Abstract:

Carbon emissions from land‐use changes in tropical dry forest systems are poorly understood, although they are likely globally significant. The South American Chaco has recently emerged as a hot spot of agricultural expansion and intensification, as cattle ranching and soybean cultivation expand into forests, and as soybean cultivation replaces grazing lands. Still, our knowledge of the rates and spatial patterns of these land‐use changes and how they affected carbon emissions remains partial. We used the Landsat satellite image archive to reconstruct land‐use change over the past 30 years and applied a carbon bookkeeping model to quantify how these changes affected carbon budgets. Between 1985 and 2013, more than 142 000 km2 of the Chaco's forests, equaling 20% of all forest, was replaced by croplands (38.9%) or grazing lands (61.1%). Of those grazing lands that existed in 1985, about 40% were subsequently converted to cropland. These land‐use changes resulted in substantial carbon emissions, totaling 824 Tg C between 1985 and 2013, and 46.2 Tg C for 2013 alone. The majority of these emissions came from forest‐to‐grazing‐land conversions (68%), but post‐deforestation land‐use change triggered an additional 52.6 Tg C. Although tropical dry forests are less carbon‐dense than moist tropical forests, carbon emissions from land‐use change in the Chaco were similar in magnitude to those from other major tropical deforestation frontiers. Our study thus highlights the urgent need for an improved monitoring of the often overlooked tropical dry forests and savannas, and more broadly speaking the value of the Landsat image archive for quantifying carbon fluxes from land change.

Instituto de Recursos Biológicos

Author affiliation: Baumann, Matthias. Humboldt-University Berlin. Geography Department; Alemania

Author affiliation: Gasparri, Nestor Ignacio. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Ecología Regional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán; Argentina. Humboldt-University Berlin. Integrative Research Institute for Transformations in Human Environment Systems; Alemania

Author affiliation: Piquer Rodriguez, María. Humboldt-University Berlin. Geography Department; Alemania

Author affiliation: Gavier Pizarro, Gregorio Ignacio. INTA. Instituto de Recursos Biológicos; Argentina

Author affiliation: Griffiths, Patrick. Humboldt-University Berlin. Geography Department; Alemania

Author affiliation: Hostert, Patrick. Humboldt-University Berlin. Geography Department; Alemania. Humboldt-University Berlin. Integrative Research Institute for Transformations in Human Environment Systems; Alemania

Author affiliation: Kuemmerle, Tobias. Humboldt-University Berlin. Geography Department; Alemania. Humboldt-University Berlin. Integrative Research Institute for Transformations in Human Environment Systems; Alemania

Abstract:

Human activities have modified wetlands all over the word. Water control structures that are frequently implemented in these ecosystems to keep lands free of flooding can decrease or degrade habitat for biodiversity. The Paraná River Delta, one of the largest wetlands in Argentina, has recently experienced rapid cattle grazing intensification facilitated by water control structures, resulting in extensive conversion of wetlands to pastures. It is unclear if this loss of wetlands has had a negative impact on the highly diverse bird community. Here, we evaluated the changes in bird assemblages in the Lower Delta of Paraná River after 14 years of cattle grazing intensification. We compared point count data from 1997 to 1999 with data collected in 2012 and 2013 using the same survey methods. We assessed the temporal changes in bird richness and composition using paired permutation tests and multivariate analysis. We related the bird composition to landscape changes to analyse if avian changes were associated with landscape dynamics. We found that after 14 years, the bird community differed greatly. In general, species richness decreased, especially in wet years. We found fewer wetland species in recent surveys; in particular we did not register saffron‐cowled blackbird (Xanthopsar flavus), a species listed as globally vulnerable. Changes in bird composition were associated with an increase in bare soil due to land‐use changes. Even though inter‐annual differences in precipitation and river stage have great effects on the species present in the surveys, the absence of many wetland species in recent wet years, that is when habitat is suitable for them, is most likely due to changes in land cover. Globally, agricultural land use makes inroads into many wetlands, eroding their quality and extent. Maintenance of wetland species requires that conservation efforts focus on these vulnerable ecosystems before full‐scale land conversion occurs.

Instituto de Recursos Biológicos

Author affiliation: Sica, Yanina Vanesa. INTA. Instituto de Recursos Biológicos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentina

Author affiliation: Gavier Pizarro, Gregorio Ignacio. INTA. Instituto de Recursos Biológicos; Argentina

Author affiliation: Pidgeon, Anna M. University of Wisconsin‐Madison. Department of Forest and Wildlife Ecology. SILVIS Lab; Estados Unidos

Author affiliation: Travaini, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; Argentina.

