Argentine Pampas Research Articles

Achieving the Sustainable Development Goals through good enough governance: lessons from Argentine and Brazilian Municipalities

This article analyses how two environmental “good enough-governance” approaches in climate change vulnerable areas in Argentine (Pampa biome) and Brazilian (Amazon biome) municipalities have the potential of contributing to the achievement of the Sustainable Development Goals 12 (responsible consumption and production), 13 (climate action), 15 (life on land), 16 (Peace, Justice and Strong Institutions), and 17 (partnerships for the goals). Local public officials from Brazil often by-pass frustrating bureaucracy by transferring their own public responsibilities to NGOs (subsidiarity principle). Argentine public servants, on the other hand, are frequently filling the gaps left by the fragile vertical integration of environmental actions through bottom-up, horizontal initiatives among municipalities. Both approaches show strengths but also fragilities, such as the lack of policy continuity. In spite of the socio-environmental differences, many Brazilian and Argentine local agents are developing a common array of individual and social “soft skills” which are usually attributed to NGOs: goal-oriented, innovative thinking, teamwork, integration and flexibility, all necessary to the localization of the Agenda 2030. Environmental institutions and norms at the local level could be rearranged to worship these soft skills in the public sector by putting people at the centre of adaptive decision-making through capacity development, career incentives and accountability.

Water exchange processes estimation in a temperate shallow lake based on water stable isotope analysis

ABSTRACT The estimation of lake hydrological characteristics such as evaporation/inflow ratios and water residence time becomes necessary for understanding cycling and potential retention of natural and anthropogenic substances into the lake. The aim of this work was to estimate the evaporation loss and the water residence time of a temperate shallow lake based on the water isotope mass balance approach. One representative freshwater temperate shallow lake from the Argentinian Pampa Plain was selected. Groundwater, lake and stream samples (N = 56) were collected for δ 2H-H2O and δ 18O-H2O determinations. Moreover, water level fluctuations of the lake and its inflow stream were recorded with data loggers. Both the δ 2H and δ 18O relationship and d-excess of lake water indicated evaporation. Water isotopes and daily stream flow data recorded in the inflow stream evidenced groundwater contribution to Los Padres Stream. Monthly evaporation as a fraction of inflow estimations of the lake water indicated that about 20–25 ± 12% lake water was lost through lake surface evaporation and revealed that hydrologic balances were regulated mainly by changes in water inflow rather than evaporation. A mean residence time of 1.11 ± 0.65 year was also calculated. This lake hydrological information is relevant for the region and crucial to improve water management plans.

Wider road verges sustain higher plant species richness and pollinator abundance in intensively managed agroecosystems

Landscape fragmentation and farming can affect the diversity of plants and pollinators harbored by linear landscape elements (LLE) in agroecosystems. To assess the role of these habitats in sustaining plant-pollinator communities, twenty portions of LLE (road verges) were studied during two consecutive field seasons in the Argentine Pampas. A hierarchical approach was taken, describing three features of road verges in different scales of observation: width of the road verge (local scale), the land use of the neighboring fields (adjacent land use scale), and landscape heterogeneity (landscape scale). The influence of these features on the composition and abundance of entomophilous flowering plants and their visitors were examined with GLMMs. Plant and flower visitor communities in road verges were dominated by alien species. The local scale feature was the most influential, as the widest road verges had higher plant richness and higher flower visitor abundance. Contrary to our expectations, richness and abundance of both plants and flower visitors were not related to adjacent land use or landscape heterogeneity. These results suggest that the conservation and management of wider road verges should be a priority to sustain high species diversity in intensely managed agroecosystems.

The effects of extreme drought events on the morphometry of shallow lakes: Implications for sediment resuspension and littoral and pelagic zone distribution

