Phytogeography of the vascular páramo flora of Ramal de Guaramacal ( Andes , Venezuela ) and its ties to other páramo floras by Nidia

Cuello, N.L., Cleef, A.M. & Aymard, G. 2010. Phytogeography of the vascular páramo flora of Ramal de Guaramacal (Andes, Venezuela) and its ties to other páramo floras. Anales Jard. Bot. Madrid 67(2): 177-193. Ramal de Guaramacal is an outlier and lower elevation mountain range located at the northeastern end of the Venezuelan Andes. Phytogeographical patterns and affinities of the low altitude and wet vascular páramo flora of Ramal de Guaramacal, have been studied with emphasis in to the analysis of the floristic connections of the Guaramacal páramo flora with the neighboring dry páramos of the Sierra Nevada de Mérida and other páramo floras of the northern Andes and Central America. A total of 252 vascular plant taxa belonging to 150 genera and 69 families were recorded from the study area. The most species rich families are Asteraceae, Poaceae, Ericaceae and Orchidaceae, followed by the ferns families Grammitidaceae and Lycopodiacae. The most diverse genera are the ferns Elaphoglossum, Huperzia and Hymenophyllum. The analysis of generic phytogeographical composition of páramo flora showed that 52.8% of the genera are Tropical. The Temperate component is represented by 33.3% of the genera and the Cosmopolitan component is represented by 13.9% of the genera. The Neo tropical montane element (38.9%) is high in Guaramacal páramo, the Páramo endemic element (1.9%) and the Andean alpine element (0.9%) and represented by only one genus (Lachemilla) are low compared to other páramo areas. The vascular flora of Páramo de Guaramacal is largely composed of (1) a group of Neotropical widespread distributed species (32%), (2) a group of Andean distributed species (49%), part of them confined to the Northern Andes and part widespread in the Andes from Colombia to Bolivia, and (3) a group of Venezuelan endemics (19%). From an eight páramo flora comparative dataset, the closest relationships among páramos is observed between the generic páramo floras of the Colombian Cordillera Oriental of Sumapáz and Sierra Nevada del Cocuy, which are both closeAnales del Jardín Botánico de Madrid Vol. 67(2): 177-193 julio-diciembre 2010 ISSN: 0211-1322 doi: 10.3989/ajbm.2253

Ramal de Guaramacal is an outlier and lower elevation mountain range located at the northeastern end of the Venezuelan Andes.Phytogeographical patterns and affinities of the low altitude and wet vascular páramo flora of Ramal de Guaramacal, have been studied with emphasis in to the analysis of the floristic connections of the Guaramacal páramo flora with the neighboring dry páramos of the Sierra Nevada de Mérida and other páramo floras of the northern Andes and Central America.A total of 252 vascular plant taxa belonging to 150 genera and 69 families were recorded from the study area.The most species rich families are Asteraceae, Poaceae, Ericaceae and Orchidaceae, followed by the ferns families Grammitidaceae and Lycopodiacae.The most diverse genera are the ferns Elaphoglossum, Huperzia and Hymenophyllum.The analysis of generic phytogeographical composition of páramo flora showed that 52.8% of the genera are Tropical.The Temperate component is represented by 33.3% of the genera and the Cosmopolitan component is represented by 13.9% of the genera.The Neotropical montane element (38.9%) is high in Guaramacal páramo, the Páramo endemic element (1.9%) and the Andean alpine element (0.9%) and represented by only one genus (Lachemilla) are low compared to other páramo areas.The vascular flora of Páramo de Guaramacal is largely composed of (1) a group of Neotropical widespread distributed species (32%), (2) a group of Andean distributed species (49%), part of them confined to the Northern Andes and part widespread in the Andes from Colombia to Bolivia, and (3) a group of Venezuelan endemics (19%).From an eight páramo flora comparative dataset, the closest relationships among páramos is observed between the generic páramo floras of the Colombian Cordillera Oriental of Sumapáz and Sierra Nevada del Cocuy, which are both close-Resumen Cuello, N.L., Cleef, A.M. & Aymard, G. 2010.Fitogeografía de la flora vascular del páramo de Ramal de Guaramacal (Andes, Venezuela) y sus conexiones con otras floras de páramo.Anales Jard.Bot.Madrid 67(2): 177-193 (en inglés).

