Germán Baldi

Land-Use and Land Cover Dynamics in South American Temperate Grasslands

In the Rio de la Plata grasslands (RPG) biogeographical region of South America, agricultural activities have undergone important changes during the last 15-18 years because of technological improvements and new national and international market conditions. We characterized changes in the landscape structure between 1985-1989 and 2002-2004 for eight pilot areas distributed across the main regional environmental gradients. These areas incorporated approximately 35% of the 7.5 × 10 5 km² of the system. Our approach involved the generation of land-use and land cover maps, the analysis of landscape metrics, and the computation of annual transition probabilities between land cover types. All of the information was summarized in 3383 cells of 8 × 8 km. The area covered by grassland decreased from 67.4 to 61.4% between the study periods. This decrease was associated with an increase in the area of annual crops, mainly soybean, sunflower, wheat, and maize. In some subunits of the RPG, i.e., Flat Inland Pampa, the grassland-to-cropland transition probability was high ( pG→C = 3.7 × 10-2), whereas in others, i.e., Flooding Pampa, this transition probability was low ( pG→C = 6.7 × 10-3). Our description of the magnitude, direction, and spatial distribution of land-use and land cover changes provides a basis from which to develop spatially explicit scenarios of land cover change.

Cystic echinococcosis in South America: systematic review of species and genotypes of Echinococcus granulosus sensu lato in humans and natural domestic hosts.

To systematically review publications on Echinococcus granulosus sensu lato species/genotypes reported in domestic intermediate and definitive hosts in South America and in human cases worldwide, taking into account those articles where DNA sequencing was performed; and to analyse the density of each type of livestock that can act as intermediate host, and features of medical importance such as cyst organ location.

Carbon Stocks and Fluxes in Rangelands of the Río de la Plata Basin

Abstract Grasslands are one of the most modified biomes on Earth. Land use changes had a large impact on carbon (C) stocks of grasslands. Understanding the impact of land use/land cover changes on C stocks and fluxes is critical to evaluate the potential of rangeland ecosystem as C sinks. In this article we analyze C stocks and fluxes across the environmental gradients of one of the most extensive temperate rangeland areas: the Río de la Plata Grasslands (RPG) in South America. The analysis summarizes information provided by field studies, remote sensing estimates, and modeling exercises. Average estimates of aboveground net primary production (ANPP) ranged from 240 to 316 g C · m−2 · yr−1. Estimates of belowground NPP (BNPP) were more variable than ANPP and ranged from 264 to 568 g C · m−2 · yr−1. Total Carbon ranged from 5 004 to 15 008 g C · m−2. Plant biomass contribution to Total Carbon averaged 13% and varied from 9.5% to 27% among sites. The largest plant C stock corresponded to belowground biomass. Aboveground green biomass represented less than 7% of the plant C. Soil organic carbon (SOC) was concentrated in the slow and passive compartments of the organic matter. Active soil pool represented only 6.7% of the SOC. The understanding of C dynamics and stocks in the RPG grasslands is still partial and incomplete. Field estimates of ANPP and BNPP are scarce, and they are not based on a common measurement protocol. Remotely sensed techniques have the potential to generate a coherent and spatially explicit database on ANPP. However, more work is needed to improve estimates of the spatial and temporal variability of radiation use efficiency. The absence of a flux tower network restricts the ability to track seasonal changes in C uptake and to understand fine-scale controls of C dynamics.

Revolutionary land use change in the 21st century: is (Rangeland) science relevant?

