Impacts of land use change on ecosystems and society in the Rio de La Plata basin.

The La Plata river basin (LPB) covers an area of 3.1 million km2 with a population of over 100 million people of Argentina, Bolivia, Brazil, Paraguay, and Uruguay. The LPB covers a wide geographical area, spanning a South to North latitudinal gradient, resulting in the establishment of a variety of soil - vegetation configurations, as a response to different climates. The inherent topographic heterogeneity of the LPB adds natural complexity to the basin, resulting in a combination of extensive savannah-like plateaus (cerrado) and grasslands and open fields (pampas) in its Northern and Southern portions, respectively, the largest tropical wetland area in the world in the Northwest (pantanal), as well as both dry and humid forest biomes (chaco and Atlantic forests, respectively). This varied composition of biomes and ecosystems, added to the different social and cultural setup of the LPB, resulted in diverse histories and complex patterns of land use in the basin. Rural land use and industry in the basin are responsible for 70% of the Gross National Products of the LPB countries and are in a process of continuous change, as a response to drivers such as international market trends, infra-structure and technology developments, societal evolution, and the dynamics of national policies. Possible land use changes (LUC) are limited by biophysical constraints such as unsuitable soil type, topography, or climate. However, technology development can overcome some of these limitations, as was the case of the soybean expansion to the Cerrado region of Brazil, in the eighties. Effective and sustainable management of the LPB depends on the ability of land managers from the five nations to predict the impacts LUCs on nature and society. Modeling efforts to predict environmental impacts in the LPB can benefit from knowledge acquired from impact assessments of major LUC processes. Land use change affects both the natural environment and society, therefore impact indicators should represent both dimensions. The human and natural dimensions interact both as drivers and as recipients of the impacts of LUC. The altered state of the impacted human and natural dimensions will reconfigure them as altered LUC drivers. Understanding these feedback mechanisms is a great challenge that integrates natural and social sciences. There is an urgent need for interdisciplinary research, overcoming inherent conceptual and epistemologic barriers. Decision makers and society will only act on response to global change science results, when social and natural scientists achieve an effective integrated research framework

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

Visualización y análisis de la humedad del suelo en superficie medida in situ y estimada por satelites en un sitio de la Llanura Pampeana

PosterEl agua almacenada en el suelo es una variable que controla múltiples procesos y circuitos de retroalimentación dentro del sistema climático, mediando los ciclos del agua y la energía (Seneviratne et al., 2010). En los últimos años se han logrado avances significativos en la caracterización de la humedad de suelo (HS) a escala regional, a través de estimaciones mediante teledetección y la puesta en funcionamiento de nuevas redes de medición in situ. Cada una de estas fuentes de información presenta características intrínsecas, como el rango dinámico de HS, los periodos de disponibilidad de datos y la frecuencia temporal de adquisición de los mismos. Por lo expuesto, resulta de suma importancia elaborar metodologías de visualización de la HS que nos permitan evaluar las cualidades de cada fuente de información previniendo la aplicación de supuestos y filtros adicionales sobre la dinámica natural de la HS que cada una de estas fuentes brinda. En el presente trabajo se proponen estrategias para explorar la HS de estaciones in situ y de los sistemas satelitales SMOS y SMAP. El estudio se enfoca en un sector de la llanura Pampeana de Argentina que ofrece como ventajas, además de contar con mediciones de HS in situ, paisajes relativamente homogéneos en cuanto a tipos y usos del suelos y un relieve extremadamente plano, que junto con un clima subhúmedo ofrecen un laboratorio natural de condiciones de HS.Fil: Cappelletti, L.M. Universidad de Buenos Aires - Consejo Nacional de Investigaciones Científicas y Técnicas, Centro de Investigaciones del Mar y la Atmósfera (CIMA/UBA-CONICET), Buenos Aires, Argentina; Institut Franco-Argentin d'Études sur le Climat et ses Impacts, Unité Mixte Internationale (UMI-IFAECI/CNRS-IRD-CONICET-UBA), Argentina.Fil: Sorensson, A. Universidad de Buenos Aires - Consejo Nacional de Investigaciones Científicas y Técnicas, Centro de Investigaciones del Mar y la Atmósfera (CIMA/UBA-CONICET), Buenos Aires, Argentina; Institut Franco-Argentin d'Études sur le Climat et ses Impacts, Unité Mixte Internationale (UMI-IFAECI/CNRS-IRD-CONICET-UBA), ArgentinaFil: Jobbágy, Esteban G. Universidad Nacional de San Luis. Instituto de Matemática Aplicada San Luis. Grupo de Estudios Ambientales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaRuscica, R. Universidad de Buenos Aires - Consejo Nacional de Investigaciones Científicas y Técnicas, Centro de Investigaciones del Mar y la Atmósfera (CIMA/UBA-CONICET), Buenos Aires, Argentina; Institut Franco-Argentin d'Études sur le Climat et ses Impacts, Unité Mixte Internationale (UMI-IFAECI/CNRS-IRD-CONICET-UBA), Argentina.Fil: Salvia, Maria Mercedes. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Fernández Long, M. Universidad de Buenos Aires. Facultad de Agronomía; Argentina.Fil: Gattinoni, Natalia N. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Clima y Agua; ArgentinaFil: Spennemann, P.C. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Servicio Meteorológico Nacional; Argentina Universidad Nacional de Tres de Febrero; Argentin