Introduction
Páramo is the open equatorial alpine vegetation located above the upper forest line (UFL) and below the permanent snow line from the northern Andes to Panamá and Costa Rica.However, páramo is also considered to be extended to the Amazon slopes of Bolivia (García & Beck, 2006;Rangel, 2006).Páramo flora is considered the high-mountain flora most rich in species of the world (Smith & Cleef, 1988).Phytogeographical studies at the generic level have shown that páramo flora has evolved mainly by immigration of cool-adapted plants from temperate regions (temperate elements) and, in relatively lower proportion, by adaptation of lower-elevation plants (tropical elements) to high-altitude environments and by speciation through repeated isolation in situ (Van der Hammen & Cleef, 1986;Smith & Cleef, 1988;Cleef & Chaverri, 1992;Ramsay, 1992;Ricardi & al., 1997;Sklenář & Balslev, 2007).
Páramo areas in Venezuela exhibit great environmental variability in climate at regional and local scales.Through the about 400 km southwest to northeast extension of the main Venezuelan Andean mountain chain, the Cordillera de Mérida, there is a wide range of páramo hydrological conditions, from dry páramos with 650 mm/year in a single rainy season, to permanently humid páramos with over 3000 mm distributed throughout the year (Monasterio & Reyes, 1980).The latter conditions characterize the páramo areas of Ramal de Guaramacal, an outlier and comparatively low elevation (3130 m) range located at the northeastern end of the Venezuelan Andes (Fig. 1).
Studies of phytogeography of the Venezuelan páramo flora started with a first approach of the worldwide distribution of Venezuelan páramo flora presented by Faría (1978) after the publication of the 'Flora de los Páramos de Venezuela' by Vareschi (1970).This very first flora of the páramos was not complete, but anyway representative.
More recent phytogeographical analyses of the Venezuelan páramo flora have been published by Ricardi & al. (1997Ricardi & al. ( , 2000)).The first study deals with the phytogeography of the Mérida superpáramo; the second study highlights the Sierra Nevada de Mérida as a new phytogeographical subprovince of the northern Andes.Briceño & Morillo (2002, 2006) recently published a list of the flowering species of the Venezuelan Andean páramos, first the dicots, later followed by the monocots.
The aim of this study is to analyse the phytogeographical affinities of the low altitude and wet páramo of Ramal de Guaramacal in order to contribute to a better understanding of the distribution, origin, and diversity of its flora.A detailed analysis of phytogeographic composition of Ramal de Guaramacal pá ramo flora at a genus level is justified given the importance of this low, wet and relative isolated mountain range from the main Cordillera, which also shows a distinctive flora and vegetation composition (Cuello & Cleef, 2009b).Particular emphasis is given to the analysis of the floristic connections of the Guaramacal páramo flora with the neighboring dry páramos of the Sierra Nevada de Mérida and other páramo floras of the northern Andes and Central America.
One of our main objectives was to determine whether the phytogeographical analysis and patterns of the páramo flora of Ramal de Guaramacal are determined by temperature (a function of altitude) as has been established in previous studies (e.g.Cleef, 1979;Mérida Andes, Ricardi & al., 1997, 2000) or more by the overall humidity, which characterizes the Guaramacal bamboo páramo.We have some indications that ambient humidity may play a role, e.g. in the case of the bamboo páramo of Tatamá (Cleef, 2005), the páramos of Podocarpus National Park (PNP) in southern Ecuador (Lozano & al., 2009) and also in the Talamancas of Costa Rica (Cleef & Chaverri, 1992).
The climate is very humid.According the first climatic records of the Davis Pro 2 climate station installed near the summit of Guaramacal (3100 m) by the first author beginning in December 2006, there are over 290 days/year of rain.Maximum precipitation occurs during April-July.Yearly precipitation is high, reaching over 3200 mm/year and relative humidity attains 100% most of the year.Temperatures remain low throughout the year with a diurnal temperature variation from 4-6 ºC to 14-16 ºC; mean minimum temperature of 5.3 ºC and mean maximum of 12.3 ºC; the lowest temperatures recorded being between -0.1-1.3 ºC in the month of January; the highest between 17.8-18.3ºC in the month of March, with mean yearly temperature of 8.1-8.6 ºC for the period from December 2006 -July 2009.Dominant wind directions are of ESE, SE and WNW, with a registered average speed of 3.9-5.8km/h.Maximum wind speed registered has been of 77.2 km/h, SE in the month of July 2008.
The vegetation of the Páramo of Guaramacal is characterized by a mosaic of subpáramo formations (shrub páramo, bunchgrass páramo, most common bamboo páramo), intermingled with patches of dwarf forests (Subalpine Rain Forest or SARF sensu Grubb 1977), distributed between 2800 and 3130 m (Cuello & Cleef, 2009a, b).For detailed information on forest Phytogeography páramo flora Andes and páramo vegetation of Guaramacal and other aspects of the study area we refer to Cuello & Cleef (2009a, b, c) and Cuello (1999).
The study and full inventory of the flora of the whole Ramal de Guaramacal range is still ongoing.Preliminary accounts of the vascular flora were first presented by Ortega & al. (1987) and later by Dorr & al. (2000).After that, several new records for the flora as well as new species to science have been documented for Guaramacal (Taylor, 2002;Stergios & Dorr, 2003;Stančík, 2004;Niño & al., 2005;Cuello & Aymard, 2008).A species inventory from páramo areas, including, páramo and subpáramo-connected dwarf forest vegetation islands is presented in this study (Appendix 1).

