant throughout the year. Two periods with higher rainfall can be distinguished, one around May and one around October, coinciding with the passing of the Intertropical Convergence Zone (Veneklaas 1990). This pattern has been disturbed the last few years, probably through the influence of the climatological phenomena El Niño and La Niña. The forest line is quite high in the region: the paramo vegetation starts at ca. 3700 m.

Human disturbance and the natural occurrence of landslides on steep slopes make the area a mosaic of different stages of secondary growth. This study was conducted in a 20-year old secondary growth shrub-vegetation or very open forest (fig. 6) on deserted pastureland. This area was selected because of its accessibility, its high abundance of vascular epiphytes, low stature and heterogeneity. The low stature was important to avoid the necessity to climb trees, which costs a lot of time and which is not very safe in many higher secondary forests, because trees are rather thin. Heterogeneity was needed for comparing different forest structures. All plots were situated on the top of a wide ridge, running approximately East-West, down from the main Central Cordillera chain. The area was totally surrounded by forests, which also were secondary or disturbed patches, but generally denser and higher, and probably older, than the forest in the study area. Several tall remnant trees (up to 23 m high), containing big bromeliad clusters, were present in the study area. The most abundant shrubs and tree species in the study area are the pioneer shrub Tibouchina grossa (Melastomataceae), shrubs of Escallonia cf. myrtilloides L.F.

22 (Saxifragaceae), the trees Clethra sp., three Miconia-species (Melastomataceae) and the bamboo Chusquea sp. (Poaceae). Two Weinmannia species (Cunoniaceae) are present with mostly young trees up to two meters in height and a DBH around 1cm. Weinmannia -species and Chusquea are characteristic for forests at this altitude: Chusquea scandentis- Weinmannion rollottii alliance, recorded from 2820-3250 m (Wolf 1993). Escallonia myrtilloides is more characteristic for forests near the forest line, which are more open and of lower stature (Cleef et al . in prep. in Wolf 1993), but has also been found in primary and secondary forests at 3100 m, as have several Miconia species (Cavalier 1995).

The study area is clearly distinct from some nearby patches of regenerating forest, even though they have been Figure 6 Example of a common forest structure abandoned approximately at the same in the study area, in this case in plot B. Arrows point out some bromeliads. time. When the area was abandoned some areas grew tall (15-20 m) homogenous forests with little undergrowth, while other parts, like the study-area, developed an open, heterogeneous shrub vegetation, with trees up to 8 meters (fig. 6) (excluding some remnant trees still present). This difference is probably due mainly to a different land use history. The soil in the study area has probably been compacted by the grazing of cattle and is now relatively impermeable, leaving a wet surface where peatmosses ( Sphagnum ) flourish. The taller homogenous forest has probably not been used intensively after clearcutting (Hanke 1999), so the regrowth has been easier. Geomorphology is another factor that may contribute to the difference between the two forests. The (locally) relatively flat character of the study area adds to the possibilities for stagnation of water and thus Sphagnum-growth. The other forest is situated on steeper slopes, so water can run off easier. The distribution of Bromeliaceae in this forest has been studied by Hanke (1999).

23 At this stage it is difficult to tell whether the peatmosses in the study area will eventually 'suffocate' the shrubs and trees, or whether the trees will overshadow the Sphagnum and development will go towards a cloud forest vegetation.

24 4 Method

4.1 Fieldwork All angiosperm epiphytes were sampled in eleven 5x5-m plots (plots A-K). The following criteria were used for selection of the plots: at least two trees over 4 m high should be present within the plot; the ground should be more or less level; there should not be a track or other disturbance inside the plot; there should not be more than 5 m² of bamboo inside the plot (this grows very fast and would alter the circumstances rapidly, so that the epiphytes might not yet have reacted to it). Within the plots all angiosperm epiphytes (and some terrestrial specimens of generally epiphytic species) were mapped, giving them three co-ordinates: z for height and x and y for horizontal position within the plot. Growing sites and plants were noted in separate tables, to avoid redundancy of data where several epiphytes were growing at the same position. For each growing site, the branch-size and -inclination, the exposition and position of the epiphyte on the branch (N/E/S/W-side of the branch)(top/side/bottom) and the surrounding epiphytic vegetation (mosses and lichens) were described. Every epiphyte was described by species, size, viability (alive/poor/dead) and life-stage (seedling/ juvenile/ small clone-shoot/ vegetative adult/ flowering/ fruiting). Bromeliaceae over 5 cm had three sizes taken: vertical distance and horizontal distance at the top and the base of the plant. Smaller bromeliads and species of the other families only had their vertical size taken. Of two bromeliad species ( Racinaea tetrantha and Tillandsia compacta ) the color of the leaves was recorded and light was measured (W/m²), using a Mavolux digital photometer (Gossen instruments). Trees and shrubs over 2 m were mapped and described: species, position of stem-base (xy-co-ordinates), height, DBH, total branch length per thickness-class (1-2, 2-5, 5-10, >10 cm diameter) and epiphyte-cover (cryptogams) in three vertical zones (0-1, 1-3 and >3 m). Taxa were identified by comparison to herbarium material at the Universidad de Antioquia, Medellín. Vouchers of the species have been deposited at the same herbarium. A ground-projection of the tree-crowns was drawn in a 5x5 grid representing the plot. Additional information on crowns was their height, thickness (vertical distance from top to bottom) and denseness (relative measure for the amount of branches and leaves per unit volume: open, medium or dense). Undergrowth was described in a grid of 1x1-m blocks. In the plot, plus a 1-m strip around it, the average height, denseness and species-composition of the undergrowth were recorded per block. In plots that were not level, the slope was measured with the aid of a little level on a rope. This was used to make a horizontal connection between different points around the plot border, including the corners, after which the height difference could be determined.

25 Temperature (in C°) and relative humidity (RH, in %) were measured in every plot at 0.5, 2 and 4 meters above the ground, for 3 days, starting at 12 am, with a recording every 2:24 minutes. Two plots were sampled per 3-day period, and an open reference location was measured every time, at 2 meters from the ground. The measurements were recorded by Stowaway dataloggers (Onset Corp.), which were hung up inside white wooden weather-houses (fig.7), constructed especially for this purpose after a design used by Wolf (1993). The pairs of plots measured in the same week were: A-C, B alone, D-E, F-G, H-K and I-J.

The position of the plots relative to each other and the nearest remnant trees was determined using a 50 meter measuring tape, a compass and clinometer. The clinometer was used to calculate distances to remnants. First the length of a trunk-portion was calculated from the Figure 7 The reference dataloggers in their house. angle observed between the top and a salient feature on the trunk, from a known distance. Then the angle between the same points was taken from the plot, and this was used to calculate the distance.

4.2 Data analysis Recording the exact co-ordinates of all epiphytes and other features in the plots allowed for the use of geographical information systems (GIS) in the analysis, and also for some of the more powerful statistical distance methods, like the K function (Cressie 1993, Young & Young 1998).

4.2.1 GIS Data were entered in the GIS-package ArcInfo, and analyses were carried out using both this program and the related ArcView. This is the first time that a GIS has been used to study the spatial distribution of epiphytes. GIS-software is designed for 2- dimensional data while the epiphyte data was recorded in three dimensions, so some special operations had to be used to be able to make some of the analyses.

26 GIS pre-processing Most of the time and work needed for the use of a GIS for any kind of data, is involved with the construction of the spatial database: the pre-processing phase. Once the database works well, analysis can be relatively simple. This certainly applied to this study. Figure 9 shows the steps of data handling in a general GIS approach. The drawings of the treecrown-projections were scanned and digitized. The overlap- areas, forming closed shapes and hence separate polygons in the GIS topology, were combined to make a region representing an individual crown, to which the attributes (height, denseness, etc.) were assigned. A sloping ground level was represented by a digital elevation model (DEM), which was an interpolation between the height-points measured around the plot borders. This DEM was then used to correct the height of other features. This gives a more correct representation of the spatial positions then height from the ground, which does not accurately describe the mutual positions if the ground is not level. After correction of the undergrowth-height for the ground height, a DEM was made for the upper boundary of the undergrowth by interpolation of the height between the centers of the 1x1-m blocks. The tables containing the co-ordinates of epiphyte- and tree-positions were made into point coverages, where the x and y co-ordinate determined the spatial position in the coverage, while the (corrected) z Data model co-ordinate was stored as an Legend attribute, along with the other cover information gathered in the field. treecrow ns N The epiphyte attributes (species, polygonN DE Ztop size etc.) were linked to the treecrow Zbase ns ta epiphyte positions, but stored in region bl N separate tables. 1 After the pre-processing phase the tree tree attribut spatial data of every plot was es point available in the following formats: a 1 N DEM of the undergrowth, a Z plant polygon- and a region-coverage for epiphyte local attribut env. 1 N es the tree-crowns, and point- point coverages for the positions of trees shrub and epiphytes. Additionally, for the undergr attribut owth es plots that were not level a DEM of the ground surface was also part of ground- the spatial dataset. All coverages level of a plot are defined in the same co-ordinate system. They can be Figure 8 Data model, showing the relation between thematic tables and the attached spatial related on basis of their position or components (left). A coverage has a vector format, on mutual key-attributes (fig. 8). a DEM is a digital elevation model, a raster format.

27 real world concept data model

Data model Legend

ground- coverage level DEM

table Ztop treecrowns Zbase

N 1

tree tree attributes

1 N Z 1 N plant epiphyte local env. attributes attributes

shrub undergrowth attributes

data acquisition

raw x y z a b data

(pre-) processing

analysis 5 z a b

4

3

2

1

0 distanceunder crown-top (m) N = 452 67 244 10 31 166 21 58 8 23 R. T T R. B Orc O Orchid sp Lor. Dendrop. . . rom t c spec1 penland rchid s et om hi s rant . d p pacta spec s ec ha pec pec1 ec 1 i s i s s 5 pec

presentation GIS-database

Figure 9 Scheme of the process of data handling, including the use of a GIS.

28

GIS-analysis The positions of the epiphytes relative to the crowns were determined by means of an overlay operation in ArcView. To be able to do this, it was first necessary to distinguish the highest and lowest crown above each epiphyte, out of all the overlapping crowns above some of them. Then epiphytes were assigned the heights of the top of the highest and the bottom of the lowest crown straight above or beneath it. Also the distances between epiphytes and the undergrowth-DEM were determined.

The crown-coverage provided area-values, the cover on the ground projection in m 2, for all the crowns. These, combined with the height and thickness of the crowns, were used to determine the crown-volumes per plot and per height-layer. The undergrowth-DEM was used to determine the volume of undergrowth per height-layer. These one-meter thick height-layers were used in the analysis to get a grip on the vertical variation in the amount of substrate within plots. Several possibilities for presenting the spatial data graphically, as maps, were tried out (appendix II) More detailed information on the GIS-processing will be available in a report for the Laboratory of Geo-Information science and Remote Sensing (GIRS), Wageningen Agricultural University (Bader et al . in prep).

4.2.2 Spatial point pattern To analyze the spatial pattern of the epiphytes the K( h) and L( h) functions were used (Young & Young 1998, Cressie 1993). These require a complete map of points, and can effectively summarize spatial dependence over a wide range of scales (Cressie 1993). The K function is based on the number of points within a given distance of each point. By varying this ‘given distance’ ( h), the scale at which the spatial pattern is expressed changes as well. The K function is defined as follows: K( h) = λ-1 E[number of other points within distance h of an arbitrary point] with h ≥ 0. Where λ is the intensity or density of points within the plot. Division by the intensity makes the measure independent of it, making it possible to compare patterns of different densities. As the plots of this study were rather small, a correction for the edges had to be made, resulting in the K 2(h)-function. In this function the number of points within a circle (radius = h) is divided by the proportion of the circle that is situated inside the plot. The values found are compared to a simulation envelope, which is constructed by 100 permutations of the function for completely random patterns with the specified amount of points in the specified area. If the test value is within the simulation envelope, the pattern does not deviate from complete spatial randomness (csr). If it is above it, the points are clustered, if it is below it the point-spacing shows regularity. The L 2(h)- function is an

29 adaptation of K 2(h), centered around zero, with clustering when L 2(h) is above the simulation envelope and regularity when it is lower. Calculations were made using ‘Ecostat’-software (Young & Young 1998) a. Unfortunately it is not possible in either to analyze a three-dimensional pattern directly, although the formula is applicable for 3D-point patterns as well as those in 2 dimensions. The intensity would however need to be calculated for a cube or cylinder rather than a rectangle or circle, and the distances between points with three co-ordinates. It would be interesting for future research to implement the possibility for making these calculations in statistical software, like Ecostat. In this research however, a triple two-dimensional analysis was run, looking at the xy- xz- and yz-plane separately. Clustering of epiphytes was of course expected, because the substrate has a strongly clustered distribution. However, a comparison within plots could reveal something about extra clustering of epiphyte species. The level of clustering of Racinaea tetrantha was compared to that of all epiphytes together, and R. tetrantha adults and juveniles were compared where numbers were sufficient to allow for it.

