Onset of deep drainage and salt mobilization following forest clearing and cultivation in the Chaco plains (Argentina)

Semiarid sedimentary plains occupied by dry forest ecosystems often display low groundwater recharge rates and accumulation of salts in the soil profile. The transformation of these natural systems to rain‐fed agriculture has led to raising water tables and a slow, but steady, process of groundwater and soil salinization in vast areas of Australia. In the semiarid plains of Chaco (central South America), unprecedented deforestation rates are taken place. Based on deep soil sampling (0–6 m) in seven paired stands under natural dry forest, rain‐fed agriculture and pasture, with different age of clearance (>30 years, 20 and 3 years) in Salta, Argentina, we provide evidence of groundwater recharge increase and onset of salt mobilization in areas where forests were replaced by annual croplands. Soils with higher water and lower chloride content are evidence of deep percolation and salt leaching. In Salta, stands subject to 30 years of rain‐fed cultivation had profiles with 30–46% higher moisture content and 94% lower chloride stocks compared to dry forest (0.05 ± 0.04 kg/m2 versus 0.77 ± 0.4 kg/m2). Estimates of groundwater recharge based on the displacement of chloride peaks suggested values of 27–87 mm yr−1 for agricultural soybean stands, and 10.4 mm yr−1 for pastures. While hydrological shifts in the regional groundwater system are poorly monitored and understood, our findings show that it is potentially sensitive to land use changes and to salinization processes.EEA SaltaFil: Amdam, M. Laura. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Métodos Cuantitativos y Sistemas de Información; ArgentinaFil: Aragón, Myriam Roxana. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi". Universidad Nacional de San Luis. Facultad de Ciencias Físico, Matemáticas y Naturales. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi"; ArgentinaFil: Jobbagy Gampel, Esteban Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi". Universidad Nacional de San Luis. Facultad de Ciencias Físico, Matemáticas y Naturales. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi"; ArgentinaFil: Volante, Jose Norberto. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Salta; ArgentinaFil: Paruelo, José. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Métodos Cuantitativos y Sistemas de Información; Argentin

Remote sensing in ecology and conservation: three years on

Editorial

¿Cuál es la situación de la Ley de Bosques en la Región Chaqueña a diez años de su sanción? Revisar su pasado para discutir su futuro