Methods
Páramo data were collected from phytosociological studies (Cuello & Cleef, 2009b, c) and 585 numbers of general plant collections made by the first author from páramo areas of Ramal de Guaramacal.Additional information was obtained from herbarium collections and database of Herbario Universitario PORT, UNELLEZ in Guanare.The total inventory included 255 vascular plant taxa belonging to 153 genera and 69 families that are listed in Appendix 1.Three exotic weedy taxa (Polypogon elongatus, Rumex acetosella and Sonchus oleraceus) present in disturbed areas, are listed in the Appendix 1, but excluded for the analyses.
3) Cosmopolitan component consists of only the Cosmopolitan taxa (CO).
For a biogeographical analysis into species level, overall species distribution was grouped into ten different geographic elements, adapting from previous phytogeographical studies in the Andean region such as those used by Kelly & al. (1994) and Schneider (2001).From the total 252 taxa recorded for the Guaramacal summit area, for the specific biogeographical analysis we used only 229 species with a defined distribution (those which were determined to species and/or infraespecific level), including all open páramo and dwarf forest islands (of Subalpine Rain Forest or SARF sensu Grubb 1977) vegetation species.
Floristic relationships of Guaramacal páramo generic flora to other páramo floras of the northern Andes and Central America were assessed using ordination (Detrended Correspondance Analysis -DCA, Principal Component Analysis -PCA) and classification (Cluster analysis) methods for seven additional available different páramo flora datasets.Floristic lists from each páramo site were obtained from literature or unpublished data from authors (see Table 1).The accounts on the different páramo floras were carefully screened by the authors for taxonomic update and true forest taxa were deleted.Two dataset were considered for these analyses, A) one which included the Guaramacal list of total genera of 150 from páramo & SARF combined, and B) the other that includes Guaramacal list of 108 genera from open páramo only.For these analyses, both data matrices A (404 genera × 8 sites) and B (347 genera × 8 sites) of presence/absence of genera in the eight páramo floras were analyzed using program PC- Mefford, 1999).Cluster analyses of shared genera used Sørensen (Bray-Curtis) as distance measure method and Group Average as group linkage method.