4.2.3 Climatic data The datalogger-output, consisting of ca. 1810 records with the time and the temperature- or RH -values, was condensed to the following measures (taking the 3 days together): mean, standard deviation, minimum and maximum, for temperature and RH. To be able to compare the outcome in different weeks, these values were standardized by subtracting the reference values for the corresponding weeks. Climate-differences between heights were studied visually and tested using a Kruskall Wallis test (KW).

4.2.4 Height distribution Height distributions of several epiphyte-species were tested with Kolmogorov Smirnov's (KS) test for normality. They were not normally distributed and could not be transformed to confirm to Anova-conventions. Therefor differences between height distributions of different epiphyte-species and –families were tested by means of the non-parametric Kruskall-Wallis test. Apart from height from the ground, several other ‘height’-measures were tested: distance from the undergrowth, distance from the base of the crown and distance from the top of the crown, straight up or down from the epiphyte. These alternative ‘height’-measures were compared between epiphyte-groups using a Kruskall- Wallis test. Their distributions were tested with KS test for normality, and test statistics were compared to those for height from the ground. The amount of substrate on different heights was estimated by calculating the volume of crown or undergrowth in different height layers (1 meter thick).

a Another program that can make these calculations is ‘Splus’, but this program also cannot make 3D calculations for the K function.

30 4.2.5 Other environmental factors The distribution of epiphytes over the different tree-species was compared using bar charts of this distribution per epiphyte species. The epiphyte-abundance in different plots was correlated non-parametrically (Spearman's Rho) to several plot-characteristics: total crown-cover, total crown-volume, total undergrowth-volume, basal area, and distance to nearest remnant tree. To correct for the increased probability of finding significant correlations in a correlation matrix compared to a single test, a Bonferroni correction was used. With this correction p is tested against α', which is α/ k, where k is the amount of tests for significance in a matrix (this is the same as testing p' (=p*k) against α) (Legendre & Legendre 1998). Growing site variables (branch diameter and- inclination, exposition, position on branch) were compared between epiphyte-families and between bromeliad species using a KW test.

4.2.6 Plant appearance The measure for the shape of bromeliads was defined as the angle of the outer leaves to a vertical line. The leaf color as recorded for some of the bromeliad species, was scaled from -3 (green) to 3 (red). These plant-parameters were correlated non-parametrically, with Bonferroni correction, to: height, light intensity (defined as the fraction of incoming light reaching the plant: light at plant / reference light) and a moisture indication (Spearman’s Rho-test). This moisture indication was derived from the ecology of the cryptogams surrounding the plant, based on their general occurrence on a gradient between moist stembases and exposed little branches. This meant, for instance, that most mosses were considered indicators for moisture, while Usnia got a indicator value indicating a xeric habitat.

31 5 Results

5.1 Climate Relative humidity (RH) was very high most of the time. At night it was at or near 100% at all heights (figs 10 and 11.). During warm, sunny days (the first and the third day) it dropped with the increasing temperature. On cold rainy days (the second day) the air stayed nearly saturated all day, even though the temperature did rise about 3 degrees compared to the night.

T (C ) RH (%) 5 0 1 0 0

4 5 9 0

4 0 8 0

3 5 7 0

3 0 6 0

2 5 5 0

2 0 4 0

1 5 3 0

1 0 2 0

5 1 0

0 0 12:00 18:00 0:00 6:00 12:00 18:00 0:00 6:00 12:00 18:00 0:00 6 :00 12:00 tim e Figure 10 The course of temperature and relative humidity during one of the three day measuring periods, at the reference site. Starts at 12 am on 23-11- 1999. The top graph represents the relative humidity (%), the bottom graph represents the temperature (°C). Field-notes on the climate of those days: Monday (23-11): sunny and warm all day, Tuesday: rainy and cold all day, Wednesday: dry, rain in the evening, Thursday: light rain in the morning, then dry.

1 0 0

9 5

9 0

8 5

8 0 R H (%) 4 . 0 m 7 5 2 . 0 m 7 0 0 . 5 m 6 5

6 0

5 5 12:00 18:00 0:00 6:00 12:00 18:00 0:00 6:00 12:00 18:00 0:00 6 :00 12:00 t im e a.

32 2 0 1 9 1 8 1 7 1 6 1 5 1 4 4 .0 m 1 3 T (C ) 2 .0 m 1 2 0 .5 m 1 1 1 0 9 8 7 6 5 12:00 18:00 0:00 6:00 12:00 18:00 0:00 6:00 12:00 18:00 0:00 6 :00 12:00 tim e b.

Figure 11 Course of the climate in plot H at three different heights during three days, starting at 12 am on 23-11-1999 (same period as figure 10). a.) Relative humidity (%). b.) Temperature (°C).

Average RH, as measured and after correction for the reference, differed significantly between heights (KW, p < 0.001): it decreased with distance from the ground (fig. 12). Maximum RH was always 100%, while minima differed significantly (p < 0.01), with higher values at 0.5 meter. Variations in humidity through time were lower at 0.5 m than at 2 and 4 m (p < 0.001)(fig. 13). In nearly all cases the average RH at every height in the plots was higher than that at the open reference site (fig. 11b).

101 6

100 5

99 4 98 3 97 height 2 height 96 1 95 0,5 m 0,5 m 0 94 2,0 m 2,0 m 93 -1

92 4,0 m -2 4,0 m average RH (%) average average RH (%) - ref.average average A B C D E F G H I J K A B C D E F G H I J K a. b.

Figure 12 Average of relative humidity (%) over three days at three heights in the different plots (A, B, …, K). a.) RH measured. b.) difference between the average of the reference measurement and the average of the measurements in the plot.

33 8 3.4

3.2 a 6 a 3.0 b 4 2.8 a b a 2.6

2

2.4

2.2

0 sd Temperature CI 95% 95% CI RH sd RH CI 95% N = 11 16 11 N = 9 16 10 0.5 2.0 4.0 0.5 2.0 4.0

a. height (m) b. height (m) Figure 13 Standard error as a measure for climate fluctuations (se of 1800 measurements durng three days). a.) relative humidity, b.) temperature. The graphs show the average standard error per height and the 95% confidence interval of the se in different plots.

Average temperature generally increased with height from the ground (fig. 14), but this pattern was less clear than that of the RH (p > 0.05, but p < 0.05 after correction for variation between weeks). Especially in a colder, cloudy period (plot I and J), there was hardly any difference in average temperature, and consequently a smaller variation in RH as well, between low and high positions. Minimum temperatures differed slightly between heights (KW, p < 0.05) but the maximum temperatures did not (p > 0.05). Temperature variation through time did not differ significantly between heights (p > 0.05) (fig. 13).

11.0 .2

10.5 0.0

10.0 -.2

-.4 9.5 height height

-.6 9.0 0.5 m 0.5 m -.8

8.5 2.0 m 2.0 m -1.0

8.0 4.0 m average(C) T -1.2 4.0 m average T - (C) ref average A B C D E F G H I J K A C D E F G H I J K a. b.

Figure 14 Average temperature (C °) over three days at three heights in the different plots (A, B, …, K). a.) T measured. b.) difference between the average of the reference measurement and the average of the measurements in the plot.

34 5.2 Epiphyte species Nearly all epiphytes encountered belonged to three families: Bromeliaceae, Orchidaceae and Loranthaceae. An occasional Peperomia-like epiphyte was found and some unidentified plants that were probably just accidental epiphytes growing in some detritus on the tree. This ‘rest’ group only contained 8 records and was excluded as a group from most numerical analysis.

Bromeliaceae Four species of Bromeliaceae were found within the studied plots (fig. 15) : Racinaea tetrantha (Ruiz & Pavon) M.A. Spencer & L.B. Smith (formerly Tillandsia tetrantha ), Racinaea penlandii (L.B. Smith) M.A. Spencer & L.B. Smith (formerly Tillandsia penlandii ), Tillandsia compacta Griseb., and an unidentified Tillandsia-species ( Tillandsia sp.1). Ca. 96% of all Bromeliaceae was identifiable to one of these species. Some seedlings and aberrant specimens were classified Bromeliaceae spp. Vriesea capituligera was encountered in the study area and Tillandsia complanata in a fallen remnant close by, but neither was found in the studied plots. Vriesea , Tillandsia and Racinaea are all Figure 15 The three most common species of genera from the subfamily bromeliads found. From top to bottom: Racinaea tetrantha, Tillandsia compacta (both adults but not Tillandsioideae, which typically fully grown yet) , and Tillandsia sp.1 (adult size). have plumed seeds.

Orchidaceae Although many species of Orchidaceae were present in the study area, very few were found flowering within the plots. Two species were found and recognized rather often, but they were never found flowering. Both were probably species from the genus Epidendrum , an exclusively epiphytic genus that contains 500 species (Kress 1989). The species Orchidaceae sp.5 had green leaves of about 4 cm in length and a purple stem,

35 about 5 mm in diameter, which had a woody appearance in bigger individuals. Orchidaceae sp.1 had bigger leaves (up to 6 cm) and stem (diameter of 1 cm) and generally grew rather tall, up to 1 meter, but did not seem to turn woody. Both species formed clones. Orchidaceae sp.1 was always encountered in humus accumulations at stem bases, with the roots hidden under a moss cover, while Orchidaceae sp.5 was truly epiphytic. The roots of this species were found running up to a meter up or down the tree trunk. All other orchids were taken together as Orchidaceae spp., due to difficulties in identifying and distinguishing the species and low abundance of many species. Some of these species had pseudobulbs, others did not. The only orchid found flowering within the plots was Frondaria caulescens , which was also added to the Orchidaceae spp.- group on account of its low numbers.

Loranthaceae At least two species of mistletoes were encountered. One was a Dendrophtora –species (Loranthaceae). The other was probably a Loranthacea too, but has not been identified to genus, and will be denoted as Loranthaceae sp.1. The Dendrophtora sp. is a woody shrub up to about a meter tall. It has bright orange leaves, about 10 cm in length, non-succulent and with an ovate shape. The other species is smaller (up to ca. 40 cm) and not woody. The leaves are yellowish green, up to 4 cm in length, lightly succulent and with a lanceolate shape. Both species have a simple haustorium, without external runners. Both caused a thickening of the host branch, which was more pronounced in the Dendrophtora . Many Loranthaceae are pollinated by nectar-feeding birds (Reid et al . 1993), but although hummingbirds are common in the area, no conspicuous flowers were observed in either species. Flowers were small, with a color similar to that of the rest of the plant.

5.3 Epiphyte abundance A total number of 1537 angiosperm epiphytes was recorded in the 11 plots. This number results from counting all ramets. The number of genets (genetic individuals) is somewhat lower, because the 1108 bromeliad ramets were contained in 894 dense clusters. These clusters will from now on be called genets or clones, although some of them might be formed by more than one genetic individual a. These ‘genets’ ranged from big clones (one extreme cluster contained 27 ramets) to tiny single seedlings (table 1). The Loranthaceae were represented by 73 individuals, and the Orchidaceae by 364 ramets, a few of which were parts of a clone. The demographic structure of the populations differs markedly between some species.

a An alternative term could be ‘stand’: a compact group of plants, well-separated from conspecifics (Sanford 1968, in Bøgh 1992).

36 Table 1 Number of clones (genets) of different sizes per Bromeliad species. The columns ‘%clone’ and ‘%>2’ show the percentage of ramets that are part of a clone with more than 1 and more than 2 ramets respectively. # of ramets in genet 1 2 3 4 5 6 >6 total % clone % >2 Racinaea tetrantha 420 20 10 3 3 3 6 465 31.8 25.3 Tillandsia compacta 66 6 2 0 0 3 0 77 35.3 23.5 Tillandsia sp.1 267 26 3 0 0 1 0 297 20.1 4.5 Racinaea penlandii 11 2 0 0 0 0 0 13 15.4 0.0 Bromeliaceae spp. 41 1 0 0 0 0 0 42 4.7 0.0 Total 805 55 15 3 3 7 6 894 27.3 17.6

Within the Bromeliaceae Tillandsia compacta has relatively few juveniles (fig. 16 and table 2) Loranthaceae sp.1 seems to have a younger population than Dendrophtora sp. , but this is probably due to a different age-estimate in the smaller species Loranthaceae sp.1.

160 70

140 60 120 50 100 40 80 30 60

40 20

20 10

0 0 0 - 2 6 - 8 12 - 14 18 - 20 24 - 26 30 - 32 0 - 2 4 - 6 8 - 10 12 - 14 16 - 18

vertical size of Racinaea tetrantha (cm) vertical size of Tillandsia spec.1 (cm) a. b.

20

10

0 Figure 16 Size distribution of the three most 0 - 4 8 - 12 16 - 20 24 - 28 32 - 36 40 - 44 abundant Bromeliaceae (vertical size in cm). vertical size of Tillandsia compacta Y-axis shows number of ramets in the size (cm) c. classes.