Author affiliation: Bustamante, Javier. CSIC. Estación Biológica de Doñana. Department of Wetland Ecology; España

Author affiliation: Radeloff, Volker C. University of Wisconsin‐Madison. Department of Forest and Wildlife Ecology. SILVIS Lab; Estados Unidos

Author affiliation: Quintana, Rubén D. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martín. Instituto de Investigación e Ingeniería Ambiental; Argentina

Abstract:

Context: Land-use change is the main driver of habitat loss and fragmentation worldwide. The rate of dry forest loss in the South American Chaco is among the highest in the world, mainly due to the expansion of soybean production and cattle ranching. Argentina recently implemented a national zoning plan (i.e., the Forest Law) to reduce further forest loss. However, it is unclear how the effects of past deforestation and the implementation of the Forest Law will affect forest connectivity in the Chaco. Objective: Our main goal was to evaluate the potential effect of the Forest Law on forest fragmentation and connectivity in the Argentine Chaco. Methods: We studied changes in the extent, fragmentation, and connectivity of forests between 1977 and 2010, by combining agricultural expansion and forest cover maps, and for the future in a scenario analysis. Results Past agricultural expansion translated into an overall loss of 22.5 % of the Argentine Chaco’s forests, with deforestation rates in 2000–2010 up to three times higher than in the 1980s. Forest fragmentation and connectivity loss were highest in 1977–1992, when road construction fragmented large forest patches. Our future scenario analysis showed that if the Forest Law will be implemented as planned, forest area and connectivity in the region will decline drastically. Conclusions: Land-use planning designed to protect stepping stones could substantially mitigate connectivity loss due to deforestation, with the co-benefit of preserving the greatest amount of biodiversity priority areas across all evaluated scenarios. Including scenario analyses that assess forest fragmentation and connectivity at the ecoregion scale is thus important in upcoming revisions of the Argentine Forest Law, and, more generally, in debates about sustainable resource use.

Instituto de Recursos Biológicos

Author affiliation: Piquer Rodriguez, María. Humboldt-University Berlin. Geography Department; Alemania

Author affiliation: Torella, Sebastián Andrés. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Grupo de Estudios de Sistemas Ecológicos en Ambientes Agrícolas; Argentina

Author affiliation: Gavier Pizarro, Gregorio Ignacio. INTA. Instituto de Recursos Biológicos. Grupo de Biodiversidad, Ecología y Gestión Ambiental; Argentina

Author affiliation: Volante, Jose Norberto. INTA. Estación Experimental Agropecuaria Salta. Laboratorio de Teledetección y SIG; Argentina

Author affiliation: Somma, Daniel Jorge. INTA. Estación Experimental Agropecuaria Pergamino; Argentina

Author affiliation: Guizburg, Rubén G. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución. Grupo de Estudios de Sistemas Ecológicos en Ambientes Agrícolas; Argentina

Author affiliation: Kuemmerle, Tobias. Humboldt-University Berlin. Geography Department; Alemania. Humboldt-University Berlin. Integrative Research Institute for Transformations in Human Environment Systems; Alemania

Abstract:

Rapid global changes due to changing land use, climate, and non-native species are altering environmental conditions, resulting in more novel communities with unprecedented species combinations. Understanding how future anthropogenic changes may affect novelty in ecosystems is important to advance environmental management and ecological research in the Anthropocene. The main goal of this study was to understand how alternative scenarios of future land-use change may affect novelty in ecosystems throughout the conterminous United States. We used five spatially explicit scenarios of future land-use changes, reflecting different land-use policies and changes in agricultural markets, to quantify and map potential drivers of novelty. Our results showed large areas where future land-use changes may increase novelty in ecosystems. The major land-use changes known to increase novelty, including land abandonment and land-use expansion, were widespread in all scenarios (73 million to 95 million ha), especially in the eastern U.S. and along the West Coast. Our scenarios revealed that, at broad scales, future land-use changes will increase novelty in ecosystems, and that traditional conservation policies may have limited ability to prevent the process. In places such as the eastern U.S., conserving and maintaining historical conditions and associated biological diversity may become increasingly difficult due to future land-use changes and related ecological factors. Successful biodiversity conservation and environmental management in the Anthropocene will require novel conservation approaches to be relevant in areas with high levels of novelty in ecosystems.

Instituto de Recursos Biológicos

Author affiliation: Martinuzzi, Sebastián. University of Wisconsin‐Madison. Department of Forest and Wildlife Ecology. SILVIS Lab; Estados Unidos

Author affiliation: Gavier Pizarro, Gregorio Ignacio. INTA. Instituto de Recursos Biológicos; Argentina

Author affiliation: Lugo, Ariel E. USDA Forest Service. International Institute of Tropical Forestry; Estados Unidos

Author affiliation: Radeloff, Volker C. University of Wisconsin‐Madison. Department of Forest and Wildlife Ecology. SILVIS Lab; Estados Unidos