En un complejo escenario ambiental, productivo y socioeconómico, el 28 de noviembre de 2007 fue sancionada en Argentina la Ley Nacional Nº 26.331 de “Presupuestos Mínimos de Protección Ambiental de los Bosques Nativos" (conocida como "Ley de bosques") con el propósito de proteger los bosques nativos a escala nacional. En este artículo nos proponemos realizar una síntesis crítica de la información disponible acerca de esta ley a diez años de su sanción, con una aproximación que toma en cuenta aspectos ambientales, económicos y sociales. Caracterizamos el desempeño de esta ley en la Región Chaqueña en cuanto a diferentes dimensiones, identificamos sus principales desafíos y describimos una serie de propuestas que desde el sector de Ciencia y Técnica pueden contribuir a su (re)diseño e implementación en el contexto de las actualizaciones de los Ordenamientos Territoriales de Bosques Nativos provinciales. Para ello, integramos información disponible proveniente de distintas fuentes, tales como normativas (nacionales y provinciales), literatura científica, informes de organismos estatales y de ONG y artículos periodísticos. La Ley de Bosques instaló en la opinión pública de nuestro país la problemática vinculada a la pérdida de bosques nativos y se ha posicionado como el principal instrumento de política forestal nacional para su protección. Si bien hubo una reducción en las tasas de deforestación en la región Chaqueña, no existen evidencias certeras de que esta reducción se deba a su aplicación. La Ley de Bosques en la Región Chaqueña presenta una serie de desafíos para mejorar su desempeño en cuanto a su efectividad, equidad y legitimidad social. En este trabajo se presentan diez observaciones que emergen de la revisión realizada. Por otro lado, se esbozan una serie de propuestas de investigación y acción en torno a la ley vinculadas a esas observaciones.In a complex environmental, productive and socioeconomic scenario, on November 28th, 2007, the National Act N°26.331 of “Minimum Standards for the Environmental Protection of Native Forests” (known as the “Forest Law”) was sanctioned in Argentina with the purpose of protecting native forests at the national scale. In this article, we aim to critically synthesize the available information about this law ten years after its sanction from an approach that takes into account environmental, economic and social aspects. In particular, we characterize the performance of this law in the Chaco Region in different dimensions, identify its main challenges and describe a series of proposals that from the science and technology sector can contribute to its (re)design and implementation in the context of the revisions of the Provincial Native Forest Land Use Planning Programs. In order to accomplish these objectives, we integrated information available from different sources, such as laws and regulations (national and provincial), scientific literature, reports from government agencies and NGOs and newspaper articles. The Forest Law installed in the public opinion of our country the problems related to the loss of native forests and has positioned itself as the main national instrument for forest conservation. Although deforestation rates lowered in the Chaco Region, there is no clear evidence that this reduction was due to its application. The Forest Law in the Chaco Region presents a series of challenges to improve its performance in terms of its effectiveness, equity and social legitimacy. In this paper, we present ten observations that emerge from the review carried out. On the other hand, linked to these observations, we outline a series of research and action proposals for enhancing the performance of the law.EEA BalcarceFil: Aguiar, Sebastián. Universidad de Buenos Aires. Facultad de Agronomia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Mastrangelo, Matias Enrique. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias. Grupo de Estudio de Agroecosistemas y Paisajes Rurales; Argentina. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; ArgentinaFil: García Collazo, María A. Ministerio de Ambiente y Desarrollo Sustentable de la Nación. Dirección Nacional de Bosques; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Métodos Cuantitativos y Sistemas de Información; ArgentinaFil: Camba Sans, Gonzalo H. Universidad de Buenos Aires. Facultad de Agronomia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Métodos Cuantitativos y Sistemas de Información; ArgentinaFil: Mosso, Clara E. Universidad de Buenos Aires. Facultad de Agronomía. Licenciatura en Ciencias Ambientales; ArgentinaFil: Ciuffoli, Lucía. Ministerio de Ambiente y Desarrollo Sustentable de la Nación. Dirección Nacional de Bosques; Argentina.Fil: Schmidt, Mariana. Universidad de Buenos Aires. Facultad de Ciencias Sociales. Instituto de Investigaciones Gino Germani. Grupo de Estudios Ambientales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Vallejos, María. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Métodos Cuantitativos y Sistemas de Información; ArgentinaFil: Langbehn, Lorenzo. Universidad Nacional de Santiago del Estero. Facultad de Humanidades, Ciencias Sociales y de la Salud; ArgentinaFil: Brassiolo, Miguel. Universidad Nacional de Santiago del Estero. Facultad de Ciencias Forestales; ArgentinaFil: Cáceres, Daniel. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Merlinsky, Gabriela. Universidad de Buenos Aires. Facultad de Ciencias Sociales. Instituto de Investigaciones Gino Germani. Grupo de Estudios Ambientales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Paruelo, José María. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Métodos Cuantitativos y Sistemas de Información; Argentina. Instituto Nacional de Investigaciones Agropecuarias. INIA La Estanzuela; UruguayFil: Seghezzo, Lucas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones en Energía no Convencional. Universidad Nacional de Salta. Facultad de Ciencias Exactas. Departamento de Física. Instituto de Investigaciones en Energía no Convencional; ArgentinaFil: Staiano, Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Métodos Cuantitativos y Sistemas de Información; ArgentinaFil: Texeira González, Marcos Alexis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Métodos Cuantitativos y Sistemas de Información; ArgentinaFil: Volante, Jose Norberto. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Salta; ArgentinaFil: Veron, Santiago Ramón. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Clima y Agua; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Métodos Cuantitativos y Sistemas de Información; Argentin

Quantifying Vegetation Biophysical Variables from Imaging Spectroscopy Data: A Review on Retrieval Methods