Abstract Rapidly increasing demand for food, fiber, and fuel together with new technologies and the mobility of global capital are driving revolutionary changes in land use throughout the world. Efforts to increase land productivity include conversion of millions of hectares of rangelands to crop production, including many marginal lands with low resistance and resilience to degradation. Sustaining the productivity of these lands requires careful land use planning and innovative management systems. Historically, this responsibility has been left to agronomists and others with expertise in crop production. In this article, we argue that the revolutionary land use changes necessary to support national and global food security potentially make rangeland science more relevant now than ever. Maintaining and increasing relevance will require a revolutionary change in range science from a discipline that focuses on a particular land use or land cover to one that addresses the challenge of managing all lands that, at one time, were considered to be marginal for crop production. We propose four strategies to increase the relevance of rangeland science to global land management: 1) expand our awareness and understanding of local to global economic, social, and technological trends in order to anticipate and identify drivers and patterns of conversion; 2) emphasize empirical studies and modeling that anticipate the biophysical (ecosystem services) and societal consequences of large-scale changes in land cover and use; 3) significantly increase communication and collaboration with the disciplines and sectors of society currently responsible for managing the new land uses; and 4) develop and adopt a dynamic and flexible resilience-based land classification system and data-supported conceptual models (e.g., state-and-transition models) that represent all lands, regardless of use and the consequences of land conversion to various uses instead of changes in state or condition that are focused on a single land use. Resumen La creciente demanda de alimentos, fibras y combustibles de manera simultánea con las nuevas tecnologías y la movilidad global del capital están ocasionando cambios revolucionados en el uso de la tierra en todo el mundo. Los esfuerzos para incrementar la productividad de la tierra incluyen la conversión de millones de hectáreas de pastizales a la producción de granos, incluyendo tierras marginales con bajo resistencia y resilencia a la degradación. Sostener la productividad de estas tierras requiere planeación cuidadosa del uso de la tierra y sistemas de manejo innovadores. Históricamente, esta responsabilidad se ha dejado a agrónomos y otros expertos en producción de granos. En este articulo, discutimos que los revolucionados cambios en uso de la tierra necesarios para sostener la seguridad alimentaria nacional y mundial potencialmente hacen a la ciencia del pastizal más relevante ahora que nunca. Mantener e incrementar esa relevancia requerirá de cambios revolucionarios en la ciencia del pastizal de una disciplina que se enfoca en un uso particular de la tierra o cubierta vegetal a una que considere el reto de manejar todas las tierras que en algún tiempo fueron consideradas marginales para la producción de granos. Proponemos cuatro estrategias para aumentar la relevancia de la ciencia del pastizal a un manejo global de la tierra: 1) extender nuestra conocimiento y concientización del ámbito local a tendencias globales económicas, sociales y tecnológicas con el fin de anticipar e identificar conductores y patrones de conversión, 2) enfatizar en estudios empíricos y modelaje que anticipe las consecuencias biofísicas (servicios de los ecosistemas) y sociales de cambios en la cobertura y uso de la tierra en gran escala, 3) aumentar significativamente la comunicación y colaboración con las disciplinas y sectores de la sociedad actualmente responsables en el manejo del nuevo uso de la tierra, y 4) desarrollar y adoptar un sistema de clasificación dinámica y flexible basado en la resilencia de la tierra y modelos conceptuales apoyados en datos (ejm. Modelos de Estado y Transición) que representan todas las tierras, independientemente del uso y las consecuencias en la conversión de tierras para varios usos el lugar de cambios en el estado y condición que se enfocan en un solo uso de la tierra.

Seasonal variations in small mammal-landscape associations in temperate agroecosystems: a study case in Buenos Aires province, central Argentina

Abstract We studied the associations between small mammal assemblages and patterns of land use and landscape structure, and their seasonal variations in temperate agroecosystems. We collected barn owl, Tyto alba, pellets from nest sites located in the Pampean region included in Buenos Aires province (36 sites in winter and 29 in summer). We used Google Earth and SAC-C imagery classification to describe land use and landscape structure around pellet collection sites. In winter, we found a significant relation between the relative abundances of small mammal species and landscape variables. Landscape accounted for 33.2% of variance in species data. Calomys spp. were relatively more abundant in sites with higher winter crops cover, while Akodon azarae and Oligoryzomys flavescens increased their relative abundances in sites with more grassland cover. The commensal rodents Mus musculus and Rattus spp. were relatively more abundant in sites with higher urban cover, or near households and grain storage facilities. We found no significant small mammal-landscape association in summer. Our results are in agreement with previous studies showing that land use patterns may influence small mammal assemblages. Moreover, our results also show that seasonality plays a major role modulating the intensity of these small mammal-landscape associations in temperate agroecosystems.

The imprint of humans on landscape patterns and vegetation functioning in the dry subtropics.

Dry subtropical regions (DST), originally hosting woodlands and savannas, are subject to contrasting human pressures and land uses and different degrees of water limitation. We quantified how this variable context influences landscape pattern and vegetation functioning, by exploring the associations between three groups of variables describing (i) human pressures (population density, poverty, and market isolation) and climate (water availability), (ii) landscape pattern (woody cover, infrastructure, paddock size, etc.), and (iii) vegetation functioning (magnitude and stability of primary productivity), in regions of Asia, Africa, Australia, and America. We collected data from global socioeconomic databases and remote sensing products for 4525 samples (representing uncultivated and cultivated conditions), located along 35 transects spanning semiarid to subhumid conditions. A Reciprocal Averaging ordination of uncultivated samples revealed a dominant gradient of declining woody cover accompanied by lower and less stable productivity. This gradient, likely capturing increasing vegetation degradation, had a negative relationship with poverty (characterized by infant mortality) and with market isolation (measured by travel time to large cities). With partial overlaps, regions displayed an increasing degradation ranking from Africa to South America, to Australia, to North America, and to Asia. A similar analysis of cultivated samples, showed a dominant gradient of increasing paddock size accompanied by decreasing primary productivity stability, which included all regions except Asia. This gradient was negatively associated with poverty and population density. A unique combination of small paddocks and high infrastructure differentiated Asian cultivated samples. While water availability gradients were related to productivity trends, they were unrelated to landscape pattern. Our comparative approach suggests that, in DST, human pressures have an overwhelming role driving landscape patterns and one shared with water availability shaping vegetation functioning.

