Grassland community structure in Permanent Preservation Areas associated with forestry and livestock in the Pampa biome, Southern Brazil

The Pampa biome comprises a high species richness, but has been transformed by various human activities, threatening its inherent diversity. One of the mechanisms that contributes to conservation is the Permanent Preservation Areas (PPA); however, studies related to the vegetation of these areas are scarce, especially regarding the herbaceous stratum, creating a gap in the evaluation of the conservation of the Pampa biome's grassland formations. The objective of this study was to characterize the structure of fragments of grasslands in PPA, with and without cattle grazing, inserted in a plantation of Eucalyptus saligna Sm. in the Pampa biome. The survey was conducted on 40 systematically distributed sample units in six grassland areas, three of which were occasionally exposed to grazing and three fenced off with no grazing. Cover and frequency val-ues (absolute and relative) and importance value index (IVI) were estimated for species, exposed soil and dry plant material. The difference between the areas was evaluated by the Principal Coordinate Analysis (PCoA) and ANOSIM, complemented by SIMPER. Richness, dry plant material and exposed soil were evaluated using the Kruskall-Wallis test. A total of 210 species were registered, with the Poaceae family being the most numerous, followed by Asteraceae (41), Cyperaceae (19), Fabaceae (12) and Rubiaceae (9). The areas differed in relation to richness, with grazing showing more diversity. Enclosure Area 3 did not differ from open areas 2 and 3, possibly due to the greater proximity and low cattle interference. The exposed soil did not vary according to the enclosure; however, the dry plant material was higher in the enclosed areas. The distribu-tion of species, as well as their cover and frequency were regulated according to grazing. The presence of ani-mals in PPA has modified the dynamics and botanical composition of the areas, in which richness was promoted. (c) 2021 SAAB. Published by Elsevier B.V. All rights reserved.

Automated summary

The study characterized the structure of grassland fragments in the Pampa ecosystem with and without cattle grazing, revealing that grazing areas had more diversity while enclosed areas had more dry plant material.