37 Table 2 Number of epiphyte-ramets found, of different species at different life-stages . It should be noted that the counts of seedlings probably give an under-estimation of the number of seedlings actually present, because the tiny seedlings are easily overlooked. The seedlings, being ca. 5 mm long and light green, could not be determined to species. Clonejuv = small ramet growing from a clone. Juvenile = small individual (judged per species) without floral structures. Adult = non-flowering adult. (Past) flowering = flowering, fruiting or with old fruit capsules. (past) Lifestage: seedling clonejuv juvenile adult total flowering Racinaea tetrantha 1 14 386 177 38 616 Tillandsia compacta 0 4 21 75 2 102 Tillandsia sp.1 0 0 252 82 0 334 Racinaea penlandii 0 0 3 9 1 13 Bromeliaceae spp. 22 0 19 2 0 43 Rest 0 0 7 1 0 8 Orchidaceae spp. 0 0 172 49 10 231 Orchidaceae sp.1 0 0 12 12 0 24 Orchidaceae sp.5 0 1 55 37 0 93 Loranthaceae spp. 0 0 9 2 1 12 Loranthaceae sp.1 0 0 16 1 4 21 Dendrophtora sp. 0 0 6 20 14 40 Total 23 19 958 467 70 1537

5.4 Height distribution There is an optimum height for epiphyte occurrence, which lies around 1.8 meter from the ground (fig. 17). The Height distribution of all epiphytes in all plots. distribution is 250 somewhat stretched to the 200 right because of some higher trees, 150 and therefor not normal, and the 100 mean is not equal to the optimum: the 50 mean is 2.15 meter Std. Dev = 1,18 Mean = 2,2 (std.dev. = 1.18). 0 N = 1537,00 Frequency The separate 0,0 ,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5 5,0 5,5 6,0 6,5 7,0 species also show Z (ALT), height above the ground in m an optimum, which Figure 17 Histogram of the height distribution of epiphytes, all is logically is less species taken together. clear for the species with lower abundance (appendix III).

38 The average height of epiphytes from the undergrowth was 0.8 meter (std. dev. = 1.3), and the average distance under crowns 1 meter under the crown base (std. dev. = 1.7) and 2.8 meter under the crown-top (std. dev. = 1.6). Epiphytes were not normally distributed in any of these measures, although these distributions approached normality a bit more than that for height from the ground (K-S Z =2 or 3, instead of 5). The distributions of the species separately did usually have a somewhat more normal distribution for the alternative measures than they had for height from the ground, but these are still hardly ever normal. The standard deviation (e.g. the variation) is higher for the alternative measures than for the height from the ground, for all epiphytes together as well as for the separate species (appendixIV).

5 Epiphyte species and families differ

4 significantly in their height distribution (KW, p

3 < 0.001 for both). The Orchidaceae as a family grow lowest in the forest 2 and the Loranthaceae grow at higher positions 1 (appendix III). Two epiphyte species are 0 height above the ground (m) ground the above height rather extreme compared N = 617 102 334 13 42 229 24 93 21 42 R. T. T. R. p Brom. specsOrc Or Or Lor. s Dendrop. spec to the rest; Dendrophtora te co sp c c e h hid spec1hid spec5 tr m ec1 nlan id specs p an p ec1 th acta sp. grows higher and a d ii Orchidaceae sp.1 grows Fi gure 18 Mean height and 95% confidence interval per lower than the average epiphyte species. (fig. 18). Without these species the difference between species’ height distribution is still significant. However, the differences between epiphyte species as detected by the KW-test, do not show up very convincingly in figure 18, except for the two extreme species. All other species have their optimum around 2 meter. Whether height from the ground or the alternative height measures are tested, the distributions of epiphytes-species and -families always differ significantly (always p < 0.01) (appendix V). When comparing Bromeliad-species only, the differences are not significant when looking at the distance from the top of the crown (p>0.05), but for the other measures they are (p < 0.001).

The height distribution of epiphytes does differ considerably between plots. In most plots it is just below 2 meter, but in plot B, C and K the average is higher (around 2.2, 3.2 and 2.7 m respectively), while plot H has an average around 1.2 m (but very few epiphytes:

39 26) (appendix IV). Height above the undergrowth is even more variable, as are distance under bottom and top of the crown (appendix IV). Epiphyte numbers are lower for the latter two measures, because epiphytes that are not underneath any crown are not counted; plot F is not shown, for the same reason.

5.5 Spatial point pattern In some plots the K- and L-functions of the spatial distribution of the epiphytes could not be calculated or interpreted. When epiphyte numbers were low, as was often the case when taking Racinaea tetrantha separately, the simulation envelope is very wide and irregular and the K- and L-graphs are also irregular. So for very low numbers these graphs are not very valuable. The plotted L-functions can be found in appendix VI. Two plots contained more epiphytes than the Ecostat software could handle, so in these plots distributions were not analyzed for all epiphytes together but only for Racinaea tetrantha . Epiphytes have a clustered distribution in all plots and from all angles (in xy-, xz- and yz- plane), though in some cases there is no deviance from ‘complete spatial randomness’ at bigger h. On the xy-projection clustering is strongest at a small scale (small h) and decreases when expanding the distance-circle (h) in most plots, though in some the difference is slight, or based on very low numbers. Only in one plot does the measure of clustering rise at bigger distances. On the contrary, on the xz- and yz-projections clustering increases in nearly all cases with increasing h. The distribution of R. tetrantha is sometimes more and sometimes less strongly clustered than that of all epiphytes together. R. tetrantha juveniles are more clustered than the adults of the same species in those cases where there are enough juveniles to allow for such a comparison, which are only two plots.

5.6 Phorophytes Nine tree species (or high shrubs) were regularly found in the plots. These were, in decreasing abundance: Miconia squamulosa (Melastomataceae), Clethra sp. (Clethraceae), Miconia thaezans (Melastomataceae), Weinmannia pubescens (Cunoniaceae), Escallonia myrtilloides (Saxifragaceae), Miconia pergamentacea (Melastomataceae), Tibouchina grossa (Melastomataceae), Weinmannia sp. (Cunoniaceae), and Hedyosmum sp. (Chloranthaceae). Both Weinmannia species occured mostly as very young trees of ca. 2 m tall. There was also a considerable amount of dead trees, mostly present as stems only. Some rare and/or unidentified species of shrubs (among which Disterigma acuminata (H.B.K.)) Ndzu (Ericaceae), a Ericaceae sp., a Melastomataceae sp. and a shrub with big thorns and small succulent leaves) were found higher than 2 m and registered as phorophytes.

40 The number of trees of different species encountered in the plots did not give the best representation of the amount of substrate (branches) available per species. Especially the contribution of Clethra sp. to the total branch-surface is considerably bigger than the number of trees indicates (fig. 19). The distribution of all epiphytes together over the different tree-species nicely reflects the amount of substrate available on these species. However, the separate epiphyte-species are not distributed evenly over the phorophyte- species (appendix VII).

Tree species found in all plots together Total branch surface per tree species 100 16

14 80 12

10 60

8 40 6

4 20 N=234 2

0 0 relative relative amount of barksurface # of trees of # M. squamulosaClethra spec.M. tha W E. m M Wei T. gro H rest dead tree M. C M. W E M. p W T. gros He re dead . pe e le . . e st . pube dyo sq th thae pu my inm d yrti nma erga yos r s ua ra bes r tre e g sa s sp z til a s m zan s lloi am nn mum mul ans lo men nni a e cens ec c id um s d ent ia os ens es a s es sp . s a ta s ac pec. ce pe pec ea ec c . a . .

Tree species Tree species a. b.

Figure 19 Number of trees (a.) and the amount of branch surface (b.) per tree-species. Trees from all plots added up, branch surface is a relative estimate from the length of branches in different diameter classes .

No Loranthaceae were found growing on Clethra sp., while Racinaea tetrantha and Tillandsia sp.1 occurred more on this species than on all other host-species, with Miconia squamulosa as a good second. The other Bromeliaceae and the Orchidaceae had their second-biggest abundance on Clethra , after M. squamulosa . The different Bromeliad species and the Orchidaceae were found growing on dead trees, but the only Loranthacea on a dead tree was a dead plant. No statistical tests were used to investigate the distribution of epiphyte-species over the host-species. The Χ2 –test that could have performed the analysis would have been far too elaborate to do, and low expected values for rare species would have made the test very poor.

41 5.7 Plots No correlation was found between any of the plot variables and the number of epiphytes per plot (p' > 0.05). (table 3).

Table 3 Correlations between several plot-variables and the amount of epiphytes found in each plot (no significant correlations at the .05/15 or .01/15 level, the Bonferroni-corrected significance levels). Volume of Volume of Spearman's Rho Number of Crown- Basal area crowns undergrowt (N = 11) epiphytes cover (m2) (cm2) (m3) h (m3) Number of Cor. Coef. 1.000 .506 .114 .647* .761** Epiphytes Sig. (2-t) . .113 .739 .031 .007 Crowncover (m2) Cor. Coef. .506 1.000 .427 .327 .636* Sig. (2-t) .113 . .190 .326 .035 Volume of crowns Cor. Coef. .114 .427 1.000 .036 .227 (m3) Sig. (2-t) .739 .190 . .905 .502 Volume of Cor. Coef. .647 .327 .036 1.000 .591 undergrowth (m3) Sig. (2-t) .031 .326 .915 . .056 Basal area (cm2) Cor. Coef. .761 .636 .227 .591 1.000 Sig. (2-t) .007 .035 .502 .056 . Distance to nearest Cor. Coef. -.610 .000 .173 -.391 -.609 remnant (m) Sig. (2-t) .046 1.000 .612 .235 .047

5.8 Growing sites Most epiphytes were found growing on branches of 2 to 5 cm diameter. Juveniles on average occupy smaller branches than adults do. The trend as seen for adult and juvenile Racinaea tetrantha (table 4) holds for all epiphytes. The correlation (Spearman’s rho) between epiphyte size and branch size is significant at p< 0.001.

Table 4 Distribution of epiphytes over branches of different sizes. An occasional epiphyte was encountered growing on a leaf, on Frullania or on Usnia (='other'). branch class: <1 cm 1-2 cm 2-5 cm 5-10 cm >10 cm leaf other N total all epiphytes 7.4% 17.8% 45.0% 24.2% 4.2% 1.1% 0.2% 1512 adult R. tetrantha 1.4% 8.5% 46.0% 36.6% 7.5% 0.0% 0.0% 213 juvenile R. tetrantha 14.5% 27.5% 37.0% 15.8% 1.0% 3.4% 0.8% 386

Most epiphytes (1079) were growing on the side of branches, including the sides of vertical stems. Twice as many were found growing on the bottom-side of branches (275) as on the top (143). For 37 individuals the position was not recorded. These will have

42 been those that had fallen on the ground or that occupied other unusual positions. Epiphytes were distributed evenly over the compass-directions (378 North, 365 East, 315 South, 420 West, 21 60 surrounding a stem and 35 without data). 50 At only 20 sites were epiphytes growing on forks 40 between branches. This is 1.5 % of all epiphyte 30 growing sites. Most epiphytes were growing on 20 Epiphyte family vertical or near-vertical

Bromeliaceae branches. 10 The Orchidaceae were Orchidaceae more often surrounded by 0 Loranthaceae Percent -2 (dry) -1 0 1 2 3 (moist) mosses, and the Loranthaceae more by Indication for humidity at a site as indicated by mosses and lichens drought-resistant lichens, Figure 20 Distribution of epiphytes from different families while the Bromeliaceae took over sites with different bryophyte cover, expressed on a an intermediate position (fig. ‘moisture’-scale derived from these bryophytes. 20)

5.9 Plant appearance The correlation between both humidity and light to height are significant when taking all measurements together (p< 0.001 for both correlations). There was a correlation between the leaf-color of Racinaea tetrantha and height above the ground, light intensity and humidity-indication, plants close to the ground and in more shaded and moist sites being greener (table 5a). This was not clearly the case for Tillandsia compacta . For the latter species the only significant correlations was that between humidity and leaf color (table 5b).

43

Table 5 Spearman's rho correlation coefficients, for Racinaea tetrantha (a) and Tetrantha compacta (b), both for plants > 5 cm. Significance level with Bonferroni correction. Height in m above the ground. Light: light measured at plant/ reference outside, low value = much shading. Humidity: indication based on the presence of mosses and lichens, dry < 0, moist > 0. Color: ranging from green to red, green < 0, red > 0. Shape: angle of outermost leaf to vertical, big angle = wide plant. Size: vertical plant size in cm. Height z light humidity color shape height z Cor. Coef. 1.000 Sig. (2-t) . N 315 light Cor. Coef. 0.501** 1.000 Sig. (2-t) 0.000 . N 119 119 hu midity Cor. Coef. -0.345** -0.231 1.000 Sig. (2-t) 0.000 0.011 . N 315 119 315 color Cor. Coef. 0.388** 0.480** -0.248** 1.000 Sig. (2-t) 0.000 0.000 0.000 . N 272 114 272 272 shape Cor. Coef. -0.140 -0.101 0.135 -0.258** 1.000 Sig. (2-t) 0.015 0.273 0.019 0.000 . N 302 119 302 270 302 size Cor. Coef. 0.112 0.235 -0.016 0.014 0.371** Sig. (2-t) 0.046 0.010 0.782 0.815 0.000 N 315 119 315 272 302 **Correlation is significant at the .01/15 level (2-tailed). a. Racinaea tetrantha Height z light humidity color shape Height z Cor. Coef. 1.000 Sig. (2-t) . N 91 Light Cor. Coef. 0.286 1.000 Sig. (2-t) 0.113 . N 32 32 Humidity Cor. Coef. -0.041 -0.125 1.000 Sig. (2-t) 0.697 0.495 . N 91 32 91 Color Cor. Coef. 0.285 0.387 -0.355* 1.000 Sig. (2-t) 0.011 0.031 0.001 . N 79 31 79 79 Shape Cor. Coef. -0.171 0.228 0.200 -0.064 1.000 Sig. (2-t) 0.106 0.210 0.057 0.572 . N 91 32 91 79 91 Size Cor. Coef. 0.143 0.021 0.222 -0.300 -0.067 Sig. (2-t) 0.175 0.909 0.035 0.007 0.531 N 91 32 91 79 91 * Correlation is significant at the .05/15 level (2-tailed). b. Tillandsia compacta

44 6 Discussion

6.1 Climate Air humidities recorded agree with the recordings of Wolf (1993), who also found very high air humidity at this altitude. Hair extension in the hygrograph Wolf used is maximal at 95% relative humidity, so humidities over 95% could not be recorded. With the electronic dataloggers used in this study humidities up to 100% could be recorded, and were recorded most of the time. The vertical climatic gradient found with these measurements is in accordance with the trends that others have found for forest climates (Freiberg 1997, Parker 1995).

