Plant species diversity in remnant grasslands on arable soils in the cropping Pampa |
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Authors: | Silvia E Burkart Rolando J C León María C Conde Susana B Perelman |
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Institution: | 1.IFEVA-Facultad de Agronomía,UBA/CONICET,Buenos Aires,Argentina;2.Departamento Recursos Naturales y Ambiente, Facultad de Agronomía, UBA,Buenos Aires,Argentina;3.Departamento Métodos Cuantitativos y Sistemas de Información, Facultad de Agronomía,UBA,Buenos Aires,Argentina |
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Abstract: | In order to provide a baseline for management decisions, we evaluated vegetation heterogeneity among 38 remnant grasslands
located on high agronomic potential soils along a five degree-east–west transect in the cropping Pampa. This extensive region
has been cultivated for well over a century, small-scale traditional forms of agriculture were progressively replaced with
large-scale industrial forms and its cropped area has more than doubled in the last 25 years, threatening the maintenance
of biodiversity associated to productive soils. We characterized the diversity of this grassland patches, identified its main
environmental drivers and searched for factors that favor their invasion by exotic plant species. Vegetation samples were
analysed through Canonical Correspondence Analysis, proportional distribution of functional groups was compared and regression
models were estimated to identify variables associated with exotic species importance. Water availability, determined by climate
and soil characteristics, was the main driving factor of floristic heterogeneity in these grasslands. Exotic richness, mostly
of Eurasian species, increases toward the east, related to proximity to the entrance port. The functional group of C4 native grasses seems to be responsible for biotic resistance to invasion. More than 80% of the species recorded during the
first vegetation registers in 1930 are still present, while the number of exotics was seven-fold increased. Despite covering
small areas as isolated stands, these are hot spots of native biodiversity and must be the object of increasing attention
for conservation and restoration in order to protect the biodiversity of an extensive agricultural landscape. |
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