Why are forests so scarce in subtropical South America? The shaping roles of climate, fire and livestock

Bernardi, Rafael E.; Holmgren, Milena; Arim, Matı́as; Scheffer, Marten

doi:10.1016/j.foreco.2015.12.032

Cited by 48 publications

(38 citation statements)

References 52 publications

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“…In this transition zone, the combined effects of precipitation, cattle density and fire occurrence explain the extent of tree cover (Bernardi et al . ). There is no effect of temperature, rainfall variability (within or between years), soil features (nutrient availability or water holding capacity) or landscape features (distance to rivers or elevation) limiting the establishment of trees in the grassland‐dominated Pampa (Bernardi et al .…”

Section: Discussionmentioning

confidence: 97%

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Environmental drivers of species composition and functional diversity of dung beetles along the Atlantic Forest–Pampa transition zone

Silva

Cassenote

2019

Austral Ecology

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Human activities are causing a rapid loss of biodiversity, which impairs ecosystem functions and services. Therefore, understanding which processes shape how biodiversity is distributed along spatial and environmental gradients is a first step to guide conservation and management efforts. We aimed to determine the relative explanatory importance of biogeographic, environmental, landscape and spatial variables on assemblage dissimilarities and functional diversity of dung beetles along the Atlantic Forest-Pampa (i.e. forest-grassland) transition zone located in Southeast South America. We described each site according to their biogeographic position, environmental conditions, landscape features and spatial patterns. The compositional dissimilarity was partitioned into turnover and nestedness components of b-diversity. Mantel tests and generalised dissimilarity models were used to relate b-diversity and its components to biogeographic, environmental, landscape and spatial variables. Variation partitioning analysis was used to estimate the pure and shared variation in species composition and functional diversity explained by the four categories of predictors. Biome domain was the main factor causing dung beetle compositional dissimilarity, with a high species replacement between Atlantic Forest and Pampa. Biogeographic, environmental, landscape and spatial distances also affected the patterns of dung beetle dissimilarity and b-diversity components. The shared effects of the four sets of predictors explained most of the variation in dung beetle composition. A similar response pattern was found for dung beetle functional diversity, which excluded biogeographic effects. Only the pure effects of environmental and spatial predictors were significant for species composition and functional diversity. Our results indicate that dung beetle species composition and functional diversity are jointly driven by environmental, landscape and spatial predictors with higher pure environmental and spatial effects. The forest-grassland transition zone promotes a strong species and trait replacement highly influenced both by environmental filtering and dispersal limitation. Land cover configurationThe land cover conditions around sites (1 km radii circular sectors) were obtained from high-resolution satellite images

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Section: Discussionmentioning

confidence: 97%

“…There is no effect of temperature, rainfall variability (within or between years), soil features (nutrient availability or water holding capacity) or landscape features (distance to rivers or elevation) limiting the establishment of trees in the grassland‐dominated Pampa (Bernardi et al . ). Forests are concentrated close to rivers (i.e.…”

Section: Discussionmentioning

confidence: 97%

Environmental drivers of species composition and functional diversity of dung beetles along the Atlantic Forest–Pampa transition zone

Silva

Cassenote

2019

Austral Ecology

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“…Los disturbios como el pastoreo y el fuego son moduladores fuertes del paisaje, y poseen el potencial para reducir la estructura de la vegetación y alterar las propiedades físico-químicas del suelo (Milchunas and Lauenroth 1993;Belsky and Blumenthal 1997;Bernardi et al 2016). Los cambios en la estructura de la vegetación causados por estos disturbios pueden ser tan drásticos como para convertir bosques en pastizales u otras coberturas de menor complejidad estructural.…”

Section: I��unclassified

La degradación de los bosques de altura del centro de Argentina reduce su capacidad de almacenamiento de agua