Flora characteristics
To date, the vascular flora of summit areas of Ramal de Guaramacal is composed of a total of 252 taxa; 17 families, 28 genera, and 68 species of ferns, and 52 families, 122 genera and 184 species of angiosperms.In general, the most species rich families are Asteraceae, Poaceae, Ericaceae and Orchidaceae, followed by the ferns families Grammitidaceae and Lycopodiacae.
The most diverse genera are the ferns Elaphoglossum, Huperzia and Hymenophyllum.Of the 252 taxa considered, only 169 species belonging to 108 genera have been registered for proper subpáramo-páramo vegetation, excluding the SARF vegetation (Table 2).

Geographical composition of genera
The composition of genera of phytogeographic elements in páramo areas of Ramal de Guaramacal is presented in Table 3.A total of 150 genera is contained in Table 3, including 41 genera of woody, herbaceous and epiphytic plant species found inside the forest islands (of SARF vegetation) surrounded by páramo vegetation, and 27 genera present in azonal páramo vegetation.Proportions of phytogeographic elements and components of the studied data set are Phytogeography páramo flora Andes shown in Fig. 2, represented separately for: (a) all genera inclunding SARF vegetation, (b) all open páramo genera, and (c) for the genera present in azonal communities.

Tropical component
On the basis of 150 vascular plant genera more than half 61.3% (92 genera) are tropical.Neotropical montane element genera are those that range from montane forest into the supraforest zone.This element is represented by 64 genera (42.7%).Twenty two of them (including 10 herbaceous genera) correspond to SARF vegetation (Table 3).When considering only the genera recorded from páramo vegetation, the Neotropical montane element is represented by forty two genera (38.9%), four of them are found in azonal páramo (Fig. 2c).
Wide tropical element genera are widely distributed in the tropics, including those exclusively African-American and Asian-American.This element is represented by 24 genera (16%).Ten of them (including five herbaceous genera) were found in SARF islands (Table 3).When considering only páramo vegetation genera, the wide tropical element accounts for twelve genera (11.1%) and only one of them (Xyris) is found in azonal páramo.
Páramo endemic element genera are those confined to páramo (and sometimes also in the downslope Andean forests) and represented in the study area by 3 genera (2%), two of them small trees: Liba - Widespread temperate element genera are distributed in temperate and cool regions from both hemispheres.This element is represented in the study area by twenty one genera (14%).The genus Stellaria was recorded from borders of SARF vegetation.When excluding this genus, the wide temperate element is represented by 18.5% for twenty páramo genera, eight of them counted from azonal páramo.
Austral-Antarctic element genera have southern temperate distribution.This element is represented by fifteen genera (10%).Among them, three genera were registered from SARF (Table 3).Twelve Austral-Antarctic element genera (including 8 herbaceous) of only páramo vegetation account for 11.1%.Eight genera are counted from azonal páramo.
Holarctic element genera have northern temperate

Cosmopolitan component
Cosmopolitan element genera are those with worldwide, or nearly so, distribution.The Cosmopolitan element is represented in the study area by sixteen genera (10.7%).The fern genus Asplenium, represented by the species A. serra, is found in the understory of SARF vegetation.The Cosmopolitan component for only fifteen páramo genera (13 of them herbaceous) is represented by 13.9%.In the azonal páramo the Cosmopolitan component is represented by four genera.

Species geographical range
The geographical range of the vascular species present in páramo areas of Ramal de Guaramacal, grouped in ten major groups (or distribution types), is shown in Table 4. Neotropical widespread distributed species all over in the whole Neotropics or in a wide range from Central America to Bolivia are broken down into five (1-5) groups.Andean distributed N.L. Cuello & al. species are split into groups 6 to 9. Venezuelan endemic species (group 10) is divided into four subgroups.The number of vascular species, by taxonomic groups (ferns and Angiosperms) and percentages of the total are presented for each distribution category.From the total 229 taxa determined to species, only 156 species belong to proper páramo/subpáramo vegetation.

