Evaluation of factors that affect the spatial distribution of alien shrubs to monitor their invasion in a Pampa protected landscape in Tandil, Argentina

Abstract

Invasive alien plants which replace native species represent a global threat that compromises biodiversity conservation by simplifying and homogenizing the landscape. The present study focuses on the problem of invasions in a mountainous area of the pampas (Tandil, Argentina) where several alien shrubs behave as invaders displacing a high diversity of native grassland. The aim of the study was to analyze, by means of geographical information system, the distribution of the most conspicuous alien shrub populations in relation to natural and anthropogenic factors in a protected area of landscape of the pampa region, in order to contribute to decision making and management based on knowledge. The selected working areas were those with spontaneous vegetation, conducting unsupervised classification of SPOT satellite images. A number of points in invaded areas were georeferenced in field to control the classification made by geographical information system. To measure the influence of the factors analyzed in the dispersal processes of the species spatial logistic regression techniques were used. Results showed that 20.40% of the study area was occupied by alien species of which 11.06% were tree plantations made by man and 9.34% corresponded to three alien shrub species distributed invading different landscape sections: Genista monspesullana occupied 307.85 ha, Rubus ulmifolius 237.82 ha and Spartium junceum 126.55 ha. In order to explain R. ulmifolius propagation all the analysed variables except quarries and pits were significant, but streets, roads and trails and stone fences had a stronger incidence. For S. junceum the significant explanatory variables were quarries and pits, altitude and slope. For G. monspesullana the explanatory variable was streets, roads and trails.

An annotated list of the reptiles of the highland grassland of Tandilia Mountains, Argentina

“…Woody invasive species are common in some highland grassland remnants being pines (Pinus sp.) Spanish broom (Spartium junceun), Australian blackwood (Acacia melanoxylon), French broom (Genista monspessulana) and blackberry (Rubus ulmifolius) the most common ones (Kacoliris et al 2013;Márquez et al 2019).…”

“…The biodiversity of the Tandilia Mountain System remnants is facing a combination of threats (Kacoliris et al 2013). Invasive woody plant species are replacing the grassland and homogenizing the landscape (Zalba and Villamil 2002;Márquez et al 2019). The overgrazing, quarry activities, and the urban growth over the mountains accentuate the degradation, fragmentation, and isolation of grassland remnants (Cepeda et al 2013).…”