6.2 Epiphyte species and abundance Racinaea tetrantha , R. penlandii and Tillandsia compacta have a rather similar growth form. They all have a tank and few trichomes. Tillandsia sp.1 has a narrower shape and smaller tank and a high cover of trichomes on the entire leaves. This species could be classified as an intermediate between tank- and atmospheric-absorbing trichome type in the classification of Pittendrigh (1948), while the other three are typical tank-absorbing trichome species. R. tetrantha and T. compacta have a C3-photosynthesis and a chlorophyll concentration of 1.3 and 1.4 mg/g dry weight respectively (Martin 1994). No information is available on the physiology of the other species.

The total number of epiphytes encountered in the study area is relatively high for this region. Hanke (1999) encountered 200 bromeliad-ramets bigger than 5 cm (in 125 genets) in a 10x5 m transect that was less than a kilometer away from the plots studied here. Although the eleven plots only have a surface 1.1 times that of Hanke’s transect, 4.5 times as many bromeliads bigger than 5 cm were recorded (907). Hanke worked in a homogenous, relatively tall forest of approximately the same age as the area of this study. In that forest Racinaea tetrantha was the most abundant species, followed by Tillandsia compacta . The two other species found were not identified and also very low in numbers (8 and 1 plants). It is interesting to notice that the second abundant species in this study, Tillandsia sp.1, seems to be totally or mostly absent in the taller forest. This, together with the small tank and high trichome-density of this species, could lead to the supposition that this species needs the circumstances associated with a more open forest structure. Seeing R. tetrantha and T. compacta do grow in the tall forest, these are apparently suited for a different range of circumstances. This would be expected to be reflected also in the distribution of these species within the heterogeneous forest.

Compared to primary upper montane cloud forests, the epiphyte diversity in this secondary forest is rather low. Although monitoring species richness was not the purpose of this research, all angiosperm epiphytes were sampled, and some comparisons can be made. Especially the dicotyledons are under-represented in this

45 forest. Bøgh (1992) found 14 species of dicotyledonous real epiphytes, belonging to 6 families, in an Ecuadorian montane rain forest at 2900 m. In this study, even if all ‘rest’ specimens would be different species and real epiphytes, which is unlikely, the number of dicot species would only be 10 (including the two Loranthaceae), but 6 is probably a generous guess. Serna (1994) found 6 dicot species, excluding Loranthaceae, in 30 trees in a relatively undesturbed rain forest at 3200 m on the Eastern Cordillera, Colombia. Bøgh (1992) found 57 species of monocotyledons in three families (including 6 Bromeliaceae, among which Tillandsia tetrantha and T. complanata , and 48 Orchidaceae), and Serna (1994) recorded 3 Bromeliaceae (including Tillandsia complanata ) and 6 orchid species. Wolf (1993) found 23 species of angiosperm epiphytes in the ‘Upper Montane Rain forest canopy “typicum” community’ alone. The total number of angiosperm species in the upper montane rain forest he studied, a forest no more than a few kilometers from the site of the present study, is probably much higher still. A family that was absent from the study area, although at least one species has been observed growing prolifically in a higher, denser forest close by, was that of the Araceae. The number of Orchidaceae species can not be determined, but at least 5 different flowering species were present in the area, which were not either Orchidaceae sp.1 or sp.5, and the number of species is probably greater than 7 when including other vegetative species. Both the number of species in the Bromeliacea and inthe Orchidaceae are intermediate scores compared to other forests at the same height (Sugden & Robins 1979, Bøgh 1992, Serna 1994).

6.3 Population structure The bromeliad species show great differences in their abundance and population structure (fig.15 and table 2). Oostermeyer et al . (1994) describes a population structure with high proportions of seedlings and juveniles and few generative adults as being typical for populations in an invasive stage. This could be applicable to Racinaea tetrantha , which has a high proportion of juveniles, including very small ones (1-2 cm). R. tetrantha is the only Bromeliad with a considerable proportion of plants that have flowered, which is easily related to the high abundance of small juveniles. However, Tillandsia sp.1 was never encountered with flowers, so the abundance of juveniles in this population can not be explained this way. Seeing the species has characteristics of atmospheric bromeliads, it is not unlikely that, like most atmospherics, it grows very slowly (Benzing 1981c). This would mean that the small juveniles may not very young and their flowering parents may already have died. Another explanation could be, that a propagating population has not yet been established and seeds still arrive only from surrounding vegetation or remnant trees in the area.

The absence of flowering Tetrantha sp.1 and the absence of small juveniles of T. compacta (the one specimen < 2 cm found may well have been a misclassification), could also lead to the hypothesis that these are in fact one species. Many tank-

46 absorbing trichome bromeliads are ‘heterophyllous’, having atmospheric juveniles and broad-leaved tanks as adults (De Granville 1978, Adams & Martin 1986a + b, Smith 1989). However, in this case the species did have overlap in size and no transition phases were found, making the hypothesis very unlikely. However, a few, maybe 10, juvenile bromeliads were found that did not look like small versions of any of the bromeliad-species found as adults, but that looked very similar to the juveniles of the notably heterophyllous species Tillandsia deppeana (Adams & Martin 1986a + b). The adults of T. deppeana are broad-leaved tank epiphytes, looking similar to the tank bromeliads found in this study. It can therefor not be ruled out that Tillandsia compacta does indeed have atmospheric juveniles, and that 10 small juveniles of this species were found. However, there is no evidence for this, and 10 is still a very low number. It would be interesting to have another look in the area in different seasons or years, to see if there will be a season of flowering and/or germination for Tillandsia sp.1 and T. compacta .

The high proportion of juveniles gives a relatively high estimation of the population size of Racinaea tetrantha and Tillandsia sp.1, because many of the juveniles will probably not survive to adulthood. However, even without counting the juveniles (table 2), R. tetrantha is by far the most abundant species. Tillandsia sp.1 and T. compacta are then equally abundant. The species Racinaea penlandii was very rare compared to the other species. Seeing that vegetatively it is very similar to R. tetrantha , some individuals may have been overlooked, but it is definitely much rarer than the other three species. Maybe it has only recently arrived in the area, which would explain it's low abundance.

Most apparently suitable sites are as yet unoccupied by vascular epiphytes, which indicates that competition for space is not a limiting factor for the settlement of vascular epiphytes in this forest. Competition with bryophytes is unlikely. Bennett (1987) found a higher abundance of bromeliad seeds and seedlings on epiphytic bryophytes than on exposed bark. Bigger bromeliads are often associated with bryophytes, although this is more likely a reaction of the bryophytes to the bromeliad than the other way round. Orchid roots are also often found growing underneath bryophytes, in the organic matter that accumulates there. However, some interference may occur between cryptogams and young vascular epiphytes, which is demonstrated by the observation of a small Tillandsia sp.1 (ca. 3 cm long) that had been overgrown to half of its length by a foliose lichen (also an indication that growth is rather slow in this species). Other factors determining population size and 'community'-structure will be discussed in the next chapter (6.4).

The three different epiphyte families all have quite a distinct biology, especially for their nutrient acquisition and seed dispersal (see chapter 1). This could have an influence on

47 their habitat-preferences and spatial distribution. Some small differences could indeed be detected, as seen below.

6.4 Height distribution

Height of the epiphytes The epiphytes occur at all heights, but with a clear optimum around 1.8 meter from the ground. The height at which the peak of epiphyte occurrence occurs, is within the height- layer of 1 to 2 meter, with a relatively high volume of crowns or undergrowth (mainly undergrowth at this height) (fig 21). It would seem logical to conclude that this undergrowth must be an important substrate for the epiphytes. However, by far the most epiphytes are situated above the undergrowth (appendices IV and V). The undergrowth in the layer will mainly be situated at the bottom of it, and it generally stays beneath 1.5 meter. The tree-crowns generally start higher up (fig. 20). This means that the amount of available substrate around 2 meter is actually rather low, but it consists mainly of tree trunks rather than small branches. As this substrate is generally older and more constant than undergrowth shrubs or crown branches, the amount of suitable substrate may actually not be much lower, and possibly higher, at this than at other heights.

Figure 21 Distribution of undergrowth- and crown volume over different heights per plot.

Inside the crowns and in the undergrowth shading may limit epiphyte growth. Between the crowns and the undergrowth shading is limited, as the open character of the vegetation allows for light to easily enter underneath crowns from the sides. This may be

48 an important explanation for the abundance of epiphytes at this height. A different factor that may influence the distribution is the supply of propagules. The chance of a wind- dispersed seed being intercepted by the crowns and undergrowth is probably higher than the chance of it landing on a tree trunk, but the first substrate a seed meets in a crown or shrub is likely to be a leaf or small branch, which can at most allow for germination, but not for growth to maturity. The relatively open space between 2 and 3 m may also allow for more air movement carrying wind-dispersed seeds. The recordings of the climate do not indicate any special characteristic around 2 meter; it is an intermediate position. If climatic measurements had been taken at more different heights, e.g. every meter, this might have shown some special feature around 2 meter that can now not be distinguished.

Height differences between the three families are significant, though not very big. Especially when looking at the shape of the distributions (appendix III), the difference does not seem very important. Still, as the order of Orchidaceae growing lower than Bromeliaceae is a result shared by other studies of upper montane cloud forests (e.g. Bøgh 1992, Serna 1994), it may reflect a general trend. The lower positions for orchids could be explained, by their preference for mossy patches (fig.19), which provide their roots with a moist and rich environment, and which occur most at lower heights. The reverse is true for the Loranthaceae, which tend to grow on clean branches and need a young surface to establish themselves, because the haustorium cannot enter old bark (Goebel 1889). Another possible factor is the difference in seed dispersal between the families. The distribution of the Loranthaceae is naturally influenced by the behavior of the birds that disperse them (Godschalk 1983). The plot where most Loranthaceae were found (plot C) was among the densest and highest plots. High trees may be the preferred habitat for birds, which may put the Loranthaceae at relatively high positions compared to the wind dispersed species. Also the birds can not perch on the vertical trunk, restricting the seed-attachment to relatively small branches, which are most abundant in the undergrowth and the canopy. Of these two habitats the canopy may be preferred by the birds, for safety, and may also be more suitable for the mistletoes, for higher light-intensities and lifespan of the branches.

Ecological equivalence and coexistence Differences between species, especially the different bromeliads, may be statistically significant, but most differences are too small to be ecologically significant. Differences in morphology, like the atmospheric characteristics of Tillandsia sp.1 versus the tank- habitus of the other abundant species, Racinaea tetrantha and Tillandsia compacta, could reflect adaptations to a different environment. This could be expected to result in a different height distribution, but this was not found in this case. However, if the spatial distribution is most strongly influenced by seed-dispersal, this result is no longer

49 surprising. As the bromeliad species have very similar plumed seeds they would be expected to be dispersed similarly. In other studies different Bromeliaceae are usually found to grow at different heights (Pittendrigh 1948, Bennett 1987, Fischer & Araujo 1995). These studies, however, have considered a wider range of bromeliad types and a longer climatological gradient in the forest. In the forest area studied here the circumstances may not be diverse or extreme enough to cause a differentiation of heights in these bromeliads.