Páramo flora relationship
Fig. 3 shows the dendrograms of generic similarity among páramo sites resulting from the cluster analyses.In both graphs, over fifty percent of similarity, four main groups can be recognized.The results of ordination also show that for dataset A (that includes the páramo and SARF genera from Guaramacal) páramos with greatest values of humidity and rainfall according to Table 1 are grouped in line to the lower right corner on both DCA(a) and PCA(b) diagrams (e.g.Tatamá massif, 4100 m, ~2000-3000 mm/year (Cleef & al., 2005); South Ecuador, PBR, 3695 m, ~5000 mm/year (Lozano & al., 2009); and Guaramacal, 3100 m, > 3200 mm/year and relative humidity of 100% during most part of the year), while drier and higher elevation páramos are grouped to the lower left corner of DCA(a) and upper left corner of PCA(b).However, that humidity relationship is not obvious for dataset B (that with Guaramacal only open páramo genera), where páramo sites seem to be arranged mainly in relation to an altitudinal gradient in axis 2 of PCA(d).
Compared to other generic páramo floras (Table 5), Guaramacal shows the greatest proportion of Neo tropical montane element genera and the lowest proportion of Andean-Alpine element genera.The proportion of the Holarctic element is the lowest of all páramo floras compared, but the Cosmopolitan element is the highest.
Páramos of Colombian Cordillera Oriental (S.N.Cocuy and Sumapaz) and Sierra Nevada de Mérida show the most similar proportions of phytogeogra phic elements among them.Páramos of Costa Rica/Pa nama and Tatamá show the lowest proportion of Páramo endemic genera.Páramos of South Ecuador and Guaramacal show both more similar (the highest) proportions of Neotropical genera and also the lowest proportions of Holarctic genera.

Floristic features
As in almost all páramo and other alpine floras (Rangel-Ch., 2000b;Vargas & Sánchez, 2005; Rivera-N.L. Cuello & al. Díaz, 2007;Rangel-Ch. & al., 2008;Briceño & Morillo, 2002, 2006;Lozano & al., 2009), Asteraceae and Poaceae rank as most dominant in terms of genera and species (Table 2).Remarkable for the páramo of the study area is the third position of Ericaceae with 10(8) genera and 15(13) species.Orchids and Grammitidaceae take the 4 th and 5 th position respectively in the general flora list, but for proper páramo flora only, Lycopodiaceae is more diverse.The relative importance of pteridophytes under wet climate is also sup- In terms of number of species (Table 2) Elaphoglossum, Huperzia and Hymenophyllum and Chusquea take the first four positions in the general flora list.For páramo flora only, Chusquea, Huperzia and Rhynchospora with six species are the most diverse genera.The high diversity of Rhynchospora is remarkable.Rhynchospora sect.Paniculatae is supposed to be derived from lowland savanna stock (Wayt Thomas, pers.comm.).Earlier it was supposed that the ascent to the Andean páramos from savanna flora was most likely from the lower ranges of the eastern extreme/ end of the Andes of Venezuela (Cleef & al., 1993).Rhynchospora oreoboloidea Gómez-Laur. of the Holarctic sect.Oreoboloides, a common species of the lower páramos in the northern Andes and in the Talamancas, is absent in the Guaramacal páramo.In Colombian páramos hardly there are found 6 different species of Rhynchospora in one study site.
In conclusion, the taxa listed in Table 2 are almost all indicative of wet páramo climate.Hypericum and Pentacalia contain species thriving both under wet and drier páramo climate.

