A Short Description:
The phyllosphere (upper surface of leaves) of understorey plants in tropical rainforests frequently show a dense cover of epiphylls. These organisms belong to various taxonomic groups, where foliicolous lichens (Farkas & Sipman 1993) and foliose liverworts (Gradstein 1997, Lücking 1997) are the most frequent. Moreover numerous members of bacteria, cyanobacteria, algae and fungi occur.
The hot spot of tropical bryophytes are located in montane cloud forests, where they grow terrestrial, lithophytic, epiphytic and epiphyllous. In lowland rain forests (0 - 500 m a.s.l.) diversity is usually rather low. Bryophytes of lowland rain forests are dominated by liverworts belonging to the family of Lejeuneaceae, which often colonize upper surfaces of vascular plants with humid conditions (Gradstein, Churchill, Salazar-Allen 2001).
The main focus of my research is the colonization of vascular plants with epiphyllous bryophytes and influences of environmental parameters. Collection of leaf samples and microclimate parameters were performed along a topographical transect in the lowland forest "Esquinas", southwest coast of Costa Rica (N 8°41´, W 83°13´), an area with high precipitation (6240 mm/a).
2. Material and Methods
Three characteristic sample sites - ravine, slope, ridge - were selected on the assumption of different microclimates - humid, intermediate, comparatively dry - leading to the hypothesis that the different climatic parameters will cause differences in epiphyll colonization.
Four species of understorey plants with five individuals on each sampling site were identified: Carludovica
drudei (Cyclanthaceae), Asplundia pittieri (Cylanthaceae), Costus
laevis (Costaceae), Dieffenbachia sp. (Araceae).
From each plant two leaves were collected, leaf area and percentage of epiphyll cover (only bryophytes) were determined and the leaves dried and archived in vouchers for later taxonomic analysis.
Taxonomic analysis of collected material was carried out at "Systematische Botanik, University Göttingen" and "Dep. CVL, University of Vienna". As the colonization of the leaves by epiphyllous bryophytes can result in extremely heterogenous growth patterns random sampling was chosen to select 12 locations on each leaf. For each location measuring 1 cm² all bryophyte species were identified by means of binocular, microscope and key information from literature.
Microclimatic parameters - humidity, temperature and available light - were recorded for each sampling site. Humidity and temperature were recorded by data loggers. For determination of potential light consumption hemispherical photographs by means of a fisheye lens were taken and processed with the tool "Hemiview Canopy Analysis Software 2.1" (Delta-T Devices Inc.).
Data on occurrence of identified species, hostplant characteristic, microclimate parameters and available light will be submitted to statistical analysis.
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Coley, P. D., Kursar, T. A.,1996: Causes an Consequences of epiphyll colonization.In Mulkey et. al. (eds.). Tropical forest plant ecophysiology, 337 –362.
Coley, P. D., Kursar, T. A. and Machado, J.,1993: Colonization of tropical rain forest leaves by epiphylls: Effects of site and host plant leaf lifetime. Ecology, 74(2), 619– 623.
Farkas, E. E.,Sipman, H. J. M.,1993:Checklist of Foliicolous Lichens and their Lichenocolous Fungi. Trop. Bryol. 7: 93 – 148.
Gradstein, S. R.,1992a: The vanishing tropical rain forest as an environment for bryophytes and lichens. Pp. 234-258 in Bates, J. W. & Farmer, A. W. (eds). Bryophytes and lichens in a changing environment. Clarendon Press,Oxford.
Gradstein, S. R., 1992b: Threatened bryophytes of the neotropical rain forest: a Status report. Tropical Bryology 6:83-94.
Gradstein, S. R., Hietz P., Lücking, R., Lücking, A., Sipman, H. J., Vester, H. F. M., Wolf, J. H. D. & Gardette, E.,1996: How to sample the epiphytic diversity of tropical rain forests. Ecotropica 2:59-72.
Gradstein, S. R.,1997: The taxonomic diversity of epiphyllous bryophytes. Abstr. Bot. 21(1): 15-19.
Gradstein, S. R., Churchill, s. P., Salazar-Allen, N., 2001: Guide to the Bryophytes of Tropical America. Memoirs of The New YorkBotanical Grarden Volume 86.
Gradstein, S. R., Hietz, P., Lücking, R., Lücking, A., Sipman, H. J. M.,Vester, H. R. M., Wolf, J. H. D. and Gardette, E., 1996:How to sample the epiphytic diversity of tropical rain forests. Ecotropica 2: 59–72.
Lücking, A., 1997: Diversity and distribution of epiphyllous bryophytes in a tropical rainforest in Costa Rica. Abstr. Bot. 21(1): 79-87.
Monge-Nájera, J., 1989: The relationship of epiphyllous liverworts with leaf characteristics and light in Monte Verde, Costa Rica. Cryptogamie, Bryol. Lichenol. 10 (4): 345 –352.
Pócs, T., 1995: Epiphyllous liverwort diversityat world-wide level and itsthreat and conservation. InC. Delgadillo M. (ed.), International Bryological Conference: Tropical Bryophytes: Biology, Diversity and Conservation, 40 –41.
Roskoski, J. P.,1981: Epiphyll dynamics of a tropical understory. OIKOS 37: 252 – 256.
Wanek, W., Pörtl, K., Wania, R., 2004: Effects of epiphyll colonization on phyllosphere nutrient relations in a tropical wet forest, Costa Rica.- Proceedings of the 2nd Symposium of the A.F.W. Schimper-Foundation. Breckle, .-W., Schweizer, Birgit and A. Fangmeier (Eds), 129-144.
Weber, A. et. al., 2001: An introductory field guide to the flowering plants of the Golfo Dulce Rain Forests Costa Rica. Stapfia 78, HRSG.: Biologiezentrum des OÖ Landesmuseums.