Die Tropenstation La Gamba

Die „Tropenstation La Gamba“ in Costa Rica – Wissenschaftlicher Bericht
Non-indigenous plants in a tropical lowland region in Costa Rica
Huber W, Weissenhofer A, Mayer V, Schaber D, Schembera E,
University of Vienna, Department of Palynology and Structural Botany, Austria
4 th European Conference on Biological Invasions, Vienna, 27. – 29. Sept. 2006
We report an investigation of vascular plants in a wet tropical lowland region of southern
Costa Rica (near the Tropenstation La Gamba – www.lagamba.at). We recorded
vegetation composition in 18 different habitats, using vegetation plots with sizes ranging
from 2.25 to 1,500 m 2 . A total of 770 species of vascular plants were found. Of these, 25
(3.2%) were non-indigenous.
The habitats investigated ranged from primary forest to cultivated land. The average
annual precipitation of 5,690 mm, the annual mean temperature of nearly 28°C and the
absence of a pronounced dry season (Weber et al. 2001) have resulted in the establishment
of a “perhumid tropical lowland wet forest”. During the time of cultivation and increasing
land use, especially since the beginning of the 20 th century when the United Fruit
Company began to clear forest, largely for banana cultivation, plants from other tropical
regions have been introduced into the area around the Golfo Dulce. Agricultural land with
plantations of trees, manioc or rice and pasture is now common and primary forest is
largely restricted to the national parks (Corcovado and Piedras Blancas).
No exotic plant species were counted in the primary research plots on the ridge, in the
clearing with the dominant fern Dicranopteris, on the rock in the surge and in the steep
coastal forest of the Golfo Dulce. In the plots of cultivated land (plantations) more nonindigenous
plants were found. Six species were counted in the teak (Tectona grandis)
plantation and four in the Gmelina arborea plantation. In the pasture land, swampy
pasture land and pasture edges we found a total of seven non-indigenous plants. On the
two coastal research plots, three non-indigenous plants were identified. In two natural
habitats on the coast of the Golfo Dulce the non-indigenous Cocos nucifera and
Terminalia catappa are the dominant arboreal species.
The alien fern Nephrolepis multiflora is dominant in wet, open areas outside the forest. In
total there are more non-indigenous plants outside the primary forest, especially in pasture
land and cultivations. The invasion of alien plants in the tropical lowlands of south-west
Costa Rica is not as pronounced as in the country's highlands (Bernhard & Koch 1994).
The non-indigenous vascular plants we identified are Allamanda cathartica
(Apocynaceae), Arachis pintoi (Fabaceae), Cocos nucifera (Arecaceae), Citrus
aurantifolia (Rutaceae), Terminalia catapa (Combretaceae), Costus speciosus
(Costaceae), Desmodium adscendens( Fabaceae), Eichhornia crassipes (Pontederiaceae),
Elaeis guineensis (Arecaceae), Emilia fosbergii (Asteraceae), Ficus benjamina
(Moraceae), Gmelina arborea (Verbenaceae), Hedychium coronarium (Zingiberaceae),
Kyllinga odorata (Cyperaceae), Lagerstroemia speciosa (Lythraceae), Ludwigia
hyssopifolia (Onagraceae), Ludwigia octovalvis (Onagraceae), Mimosa pudica
(Mimosaceae), Nephrolepis multiflora (fern, Oleandraceae), Quararibea cordata
(Malvaceae/Bomb.), Senna alata (Caesalpiniaceae), Syzygium jambos (Myrtaceae) and
Tectona grandis (Verbenaceae).
Literature:
Bernhard KG & Koch M. (1994): Eingeführte Pflanzen aus Europa als Bestandteil der
Vegetation Costa Ricas (Zentralamerika). – Bauhinia 11/2: pp. 121-127.
Weber A., Huber W., Weissenhofer A., Zamora N., Zimmermann G. (2001): An
introductory Field Guide to the Flowering Plants of the Golfo Dulce Rainforests -
Corcovado Nationalpark and Piedras Blancas Nationalpark ("Regenwald der
Österreicher"). – Linz: OÖ Landesmuseum Stapfia 78: pp. 462.
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