The receptors for gibbon ape leukemia virus and amphotropic murine leukemia virus are not downregulated in productively infected cells

<p>Abstract</p> <p>Background</p> <p>Over the last several decades it has been noted, using a variety of different methods, that cells infected by a specific gammaretrovirus are resistant to infection by other retroviruses that employ the same receptor; a phenomenon termed receptor interference. Receptor masking is thought to provide an earlier means of blocking superinfection, whereas receptor down regulation is generally considered to occur in chronically infected cells.</p> <p>Results</p> <p>We used replication-competent GFP-expressing viruses containing either an amphotropic murine leukemia virus (A-MLV) or the gibbon ape leukemia virus (GALV) envelope. We also constructed similar viruses containing fluorescence-labeled Gag proteins for the detection of viral particles. Using this repertoire of reagents together with a wide range of antibodies, we were able to determine the presence and availability of viral receptors, and detect viral envelope proteins and particles presence on the cell surface of chronically infected cells.</p> <p>Conclusions</p> <p>A-MLV or GALV receptors remain on the surface of chronically infected cells and are detectable by respective antibodies, indicating that these receptors are not downregulated in these infected cells as previously proposed. We were also able to detect viral envelope proteins on the infected cell surface and infected cells are unable to bind soluble A-MLV or GALV envelopes indicating that receptor binding sites are masked by endogenously expressed A-MLV or GALV viral envelope. However, receptor masking does not completely prevent A-MLV or GALV superinfection.</p

Protecting climate with forests

Policies for climate mitigation on land rarely acknowledge biophysical factors, such as reflectivity, evaporation, and surface roughness. Yet such factors can alter temperatures much more than carbon sequestration does, and often in a conflicting way. We outline a framework for examining biophysical factors in mitigation policies and provide some best-practice recommendations based on that framework. Tropical projects-avoided deforestation, forest restoration, and afforestation-provide the greatest climate value, because carbon storage and biophysics align to cool the Earth. In contrast, the climate benefits of carbon storage are often counteracted in boreal and other snow-covered regions, where darker trees trap more heat than snow does. Managers can increase the climate benefit of some forest projects by using more reflective and deciduous species and through urban forestry projects that reduce energy use. Ignoring biophysical interactions could result in millions of dollars being invested in some mitigation projects that provide little climate benefit or, worse, are counter-productive

Altitudinal variation in soil organic carbon stock in coniferous subtropical and broadleaf temperate forests in Garhwal Himalaya

<p>Abstract</p> <p>Background</p> <p>The Himalayan zones, with dense forest vegetation, cover a fifth part of India and store a third part of the country reserves of soil organic carbon (SOC). However, the details of altitudinal distribution of these carbon stocks, which are vulnerable to forest management and climate change impacts, are not well known.</p> <p>Results</p> <p>This article reports the results of measuring the stocks of SOC along altitudinal gradients. The study was carried out in the coniferous subtropical and broadleaf temperate forests of Garhwal Himalaya. The stocks of SOC were found to be decreasing with altitude: from 185.6 to 160.8 t C ha^-1and from 141.6 to 124.8 t C ha^-1in temperature (<it>Quercus leucotrichophora</it>) and subtropical (<it>Pinus roxburghii</it>) forests, respectively.</p> <p>Conclusion</p> <p>The results of this study lead to conclusion that the ability of soil to stabilize soil organic matter depends negatively on altitude and call for comprehensive theoretical explanation</p

Ideas and perspectives: strengthening the biogeosciences in environmental research networks