An unprecedented spectroscopic data stream will soon become available with forthcoming Earth-observing satellite missions equipped with imaging spectroradiometers. This data stream will open up a vast array of opportunities to quantify a diversity of biochemical and structural vegetation properties. The processing requirements for such large data streams require reliable retrieval techniques enabling the spatiotemporally explicit quantification of biophysical variables. With the aim of preparing for this new era of Earth observation, this review summarizes the state-of-the-art retrieval methods that have been applied in experimental imaging spectroscopy studies inferring all kinds of vegetation biophysical variables. Identified retrieval methods are categorized into: (1) parametric regression, including vegetation indices, shape indices and spectral transformations; (2) nonparametric regression, including linear and nonlinear machine learning regression algorithms; (3) physically based, including inversion of radiative transfer models (RTMs) using numerical optimization and look-up table approaches; and (4) hybrid regression methods, which combine RTM simulations with machine learning regression methods. For each of these categories, an overview of widely applied methods with application to mapping vegetation properties is given. In view of processing imaging spectroscopy data, a critical aspect involves the challenge of dealing with spectral multicollinearity. The ability to provide robust estimates, retrieval uncertainties and acceptable retrieval processing speed are other important aspects in view of operational processing. Recommendations towards new-generation spectroscopy-based processing chains for operational production of biophysical variables are given

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Agricultural expansion in the Semiarid Chaco: poorly selectivecontagious advance

Clearance for agriculture or cattle ranching was the dominant land-cover change during the last two decades in the South American Dry Chaco. The Argentinean portion has been particularly affected, presenting greater deforestation rates than the continental and global averages. Little is known on the control factors of the location and the spatial clearance patterns. In this article we studied (a) deforestation dynamics in the Argentinean Dry Chaco and the factors determining land clearing locations for the last 25 years; (b) changes in the relative impact of those factors through time and space; and (c) the effect of regulations aimed to control the location and magnitude of land transformation. We also tested the “expansion of the agricultural frontier” hypothesis for the Argentinean Chaco. To identify the factors that defined agricultural expansion we used binomial logistic models that were fitted to a set of independent variables (bio-physical, infrastructure and political factors) that could eventually influence the distribution of new agricultural areas. Results indicate that the Forest Law devised by the Argentinean federal government to control the clearing process was insufficient to restrict both the area transformed per year and clearance locations. Agriculture is expanding over marginal areas and land clearing dynamics have been increasingly associated to the proximity to already cleared areas, defining a frontier—advancement pattern which gives the idea of a contagion process. According to our results, the relative importance of the anthropic factors associated to the agricultural expansion in the region increased through time.Fil: Volante, Jose Norberto. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Salta; ArgentinaFil: Mosciaro, Maria Jesus. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Salta.Laboratorio de Teledetección y SIG; ArgentinaFil: Gavier Pizarro, Gregorio Ignacio. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Recursos Biológicos; ArgentinaFil: Paruelo, José María. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentin

Variation of grazing-induced vegetation changes across a large-scale productivity gradient

Questions: Does the magnitude of grazing-induced changes in species composition vary with habitat productivity? How does the sign and magnitude of grazing effects on species richness and beta-diversity change with increasing productivity? Do major life forms exhibit consistent responses to grazing along productivity gradients? Location: Steppes and grasslands of southern South America in Argentina and Uruguay. Methods: We evaluated grazing effects on plant composition, species richness, beta-diversity and life-form abundances along a ten-fold, regional productivity gradient and within subregions of contrasting productivity, using a common sampling protocol for 23 paired grazed vs ungrazed plots. The annual integral of the normalized difference vegetation index was used as a surrogate for above-ground net primary productivity. Results: Compositional dissimilarity between grazed and ungrazed plots, as well as grazing-induced differences in plant richness and beta-diversity all increased with habitat productivity. Grazing decreased species richness in low-productive steppes but enhanced the richness of high-productive grasslands. On average, grazing reduced beta-diversity in high-productive sites but not in low-productive sites. Dominant species were more strongly suppressed by grazing towards productive grasslands. Grazing generally decreased shrub species cover, whereas graminoid and forb cover did not consistently change with grazing through the productivity gradient. Conclusions: Our results indicate that the overall grazing effects on vegetation structure increased along a regional productivity gradient. Yet the sign of grazing impacts on species richness and beta-diversity shifted with habitat productivity, in agreement with models of herbivore-mediated co-existence and species colonization in productive systems. Further, we found that narrowing the spatial extent of analysis to the subregion generally obscured grazing–productivity relationships. Biodiversity conservation programmes should carefully weigh the varied impacts of livestock grazing across productivity gradientsFil: Lezama, Felipe. Universidad de la República. Facultad de Agronom ía. Unidad de Sistemas Ambientales; UruguayFil: Baeza, Santiago. Universidad de la República. Facultad de Agronom ía. Unidad de Sistemas Ambientales; UruguayFil: Altesor, Alice. Universidad de la República. Facultad de Ciencias. Instituto de Ecolog ía y Ciencias Ambientales; UruguayFil: Cesa, Ariela. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Chaneton, Enrique Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad de Buenos Aires. Facultad de Agronomia; ArgentinaFil: Paruelo, José. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Métodos Cuantitativos y Sistemas de Información; Argentin