A different explanation could be that the species are in fact ecologically interchangable, a conclusion that has been drawn for some other groups of epiphytes (Yeaton & Gladstone 1982, Benzing 1981b). Co-existence is usually considered possible only if some sort of resource partitioning takes place (De Kroon 1998), which is typically not the case if species are each others’ ecological equivalents. However, alternative models of species diversity can describe a situation of cohabitation that is not governed by direct interactions between plants. Benzing (1981b) compared the distribution of epiphytes in a dry open forest to that of sessile organisms on coral reefs and rocky shores. Here patches that become available for settlement are colonized by the first propagule to arrive, regardless of its competitive capacity. This chance-mechanism is said to maintain species-diversity in these systems. The patchiness and variability of the substrate available to epiphytes and the lottery- aspect of seed arrival at a given site, does indeed to justify such a comparison. Indeed a similar mechanism has been proposed for cryptogamic epiphytic vegetations, where the success of a species at a site is determined chiefly by the chance and the time of the arrival of propagules (Barkman 1958, Wolf 1993). Only if the suitability of a site changes is the timing to arrive at that site of importance for the chance of successful establishment. In the situations described above the suitability is decreased by the settlement of competitors. However, for vascular epiphytes the situation is a bit different, because competition between species is not an important mechanism (De Granville 1978). Suitability of a site can still change, e.g. by changing bark characteristics or light climate, but it is less likely. This means that the spatial aspect of propagule supply is more important than the timing. Since the substrate can never be saturated with seeds from one population, there are always suitable sites left for other species to settle, as long as new sites become available frequently enough (Benzing 1981b, Bennett 1986), or, as in this forest, as long as many suitable sites have not yet been occupied. The population sizes of cohabiting species may then simply be a function of the amount of seeds that have been produced and dispersed in the area (Yeaton & Gladstone 1982). The differences in abundance of the bromeliad species can than be explained quite easily, the different population structures indicating a difference in life-strategies, causing a different seed production, causing a different abundance.

50 Defining the vertical position Height above the ground is nearly always found to be an important factor for epiphyte occurrence (e.g. Pittendrigh 1948, Wolf 1993, Hietz 1995), but the circumstances that determine the occurrence of epiphytes high in the crown may also prevail elsewhere in the forest. High light intensities at forest edges, e.g. at ridges, clearings or streams, can allow the canopy epiphytes down to ground level, given the right substrate is found there (De Granville 1978). The zonations (Johansson 1974) that are so widely used also indicate that the distribution of epiphytes should be more related to the surrounding vegetation structure than to height from the ground (fig. 4). However, the fact that height from the ground is more constant between plots than the distances of epiphytes to the crown and the undergrowth (appendix IV), is an indication that in this case height is probably the best measure for describing vertical epiphyte positions. If a zonation-type measure had been more adequate, the distance from the top and/or the bottom of the crown should have been more constant, looking at the variation in a species’ distribution as well as at differences between plots, than the height from the ground. Due to the simplicity of the GIS model used, the alternative measures were only vertical distances, which do not fully consider the structure of the vegetation surrounding the epiphyte. However, even these simple measures do give an additional dimension to the information on epiphyte position. Their variability indicates that they are more dependent on plot-structure than height from the ground is, which means that although the ‘host- vegetation’ differs considerably in height between plots, the epiphytes stay more or less at the same height from the ground.

It must be noted here that the situation might be different for communities of cryptogamic epiphytes. The predominance of lichens, Usnia spp. in particular, and the absence of green mosses on small branches, usually situated in the periphery of crowns, was apparent in the field, though no numerical data is available to verify this impression. A rough idea of the height distribution of different cryptogam-groups can be gotten from appendix VIII.

6.5 Spatial pattern

Clustering of the epiphytes The fact that epiphytes had a clustered distribution does not come as a surprise. The different clustering at different scales indicates, however, that the clustering of the substrate occurs at several levels. On the xy-projection the epiphytes are clustered most strongly at small distances. This can be explained by the occurrence of many individuals straight above each other on vertical tree trunks and close to each other within a tree crown. Especially the positioning of epiphytes at the same xy-coordinates gives a strong clustering. At bigger distances, maximum 2.5 meter in these plots, the denseness of

51 these clusters is no longer recognized, and the K(h)-function reflects the distributions of the clusters. Apparently these are distributed more (but still not totally) randomly, reflecting the distribution of trees and crowns in the plots. Looking at the plots from the side, the level of clustering increases at bigger scales (appendix VI). This may reflect the height distribution of the epiphytes, which has been shown to be 'clustered' around a height of ca. two meter from the ground.

Apart from the statistical tests, which are of limited applicability in this situation, some qualitative remarks can be made about the clustering of species. The Loranthaceae very often occurred close together, with many plants on a single tree and none in others, and, on a bigger scale, in one plot much more than in others. Behavior of the birds that disperse the seeds may be an important factor in this clustering (Godschalk 1983). They may wipe several seeds on a branch at once, sowing a little cluster. Also, if they tend to return to, or stay in, the same trees to feed or roost, those trees will receive more regurgitated or defecated seeds, more mistletoes can grow on it, and it will be even more popular with the birds. In the Bromeliaceae a clustering was also observed in some cases. In the first plot a big ‘cloud’ of Racinaea tetrantha juveniles was found within a radius of 2 m from a big adult of the same species (fig. 7), mostly below it. This adult clone had 27 ramets (the biggest clone found in any plot), some of which had just fruited and were dying, and some of which were already dead but still had the old inflorescence with pods attached to it. Seeing no information is available on the germination- and growth rate, it is impossible to say whether the juveniles that were found, most between 1 and 3 cm in length, were dispersed in the last fruiting period or the one before, but in either case it was obvious who the parent was. A similar pattern was found by Benzing (1981c) for 1-year old seedlings of Tillandsia circinnata in open conifer-crowns. These seedlings, when numerous, were mostly clustered around an adult which had fruited the previous season. However, seedlings were also found in trees where no flowering had taken place the previous year, which is an observation shared by the present study. Yeaton & Gladstone (1982) also found that orchid species were most often their own nearest neighbor, a clustering that he suggested could be explained by local seed dispersal and/or the benefit of possibly taxonomically specific micorrhiza around the roots of adult plants to seedlings of the same species.

Describing spatial patterns The plots in this study were too small to study spatial patterns independent of the shape and position of trees. A plot-size of e.g. 50 X 50 meters would reveal more information on possible clustering of species. For such a study a homogenous forest would be more suitable. At this scale it is not necessary to register the exact positions of every epiphyte. Numbers of individuals in a 2D lattice-model would be sufficient. Such an approach is currently being elaborated by Van Dunné in the close-by homogenous forest mentioned

52 before. Madison (1979) has also sampled epiphyte distribution on such a scale, recording the presence of epiphyte species on rubber trees in a 1 ha. plot in a homogenous plantation. He used a Χ2-test on groups of 5 trees in a row to study clustering of species. A geo-statistical analysis of the data would probably reveal more information on the actual spatial distribution, and would be an interesting exercise. When studying epiphyte clustering at a smaller scale, within one or a few trees, the distribution of the substrate becomes an important factor, one that is difficult to describe or quantify. A GIS may prove a useful tool if attempts to do so are to be undertaken (see chapter 6.10). An alternative method for analyzing spatial patterns of epiphytes, on a very detailed scale, was described by Hazen (1966), who considered the spatial distribution as distances along a branch. He transforms the branch to a straight line by inserting the length of side branches at the points where they branch of, and then analyses the randomness of epiphyte distribution by their position on this line. However, his assumption ‘that interaction occurs along a branch, not between neighboring branches…’ does not seem to justify this one dimensional approach. Vester & Gardette (1996) proposed ‘three dimensional mapping’, mapping ‘large individuals … individually and patches of small individuals or colonies … by indicating form, extension and position of the patch.’ Unfortunately this method is not described to any detail, leaving unclear whether a truly three dimensional method for mapping has been developed, or whether two dimensional maps of the tree-shape, as have been used by Dickinson (1993), are meant, and in what way these maps are to be analyzed. Drawing epiphytes in trees and forests by side views is a method used by some early researchers (Pittendrigh 1948, Veloso & Klein 1957, in Smith & Downs 1974), and can provide a fair bit of insight in epiphyte-patterns. However, a good sideview is difficult to obtain in many forests and the method is two dimensional, with all the restrictions of such a reduction, and rather qualitative. For the moment it seems safe to conclude that a good method for analyzing spatial distributions of epiphytes has not yet been developed, and the challenge remains to find a solution to this problem.

6.6 Phorophytes Loranthaceae, being hemi-parasites, have a very close connection with their hosts. This could explain the fact that the distribution of this group over the different tree species differs from that of the Bromeliaceae and Orchidaceae. The absence of Loranthaceae on Clethra sp. may be caused by some incompatibility-mechanism. Several such mechanisms have been described (see chapter 1.6), but it will require additional research to determine what ecological or physiological mechanisms cause the absence of mistletoes on this Clethra - species. Absence of live Loranthaceae on dead trees can easily be explained by the lack of sap stream in dead trees, which leaves the mistletoes without the necessary supply of water and nutrients.

53 The other epiphyte-families do not seem to have a specific preference for host-species, nor do the different species. Adults and juveniles of a species could theoretically have different distributions, due to ages of trees or possible incompatibility between epiphyte and phorophyte having its effects only after some time has passed. Adults and juveniles of Racinaea tetrantha do show a different distribution over the host-species. However, the majority (89) of the R. tetrantha juveniles on Clethra were found in only one tree, which strongly affects this result. It does not seem likely that adults and juveniles have a significantly different distribution over phorophyte species in this case. Host specificity, the restriction of an epiphyte species to one or more host-species, has been reported by some authors (e.g. Went 1940), but has been rejected by others (e.g. Johansson 1974), and apparently no mechanisms have been demonstrated (Benzing 1995). Variation in the suitability of trees as hosts for epiphytes, including non-vascular epiphytes, is usually attributed to bark characteristics like roughness (Goebel 1889, Catling & Lefkovitch 1989, Kernan & Fowler 1995) and chemical composition with regard to nutrient supply (Gustafsson & Eriksson 1995, Gauslaa et al. 1998) or inhibitory substances (Frei & Dodson 1972), and sometimes tree age or tree growth rate (Went 1940, Wolf 1993, 1994) and tree-architecture (Migenis & Ackerman 1993). The main tree-species in this study all had rather similar bark characteristics, with medium rough trunk-surfaces and smoother branches. The only species with peeling bark, which has a negative impact on epiphyte establishment (Johansson 1974), were Tibouchina grossa and Escallonia myrtillioides . These were shrubs and hardly ever high enough to be recorded as trees, so they would not be expected to harbor many epiphytes. However, other shrub-species contained quite a few epiphytes, especially bromeliad juveniles, while these shrubs contained no and very little epiphytes respectively. This could be attributed to the character of their bark, but also to their limited age ( Tibouchina grossa is typical pioneer-shrub, so will have a high growth rate, Escallonia propagates quickly by sending out underground runners from which new shoots rise). A bigger Escallonia tree (DBH ca. 10 cm) outside the plots did contain considerable numbers of epiphytes, mainly orchids. In contrast to the tendency on other trees, most epiphytes on this tree were situated in the forks of branches. Those trying to establish on the trunk had apparently had problems with the peeling bark.

6.7 Plots Although no significant correlations were found, there does seem to be a positive relation between the basal area and the number of epiphytes in a plot (p < 0.001 before Bonferroni correction). This conclusion is justified by the total logic of the relation, more basal area meaning more substrate for the epiphytes. The weakness of the relation however, and the lack of correlation of epiphyte numbers with crown-cover or -volume, even before Bonferroni, may reflect an equilibrium between positive and negative properties of dense crown-cover for epiphytes: extra availability of substrate vs. extra shading.

54 Distance to remnants on this scale, where the greatest distance between a plot and a remnant tree was 68 m, is probably of little importance for supply of propagules, because of the effective seed dispersal. All species found in this study belonged to families whose seeds can travel through the air, either in the guts of birds (Loranthaceae) or being carried by the wind, thanks to minute size (Orchidaceae) or plumed appendages (Bromeliaceae). Seeds of Guzmania monostachia and Tillandsia fasciculata (both species in the subfamily Tillandsioideae) remained air-borne for 15 and 12 seconds respectively when dropped from a height of 2 m, compared to 3 seconds for dandelion seeds ( Taraxacum officinalis ) (Smith & Downs 1974). From 10 m higher up the flight time could than be up to 90 seconds, which would allow for dispersal over considerable distances when there is any wind. It is also likely that frugivorous birds can disperse the seeds of the Loranthaceae over considerable distances (Hawksworth 1983). This implies that the tall remnants growing inside the studied forest are not necessarily the only source of epiphyte seeds for this area, but that seeds may also arrive from the surrounding forests. This idea is supported by the results of Denslow & Gomez (1990), who found that only a small fraction of the seed rain in forest gaps could be attributed to adult trees within 50 m, and Martinez-Ramez & Soto-Castro (1993, in Loiselle et al .), who found that only ca. 50 % of the seed rain in a Mexican wet forest came from within their 25 x25-m plots.

6.8 Growing sites Seedlings and small juveniles of Racinaea tetrantha were found growing on leaves of Clethra sp., on small dead branches and even on ‘branches’ of the fruticose lichen Usnia sp. and the livermoss Frullania sp. These are obviously not very persistent growing sites, so these individuals will never grow to maturity. Seedlings and small juveniles of the same species and Tillandsia sp.1 were also encountered on young W. pubescens -trees. The substrate in these cases was a shorthaired green skin rather than corky tree bark. These examples indicate that germination can occur on many different substrates. Unfortunately, since young Weinmannia-shoots don’t remain the way they are either, the fate of epiphytes on such substrates can not be studied independently of the unstable character of their substrate. In this study no preference for compass orientation was found. Bennett (1987) did find an aspect preference for a bromeliad species in Florida, but not for others. If this finding reflects any ecological differentiation, based on a light or moisture difference, this is expected to be stronger in Florida than in Colombia, on account of the latitude. Also it would be expected to be more pronounced in trees with a bigger diameter. Branch inclination does not seem to limit epiphyte settlement in this forest. The high proportion of epiphytes growing on vertical branches probably reflects the high proportion on tree trunks. This can also be seen in the height-distribution of the epiphytes.

