Open Access

ARTICLE

Grasslands Response to Livestock Grazing Intensity in the Austral Pampas (Argentina): Testing the Intermediate Disturbance Hypothesis

Ana Elena de Villalobos^1,2,*, María Andrea Long^1,2

1 Grupo de Investigación en Ecosistemas de Pastizal (GIEP), CERZOS, CONICET, Bahía Blanca, 8000, Argentina
2 Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, 8000, Argentina

* Corresponding Author: Ana Elena de Villalobos. Email:

(This article belongs to the Special Issue: Ecology of Rangelands in Argentina)

Phyton-International Journal of Experimental Botany 2024, 93(8), 2037-2050. https://doi.org/10.32604/phyton.2024.053928

Received 14 May 2024; Accepted 19 July 2024; Issue published 30 August 2024

Abstract

Livestock grazing has a significant impact on natural grasslands, with approximately one-third of the world’s land area dedicated to this industry. Around 20% of global grasslands are highly degraded due to overgrazing, affecting their productivity and conservation capacity. Best practices are required to ensure sustainable livestock production that supports biodiversity. The Intermediate Disturbance Hypothesis (IDH) suggests that environments with moderate levels of disturbance exhibit a higher species diversity. Moderate grazing can reduce the dominance of certain species, thereby enhancing plant diversity. However, concerns arise regarding the increase of exotic and unpalatable species under moderate grazing levels, complicating grassland conservation efforts. The impact of livestock grazing on the functional structure of grasslands depends on factors such as grazing intensity, livestock species, and environmental conditions. Variations in grazing intensity may increase specific and functional diversity under moderate grazing, potentially masking the presence of invasive exotic species. In the Austral Pampas (Pampean phytogeographic province, Buenos Aires, Argentina), grasslands face various pressures from domestic livestock grazing that endanger their integrity if not properly managed. Therefore, our study aims to investigate potential differences in species richness and diversity, functional diversity, exotic plant abundance, and the number and distribution of plant functional groups across varying grazing intensities. The IDH is utilized as a tool to regulate livestock pressure for grassland conservation. Species and functional diversity indices were used to assess the impact of grazing on grassland diversity. Moderate grazing increased species and functional diversity, while intensively grazed or ungrazed areas showed reduced diversity. Livestock presence influenced the balance between native and exotic plants, with ungrazed areas having higher native plant abundance and grazed areas exhibiting higher exotic plant abundance. Grazing also influenced the composition of functional groups, with grazing-avoiding species being more prevalent in heavily grazed areas. Principal Component Analysis revealed a clear association between vegetation composition and livestock grazing intensity. These findings offer valuable insights into effectively managing grazing intensity for biodiversity conservation purposes.

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Keywords

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Supplementary Material

Supplementary Material File

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