RESUMEN La estabilidad de los ecosistemas está directamente relacionada con un alto valor de biodiversidad y, en este sentido, los efectos antrópicos han generado condiciones negativas sobre los pastizales naturales. El objetivo del trabajo fue evaluar la respuesta del pastizal natural de un bosque nativo degradado del Espinal argentino con arbustivas por medio de un control químico aéreo en un sistema ganadero con pastoreo rotativo de baja carga instantánea. El estudio se realizó en el Área Natural Protegida Reserva de Usos Múltiples Estancia "El Carayá" ubicada en el centro-norte de Entre Ríos, Argentina. Se realizaron 16 evaluaciones desde el año 2012 al 2015 sobre el sector tratado químicamente con Picloram+2,4-D y tres sectores sin tratamiento. En cada evaluación se cuantificó la cobertura vegetal, la composición florística de las especies forrajeras más representativas y la biomasa vegetal, comparadas mediante pruebas no paramétricas. Los resultados de este trabajo comprueban que la utilización de una técnica de control químico aéreo aumentó significativamente, un 44%, la cobertura y biomasa en las áreas tratadas de las especies forrajeras respecto al testigo. El control químico sobre las arbustivas persistió en el tiempo con una efectividad considerable durante los años de evaluación. Por otro lado, la composición florística de las especies herbáceas no presentó diferencias significativas entre tratamientos.

Herbivory is an important factor to generate spatial mosaics with variations in a plant community composition and organization. The objective of this work was to determine the impact of Atta vollenweideri Forel 1893 nests on herbaceous and shrub vegetation in a degraded native forest of the Espinal ecoregion. The study was carried out in the Protected Area and Multiple Use Nature Reserve called Estancia "El Carayá" (Entre Ríos, Argentina). Ten A. vollenweideri nests were selected by simple random sampling through internal roads, and two transects were drawn from the center of the nest (0 m) up to 60 m away in opposite directions. The line intercept method was used to quantify the percentage of vegetation cover of herbaceous and shrub species, while the floristic composition was estimated by the Canfield method. Afterwards, a nonparametric test between positions and a conglomerate analysis to evaluated distance were applied. Grass species, legumes, and sedges fell in the adjacent areas to nests, highlighting the bare soil at the crest and base of the nests. Fifteen plant species were identified, and two families correspond to monocotyledonous and dicotyledonous species. In conclusion, the nests of A. vollenweideri affect the community of herbaceous and shrub vegetation of the studied degraded native forest of the Espinal ecoregion since these ants perform a high selection of herbaceous species considered as pioneers of plant successions.

In forests, it is possible to sequester the carbon emitted by industrial activities, although global deforestation has recently increased considerably. Protected Areas make a significant contribution to mitigate negative effects of climate change. In this sense, the aim of this study is to estimate the carbon storage of the different types of subtropical native forests in the Protected Area «Estancia El Caraya» (hereinafter -PA «El Caraya»), located in the Mesopotamian Spinal. The study was carried out in the province of Entre Rios, Argentina. We evaluated the carbon stock in the soil and herbaceous, shrub and tree components of five various environments with native forests as the dominant biome. The soil component represented 81% of the carbon stock in native forest, while the remaining percentage is distributed in trees (11%), shrubs (6%), and herbaceous vegetation (2%). Native forest of PA «El Caraya» stores 0.974 t C × km -2 (3.56 t CO 2 × km -2 ), 39.4% less than the world average in this conservation category. These differences are due to the high heterogeneity of the natural environments in the world due to the very diverse ecological conditions. Proper management practice of subtropical native forests in the Spinal Mesopotamian contributes highly to reduction of carbon in atmosphere. Application of forest management techniques in Protected Areas allows obtaining sustainable forests that maximise the potential of this area.

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