55 There are no indications that 'canopy soil', humus accumulation on branches, has an influence on the epiphytes in this study. Very few epiphytes were found growing on forks of branches, a result shared by the study of bromeliads by Hanke (1999). Freiberg (1996) finds the biggest diversity of vascular epiphytes in a tropical lowland rain forest tree on the topside of branches, and attributes this to the humus layer present there. Rudolph et al. (1998) defined the surface available for settlement by vascular epiphytes in a tropical lowland rain forest as the upper half of the branches, and ignored ‘the few’ epiphytes growing on the underside. In the present study, however, the top was the least frequented side of the branches, while the sides were frequented most. This may be explained quite simply by the characteristics of the trees, which are relatively small and young and with little humus accumulation on the branches. The ‘preference’ for the sides also reflects the preference for vertical stems, which only have sides. However, Bøgh (1992), studying epiphytes in an undisturbed montane rain forest at 2,900 m in Ecuador, also found relatively little epiphytes growing in humus deposits. A possible explanation for the difference in humus dependence of epiphytes between tropical montane rain forests and lowland rain forests, may be the different importance of the water storing characteristics of humus and its role in maintaining a moist microclimate (Freiberg 1997). These properties are probably more important in hot lowland forests, where recurrent drought is a common canopy-feature, than in the much cooler and wetter montane forests (Bøgh 1992). The character of the epiphytes could also be another explanation for the lack of preference for humous sites. Most epiphytes were hemi-parasites (Loranthaceae) or tank and/or atmospheric epiphytes (Bromeliaceae). These are not dependent on humus for water or nutrients, so they do not need to follow patterns of humus accumulation, even if there is any. The only species that may be humus-dependent, are some Orchidaceae. A species that is certainly a humus-epiphyte is Orchidaceae sp.1, which was found on stem-bases only. The most abundant orchid, Orchidaceae sp.5, did have roots partly growing underneath mats of mosses, where a thin humus layer may have developed, but roots also grew on exposed bare bark, and orchid roots can take up water and nutrients directly from rain and mist (see chapter 1.5). The many species of rarer orchids varied in their apparent humus- preference.

6.9 Plant appearance Close to the ground the environment is darker and more moist, and bromeliads that grow here are greener than those growing at more exposed sites higher up in the plot. For Tillandsia compacta this correlation is not very strong. This may be due to the lower number of plants tested, but it could also reflect a lower plasticity in this species compared to Racinaea tetrantha .

56 Even within big clusters (clones) a color-gradient can sometimes be observed, the plants growing towards the top of the cluster having more red coloration (fig.22). This is most probably caused by the amount of light reaching the plant, as cyanic pigmentation under high radiation has been reported for many bromeliad species (Benzing & Friedman 1981a). The color of Tetrantha sp.1 was not recorded after doing so in the first two plots, because there was very little variation in their greenish tint. The high trichome coverage of this species may make protection against radiation by pigmentation unnecessary. Green plants also tend to be wider. This is a shape that could be expected to be common in plants growing low in the plots, because it helps to increase the leaf-area exposed to light. However, no Figure 22 Big bromeliad cluster showing a color gradient from green to red leaves going upwards in significant correlation was found the cluster. between the leaf angle and the amount of light, the humidity or the height from the ground, even though all these are correlated to color. Apparently the correlation between plant color and shape is based on a different variation than that between color and the other factors. The plant shape is also correlated to the size of the plant. The size does not explain the relation shape-color, however.

6.10 GIS There are several reasons why the GIS-database has been useful for analyzing this data, and why it can be useful to handle similar information. The possibilities for correcting positions for the ground level was of limited or no importance in most plots, because they were selected on level ground. However, there was one plot with a gully running through it, and some different levels in the rest of the plot. In this case the mutual positions of the epiphytes would have been strongly distorted if distance from the ground had been taken as the height-position of all epiphytes. In general this applies for any strongly irregular terrain, like steep slopes.

57 The most important reason to use a GIS however, is the possibility to analyze data topologically, e.g. linking the position of epiphytes to the vegetation structure (crowns and undergrowth). As yet the possibilities for exploiting the 3-dimensionality of the information are rather limited, but three-dimensional GIS-systems will probably become available in the future (Raper & Kelk 1991, Hack & Sides 1994, Breunig 1999). Apart from the simple vertical distances as calculated within this research, it may than be possible for example, to deduct the amount of shading at a given position by counting the crown-surfaces within a cone or hemisphere above it. In many epiphyte studies the trees are sampled per zone (Johansson 1974), which may obscure alternative patterns of epiphyte occurrence. Dickinson et al . (1993), who mapped all epiphyte communities on an emergent tree (drawing the tree with the communities on it), could confirm the zonations in epiphyte communities only for the outer canopy, while the inner canopy showed complex patterns. Registering epiphyte- positions independently of any presumed zones or categories, purely spatially, may be a method to overcome the limitations of zonation-systems, especially with the development of methods to link various ecological parameters to the sites in GIS. By storing the exact position of the epiphytes and the phorophytes, the position of epiphytes in any of the zones-systems as used by Johansson (1974) and many others, can still be deduced from the data, even if it was not registered in the field. In this way comparisons can easier be made with data of previous studies. To be able to do this with more detail, some additional parameters will have to be measured in the field, to create a more realistic model of tree-architecture than a wide cylinder (crown) on a narrow cylinder (stem). Such a model could also be very useful for estimating substrate (branch surface) quantities. Co-operation with tree-architecture specialists would be advisable. Another application for GIS in canopy research could be 3D-network analysis, e.g. to calculate the efficiency of ant-routes between their nest and different food-sources, or dispersal of bromeliad tank inhabitants. The positions of nests, food or bromeliads could be combined with the pattern and characteristics of branches connecting the sites. The animal characteristics could be an additional aspect of such a database: flying or jumping animals would have quite different routes than those confined to walking, and the branches will look quite different to big or small animals and to predators and preys, to name a few examples. The possibility for integration of such different kinds of spatial and thematic data makes GIS especially suitable for some ecological applications, also in three dimensions. A third advantage of having the data in a GIS, are the graphic possibilities for representing the data, as maps. Appendix II shows some possibilities readily available. It is as yet not possible to represent stacks of points or floating cylinders ('tree crowns') in a 3D picture within GIS software. Three-dimensional drawing programs, usually used for designing purposes, can make such representations, but lack a ready possibility for entering the data as co-ordinates in a table or from a GIS coverage or grid, as would be necessary in this case. Integration of 3D graphics software and GIS sytems are being

58 worked on, however, so these problems will be probably be solvable in the future (Hoinkes & Lange 1995, Verbree et al . 1999).

7 Conclusion The development of methods for describing (spatial) epiphyte distribution remains a challenge. The possibilities of GIS as a tool in such methods need more investigation, and will increase strongly when 3-dimensional GIS will become available. Some patterns in the distribution of epiphytes have been detected in this explorative study. However, to get insight into the mechanisms underlying these patterns, a more detailed, preferably experimental research would be necessary. The different population structures of the bromeliad species form another subject calling for a closer investigation. Different life-strategies could be at the base of this, and these could be important in influencing the rate and patterns of dispersal of different epiphyte- species.

59 References

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66 Went F.W. 1940. Soziologie der Epifyten eines tropischen Urwaldes. Ann. Jard. Bot. Buitenz., 50 : 1-98. Whitacre D.F. 1981. Additional techniques and safety hints for climbing tall trees, and some equipment and information sources. Biotropica 13 (4): 286-291. Williams-Linera G., V. Sosa & T. Platas 1995. The fate of epiphytic orchids after fragmentation of a Mexican cloud forest. Selbyana 16 (1): 36-40. Wolf J.H.D. 1993. Ecology of epiphytes and epiphyte communities in montane rainforests, Colombia. PhD dissertation, University of Amsterdam. Wolf J.D.H. 1994. Factors controlling the distribution of vascular and non-vascular epiphytes in the Northern Andes. Vegetatio 112 : 15-28. Yeaton R.I. & D.E. Gladstone 1982. Thepattern ofcolonization of epiphytes on calabash trees ( Cresentia alata HBK.) in Guanacaste province, CostaRica. Biotropica 14 (2): 137- 140. Young L.Y. & J.H. Young 1998. Statistical Ecology. Kluwer Academic Publishers, Boston-Dordrecht-London.

67 Appendix I : Evaluation of some methods

Field methods Apart from the methods described in this report, many others have been considered or tried out, but have been considered unsuitable or unnecessary. Such 'failures' are however an integrated part of any research, and can be very interesting for others doing similar work, encountering similar problems. Also they may answer some 'but why didn't they…?' questions.

One idea was to catch mist at different heights, to see if there were differences in amount and nutrient-contents (which could be important to the more atmospheric Bromeliads). Some ‘fog catchers' were constructed, using plastic mosquito mesh. This material was shaped into cylinders and cones attached to funnels. A roof-structure kept out the rain, catching only the ‘horizontal precipitation’. Unfortunately these fog catchers didn’t work (no water was collected at all), though similar constructions have been used successfully in other studies (Cavalier & Goldstein 1989, Cavalier et al . 1996). In these studies the volume of fog intercepted by the mesh was calculated by subtracting the amount of rain caught in rain gauges from the amount of rain and fog in the fog catchers. These fog catchers did not have roofs, like the ones tried out in this study did. This might somehow explain the difference, because mist was certainly a frequent phenomena in the area. Another idea was to collect water from Bromeliad-tanks (to measure pH and nutrient content). This could be done, but only very large plants contained enough water for analysis, so no systematic sampling was possible. Also the water contained by one plant was very different in leaf-axis of different ages (the older leaves containing much more organic material), which might cause a higher variation within the plant than between plants. Therefor the sampling of tank-water was only carried out to get an indication on tankwater characteristics in general. To get an indication of the light-circumstances in the different plots, fish-eye photography was going to be used. Unfortunately something was wrong with the camera, and after it was sent away to be repaired it never came back. Some ideas could be, and were carried out in the field, but turned out to have been a lot of work for little result. This applies to the description of the Bromeliads, which was done more elaborately than necessary. This is mainly due to the novelty of the species; afterwards it was easy to think of better measures. Also it was due to the original plan to measure more direct environmental variables at the plant itself, to relate those to the plant's morphology (including plant shape, color, and also leaf-thickness and trichome- cover). For example: The color of Bromeliads was at first described with the help of color-charts. After the experience of 2 plots, seeing less variation in the shades than had been expected, it was decided to revert to a distinction between red and green, and the pattern. This was taken for the middle and tip of the leaf separately, which wouldn't have

68 been necessary either, because they were later merged again to get one color-index- number per plant. At first the color of all Bromeliads was described, later only that of Racinaea tetrantha and Tillandsia compacta adults within reach of the photometer. Also the undergrowth was divided into two layers where these were obviously present. Two DEM’s were made from these layers, which caused problems with intersecting layers where one of the layers was not present. The DEM of the top layer was made so that it was never lower than the bottom layer. In the end the DEM of the top layer was the only one used for the analysis, and it would have been a lot easier to describe this layer only. If the thickness (vertical size)of the layers had also been recorded, the constructions of the DEM’s would have been even more complicated, but more extra information would have been deduced from the division of the 2 layers. However, as very few epiphytes occurred far under the top of second layer of the undergrowth, this extra infomation would not have added much ecological information about the epiphytes.

Analysis The analysis of the data turned out to be rather complicated, because of the unusual dataset. Several statistical techniques were tried out, but many did not produce any interesting results, and others were simply not possible. An hierarchical clustering of 1-m height layers on their species composition was carried out and the resulting clusters (taking only 4) were compared for several environmental factors, among which climatic variables. A significant difference between clusters was found, but the difference did not correspond with the order of division in the clustering dendrogram. Although ordinations have been used succesfully for vegetation data of cryptogamic epiphytes (Kenkel & Bradfield 1986, Oksanen 1988, Wolf 1993), analysis of the ‘height- zone-plots’ mentioned before, using several ordination methods ((D)CA, CCA, PCA), did not yield very exiting results (most variation was explained by the ‘variables’ ‘plot A’ and ‘plot C’). An explanation of this may be that ‘species composition’ is not exactly what was studied in this research, and that variation in the species data was probably too small to be suitable for correspondence analysis. The epiphytic ‘vegetation’ has a much higher surface-cover of mosses and lichens than of vascular epiphytes in most places. Taking only the vascular plants, even only the angiosperms, does not give a representation of a community, but of individual populations, which apparently have little interaction with each other. Another promising option was to cluster the epiphytes spatially and investigate the species-composition of the clusters, to detect clustering of species. The epiphytes could indeed be clustered, using the three co-ordinates as the input for a hierarchical cluster analysis (using euclidean distance as the distance measure, best results with nearest neighbor for the cluster method). However, investigating the resulting clusters turned out to be more difficult than expected. The most suitable method would be a Χ2 –test, but this would require a calculation of all expected values for the species in the clusters,

69 which would be very impractical. Besides that, a lot of the clusters would turn out very small (groups of 1, 2 or 3 outlying epiphytes), which would make it necessary to group them to be able to use them in a Χ2 –test, which would disturb the whole idea of the analysis. Not all data collected in the field have yet been used in the analysis, nor have all possible analysis been carried out or has all information been extracted from the data. However, a fair amount has been, sufficient to distinguish some patterns and attempt some answers. Most explanations of results remain rather speculative, adding an extra portion to the speculations of other epiphyte-researchers, which is as far as we might ever get at truly understanding any ecosystem.