Shallow lakes, because of their depth, are more vulnerable to the effects of wind and changes in precipitation and evaporation that deeper lakes and thus respond more dramatically to extreme climatic events, such as drought. The morphology of shallow lakes influences many of their physical, chemical, biological and sedimentological processes including sediment resuspension. Sediment resuspension can trigger undesired effects such as eutrophication, increase in turbidity, cyanobacterial blooms, and also affects the distribution and extent of the littoral and pelagic zones (habitat distribution) with potentially negative consequences on biodiversity and loss of native species. These problems are an increasing concern in the face of global warming. To understand how changes in lake' morphometry, triggered by extreme drought events influence sediment resuspension and habitat distribution, we studied four shallow lakes located in the southwest of the Argentinean Pampas. Each lake was characterized by its bathymetry, morphometric parameters (including area, shore development, dynamic ratio, critical depth), the spatial distribution of the littoral and pelagic areas, and the effect of the waves on sediment resuspension. We measured the Area and Shore development again during selected extreme drought periods identified through the Standardized Precipitation-Evapotranspiration Index. Then, for the given drought period, we calculated the extent and distribution of littoral and pelagic areas and the critical depth at which sediment resuspension occurred and then estimated the percentage of the lake that would be affected by it. We found that Pampean lakes are profoundly affected by sediment resuspension triggered by wind during extreme dry events. Droughts have different effects depending on lake morphology. Dry periods caused not only a decrease in water volume, but also modified the extension of littoral and pelagic zones and increased sediment resuspension. These results have significant implications for the preservation of these rich ecosystems, especially in the context of global warming.

Prediction of topsoil properties at field-scale by using C-band SAR data

Designing and validating digital soil mapping (DSM) techniques can facilitate precision agriculture implementation. This study generates and validates a technique for the spatial prediction of soil properties based on C-band radar data. To this end, (i) we focused on working at farm-field scale and conditions, a fact scarcely reported; (ii) we validated the usefulness of Random Forest regression (RF) to predict soil properties based on C-band radar data; (iii) we validated the prediction accuracy of C-band radar data according to the coverage condition (for example: crop or fallow); and (iv) we aimed to find spatial relationship between soil apparent electrical conductivity and C-band radar. The experiment was conducted on two agricultural fields in the southern Argentine Pampas. Fifty one Sentinel 1 Level-1 GRD (Grid) products of C-band frequency (5.36 GHz) were processed. VH and VV polarizations and the dual polarization SAR vegetation index (DPSVI) were estimated. Soil information was obtained through regular-grid sample scheme and apparent soil electrical conductivity (ECa) measurements. Soil properties predicted were: texture, effective soil depth, ECa at 0-0.3m depth and ECa at 0-0.9m depth. The effect of water, vegetation and soil on the depolarization from SAR backscattering was analyzed. Complementary, spatial predictions of all soil properties from ordinary cokriging and Conditioned Latin hypercube sampling (cLHS) were evaluated using six different soil sample sizes: 20, 40, 60, 80, 100 and the total of the grid sampling scheme. The results demonstrate that the prediction accuracy of C-band SAR data for most of the soil properties evaluated varies considerably and is closely dependent on the coverage type and weather dynamics. The polarizations with high prediction accuracy of all soil properties showed low values of σVVo and σVHo, while those with low prediction accuracy showed high values of σVVo and low values of σVHo. The spatial patterns among maps of all soil properties using all samples and all sample sizes were similar. In conditions when summer crops demand large amount of water and there is soil water deficit backscattering showed higher prediction accuracy for most soil properties. During the fallow season, the prediction accuracy decreased and the spatial prediction accuracy was closely dependent on the number of validation samples. The findings of this study corroborates that DSM techniques at field scale can be achieved by using C-band SAR data. Extrapolation y applicability of this study to other areas remain to be tested.

Influence of soil water holding and transport capacity on glyphosate dynamics in two agricultural soils from Pampas Region

Water dynamics is one of the most important regulating factors on glyphosate fate in agricultural soils. The objectives of this work were: i- to determine static and dynamic soil physical quality (SPQ) indicators during the crop cycle in two different textured soils from Argentinean Pampas Region, under no tillage (NT) and conventional tillage (CT); ii- to quantify glyphosate accumulation during the crop cycle in two different textured soils of Argentinean Pampas Region under NT and CT; and iii- to determine the relationship between glyphosate accumulation and vertical transport during the crop cycle with the static and dynamic SPQ indicators. Static and dynamic SPQ indicators and Total Extractable Glyphosate (TEG) were determined in a silty loam typic Argiudoll (Pergamino site, PER) and in a sandy loam Entic Haplustoll (Dorila site, DOR) at the beginning and the end of the crop cycle. In general, soils under NT showed higher values of plant available water content (PAWC) and lower values of saturated hydraulic conductivity (K0) as compared with CT. PER showed higher values of water content at wilting point (θWP), as compared with DOR. High values of θWP, along with low values of K0 were correlated to glyphosate accumulation, especially in the top soil. On the other hand, high values of K0 may favor vertical transport, as was observed under CT for PER. Our results show that repeated glyphosate application could lead to its accumulation in agricultural soils, depending of the soil type and tillage systems, implying a potential risk of soil pollution.

