Nitrogen and Carbon Isotopic Dynamics of Subarctic Soils and Plants in Southern Yukon Territory and its Implications for Paleoecological and Paleodietary Studies

We examine here the carbon and nitrogen isotopic compositions of bulk soils (8 topsoil and 7 subsoils, including two soil profiles) and five different plant parts of 79 C3 plants from two main functional groups: herbs and shrubs/subshrubs, from 18 different locations in grasslands of southern Yukon Territory, Canada (eastern shoreline of Kluane Lake and Whitehorse area). The Kluane Lake region in particular has been identified previously as an analogue for Late Pleistocene eastern Beringia. All topsoils have higher average total nitrogen δ15N and organic carbon δ13C than plants from the same sites with a positive shift occurring with depth in two soil profiles analyzed. All plants analyzed have an average whole plant δ13C of −27.5 ± 1.2 ‰ and foliar δ13C of ±28.0 ± 1.3 ‰, and average whole plant δ15N of −0.3 ± 2.2 ‰ and foliar δ15N of ±0.6 ± 2.7 ‰. Plants analyzed here showed relatively smaller variability in δ13C than δ15N. Their average δ13C after suitable corrections for the Suess effect should be suitable as baseline for interpreting diets of Late Pleistocene herbivores that lived in eastern Beringia. Water availability, nitrogen availability, spacial differences and intra-plant variability are important controls on δ15N of herbaceous plants in the study area. The wider range of δ15N, the more numerous factors that affect nitrogen isotopic composition and their likely differences in the past, however, limit use of the modern N isotopic baseline for vegetation in paleodietary models for such ecosystems. That said, the positive correlation between foliar δ15N and N content shown for the modern plants could support use of plant δ15N as an index for plant N content and therefore forage quality. The modern N isotopic baseline cannot be applied directly to the past, but it is prerequisite to future efforts to detect shifts in N cycling and forage quality since the Late Pleistocene through comparison with fossil plants from the same region

Economics of Land Degradation in Argentina

Argentina is one of the countries with a vibrant agricultural sector, which provides both economic development opportunities and environmental challenges. Argentina was selected as a case study due to its rich land degradation data, its diverse agroecological systems, and rapid poverty reduction. The country also represents high human development index countries. This study reports the cost of land degradation, the cost of inaction and cost and benefits of taking action against land degradation. The total loss of ecosystem services due to land-use/cover change (LUCC), wetlands degradation and use of land degrading management practices on grazing lands and selected croplands is about 2007 US$75 billion, which is about 16$4 per US$ invested—justifying the need to take action to improve human welfare and environmental protection. The actions against land degradation include investment in restoration of degraded lands and prevention of land degradation through stricter regulation of agricultural expansion into forests and other higher value biomes. They also include reforestation and other restoration efforts; protection wetlands and restoration of degraded wetlands. The excessive use of agrochemicals also require action to regulate their potential off-site effects. Case studies also show that promotion of rotational grazing, extending conservation agriculture beyond soybean; tillage method and crop-livestock production systems offer promising strategies for addressing land degradation. The world has a lot to learn from Argentina—given its rapid poverty reduction and successful adoption rate of conservation agriculture using public-private partnership. If Argentina aims at maintaining its economic and social development, it will need to work harder to address its growth-related environmental challenges that affect the poor the most. Argentina is better prepared to face these challenges. This study will contribute to informing policy makers on the best strategies for taking action against land degradation and the returns to such actions.Fil: Bouza, Mariana Eve. Universidad Nacional del Sur; ArgentinaFil: Aranda Rickert, Adriana Marina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Brizuela, Maria Magdalena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Wilson, Marcelo Germán. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Sasal, Maria Carolina. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Sione, Silvana. Universidad Nacional de Entre Ríos. Facultad de Ciencias Agropecuarias; ArgentinaFil: Beghetto, Stella. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Gabioud, Emmanuel Adrián. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Oszust, José Daniel. Universidad Nacional de Entre Ríos. Facultad de Ciencias Agropecuarias; ArgentinaFil: Bran, Donaldo Eduardo. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Velazco, Virginia. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Gaitán, Juan José. Instituto Nacional de Tecnología Agropecuaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Silenzi, Juan Carlos. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Echeverría, Nora Elena. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: de Lucia, Martín Pascual. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Iurman, Daniel Eduardo. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Vanzolini, Juan. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Castoldi, Federico José. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Hormaeche, Joaquin Etorena. Secretaría de Ambiente y Desarrallo Sustentable de la Nación; ArgentinaFil: Johnson, Timothy. International Food Policy Research Institute; Estados UnidosFil: Meyer, Stefan. International Food Policy Research Institute; Estados UnidosFil: Nkonya, Ephraim. International Food Policy Research Institute; Estados Unido