70 Appendix II-1: Maps of the plots: some graphics

DEM of the undergrowth of plot A. The way the shrub layer was sampled, in a regular grid, and the type of interpolation between the measured points, were not ideal for the construction of a realistic model of the undergrowth. This influences the value of figure 21, showing the distribution of undergrowth-volume. Sampling and interpolation methods need adjustment to serve specifically for describing a vegetation surface.

A sketch of a 3D model, as could be made using CAD Using Virtual Reality graphics may be an interesting techniques. Making such a picture representing the data possibility in the future (e.g. Verbree et al . 1999). could be done by linking GIS and CAD systems, and in the future by using 3D GIS. Better crown shell models would be desirable, and some existing models may be of use (e.g. Horn 1971, Koop 1989). Another option (depending on the studied scale) could be the use of detailed models of tree architecture (e.g. Bouchon et al. 1997). 71 Appendix II-2: Plot A

72 Appendix II-3: Plot B

73 Appendix II-4: Plot C

74 Appendix II-5: Plot D

75 Appendix II-6: Plot E

76 Appendix II-7: Plot F

77 Appendix II-8: Plot G

78 Appendix II-9: Plot H

79 Appendix II-10: Plot I

80 Appendix II-11: Plot J

81 Appendix II-12: Plot k

82 Appendix III-1: Height distribution of all epiphytes.

Height from the ground Distance from undergrowth 300 300

200 200

100 100

Std. Dev = 1.18 Std. Dev = 1.40 Mean = 2.2 Mean = .8 0 N = 1539.00 0 N = 1539.00 0.0 .5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 -2.5-2.0-1.5-1.0-.50.0.5 1.01.52.02.53.03.54.04.55.05.56.06.5

Z (ALT), height above the ground in m distance (m)

Distance from bottom of crowns Distance from top of crown 200 200

100 100

Std. Dev = 1.75 Std. Dev = 1.64 Mean = 1.0 Mean = 2.8 0 N = 1092.00 0 N = 1092.00 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 -3.5 -2.5 -1.5 -.5 .5 1.5 2.5 3.5 4.5 5.5 6.5 7.5

distance (m) distance (m)

One-Sample Kolmogorov-Smirnov Test

Z (ALT), height above the ground in distance distance distance m (m) (m) (m) N 1539 1539 1092 1092 Normal Parameters a,b Mean 2.1517 .8335 1.0100 2.7822 Std. Deviation 1.1824 1.3995 1.7453 1.6375 Most Extreme Absolute .121 .050 .082 .059 Differences Positive .121 .050 .082 .030 Negative -.045 -.036 -.064 -.059 Kolmogorov-Smirnov Z 4.754 1.978 2.710 1.941 Asymp. Sig. (2-tailed) .000 .001 .000 .001 a. Test distribution is Normal. b. Calculated from data.

83 Appendix III-2: Height distribution of the Bromeliaceae.

Bromeliaceae: height from the ground 200 Bromeliaceae: distance from undergrowth 100

80

60 100

40

Std. Dev = 1.15 20 Std. Dev = 1.37 Mean = 2.2 Mean = .9 0 N = 1108.00 0 N = 1108.00 0.0 .5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 -2.0-1.5-1.0-.50.0 .5 1.01.52.02.53.03.54.04.55.05.56.0 Z (ALT), height above the ground in m distance (m)

Bromeliaceae: distance from bottom of crown Bromeliaceae: distance from top of crown 160 140

140 120

120 100 100 80 80 60 60 40 40 Std. Dev = 1.82 Std. Dev = 1.69 20 Mean = 1.0 20 Mean = 2.8 0 N = 804.00 0 N = 804.00 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 distance (m) distance (m) One-Sample Kolmogorov-Smirnov Test

Z (ALT), height above the ground in distance distance distance m (m) (m) (m) N 1108 1108 804 804 Normal Parameters a,b Mean 2.2092 .9005 .9888 2.8378 Std. Deviation 1.1545 1.3688 1.8166 1.6929 Most Extreme Absolute .140 .047 .093 .078 Differences Positive .140 .047 .093 .028 Negative -.052 -.033 -.070 -.078 Kolmogorov-Smirnov Z 4.665 1.559 2.623 2.202 Asymp. Sig. (2-tailed) .000 .016 .000 .000 a. Test distribution is Normal. b. Calculated from data.

84 Appendix III-3: Height distribution of the Orchidaceae.

Orchidaceae: height from the ground Orchidaceae: distance from undergrowth 40 40

30 30

20 20

10 10 Std. Dev = 1.02 Std. Dev = 1.28 Mean = 1.8 Mean = .5 0 N = 346.00 0 N = 346.00 0.0 .5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 -2.0-1.5 -1.0 -.5 0.0 .5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Z (ALT), height above the ground in m distance (m)

Orchidaceae: distance from bottom of crown Orchidaceae: distance from top of crown 50 40

40 30

30 20 20

10 10 Std. Dev = 1.45 Std. Dev = 1.40 Mean = 1.2 Mean = 2.8 0 N = 245.00 0 N = 245.00 -1.5-1.0-.50.0 .5 1.01.52.02.53.03.54.04.55.05.56.06.5 -.5 0.0 .5 1.01.52.02.53.03.54.04.55.05.56.06.57.0

distance (m) distance (m)

One-Sample Kolmogorov-Smirnov Test

Z (ALT), height above the ground in distance distance distance m (m) (m) (m) N 346 346 245 245 Normal Parameters a,b Mean 1.8368 .5060 1.2023 2.7919 Std. Deviation 1.0240 1.2752 1.4510 1.3969 Most Extreme Absolute .060 .053 .097 .057 Differences Positive .060 .053 .097 .057 Negative -.046 -.042 -.046 -.030 Kolmogorov-Smirnov Z 1.110 .981 1.511 .895 Asymp. Sig. (2-tailed) .170 .291 .021 .400 a. Test distribution is Normal. b. Calculated from data.

85 Appendix III-4: Height distribution of the Loranthaceae.

Loranthaceae: height from the ground Loranthaceae: distance from undergrowth 30 20

20

10

10

Std. Dev = 1.77 Std. Dev = 1.97 Mean = 2.8 Mean = 1.4 0 N = 75.00 0 N = 75.00 .5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 -2.5-2.0-1.5-1.0-.50.0.5 1.01.52.02.53.03.54.04.55.05.56.06.5 Z (ALT), height above the ground in m distance (m)

Loranthaceae: distance from bottom of crown Loranthaceae: distance from top of crown 10 10

8 8

6 6

4 4

2 Std. Dev = 1.90 2 Std. Dev = 1.63 Mean = .1 Mean = 1.6 0 N = 34.00 0 N = 34.00 -3.5-3.0-2.5-2.0-1.5-1.0 -.5 0.0 .5 1.0 1.5 2.0 2.5 3.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 distance (m) distance (m)

One-Sample Kolmogorov-Smirnov Test

Z (ALT), height above the ground in distance distance distance m (m) (m) (m) N 75 75 34 34 Normal Parameters a,b Mean 2.8303 1.4343 .1185 1.6394 Std. Deviation 1.7703 1.9670 1.8992 1.6330 Most Extreme Absolute .209 .183 .172 .129 Differences Positive .209 .183 .172 .129 Negative -.135 -.103 -.137 -.076 Kolmogorov-Smirnov Z 1.813 1.588 1.003 .755 Asymp. Sig. (2-tailed) .003 .013 .267 .619 a. Test distribution is Normal. b. Calculated from data.

86 Appendix III-5: Height distribution of Racinaea tetrantha.

Racinaea tetrantha: height from the ground Racinaea tetrantha: distance from undergrowth 100 60

80 50

40 60 30 40 20

20 Std. Dev = 1.13 Std. Dev = 1.33 10 Mean = 2.3 Mean = 1.0 0 N = 617.00 0 N = 617.00 0.0 .5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 -2.0-1.5-1.0-.50.0 .5 1.01.52.02.53.03.54.04.55.05.56.0 Z (ALT), height above the ground in m distance (m)

Racinaea tetrantha: distance from bottom of crown Racinaea tetrantha: distance from top of crown 120 100

100 80 80 60 60 40 40

Std. Dev = 1.68 20 20 Std. Dev = 1.57 Mean = .7 Mean = 2.8 0 N = 452.00 0 N = 452.00 -3.5 -2.5 -1.5 -.5 .5 1.5 2.5 3.5 4.5 5.5 6.5 -2.0-1.5-1.0-.50.0.51.01.52.02.53.03.54.04.55.05.56.06.57.0 distance (m) distance (m) One-Sample Kolmogorov-Smirnov Test

Z (ALT), height above the ground in distance distance distance m (m) (m) (m) N 617 617 452 452 Normal Parameters a,b Mean 2.2650 .9955 .7267 2.7900 Std. Deviation 1.1315 1.3279 1.6816 1.5682 Most Extreme Absolute .166 .057 .110 .102 Differences Positive .166 .057 .110 .059 Negative -.063 -.033 -.091 -.102 Kolmogorov-Smirnov Z 4.115 1.406 2.333 2.167 Asymp. Sig. (2-tailed) .000 .038 .000 .000 a. Test distribution is Normal. b. Calculated from data.

87 Appendix III-6: Height distribution of Tillandsia compacta

Tillandsia compacta: height from the ground Tillandsia compacta: distance from undergrowth 30 20

20

10

10

Std. Dev = 1.23 Std. Dev = 1.38 Mean = 2.3 Mean = 1.0 0 N = 102.00 0 N = 102.00 0.0 .5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 -1.5-1.0 -.5 0.0 .5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 Z (ALT), height above the ground in m distance (m)

Tillandsia compacta: distance from bottom of crown Tillandsia compacta: distance from top of crown 14 10

12 8 10

8 6

6 4 4 Std. Dev = 1.90 2 Std. Dev = 1.99 2 Mean = 1.3 Mean = 2.9 0 N = 67.00 0 N = 67.00 -3.0-2.5-2.0-1.5-1.0-.50.0.51.01.52.02.53.03.54.04.55.05.56.0 -2.0-1.5-1.0-.50.0.51.01.52.02.53.03.54.04.55.05.56.06.57.07.5

distance (m) distance (m) One-Sample Kolmogorov-Smirnov Test

Z (ALT), height above the ground in distance distance distance m (m) (m) (m) N 102 102 67 67 Normal Parameters a,b Mean 2.3217 1.0117 1.3149 2.8872 Std. Deviation 1.2281 1.3753 1.9014 1.9915 Most Extreme Absolute .077 .054 .087 .085 Differences Positive .077 .054 .086 .085 Negative -.053 -.050 -.087 -.070 Kolmogorov-Smirnov Z .778 .545 .715 .697 Asymp. Sig. (2-tailed) .581 .928 .686 .716 a. Test distribution is Normal. b. Calculated from data.

88 Appendix III-7: Height distribution of Tillandsia sp.1.

Tillandsia sp.1: height from the ground Tillandsia sp.1: distance from undergrowth 70 50 60 40 50

40 30

30 20 20 Std. Dev = 1.21 10 Std. Dev = 1.45 10 Mean = 2.1 Mean = .8 0 N = 334.00 0 N = 334.00 0.0 .5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 -2.0-1.5-1.0 -.5 0.0 .5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 Z (ALT), height above the ground in m distance (m)

Tillandsia sp.1: distance from bottom of crown Tillandsia sp.1: distance from top of crown 60 50

50 40 40 30 30 20 20

Std. Dev = 1.86 10 10 Std. Dev = 1.79 Mean = 1.2 Mean = 2.9 0 N = 244.00 0 N = 244.00 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 -3.0-2.5-2.0-1.5-1.0-.50.0.51.01.52.02.53.03.54.04.55.05.56.06.5 distance (m) distance (m) One-Sample Kolmogorov-Smirnov Test

Z (ALT), height above the ground in distance distance distance m (m) (m) (m) N 334 334 244 244 Normal Parameters a,b Mean 2.1208 .7627 1.1988 2.8858 Std. Deviation 1.2072 1.4535 1.8555 1.7911 Most Extreme Absolute .162 .114 .122 .101 Differences Positive .162 .114 .122 .061 Negative -.076 -.070 -.072 -.101 Kolmogorov-Smirnov Z 2.969 2.080 1.899 1.584 Asymp. Sig. (2-tailed) .000 .000 .001 .013 a. Test distribution is Normal. b. Calculated from data.

