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.
Highlights
Biodiversity plays a key role in the balance and stability of life in human development
This study focuses on the problem of invasions occurring in a protected landscape area of a mountainous region of the Pampas (Tandil, Argentina) where several alien shrubs behave as invasive displacing a high diversity of native grassland
Out of the total 3,481 ha of the complementary analysis area, 717.87 ha are occupied by alien woody plants, which represent 20.62% of the complementary area. These are constituted by 10.95% (381.45 ha) of groups of alien trees, planted or invaders, 4.09% (142.48 ha) of G. monspessulana, 3.64% (126.87 ha) of R. ulmifolius, and 1.93% (67.07 ha) of S. junceum (Table 2)
Summary
Biodiversity plays a key role in the balance and stability of life in human development It is responsible for several ecological services in ecosystems: taking part in the regulation of the composition of atmospheric gases, protecting coastal areas, regulating hydrological cycles and climate, generating and preserving soils, dispersing and degrading waste, pollinating crops and absorbing pollutants among others. Invasive alien plants compromise biodiversity conservation taking the place of native species, simplifying and homogenizing the landscape. It is necessary before the species have spread widely that they be targeted for eradication if a feasible method can be identified (Mack et al, 2000; Simberloff et al, 2013; Simberloff, 2014). They can be as harmful for native species and ecosystems as habitat loss and degradation (IUCN, 2000)
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