The lowland seasonally dry subtropical forests in central Argentina: vegetation types and a call for conservation

Sebastián R Zeballos,Melisa A Giorgis,María Del Rosario Iglesias,Juan J Cantero,Alicia T.R Acosta,Marcelo R Cabido

doi:10.3897/vcs/2020/38013

Abstract

Aims: The native woody vegetation from the Espinal phytogeographic province in central Argentina, found in subtropical-warm temperate climates, represents part of the southernmost seasonally dry forest in South America. Although this vegetation has been studied for over a century, a complete phytosociological survey is still needed. This lack of knowledge makes its spatial delimitation and the establishment of efficient conservation strategies particularly difficult. The main goals of this study were to classify these forests and assess their current forest cover and to better define the extent of the Espinal phytogeographic province in Córdoba region, central Argentina. Study area: Espinal Phytogeographic Province in Córdoba region, central Argentina (ca. 101,500 km2). Methods: We sampled 122 stands following the principles of the Zürich-Montpellier School of phytosociology; relevés were classified through the ISOPAM hierarchical analysis. The extent of the Espinal phytogeographic province was established by overlaying previous vegetation maps, and a map showing the current distribution of forest patches was constructed based on a supervised classification of Landsat images. Results: Four woody vegetation types of seasonally dry subtropical forest were identified based on the fidelity and the abundance of diagnostic species: (1) Aspidosperma quebracho-blanco forest; (2) Zanthoxylum coco forest; (3) Geoffroea decorticans forest; and (4) Prosopis caldenia forest. These vegetation types were segregated along gradients of temperature and precipitation seasonality and soil-texture and sodium content. The remaining forest patches represent 3.43% of the extent of the Espinal province in Córdoba region of which only 1.05% is represented in protected areas. Conclusions: We present a classification of the Espinal forest based on a complete floristic survey. Despite the dramatic forest loss reported, our results show that some forest patches representative of the Espinal are still likely to be found in the area. However, urgent measures should be taken to establish new protected natural areas in order to preserve the last remaining forest patches. Taxonomic reference: Catálogo de las Plantas Vasculares del Cono Sur (Zuloaga et al. 2008) and its online update (http://www.darwin.edu.ar). Abbreviations: ISOMAP = isometric feature mapping; ISOPAM = isometric partitioning around medoids.

Highlights

Dry tropical and subtropical forests are a potentially extensive set of types in South America (DRYFLOR et al 2016; Kuemmerle et al 2017) and are among the most threatened ecosystems in the world, with ca. 10% of their original extent remaining (Bastin et al 2017)
Since different authors propose different boundaries for the Espinal phytogeographic province, the vegetation survey was carried out in the Espinal area indicated in Figure 1B (Lewis and Collantes 1973), and in areas included in the Espinal by other authors (Cabrera 1976; Cabido et al 2018; Morello et al 2018; Oyarzábal et al 2018)
In this study we provide baseline information concerning the floristic heterogeneity and diversity of native forest types of the Espinal forest region in central Argentina

Summary

Introduction

Dry tropical and subtropical forests are a potentially extensive set of types in South America (DRYFLOR et al 2016; Kuemmerle et al 2017) and are among the most threatened ecosystems in the world, with ca. 10% of their original extent remaining (Bastin et al 2017). Cabrera (1976) defined the Espinal as an “impoverished Chaco” due to the lack of several dominant trees, mainly Schinopsis lorentzii and S. balansae (i.e, red quebrachos) and a lower tree canopy (Bucher 1982; Cabido et al 2018). These differences in floristic composition and physiognomy may be due to changes in temperature (mainly a decrease in annual mean temperature and an increase in frost frequency) in the Espinal as a consequence of the increase in latitude (Bucher 1982; Morello et al 2018)

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Conclusion