Appendix C. Trends in integrated precipitation use efficiency and precipitation marginal response.

Trends in integrated precipitation use efficiency and precipitation marginal response

How To Be General, Yet Specific: The Conundrum of Rangeland Science in the 21st Century

A critical challenge for range scientists is to provide input to management decisions for land units where little or no data exist. The disciplines of range science, basic ecology, and global ecology use different perspectives and approaches with different levels of detail to extrapolate information and understanding from well-studied locations to other land units. However, these traditional approaches are expected to be insufficient in the future as both human and climatic drivers change in magnitude and direction, spatial heterogeneity in land cover and its use increases, and rangelands become increasingly connected at local to global scales by flows of materials, people, and information. Here we argue that to overcome limitations of each individual discipline, and to address future rangeland problems effectively, scientists will need to integrate these disciplines successfully and in novel ways. The objectives of this article are 1) to describe the background, historical development, and limitations of current approaches employed by these disciplines; 2) to describe an integrated approach that takes advantage of the strengths and minimizes the weaknesses of these individual approaches; and 3) to discuss the challenges and implications of this integrated approach to the future of range science when climate and human drivers are nonstationary. This integration will be critical for applying range science to the management of specific land units; will contribute to and benefit from the development of general ecological principles; and will assist in addressing problems facing society at regional, continental, and global scales

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

Carbon net emission is a critical aspect of the environmental footprint in agricultural systems. However, the alternatives to describe soil organic carbon (SOC) changes associated with different agricultural management practices/land uses are limited. Here we provide an overview of carbon (C) stocks of non-forested areas of Uruguay to estimate SOC changes for different soil units affected by accumulated effects of crop and livestock production systems in the last decades. For this, we defined levels based on SOC losses relative to the original (reference) SOC stocks: 25% or less, between 25-50%, and 50% or more. We characterized the reference SOC stocks using three approaches: 1) an equation to derive the potential SOC capacity based on the clay and fine silt soil content, 2) the DayCent model to estimate the SOC stocks based on climate, soil texture and C inputs from the natural grasslands of the area, 3) an estimate of SOC using a proxy derived from remote sensing data (i.e., the Ecosystem Services Supply Index) that accounts for differences in C inputs. Depending on the used reference SOC, the soil units had different distributions of SOC losses within the zones defined by the thresholds. As expected, the magnitude of SOC changes observed for the different soil units was related to the relative frequency of annual crops, however, the high variability observed along the gradient of land uses suggests a wide space for increasing SOC with agricultural management practices. The assessment of the C stock preserved (CSP) belowground and the potential for increasing C sequestration (CAP) are critical components of the C footprint of a given system. In this article we propose a methodological road map to derive indicators of CSP and CAP at the farm level combining both, biogeochemical simulation models and conceptual models based on remotely sensed data. We recognize at least three critical issues that require scientific and political consensus to implement the use of the proposed CSP and CAP criteria: (1) how to define potential or reference C stocks, (2) how to estimate current C stocks over large areas and in heterogeneous agricultural landscapes, and (3) what is a reasonable/acceptable threshold of C stocks reduction