Volume 35, Issue 3 pp. 1098-1109
RESEARCH ARTICLE

Shrub encroachment occurs near previously invaded areas in Patagonia (southern South America)

Paula Estelí Romero-Ovalle

Corresponding Author

Paula Estelí Romero-Ovalle

Instituto Patagónico para el Estudio de los Ecosistemas Continentales, IPEEC-CONICET, Puerto Madryn, Chubut, Argentina

Correspondence

Paula Estelí Romero-Ovalle, Instituto Patagónico para el Estudio de los Ecosistemas Continentales, IPEEC-CONICET, Boulevard Brown 2915, (9120) Puerto Madryn, Chubut, Argentina.

Email: [email protected]

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María Victoria Campanella

María Victoria Campanella

Instituto Patagónico para el Estudio de los Ecosistemas Continentales, IPEEC-CONICET, Puerto Madryn, Chubut, Argentina

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Miguel Pascual

Miguel Pascual

Instituto Patagónico para el Estudio de los Ecosistemas Continentales, IPEEC-CONICET, Puerto Madryn, Chubut, Argentina

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Martín García-Asorey

Martín García-Asorey

Instituto Patagónico para el Estudio de los Ecosistemas Continentales, IPEEC-CONICET, Puerto Madryn, Chubut, Argentina

Universidad Tecnológica Nacional, Facultad Regional Chubut, UTN-FRCH, Puerto Madryn, Chubut, Argentina

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Cristian Pacheco

Cristian Pacheco

Instituto Patagónico para el Estudio de los Ecosistemas Continentales, IPEEC-CONICET, Puerto Madryn, Chubut, Argentina

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Cristian Barrionuevo

Cristian Barrionuevo

Instituto Patagónico para el Estudio de los Ecosistemas Continentales, IPEEC-CONICET, Puerto Madryn, Chubut, Argentina

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Alejandro Jorge Bisigato

Alejandro Jorge Bisigato

Instituto Patagónico para el Estudio de los Ecosistemas Continentales, IPEEC-CONICET, Puerto Madryn, Chubut, Argentina

Facultad de Ciencias Naturales y de la Salud, Universidad Nacional de la Patagonia San Juan Bosco UNPSJB, Puerto Madryn, Chubut, Argentina

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First published: 03 November 2023

Abstract

During the last century shrub encroachment has occurred in many arid and semiarid areas of the world. Patagonia is a large xeric territory located in the southern tip of South America, which has been grazed by sheep for more than a century. In many areas overgrazing led to vegetation change (shrub encroachment), which in turn reduced sheep carrying capacity and caused ranch abandonment. However, these changes in physiognomy did not occur everywhere, and even some authors did not find evidence that shrub encroachment is currently occurring. Our objectives were to determine if encroachment really happened in NE Patagonia and, in the case of confirming shrub encroachment, to evaluate if the increase in shrub density was spatially homogeneous. We used object-based image analysis to evaluate shrub density and cover in aerial photographs taken in 1970 and 2018. In both dates, shrub density showed a clear contrast between two kinds of areas showing higher and lower density than was expected by chance. Shrub density and cover more than doubled between 1970 and 2018. This increase was concentrated in those areas with moderate or high densities of shrubs in 1970. Our results confirm the occurrence of shrub encroachment in NE Patagonia and demonstrate that it is currently concentrated near previously invaded areas. These findings have implications when defining protocols for monitoring shrub encroachment since monitors should focus on both areas that already have shrubs and areas that lack them.

CONFLICT OF INTEREST STATEMENT

The authors declare no conflict of interests.

DATA AVAILABILITY STATEMENT

The data that support the findings of this study are available from the corresponding author upon reasonable request.

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