Establishing a baseline of plant diversity and endemism on a neotropical mountain summit for future comparative studies assessing upward migration: an approach from biogeography and nature conservation

Abstract

Climate change is forcing many plant species to shift their range in search of adequate environmental conditions, being localized endemic species particularly at risk on mountain summits. The Pantepui biogeographic province, a set of flat-topped mountain summits (called tepuis) of northern South America, contains both high plant diversity and a high degree of endemism. Previous studies based on warming projections for the area suggested that half of the Pantepui endemic flora would disappear due to habitat loss by 2100. In this study, we selected one of the best-explored tepuis, Roraima-tepui, to establish the baseline of diversity and endemism for comparisons with historical data and future monitoring surveys, aimed at testing the hypothesis of upward migration of plants in response to global warming. We also analysed floristic and physiognomic features of the Eastern Tepui Chain (ETC, the mountain range where Roraima is located), and the phytogeographic patterns of both the ETC and Pantepui. The Roraima summit contains 227 species, including 44 new records, 13 exotic species (some of them with high invasive potential), and at least one species new to science. At the ETC level, Roraima is the tepui with highest species richness and degree of endemism, and shows a relatively high floristic similarity with Kukenán and Ilú. Herbaceous species dominate over shrubs on these tepuis, Tramen and Maringma, whereas on Yuruaní, Karaurín and Uei, they reach similar abundances. At the Pantepui level, endemic species have highly localized distribution patterns (17% local endemics). Conservation opportunities are evaluated in light of these results.

Key words:

• climate change
• floristic survey
• Guayana region
• Pantepui
• phytogeography
• plant invasion

Acknowledgements

This research was supported by the BBVA Foundation (project BIOCON 08-188/09 to Valentí Rull). Fieldwork permits were granted by the National Commission for the Protection of Tepuis, the National Office of Biological Diversity of the Ministry of Environment of Venezuela (ref. PRE-CE-2010-001), the National Parks Institute (refs. PAA-261-2010 and PAA-010-2012), and the indigenous community of Paraitepuy de Roraima. We thank our guides Elías Lezama and Marcos Wilson for their support in the field. Montserrat Roig, Encarni Montoya, Jesús Hernández and Francisco Oliva collaborated on the logistics of the expeditions. We thank the following botanists for their help with the identification of botanical material: Alan R. Smith and Julián Mostacero (pteridophytes), Gerardo Aymard (Rhamnaceae), Germán Carnevali (Orchidaceae), Gerrit Davidse (Cyperaceae, Poaceae), Gilberto Morillo (Apocynaceae), José Ramón Grande (Lentibulariaceae), Paolo Pedraza (Ericaceae) and John Pruski and Vicki Funk (Asteraceae). We are also grateful to the following herbaria for providing information on the species of interest: VEN, GUYN, MYF, MY, CAR, US and MO, and to Charles Brewer Carías, Carol Kelloff and Philippe Kok for providing maps and photographs of the ETC summits.

Associate Editor: Nadia Bystriakova