Grazers and fires. Their role in shaping the structure and functioning of the Río de la Plata Grasslands

Abstract

The Río de la Plata Grasslands (RPG) are one of the largest areas of open ecosystems (grasslands, shrublands and savannas) in the world. Historically these systems have experienced, and continue to experience, an enormous loss of natural habitats. Moreover, their importance has been largely invisible in comparison to forested systems. The remaining area of open ecosystems in the RPG region varies according to the source from 38% to 58% of the original area. Open Ecosystems (OE) are a special case of agroecosystems because they can combine the provision of both provisioning and regulating and supporting ecosystem services (ES). Preserving the provision of ES in these natural habitats depends, in part, on understanding the role of the two main disturbances operating in them: grazing and fire. Although these two disturbances are natural components of OE, both are manipulated by humans. In this paper we reviewed the role played by fire and grazing in the structure and functioning of the RPG starting from the late Pleistocene and summarizing current evidence on the effects of fire and grazing on vegetation, fauna and biogeochemical processes. The evidence indicates that among agricultural activities, direct grazing systems in OE have the lowest environmental footprint. And, at the same time are the key for habitat preservation and ES supply. Overall, the OE of the RPG still represent a high proportion of the area, are capable of covering 2.5% of the world's population needs of high quality protein, and at the same time guarding the regulation of key processes.

Understanding the changes induced by the incorporation of trees in low densities into livestock systems: relevance of a long-term interdisciplinary experimental platform

“…The Río de la Plata grasslands, an expansive region encompassing Uruguay and portions of Brazil and Argentina, constitute one of the world's major areas of natural pastures, spanning over 700,000 km2 (Baeza & Paruelo, 2020). Within this important ecosystem, recognized for its environmental services such as carbon sequestration, erosion control, and water quality preservation, a wide diversity of C3 and C4 herbaceous species coexist, which represents the primary forage substrate for a cattle herd of over 50 million of heads (Paruelo et al 2022). In this context, the central challenge in integrating the tree component lies in preserving the existing ecosystem services offered by this resource.…”

“…It's worth noting that the knowledge surrounding Soil-Plant-Atmosphere interactions, often derived from other regions, does not consider the taxonomic heterogeneity observed in the natural grasslands. These grasslands have a history of coevolution with a low cover of trees and shrubs (Paruelo et al, 2022). Consequently, a comprehensive examination of the response exhibited by the current herbaceous vegetation to the introduction of trees, becomes essential for a thorough viability assessment.…”

Biomass fine‐scale variation is predictive of functional composition and diversity in grazed grassland

“…They are part of the Río de la Plata Grasslands, where they form the so-called northern Campos (Soriano, 1992) extending over Uruguay and southern Brazil (Overbeck et al, 2007). Longterm interaction with disturbances of fire and grazing has played an important role on the selection of species in these ecosystems (Paruelo et al, 2022). Some species evolved to be prostrate and fastgrowing, as a strategy to tolerate herbivory (Cingolani et al, 2005;Garnier et al, 2015), while others evolved as resource-accumulating, tussocks-forming species, with thick and narrow leaves normally characterized by slow growth and less selected by animals (Boggiano, 1995;Cingolani et al, 2005;Jaurena et al, 2012;Fischer et al, 2019;Ferreira et al, 2020).…”

Carbon stocks and potential sequestration of Uruguayan soils. A road map to a comprehensive characterization of temporal and spatial changes to assess Carbon footprint

“…This region covers about 853,000 km 2 and corresponds to one of the largest, most diverse, and less transformed grassland areas in the world, despite the important land cover transformation that they experienced over the last 5 decades (Oyarzabal et al 2020). Within this region, Uruguay presents the largest proportion of remaining grasslands: 53% as estimated by Paruelo et al (2022). The area transformed is devoted to tree plantations (mainly Eucalyptus), annual crops (mainly soybeans, wheat and canola) and perennial sown pastures (Baeza et al 2014, Baeza and.…”