89 Appendix IV : Different height measures per plot

4 3

3

3 2

2 2 1

1 1

0

0 -1 height above the ground (m) height above undergrowth (m) N = 224 155 349 266 77 34 111 26 116 90 91 N = 224 155 349 266 77 34 111 26 116 90 91 A B C D E F G H I J K A B C D E F G H I J K

plot id plot id

3 4

2 3

1 2

0 1

-1 0 distance under crown-base (m) distance under crown-top (m) N = 171 90 193 253 44 84 24 93 65 75 N = 171 90 193 253 44 84 24 93 65 75 A B C D E G H I J K A B C D E G H I J K

plot id plot id

Mean and standard deviation of the height of epiphytes in the different plots. Note the difference in numbers per plot. Less epiphytes are included in the distance to crowns graphs, because not all epiphytes were found underneath crowns. In plot F all epiphytes were found free from crowns.

90 Appendix V : Different height measures per species

5 3

4 2

3

1

2

0 1

0 -1 height above the ground (m) height above undergrowth (m) N = 617 102 334 13 42 229 24 93 21 42 N = 617 102 334 13 42 229 24 93 21 42 R. tetranthT. T. R. Brom. specsOrchid specsO O Lor Dendrop. s R. t T. c T. R. penl B Orchid specsOrchid spec1Orchid spec5Lor Dendrop. s r r r co sp p ch ch sp o e . sp e o m. . sp mpacta e n id id trantha mpacta e c1 la sp s e c1 a sp e n pec5 c1 n c1 d e d e a i i c p i i cs p 1 e e c c

5 4

3 4

dis 2 ta 3 nc e 1 un 2 de 0 r cr 1 ow -1 n- to 0 -2 p distance under crown-base (m) N = 452 67 244 10 31 166 21 58 8 23 N = 452 67 244 10 31 166 21 58 8 23 R. T. R. Br Or Or Or Lor De R. t T. c T. R. penl B Orchid specsOrchid spec1Orchid spec5Lor Dendrop. s T. r sp o tetr co pe om chi chi chi ndr e o m. . sp sp . trantha mpacta e d d d op. c1 a sp e ant mp ec nla . sp n c1 d e sp sp sp sp i i cs p ha act 1 ndi sp ec e a i ec ec ec ec 1 ec c s s 1 5

Mean and standard deviation of the height of epiphytes per species. Less epiphytes are included in the distance to crowns graphs, because only ca. 2/3 of the epiphytes were found underneath crowns.

91 Appendix VI-1: L 2-graphs

L2 PLOT A (x- y)

1.50

1.00

0.50 L2 Upper L2 L2 0.00 L2 Low er 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

L2 PLOT A (x- z)

1.50

1.00

0.50 L2 Upper L2 L2

0.00 L2 Low er 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

L2 PLOT A ( y-z)

1.50

1.00

0.50 L2 Upper L2 L2 0.00 L2 Low er 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

92 Appendix VI-2

R. tetrantha, plot A

2.00

1.50

1.00

L2 Upper 0.50 L2 L2 L2 Lower

0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

R. tetrantha adults, plot A

2.00

1.50

1.00

L2 Upper 0.50 L2 L2 L2 Lower

0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

R. tetrantha juveniles, plot A

1.50

1.00

0.50 L2 Upper L2 L2 L2 Low er 0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

93 Appendix VI-3

L2 PLOT B (x-y)

1.50

1.00

0.50 L2 Upper L2 L2 L2 Lower 0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

L2 PLOT B (x-z)

1.50

1.00

0.50 L2 Upper L2 L2 L2 Lower 0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

L2 PLOT B (y-z)

1.50

1.00

0.50 L2 Upper L2 L2 L2 Lower 0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

94 Appendix VI-4

R. tetrantha, plot B

2.00

1.50

1.00

L2 Upper L2

L2 0.50 L2 Lower

0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

R. tetrantha adults, plot B

2.00

1.50

1.00

L2 Upper L2

L2 0.50 L2 Lower

0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

R. tetrantha juveniles, plot B

2.00

1.50

1.00

L2 Upper 0.50 L2 L2 L2 Lower

0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1

-0.50

-1.00 h (m)

95 Appendix VI-5

R. tetrantha, plot C

2.00

1.50

1.00 L2 Upper 0.50 L2 L2 L2 Lower 0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 -0.50

-1.00 h (m)

R. tetrantha adults, plot C

2.00

1.50

1.00

L2 Upper 0.50 L2 L2 L2 Low er

0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

R. tetrantha juveniles, plot C

2.00

1.50

1.00

L2 Upper 0.50 L2 L2 L2 Low er

0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

96 Appendix VI-6

R. tetrantha, plot D

2.00

1.50

1.00 L2 Upper 0.50 L2 L2 L2 Lower 0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 -0.50

-1.00 h (m)

R. tetrantha adults, plot d

2.00

1.50

1.00

L2 Upper 0.50 L2 L2 L2 Low er

0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

R. tetrantha juveniles, plot D

2.00

1.50

1.00

L2 Upper 0.50 L2 L2 L2 Low er

0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

97 Appendix VI-7

L2 PLOT E (y-z)

1.50

1.00

0.50 L2 Upper L2 L2 Lower 0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

L2 PLOT E (x-z)

1.50

1.00

0.50 L2 Upper L2 L2 Lower 0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

L2 PLOT E (y-z)

1.50

1.00

0.50 L2 Upper L2 L2 L2 Lower 0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

98 Appendix VI-8

R. tetrantha, plot E

2.00

1.50

1.00

L2 Upper 0.50 L2 L2 L2 Lower 0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 -0.50

-1.00 h (m)

R. tetrantha adults, plot E

2.00

1.50

1.00

L2 Upper 0.50 L2 L2 L2 Low er

0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

R. tetrantha juveniles, plot E

2.00

1.50

1.00

L2 Upper 0.50 L2 L2 L2 Low er

0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

99 Appendix VI-9

L2 PLOT F (x-y)

1.5

1

0.5 L2 Upper L2 L2 Lower 0 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.5

-1 h ( m)

L2 PLOT F (x-z)

1.5

1

0.5 L2 Upper L2 L2 Lower 0 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.5

-1 h (m)

L2 PLOT F (y-z)

1.5

1

0.5 L2 Upper L2 L2 Lower 0 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.5

-1 h (m)

100

Appendix VI-10

R. tetrantha, plot F

2.00

1.50

1.00

L2 Upper 0.50 L2 L2 L2 Lower 0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 -0.50

-1.00 h (m)

L2 PLOT G (x-y)

1.50

1.00

0.50 L2 Upper L2 L2 L2 Lower 0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

L2 PLOT G (x-z)

1.50

1.00

0.50 L2 Upper L2 L2 L2 Lower 0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

101 Appendix VI-11

L2 PLOT G (y-z)

1.50

1.00

0.50 L2 Upper L2 L2 L2 Lower 0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

R. tetrantha, plot G

2.00

1.50

1.00 L2 Lower 0.50 L2 L2 L2 Upper 0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 -0.50

-1.00 h (m)

L2 PLOT H ( y-z)

1.50

1.00

0.50 L2 Upper L2 L2

0.00 L2 Low er 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m )

102 Appendix VI-12

L2 PLOT H (x-z)

1.50

1.00

0.50 L2 Upper L2 L2

0.00 L2 Low er 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

L2 PLOT H (y-z)

1.50

1.00

0.50 L2 Upper L2 L2

0.00 L2 Low er 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

R. tetrantha, plot H

2.00

1.50

1.00 L2 Upper 0.50 L2 L2 L2 Lower 0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 -0.50

-1.00 h (m)

103 Appendix VI-13

L2 PLOT I (x-y)

1.50

1.00

0.50 L2 Upper L2 L2 Lower 0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00

h (m)

L2 PLOT I (x-z)

1.50

1.00

0.50 L2 Upper L2 L2 Lower 0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00

h (m)

L2 PLOT I (y-z)

1.50

1.00

0.50 L2 Upper L2 L2 Lower 0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00

h (m)

104 Appendix VI-14

R. tetrantha, plot I

2.00

1.50

1.00 L2 Upper 0.50 L2 L2 L2 Lower 0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 -0.50

-1.00 h (m)

L2 PLOT J (x-y)

1.50

1.00

0.50 L2 Upper L2 L2 L2 Lower 0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

L2 PLOT J (x-z)

1.50

1.00

0.50 L2 Upper

L2 L2 L2 Lower 0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

105 Appendix VI-15

L2 PLOT J (y-z)

1.50

1.00

0.50 L2 Upper L2 L2 L2 Lower 0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

R. tetrantha, plot J

2.00

1.50

1.00

L2 Lower 0.50 L2 L2 L2 Upper

0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 -0.50

-1.00 h (m)

L2 PLOT K (x-y)

1.50

1.00

0.50 L2 Upper

L2 L2 L2 Lower 0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

106 Appendix VI-16

L2 PLOT K (x-z)

1.50

1.00

0.50 L2 Upper

L2 L2 L2 Lower 0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

L2 PLOT K (y-z)

1.50

1.00

0.50 L2 Upper

L2 L2 L2 Lower 0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

-0.50

-1.00 h (m)

R. tetrantha, plot K

2.00

1.50

1.00 L2 Upper 0.50 L2 L2 L2 Lower 0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 -0.50

-1.00 h (m)

107 Appendix VII-1 : Distribution on phorophytes Tree-species in the graphs : Miconia squamulosa (Melastomataceae), Clethra sp. (Clethraceae), Miconia thaezans (Melastomataceae), Weinmannia pubescens (Cunoniaceae), Escallonia myrtilloides (Saxifragaceae), Miconia pergamentacea (Melastomataceae), Weinmannia sp. (Cunoniaceae), Tibouchina grossa (Melastomataceae), Hedyosmum sp. (Chloranthaceae), rest = other species, other = epiphytes on shrubs, on the ground etc.

Epiphytes per host tree species 600

500

400

300

200

100 N=1536

0 # of epiphytes of # M . s q uCleth a m u l o sM. a thaezW. E. myrtiM Wein T . g r o sHed s a r e s t de o t h e r pubesc . pergam a d t r e e ra spe manni yosmu lloid an e a spe m sp c. s en es nt a c e a s c. e c .

Tree species

Loranthaceae per host tree species 35

30

25

20

15

10

5 N=74

0 # Loranthaceae # M. Cle M. W E M W T. H re d e ad t r eo e t h e r . . m . e g e s sq th th per dyos pub yr inm ros t uam ra s aez till ga an e s m a sce oide me a u p ns nia um los e c . ns nt s s s a ace pec pec a . . Tree species

Orchids per host tree species 140

120

100

80

60

40

20 N=346

0 # of orchids of # M. s Cleth M. W. E. m M We T. g H re d e a d t r eothe e th . p ed st p in q y er r yo r u a m u l or s a aez u b e sce nrtillo s ma o ssa a s gam sm n pe a i nia s um ns des en c. sp ta p ce ec e a c. Tree species

108 Appendix VII-2

Bromeliaceae per host tree species Bromeliaceae per host tree species 500 300

400

200 300

200 100

100 adult

0 0 juvenile # of Bromeliaceae of # bromeliad-ramets of # M Clethra M. spec. thae zansW E. M. pergamentaceaW T. H res dea d treeot M ClethraM. spec. thaeW zans E. myrtillM. pergamentaceaW T. Hedyosmumrest spec.dea other . . myrti ei edyosm h e r . . pu ei squam pu grossa t squam g nmann nm rossa d bes cens bes cens anni tr lloi o ee u des um ul ides losa ia osa a spec. spec spec.

.

host tree species host tree species

R. tetrantha per host tree species R. tetrantha per host tree species 250 175

150 200 125

150 100

75 100

50 50 N=616 25 Adults (N=377)

0 Juveniles (N=238) 0 ramets # # of R. tetrantha ramets tetrantha R. of # M. squamulosaCl M. thaeW. zans pu E. M. pergamW T. grossaHedyosmumr spec.dea d treeother M Cl M W. pubesE. myrtilloides cenM.pergamenWeinmT. H r dead treeother est . et . t edyosmest et m ei squam g hra n hra haezan r yr manni ossa bes t ann spec. ill spec. o i d e s ul um ce n s en a s ia spec. osa t ta ce a spec. s acea spec.

Tree species Tree species

T. compacta per host tree species T. spec.1 per host tree species 45 140

40 120 35 100 30

25 80

20 60 15 40 10 20 5 N=102 N=334 0 0 # T.compacta ramets T.compacta # ramets T.spec.1 of # M Clethra M spec. W. pu E. M. pergamentaceaW T. grossaH res dea other M. squamulosaCl M. thaeW. zans pu E. M. pergamW T. grossaHedyosmumr spec.dea d treeother . . edyosm est squam t m ei et m ei hae yr nm t d hra yr n bes t bes manni ti anni r ti za n s llo i d e s ee spec. llo i d e s ul ce n s um spec. ce n s osa a en a sp e c ta ce a spec.

Tree species Tree species

109 Appendix VIII: Cryptogams

b

a a

c

b a

Covering of trees by different epiphytic cryptogam-types in 3 height zones. Mosses occur mostly below 1 meter. Lichens were recorded including and excluding crustose species. In both cases the cover of stems by lichens increases with height from the ground, which is mainly caused by an increase of non-crustose species (notably Usnia spec.). Increase of lichen cover including crustose species is not significant (Anova, p>0.1) Frullania is equally abundant at all heights (p>0.05). Bars represent means, error bars 95% confidence intervals.(Tukey post-hoc test used)

110