Forest conservation: Remember Gran Chaco

TROPICAL AND SUBTROPICAL dry forests around the globe are experiencing rapid clearing and concomitant biodiversity loss ([ 1 ][1]). In their Research Article “Plant diversity patterns in neotropical dry forests and their conservation implications” (23 September 2016, p. [1383][2]), DRYFLOR et al

Is aridity restricting deforestation and land uses in the South American Dry Chaco

ABSTRACT In this paper, we explored how aridity influences the regional deforestation and land-use patterns (i.e. crops/pastures) in South American Dry Chaco. To do this, we contrasted land use during last decade (2001–2012) with a spatially explicit aridity index, which we complemented with a crop water balance model. Land-use classifications were performed by considering the temporal variability of NDVI from MODIS satellites, showing that 40 and 60% of deforested land was assigned to crops and pastures, respectively. Results indicate that although the regional deforestation pattern was not associated with the aridity gradient, with drier areas similarly deforested as wetter areas, contrasting differences were observed in the use of this land, with crops mostly located (90%) in wetter areas and pastures evenly distributed across the whole aridity gradient. This research highlighted the strong effect of water limitations on the land-use option after deforestation and may help to set the basis for future land-use planning policies.

Tree Plantation in South America and The Water Cycle: Impacts and Emergent Opportunities

South American tree plantations expand at a rate of 5,000 km2/year favored by increasingly globalized markets and local economic conditions. The main hydrological impacts of these plantations involve shifts in (a) the partition of precipitation inputs between vapour vs. liquid fluxes (associated to transpiration and canopy interception shifts) and (b) the partition of liquid fluxes between run-off and fast flow vs. deep drainage and base flow (associated to infiltration and surface water routing shifts). In sloped terrains global stream flow measurements in paired watersheds indicate declining water yields (40% less on average) under plantations vs. native vegetation. These effects are stronger under drier climates, where host vegetation is herbaceous, and where planted trees are eucalypts. In flat landscapes with native grassland vegetation, tree plantations switch the water balance from positive (net recharge) to negative (net discharge) triggering local salinization. Contrastingly, where native vegetation has been a woodland tree plantation can remediate the undesirable recharge and water table rise/salinization problems brought by agriculture. In degraded rolling (sub)tropical landscapes with intense rainfall inputs and high run-off, tree plantations can increase infiltration rates, reducing erosion, stabilizing flow, but cutting total water yield. As a result of these shifts, erosion can be reduced and the stability and quality of water provision improved, yet these benefits can be erased by large scale clear cutting practices. Context (climate, current vegetation and topography/geology) and design (species, densities, harvesting methods, and scale/pattern) can decide the magnitude and sign of tree plantations effects and need to be carefully considered to get the best ecological outcome of afforestation in the continent.

Variations in Anarthrophyllum rigidum radial growth, NDVI and ecosystem productivity in the Patagonian shrubby steppes

The lack of long-term records of productivity is a critical limitation to the study of ecosystem dynamics. Annual rings, a measure of growth in woody species, are a useful tool to document ecosystem dynamics. Time series of the Normalized Difference Vegetation Index (NDVI) provide estimates of ecosystem productivity through satellite-derived data on the fraction of photosynthetic active radiation absorbed by vegetation. In the Patagonian steppes, we relate changes in NDVI to interannual variations in the radial growth of the shrub Anarthrophyllum rigidum. A widely distributed network of 15 ring-width chronologies of A. rigidum was used to estimate changes in NDVI across the Patagonia steppe (35°–50°S). In most sites, interannual variations in shrub growth and NDVI are regulated by winter precipitation. The water accumulated in the soil during winter is used by A. rigidum during the growing season, concurrent with the maximum NDVI values. At 10 from the 15 selected sites, variations in the radial growth of A. rigidum explained between 23 and 62% of the total variance in seasonal NDVI, suggesting that the A. rigidum growth at some sites provides good estimates of productivity in the Patagonian shrubby steppes during the growing season. However, we were unable to determine clear relationships between radial growth and NDVI at high-elevation mountainous sites or where intensive grazing by sheep masked the effect of climate variability on shrub growth. We conclude that dendrochronological methods can complement other estimates to reconstruct variations of productivity, supplementing and extending the few short records available in the Patagonian steppe.