Floristic patterns of the neotropical forests, savannas and scrublands with Trithrinax campestris (Arecaceae) in central Argentina

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By Sebastián R. Zeballos, Marcelo R. Cabido, Juan J. Cantero, Alicia T.R. Acosta, M. Virginia Palchetti, Juan Argañaraz, Paula I. Marcora1, Paula A. Tecco, Ana Ferreras, Guillermo Funes, Victoria M. Vaieretti, Georgina Conti & Melisa A. Giorgis

Open palm (Trithrinax campestris) savanna with a shrubby understory dominated by the thorny Vachellia caven on rocky and sandy soils in western Córdoba Province, central Argentina. Photo credit: Juan J. Cantero.

For centuries, palm species have not only captured the attention of naturalists, ecologist, gardeners, but also of food and textile industry. Palm species have a particular distribution, being an important component of plant communities in tropical and subtropical environments. Particularly, Trithrinax Martius is a neotropical genus of palms (Arecaceae) distributed in the subtropical and warm temperate region of South America. In central Argentina, this genus reaches its southern extreme distribution with Trithrinax campestris, inhabiting different vegetation types in the Espinal and Chaco phytogeographical provinces.

Like many palms worldwide, T. campestris is a keystone species for local people that traditionally use its leaves and spines to make handicrafts such as baskets and various other objects. Moreover, in the last decades, mature specimens have been exported to European countries for use in gardening; only in 2003, such export generated an income of 600,000 USD. At the same time, vegetation types with T. campestris are highly threatened by anthropogenic fires, livestock overgrazing, and because many habitats previously occupied by communities with palms have been replaced by soybean and corn crops and by pastures. Consequently, the conservation status of T. campestris nowadays is vulnerable, and there is an urgent call for the development of adequate conservation and restoration strategies based on current knowledge about its distribution and ecology. Therefore, our study aimed to describe the floristic composition of the vegetation types in which this palm occurs in central Argentina, and explore the relationship of these types to various environmental factors and fire occurrence.

Anthropogenic activities threatening the natural populations of the palm Trithrinax campestris: A conversion of closed palm scrubland to agriculture (soybean cultivation) in the northwestern hilly plains of Córdoba Province; and B open grassland savanna after a devastating fire in northern Córdoba Province. Photo credit: Juan J. Cantero (A) and Sebastián Zeballos (B).

Despite the fact that several studies have been done involving this iconic species, none reported the complete floristic composition of the communities in which this palm occurs and neither their relationship with environmental factors. In this article, we reported four vegetation types with T. campestris that differed in floristic composition and in diagnostic species. Differences in floristic composition were related to elevation, topography and climatic variables, but not with the occurrence of fire. Our results showed that either as isolated individuals intermingled in forests, savannas and scrublands, or as denser populations, this palm could occupy sites with different topography and soils along a wide gradient of environmental conditions.

Examples of vegetation types comprising Trithrinax campestris in the study area in central Argentina. A Palm savanna with T. campestris in a matrix of grasslands on gentle hillside slopes; B Scrubland dominated by Vachellia caven and T. campestris on rocky soils; C Mountain Chaco forest dominated by Schinopsis marginata with scattered individuals of T. campestris on steep mountain slopes; and D Espinal forest with Celtis tala, Prosopis nigra and T. campestris on deep soils in lowland areas. (Fig. 2 from Zeballos et al. 2021).

It is accepted nowadays that the current distribution of palms is limited by climatic conditions prevailing during the cold season and that under climate warming scenarios, some palm species may be extending their ranges into higher latitudes and altitudes. Moreover, the knowledge of the effects of human activities (like fire and grazing) on the population dynamics of T. campestris, as well as its germination ecology, is still preliminary. Therefore, future studies should extend the floristic survey to other areas in which the vegetation types comprising T. campestris have been reported. Future successional and demographic studies should also complement our survey to give a more complete picture of the species’ actual conservation status and the vegetation types in which it occurs.

This is a plain language summary for the paper of Zeballos et al. published in the Vegetation Classification and Survey (https://doi.org/10.3897/VCS/2021/59384). This post was prepared by Sebastián R. Zeballos, Marcelo R. Cabido, Juan J. Cantero, Alicia T.R. Acosta & Melisa A. Giorgis.