et al. 2017

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R��. La capacidad del suelo de almacenar y regular el flujo de agua depende en gran medida de su su tasa de infiltración y profundidad. Los disturbios como el pastoreo y el fuego son moduladores fuertes del sistema vegetación-suelo, ya que son capaces de alterar la tasa de infiltración y la profundidad del suelo. En sistemas montanos estacionales, esto repercute sobre la capacidad de liberar lentamente el agua almacenada hacia el caudal de los arroyos. Nos propusimos indagar si las variaciones en la estructura de la vegetación, debidas en su mayoría al pastoreo y al fuego, de los bosques de altura de Polylepis australis Bi�er de las sierras de Córdoba se asocian a variaciones en las propiedades del suelo en general y, en particular, a aquellas que regulan la capacidad de almacenar agua. Para abarcar la variabilidad completa de estructura de la vegetación seleccionamos 28 sitios distribuidos en tres establecimientos con distintos manejos, y restringimos las variaciones topográficas. No detectamos asociaciones entre la estructura de la vegetación y la topografía; es decir, en general, logramos restringir el efecto topográfico. Por otro lado, aquellos sitios con vegetación más estructurada presentaron suelos con menor densidad aparente y mayor contenido de materia orgánica y capacidad de campo. En relación a la capacidad de almacenamiento de agua, los suelos más profundos y con mayor tasa de infiltración fueron los menos densos, con mayor contenido de materia orgánica y mayor capacidad de campo, asociados a una vegetación más estructurada. Es decir, mientras más conservado se encuentra el sistema vegetación-suelo de los bosques de P. australis, mayor cantidad de agua puede ingresar al suelo y ser almacenada. En consecuencia, las alteraciones del sistema vegetación-suelo, dadas principalmente por el pastoreo y el fuego, reducen la capacidad de almacenar agua de los bosques de altura del centro de la Argentina.[Palabras clave: Polylepis australis, tasa de infiltración, profundidad del suelo, estructura de la vegetación, suelo, montañas, pastoreo, fuego, disturbio, ecohidrología] A��. The degradation of highland woodlands of central Argentina reduces their soil water storage capacity. Soil water storage capacity and flow regulation relies mostly upon infiltration rate and soil depth. Disturbs such as grazing and fire strongly modulate the vegetation-soil system, and are capable of altering the infiltration rate and soil depth, as well. In mountain seasonal ecosystems, this impacts on soil capacity to slowly release water into streams. We aimed at analyzing if changes in vegetation structure and soil properties, mainly as a consequence of grazing and fire, of highland Polylepis australis Bi�er woodlands of Córdoba mountains, also include alterations in general soil properties and, in particular, in those related to soil water storage capacity. In order to encompass the complete variability in vegetation structure we selected 28 sites in paddocks with different managements, restricting topographic variations. W...

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“…Croplands tend to occupy the more fertile soils, and their expansion at the expense of forests can be linked to global and local drivers such as demands from international markets and local agricultural practices (Geist andLambin 2002, Richards et al 2012). Tree expansion into grasslands has also been observed in South America (Gautreau 2010, Chaneton et al 2012, Müller et al 2012, González-Roglich et al 2015 and correlated to land uses and disturbance regimes (Chaneton et al 2012, Müller et al 2012, Blanco et al 2014, Bernardi et al 2016b, Brazeiro et al 2018). Although the transition from forests to grasslands as a direct consequence of agricultural spreading has been fairly well established , Vega et al 2009), the net result of this process with the opposite trajectory of tree expansion into grasslands remains less well understood, despite the major ecological and economic consequences.…”

Section: Introductionmentioning

confidence: 98%

“…Humans have therefore exerted strong influences through land conversion and the modification of disturbance regimes that can affect forest cover. Recent field experiments and observations indicate that fire and livestock currently limit forest expansion across southeastern South America (Pillar and Quadros 1997, Müller et al 2012, Blanco et al 2014, Bernardi et al 2016b, Etchebarne and Brazeiro 2016, Brazeiro et al 2018. Indeed, livestock densities in the Campos are among the highest in South America, which may also explain the low fire frequencies of this region (Di Bella et al 2006, Bernardi et al 2016b.…”

Section: Introductionmentioning

confidence: 99%

Forests expand as livestock pressure declines in subtropical South America

Bernardi¹,

Buddeberg²,

Arim³

et al. 2019

E&S

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Forests, savannas, and grasslands are prevalent across the landscapes of South America. Land uses associated with these ecosystems have influenced economies from household to country scales, shaping social-ecological organization across the region since pre-Hispanic societies. Recent studies suggest that tropical and subtropical grasslands, savannas, and forests represent alternative ecosystem states. Transitions between these ecosystem states can be promoted by changes in disturbance regimes and by land uses determined by the organization of societies and their activities. We analyzed how changes in agriculture, fire, and livestock management influenced forest cover over a 45-year span (1966-2011) in the Campos region, an extensive subtropical ecotone between rain forests and grasslands of South America. We found that forests contracted in areas with high crop agriculture, whereas forests increased in those grasslands where livestock densities had been reduced. These patterns were strongly associated with soil and topographic conditions because they broadly determine the potential land productivity and use. Our results show that current land use and disturbance regimes explain the large extent of grasslands across the South American Campos and suggest that changes in land use and disturbance regimes could facilitate or prevent transitions between subtropical forests, savannas, and grasslands altering the provision of ecosystem services linked to them.Ecology and Society 24(2): 19 https://www.ecologyandsociety.org/vol24/iss2/art19/ analyzed changes in native forest cover over a 45-year period in Uruguay in relation to fire occurrence, livestock density, agricultural land cover, climate, soils, topography, and road density.

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Why are forests so scarce in subtropical South America? The shaping roles of climate, fire and livestock

Cited by 48 publications

References 52 publications

Environmental drivers of species composition and functional diversity of dung beetles along the Atlantic Forest–Pampa transition zone

Environmental drivers of species composition and functional diversity of dung beetles along the Atlantic Forest–Pampa transition zone

La degradación de los bosques de altura del centro de Argentina reduce su capacidad de almacenamiento de agua

Forests expand as livestock pressure declines in subtropical South America

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