Diversity of vascular epiphytes along an altitudinal gradient in Veracruz, Mexico Valeria Guzmán-Jacob1, Thorsten Krömer3, Gerhard Zotz2, Holger Kreft1 1
Biodiversity, Macroecology & Conservation Biogeography Group, University of Göttingen,
[email protected] 2 Universität Oldenburg, Institut für Biologie und Umweltwissenschaften, AG Funktionelle Ökologie 3 Centro de Investigaciones Tropicales (CITRO), Unversidad Veracruzana, Xalapa, Ver., Mexico
Introduction Vascular epiphytes are non-parasitic plants growing on other plants, commonly trees, without contact to the soil (Zotz 2013). They are diverse elements of tropical forests. Despite their ecological importance, vascular epiphytes are among the least studied plant groups.
Results We recorded a total of 372 vascular epiphyte species, distributed in 15 families and 87 genera. The most representative groups in the mid-elevations were pteridophytes, followed by orchids and bromeliads, whereas orchids were dominant in the lower part (Fig. 4).
Question How do diversity, floristic composition, and species distributions of vascular epiphytes change along gradients of elevation and anthropogenic disturbance?
100
Others
80
Species
Study site Central region of Veracruz State, Mexico, between 15 and 3500 m of elevation, (Figs. 1 and 2).
120
Araceae 60
Cactaceae Piperaceae
40
Bromeliaceae 20
Orchidaceae Pteridophyte
0 15
500
1000
1500
2000
2500
3000
3500
Elevation (m a.s.l.) Fig. 4: Number of species per taxonomic group in each elevational belt.
Old Growth forest Disturbed Secondary
Fig. 1: Central Veracruz, Cofre de Perote slope, (CarvajalHernández & Krömer 2015).
Fig. 2: Cofre de Perote mountain and La Mancha, biological station.
Methods • Eight different elevational belts of 500 m each. • Six different types of vegetation, (Fig. 3). • A total of 120 plots, five in each of three levels of disturbance. • One mature tree per plot were climbed, from the base to the outer portion of the tree crowns. Fig. 5: Number of species in each elevational belt, showing differences between the disturbance gradient.
The highest species richness was found at 1500 m elevation in the old-growth forest pteridophytes contribute about 50% of all species. The disturbed forest plays an important role in the conservation of species, showing surprisingly a higher species-richness than in the old growth forest.
Fig. 3: Locations: 1) La Mancha (0-20 m); 2) Palmarejo (500 m); 3) Chavarrillo (1,000 m); 4) Los Capulines (1,600 m); 5) El Zapotal (2,000 m); 6) El Encinal (2,500 m); 7) Los Pescados (3,000 m) and 8) El Conejo (3,500 m).
Brassavola cucullata
Peperomia sp.
Tillandsia imperialis
Anthurium scandens
Pinguicula moranensis
Acknowledgements: DAAD scholarship number: 91570360. Field work assistants: Samaria Armenta, Alma Bautista, César Carvajal, Emmanuel, Pedro Díaz, Jorge Gómez, Calixto, Noé Velazquez, Joaquim Vea, Leticia, Daniela Vergara, Evelin, José Manuel, Roberto, David, Meraiz. The research stay of Thorsten Krömer is supported by CONACyT.
Discussion • The number of species recorded in this study is twice as high, as in the study conducted in the same area by Hietz et al. (1994) along an elevational gradient between 720-2370 m. • The decrease in species richness at 1000 m is probably due to the scarcity of good phorophytes and the lower air humidity might be a negative factor for their establishment. • Above 3000 m the number of species decreases considerably, probably because of periodic freezing temperatures.
Prosthechea vitellina
Asteraceae
Tillandsia violacea
Epiphyllum sp.
Ericaceae
References Zotz, G. (2013) The systematic distribution of vascular epiphytes: a critical update. Botanical Journal of the Linnean Society, 171, 453–481. Perry, D.R. (1978) A method of access into the crowns of emergent and canopy trees. Biotropica 10, 155-157. Carvajal-Hernández, C.I. & Krömer, T.(2015) Riqueza y distribución de helechos y licófitos en el gradiente altitudinal del Cofre de Perote, Centro de Veracruz, México. Botanical Sciences 93, 601-614. Photographs: Valeria Guzmán-Jacob