Phytogeographical composition at genus level
Based on the studies of the Tatamá páramo flora (Cleef, 2005) or that of the Talamancas in Costa Rica (Cleef & Chaverri, 1992) we expected that humidity would play a role in determining the floristic composition of the Guaramacal range.In fact values for the Neotropical montane element (38.9%) are high in the Guaramacal páramo, as well as for the Austral-Phytogeography páramo flora Andes Antarctic element (11.1%).Increased values for the Austral-Antarctic element also have been observed in the Podocarpus National Park, Tatamá and Talamanca páramos.However the substantial proportion of the Neotropical montane element may also be related to the low altitude of the Guaramacal range, 3000 m more or less, and one summit at 3130 m.Páramo endemic genera rank low (2%), probably also because of the general low altitude and one predominant humid climate type.There are also fewer distinct habitats in the Guaramacal páramo, as caused by the limited altitudinal amplitude of maximally about 200 m, but most of the range even less.It is striking that the Andean-alpine element is represented only by one genus (Lachemilla) and that the Holarctic element only accounts for 3.6%.Genera belonging to both these elements are mostly herbaceous and favoured by higher altitude.Further they are well adapted to periodical stress by dryness (Gutte, 1992).We suppose that bamboo páramo has been present in the summit area of Ramal de Guaramacal since Holocene times and that the prevailing wet climate served as a kind of filter preventing the arrival or survival of dry páramo species from the Mérida páramos.
Another interesting feature is the relative isolation of the Guaramacal páramo from the main cordillera of the Sierra Nevada de Mérida.A small connection is found on the northern side at about 2200 m.During glacial times the summit areas of Guaramacal range were glaciated; remnants of former glacial lakes with terminal moraines are still present at different sites in the páramo belt as well as at lower altitude of about 2000 m near the Park headquarters.Páramo vegetation actually occurred during glacial times at lower altitude along the very steep slopes.In the uppermost part of Guaramacal range with a type of superpáramo, which is completely absent today.Isoëtes karstenii, a submerged species found from grass páramo up to the highest lakes in the superpáramo in Colombia (Cleef, 1981;Salamanca & al., 2003) and Venezuela (Fuchs-Eckert, 1982;Small & Hickey, 2001) has been found in a small lake in the Guaramacal páramo.Its presence in a glacial lake in the modern páramo of Ramal de Guaramacal can probably be considered as a 'glacial relict'.The Temperate component is best represented in azonal páramo vegetation (Sphagnum bogs) on top of Ramal de Guaramacal (Fig. 2c).
When the genera of the SARF vegetation in the Guaramacal bamboo páramo are taken into account the overall proportion of the Tropical component rises from 53.6% to 61.6%, mainly because of more Neotropical montane and Wide tropical genera.For comparison with other páramo floras (Table 5), the taxa from SARF vegetation (column a) have not to be considered, though, sometimes this is difficult to do as well.Looking at the case of the extremely humid páramos of Podocarpus National Park in southern Ecuador (Lozano & al., 2009), with a gradual transition of SARF into shrub páramo, it is noticeable that even the trees adapt to the general structure of shrub páramo vegetation (Bussmann, 2002;Richter & Moreira-Muñoz, 2005;Peters, 2009, Lozano & al., 2009;Cleef, pers. obs.).

Species geographic range
The tropical American part of the vascular flora of Páramo de Guaramacal is largely composed of (1) Neotropical widespread distributed species all over the Neotropics or in a wide range from Central America to Bolivia, (2) a group of Andean distributed species, part of them confined to the northern Andes and part widespread in the Andes from Colombia to Bolivia, and (3) a group of Venezuelan endemics (Table 4).
There is quite a difference between the 156 species with defined geographical distribution range reported for the Guaramacal páramo and the 229 species for the páramo including the SARF islands of Guaramacal.However, the phytogeographical proportions change slightly between both data bases: they maintain rather the same percentages.Looking more closely at the three main distribution types of the Guaramacal páramo flora (sensu stricto, without the SARF islands) we can state that there are 50 species, i.e. ca.32%, for the groups or distribution types 1-5 (e 4), these species displaying a more wide Neotropical distribution.The second and largest species group includes the distribution types 6-9 and is basically tropical Andean in distribution and accounts for seventy six species or about 49%.Group 10 contains thirty species (about 19%) all endemic to Venezuela.
N.L. Cuello & al.Ten spe cies (6.4%) are narrow endemics of the Guara macal páramo.They include 3 species of Espeletiinae stem rosettes: two species of Ruilopezia, and one species of Libanothamnus.Also, two species of Mi conia, one species each of Bomarea, Epidendrum, Fes tuca, Ilex and Rhynchospora.
About 70 species or about 30% of the Guaramacal páramo species are shared with Central America -surprising given the distance and remoteness of Ramal de Guaramacal, although 30 of them correspond to ferns (Table 4).In contrast, only 3 species (1.9%) are shared with the Guayana Highlands which are at much closer distance indicating lack of exchange between these two areas.Most remarkable is the northernmost extension of the bamboo species Chusquea steyermarkii.

