Forests expand as livestock pressure declines in subtropical South America

Abstract

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.

Effects of forest preservation, livestock exclusion, and use of shrubs as potential nurses on planting success of an endangered tree

“…1 Faculty of Exact, Physical and Natural Sciences, Center of Ecology and Renewable Natural Resources, National University of C ordoba, Av. Vélez Sarsfield 1611, C ordoba, X5016GCA, Argentina 2 denser woody vegetation and lower livestock densities (Howard et al 2012;Bernardi et al 2019).…”

“…In turn, soil erosion reduces soil nutrients and further increases water runoff, reducing water availability to plants (Cingolani et al 2013; Ellison et al 2017; Sparacino et al 2020). As a consequence, seasonally dry forests grazed for long periods are composed of a mosaic of physically degraded environments induced by grazing‐related erosion combined with relatively fertile forest islands with denser woody vegetation and lower livestock densities (Howard et al 2012; Bernardi et al 2019).…”

Caracterización de ecotonos entre biomas de bosque y biomas abiertos en un área protegida en Uruguay

“…Los biomas abiertos presentan su propia composición e, incluso, pueden poseer endemismos, por lo que no son un simple empobrecimiento de especies de biomas boscosos ni corresponden a sitios deforestados Veldman et al 2015;Bond 2019;Silveira et al 2020;Pausas and Bond 2020). Entender los determinantes de la coexistencia de biomas de bosque y abiertos es un tema que históricamente ha sido de interés y tiene mucha vigencia al día de hoy (e.g., Holdridge 1947;Whittaker 1975;Hirota et al 2011;Staver et al 2011;Bernardi et al 2016Bernardi et al , 2019aPausas and Bond 2020).…”

“…La ubicación de Uruguay en el clima donde pueden coexistir diferentes tipos de biomas, sin la presencia de un período seco que limite el desarrollo de bioma de bosque, lo hace un estudio de caso atractivo para profundizar el conocimiento sobre los procesos que determinan las transiciones entre biomas abiertos y biomas de bosque. En los últimos años ocurrió un gran avance en el conocimiento sobre la respuesta de diferentes biomas al manejo ganadero u otras variables en Uruguay, pero estos estudios se centran en un solo bioma (e.g., Altesor et al 2019;López-Marisco et al 2020) o en sectores homogéneos de diferentes biomas dentro de un gradiente más amplio (Gautreu and Lezama 2009), se basan en información obtenida por sensores remotos (e.g., Bernardi et al 2016Bernardi et al , 2019aGallego et al 2020) o abordan áreas de estudio pequeñas y se contrastan solo dos sitios (i.e., ~100 ha) (Brazeiro et al 2018). Por lo tanto, en Uruguay existe poca información y estudios de campo sobre la dinámica de transiciones entre biomas abiertos y biomas de bosque.…”

Seeking sustainable pathways for land use in Latin America

“…Three of our contributions address this gap. Bernardi et al (2019) investigated how the forest to savannas and grasslands transitions in natural grasslands of Uruguay is shaped by land use change over a 45-year time series , concluding that current land use changes can prevent or facilitate forest transitions and the ecosystem services they provide. Calaboni et al (2018) studied deforestation and afforestation patterns in Sao Paulo (Brazil).…”