Many scientific approaches are improving our understanding and management of the rapidly changing environment. Long-term environmental research networks are one approach to advancing local, regional, and global environmental science and education. A remarkable number and wide variety of environmental research networks operate around the world today. These are diverse in funding, infrastructure, motivating questions, scientific strengths, and the sciences that birthed and maintained the networks. Some networks have individual sites that were selected because they had produced invaluable long-term data, while other networks have new sites selected to span ecological gradients. However, all long-term environmental networks share two challenges. Networks must keep pace with scientific advances and interact with both the scientific community and society at large. If networks fall short of successfully addressing these challenges, they risk becoming irrelevant. The objective of this paper is to assert that the biogeosciences offer environmental research networks a number of opportunities to expand scientific impact and public engagement. We explore some of these opportunities with four networks: the International Long Term Ecological Research programs (ILTERs), the Critical Zone Observatories (CZOs), the Earth and Ecological Observatory networks (EONs), and the FLUXNET program of eddy flux sites. While these networks were founded and grown by interdisciplinary scientists, the preponderance of expertise and funding have gravitated activities of ILTERs and EONs toward ecology and biology, CZOs toward the Earth sciences and geology, and FLUXNET toward ecophysiology and micrometeorology. Our point is not to homogenize networks, nor to diminish disciplinary science. Rather, we argue that by more fully incorporating the integration of biology and geology in long-term environmental research networks, scientists can better leverage network assets, keep pace with the ever-changing science of the environment, and engage with larger scientific and public audiences

Carbon storage of headwater riparian zones in an agricultural landscape

<p>Abstract</p> <p>Background</p> <p>In agricultural regions, streamside forests have been reduced in age and extent, or removed entirely to maximize arable cropland. Restoring and reforesting such riparian zones to mature forest, particularly along headwater streams (which constitute 90% of stream network length) would both increase carbon storage and improve water quality. Age and management-related cover/condition classes of headwater stream networks can be used to rapidly inventory carbon storage and sequestration potential if carbon storage capacity of conditions classes and their relative distribution on the landscape are known.</p> <p>Results</p> <p>Based on the distribution of riparian zone cover/condition classes in sampled headwater reaches, current and potential carbon storage was extrapolated to the remainder of the North Carolina Coastal Plain stream network. Carbon stored in headwater riparian reaches is only about 40% of its potential capacity, based on 242 MgC/ha stored in sampled mature riparian forest (forest > 50 y old). The carbon deficit along 57,700 km headwater Coastal Plain streams is equivalent to about 25TgC in 30-m-wide riparian buffer zones and 50 TgC in 60-m-wide buffer zones.</p> <p>Conclusions</p> <p>Estimating carbon storage in recognizable age-and cover-related condition classes provides a rapid way to better inventory current carbon storage, estimate storage capacity, and calculate the potential for additional storage. In light of the particular importance of buffer zones in headwater reaches in agricultural landscapes in ameliorating nutrient and sediment input to streams, encouraging the restoration of riparian zones to mature forest along headwater reaches worldwide has the potential to not only improve water quality, but also simultaneously reduce atmospheric CO₂.</p

Increased Litterfall in Tropical Forests Boosts the Transfer of Soil CO2 to the Atmosphere

Aboveground litter production in forests is likely to increase as a consequence of elevated atmospheric carbon dioxide (CO2) concentrations, rising temperatures, and shifting rainfall patterns. As litterfall represents a major flux of carbon from vegetation to soil, changes in litter inputs are likely to have wide-reaching consequences for soil carbon dynamics. Such disturbances to the carbon balance may be particularly important in the tropics because tropical forests store almost 30% of the global soil carbon, making them a critical component of the global carbon cycle; nevertheless, the effects of increasing aboveground litter production on belowground carbon dynamics are poorly understood. We used long-term, large-scale monthly litter removal and addition treatments in a lowland tropical forest to assess the consequences of increased litterfall on belowground CO2 production. Over the second to the fifth year of treatments, litter addition increased soil respiration more than litter removal decreased it; soil respiration was on average 20% lower in the litter removal and 43% higher in the litter addition treatment compared to the controls but litter addition did not change microbial biomass. We predicted a 9% increase in soil respiration in the litter addition plots, based on the 20% decrease in the litter removal plots and an 11% reduction due to lower fine root biomass in the litter addition plots. The 43% measured increase in soil respiration was therefore 34% higher than predicted and it is possible that this ‘extra’ CO2 was a result of priming effects, i.e. stimulation of the decomposition of older soil organic matter by the addition of fresh organic matter. Our results show that increases in aboveground litter production as a result of global change have the potential to cause considerable losses of soil carbon to the atmosphere in tropical forests