Species composition, structure, and functional traits in Argentine Chaco forests under two different disturbance histories

Abstract

Over the last two decades, the Chaco region has experienced accelerated land-conversion processes that have developed into a mosaic of disturbances attributable to fires, forest logging, and livestock grazing in its native forests. In this paper, we describe the species composition and structure of two forests in semi-arid Argentine Chaco. Both forests have kept two different land uses in the last three decades: (a) a protected area (NR-Pizarro), and (b) an experimental area (ER-Inta) with land management practices. We analyse changes in species composition and plant functional traits as a response to disturbance history. We differentiate the disturbance history of the last 30 years in both sampling sites. To measure the plant communities, we used transects. We determined species, plant stem diameter, and height of 1315 woody plants >1 cm in diameter. Selected plant functional traits included: growth form, number of stems, spinescence, intensity of sprouts, and leaf texture. We registered 36 native woody species belonging to the Fabaceae and Capparaceae families. We found differences in the species composition of both sampling areas. Plant diameter and height averages decreased when comparing the protected area to the experimental area. Shrubby growth form, coriaceous leaves, absence of spines, and low sprouts were more frequent in the protected area. By contrast, in the experimental area, subshrubs, spines, and high sprouts prevailed. We reaffirmed the gradient of disturbances in both areas. A broader separation in plant functional traits occurred in the two sampling areas due to disturbance histories.