Gregariousness in the giant sloth Lestodon (Xenarthra): multi-proxy approach of a bonebed from the Last Maximum Glacial of Argentine Pampas

Megamammals constituted an important component in the Pleistocene faunal communities of South America. Paleobiological and paleoecological studies involving different megamammal taxa have increased significantly in the last years, but there are still several poorly-known issues of its life history. In this work, we analyze an assemblage composed of 13 individuals of different ontogenetic stages, and possibly different sex, belonging to the giant ground sloth Lestodon armatus (Xenarthra, Folivora), recovered from Playa del Barco site (Pampean Region, Argentina). A dating of 19,849 years Cal BP allows assigning this assemblage to a period of the MIS (Marine Isotope Stage) 2 related to the end of the Last Glacial Maximum. Based on multiple lines of research (e.g. taphonomy, paleopathology, osteohistology, isotopy), we interpret the origin of the assemblage and diverse paleobiological and paleoecological aspects (e.g. social behavior, ontogenetic changes, sexual dimorphism, diseases, resource and habitat use, trophic relationships) of L. armatus. Evidence suggests that the assemblage was formed by a local single event of catastrophic mortality, which affected different members of a social group. This record represents the first accurate evidence of gregariousness for this ground sloth, providing new data on a poorly-known behavior among extinct Folivora.

Las relaciones sociales en el sector agropecuario pampeano argentino: análisis de los diferentes tipos de sujetos agrarios a partir de los modos en que construyen sus vínculos en la producción

En el contexto de las profundas transformaciones que atraviesan al sector agropecuario de la región pampeana argentina en la actualidad, se analiza de qué modo se han redefinido y cuáles son las características centrales de las relaciones sociales entre los actores involucrados en la producción. El principal objetivo de este artículo es mostrar cómo los distintos tipos de relaciones resultan un elemento clave para la caracterización de los sujetos sociales agrarios actuales. Para ello se trabajó con una muestra de 38 explotaciones agropecuarias de distinto tamaño y perfil en tres partidos de la provincia de Buenos Aires (perteneciente a la región pampeana). A partir de entrevistas semiestructuradas a productores agropecuarios y otros actores involucrados, se reconstruyeron los tipos de estructuras de relaciones sociales en la esfera de la producción, y los tipos de lógicas con las cuales manejan la producción. Mediante este análisis, se identificó una tendencia a la mercantilización de las relaciones sociales en el agro, pero que se encuentra limitada en su plena expansión por la persistencia de una lógica que combina un anclaje en los parámetros científicos y de mercado, con una valorización de las trayectorias y saberes locales e históricos de cada espacio productivo.Ideas destacadas: artículo de investigación que aborda las transformaciones recientes en el agro pampeano argentino, y muestra cómo se reconfiguran las relaciones sociales en la actualidad. Mediante un análisis empírico en tres partidos de la provincia de Buenos Aires y de entrevistas en profundidad a productores agropecuarios, se identifica la coexistencia de distintos tipos de vínculos, y se subraya que la dimensión relacional resulta central para profundizar en el análisis de los sujetos agrarios y caracterizarlos.

Soil survey reveals a positive relationship between aggregate stability and anaerobically mineralizable nitrogen

