Shrub encroachment in Argentinean savannas

Abstract

Abstract. In the Wet Chaco region of Argentina, increasing shrub encroachment in savannas over the last few decades has led to important changes in the structure and functioning of the landscape. Some sectors of this territory are characterized by the appearance of circular clusters of woody patches, dispersed throughout the grassland matrix. The increasing size of these patches leads to a gradual change from grassland to dense shrubland. We studied these circular woody patches in the eastern region of the Argentine province of Formosa and characterized the variation in terms of floristic composition, diversity and predominant seed dispersal mode in different size patches. We observed an increase in species richness, diversity and compositional heterogeneity among patches with increasing patch size. Seed dispersal by animals, especially birds, is an important factor in the expansion of these woody vegetation patches within the grassland matrix.

Are Fabiana imbricata shrublands advancing over northwestern Patagonian grasslands? A population dynamics study involving fire and precipitation

“…Coloured cells show the frequencies for which no significant differences were found. 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2 2 3 1-Annual 2-3 each 4 3-2 each 3 4-1 each 2 5-1 each 3 6-1 each 4 7-1 each 5 8-1 each 6 9-1 each 7 10-1 each 8 11-1 each 9 12-1 each 10 13-1 each 20 14-1 each 30 happens because shrub advance usually induces drastic changes in a landscape stemming from the increase of unpalatable woody species at the expense of palatable grass species, thus reducing the carrying capacity of rangelands (Cabral et al, 2003). However, biodiversity changes are relative to the analysis of spatial scale.…”

Detection of two intermixed invasive woody species using color infrared aerial imagery and the support vector machine classifier

“…Remote sensing techniques for accurate mapping of invasion offer a unique set of advantages including repeatability, large area coverage, and cost-effectiveness over ground-based methods over time and space. [34][35][36] Extent of mesquite distribution has been well reported from southwestern United States, South America, Australia, and India, [37][38][39][40] while that of juniper distribution is well recorded. 19,[41][42][43] As both species occupy a significant area of grasslands and rangelands, their invasion has raised several environmental concerns around the world.…”

Facilitation by a Spiny Shrub on a Rhizomatous Clonal Herbaceous in Thicketization-Grassland in Northern China: Increased Soil Resources or Shelter from Herbivores

“…The encroachment of woody plants into grasslands, or the thicketization of grasslands, occurs worldwide (Archer, 1995; van Auken, 2000; Asner et al, 2003; Cabral et al, 2003; Laiolo et al, 2004; Brook and Bowman, 2006; Wigley et al, 2010; Soliveres et al, 2014; Masson et al, 2015). Possible drivers of these changes in the vegetation structure include climate change (Fensham et al, 2005; IPCC, 2013), livestock grazing (Brown and Archer, 1999; Sharpe and Bowman, 2004), altered fire regimes (Brook and Bowman, 2006; Srinivasan, 2012), and elevated carbon dioxide (Bond and Midgley, 2000).…”