Páramo flora relations
We found a strong floristic similarity and similar phytogeographical composition among the páramo floras of Sierra Nevada del Cocuy, Sumapáz and Mérida páramos (Figs. 3, 4; Table 5).These mountain chains are contiguous in geographical position and display similar climatic characteristics with regard to the exposition of the ascending trade winds loaded with atmospheric water and the drier wind shadow areas.The Central American páramos of Panamá and Costa Rica, which are more humid, present about 75% similarity of páramo flora with those of the Mérida and Colombian Eastern Cordillera páramos (Fig. 3a).The Colombian Perijá páramo (drier side) ranks with about 40% similarity versus the wet páramo cluster of Guaramacal and PNP in S. Ecuador.Both remote páramo floras are similar at about a 60% value, which is most remarkable, because of the large distance between both areas.The similarity between the pá ramo floras of Guaramacal and PNP of South Ecuador is observed only when considered the páramo and SARF genera of Guaramacal (Fig. 3a).
When considered only open páramo genera of Guaramacal (Fig. 3b), the páramo flora of Guaramacal is not related to any other of the paramo floras analyzed, and in this case PNP (South Ecuador) flora appears to be rather related with the group formed by the páramo of Perijá and the group of drier and higher paramos of S. Cocuy, Sumapáz and S.N.Mérida, conversely, in this case, the páramo flora of Costa Rica/Panama has little relationship with this group.On the other hand, in the DCA and PCA ordinations, when SARF genera of Guaramacal are not included (Fig. 4c, d), the relationship to a humidity gradient is not so obvious, and an altitudinal gradient seem to prevail in PCA (Fig. 4d), while in the DCA (Fig. 4c) the relationship to those environmental variables is not so clear, and instead of them a latitudinal gradient may be detected.
Judging from the results it is most clear that the wet páramos floras are more similar to each other than to seasonally dry páramos (containing both dry bunchgrass páramo and bamboo páramo).In the case of the exclusively wet páramos it appears that humidity is more important than a temperature gradient.In fact the Ecuadorian Podocarpus National Park and Guaramacal páramos are similar in that both are relatively low in altitude with a maximum of about 200 m altitudinal amplitude in Guaramacal and about 400-500 m in the Podocarpus National Park although the highest core area of the latter reaches ~3700 m in elevation.That the ambient humidity gradient apparently overrules that of temperature (viz.altitude), seems also confirmed by the DCA en PCA ordination diagrams of Fig. 4 (a, b), which are based on a comparison of eight páramo floras.
páramo and SARF combined (Fig. 3a), however no relationship of Guaramacal to any other páramo flora is observed when taking into account only the open generic páramo flora of Guaramacal.Fig. 4 shows the resulting DCA (a, c) and PCA (b, d) ordination diagrams for both A (a, b) and B (c, d) datasets of presence/absence of genera and 8 páramo floras analyzed.An altitudinal gradient may be represented on axis 1 of DCA (a) and axis 2 of PCA (d), while a humidity gradient is mainly captured by axis 2 of PCA (b).

Table 1 .
Reference information for the eight páramo flora dataset used for comparative multivariate analysis.

Table 2 .
Most diverse families and genera from the vascular flora of summit areas (including SARF and excluding exotic weeds) of Ramal de Guaramacal, Andes, Venezuela.For only proper páramo flora numbers of taxa are indicated in parenthesis.

Table 4 .
The closest relationships (about 90%) among páramos is observed between the generic páramo floras of the Colombian Cordillera Oriental of each Sumapaz and Sierra Nevada del Cocuy, which are both closely related to Sierra Nevada de Mérida in Venezuela.The generic páramo flora of Ramal de Guaramacal shows the closest relationship to southern Ecuador páramo flora of Po docarpus National Park, with more than 50% similarity, when considering Guaramacal generic flora from Analysis of the geographic range of the páramo flora based on 229 taxa with a defined geographical range in Appendix 1.
F, ferns and fern allies; A, angiosperms; %, percentage of total vascular species.Numbers in parentheses are percentages of total Venezuelan endemics.