Abstract Soil health status should be monitored to allow planning sustainable management, but indicators available do not encourage frequent soil health evaluation because of the complexity, time-consumption, and expensiveness of the methodologies. Aggregate stability (AS) is a good soil physical health indicator associated with soil (SOC) and particulate (POC) organic carbon but is difficult to monitor. Anaerobically mineralizable nitrogen (AN) has been proposed as soil health indicator because is cheap, simple, and safe to measure, is sensitive to soil-use changes, is also related to soil (SOC) and particulate (POC) organic carbon, and is frequently determined by farmers in Mollisols of the Southeastern Argentinean Pampas to support soil fertility diagnosis. We hypothesize that AN is positively related to and can be used as indicator of AS. Soil samples were taken at 0–5 and 5–20 cm depths from 46 sites throughout the southeastern Buenos Aires province, Argentinean Pampas. In each site, we sampled Mollisols under continuous cropping (CC) and others that had not been disturbed for many years (pseudo-pristine, PRIS). We determined texture, SOC, mineral-associated organic C, POC, AS and AN. We also calculated variable values for 0–20 cm. Soil organic carbon, POC, AN and AS were reduced by continuous cropping. Anaerobically mineralizable N was positively related to SOC (R2 = 0.74, 0.46, and 0.62 at 0–5, 5–20, and 0–20 cm) and POC (R2 = 0.73, 0.33, and 0.60, respectively). An important proportion of the total variability in AS was explained by SOC (R2 = 0.77, 0.65, and 0.73 at 0–5, 5–20, and 0–20 cm, respectively), POC (R2 = 0.75, 0.63, and 0.73, respectively), and AN (R2 = 0.78, 0.69, and 0.81, respectively). The AS increased with the increase of SOC, POC, and AN at all three depths, with slopes that did not differ between CC and PRIS, but with intercepts that differed. Neither sand nor clay contents significantly contributed to explain the variations in AS as a function of SOC, POC, and AN. An independent validation of the regression model relating AS and AN at 0–20 cm was done and the output was very good (RPIQ (ratio of performance to interquartile distance) = 2.20). Results support our hypothesis because AN was positively related to AS. Consequently, AN would be a good indicator of AS, SOC, and POC. Based on our results, we consider that a simple and cheap soil analysis as AN can not only be used to diagnose soil fertility, but to monitor soil physical and biochemical health status.

The Diversification and Intensification of Crop Rotations under No-Till Promote Earthworm Abundance and Biomass

The diversification and intensification of crop rotations (DICR) in no-till systems is a novel approach that aims to increase crop production, together with decreasing environmental impact. Our objective was to analyze the effect of different levels of DICR on the abundance, biomass, and species composition of earthworm communities in Argentinean Pampas. We studied three levels of DICR—typical rotation (TY), high intensification with grass (HG), and with legume (HL); along with three references—natural grassland (NG), pasture (PA), and an agricultural external reference (ER). The NG had the highest earthworm abundance. Among the DICR treatments, abundance and biomass were higher in HL than in HG and, in both, these were higher than in TY. The NG and PA had a distinctive taxonomic composition and higher species richness. Instead, the DICR treatments had a similar richness and species composition. Earthworm abundance and biomass were positively related to rotation intensity and legume proportion indices, carbon input, and particulate organic matter content. The application of DICR for four years, mainly with legumes, favors the development of earthworm populations. This means that a subtle change in management, as DICR, can have a positive impact on earthworms, and thus on earthworm-mediated ecosystem services, which are important for crop production.

Ecosystem services provided by wildlife in the Pampas region, Argentina

The expansion and intensification of human activities in the Argentinean Pampas have affected birds and mammals that inhabit the agroecosystems, threatening their populations and aggravating their conflicts with humans. On the other hand, they play different roles in the provision of Ecosystem Services (ES). Therefore, identifying and understanding the relationships between species and humans, and the delivery of ES is crucial for sustainable management of the environment. The objectives of this study were to identify ecological functions of birds and mammals and its conflicts with human activities reported by previous articles in the Pampas region; and to link these ecological functions as indicators of the potential ES provided by these species. We performed two systematic and structured searches of articles using Scopus bibliographic database, one for the ecological functions and the second one for conflicts. From the first search, we found 145 studies and 34% of them reported ecological functions, 78% were about birds and the rest about mammals. The Regulation and Maintenance ES were the most reported type and involved the provision of nutrients and pest control, with birds of prey and carnivorous mammals as the most mentioned groups. Provisioning ES were related to the provision of leather from legal hunting and genetic material, and Cultural ES were associated to species conservation. From the conflict search, we found 23 studies that mentioned negative interactions in the Pampas region, mostly with birds and associated to agricultural production damages. Many species mentioned as important ES providers, are also involved in conflicts, causing some discomfort to people. Therefore, the integration of wildlife, with its benefits and damages, could be a powerful argument to achieve the coexistence of wildlife into a landscape shaped by anthropogenic activities.

New Pampas cat Leopardus colocolo (Molina, 1782) (Mammalia: Carnivora: Felidae) records for the Chaco ecoregion raise questions on the distribution and population status of this felid in Argentina

The Pampas cat is a poorly-known small felid distributed throughout a large portion of South America, reported as extinct in the Pampas of Argentina, and absent from a large portion of the Argentine Dry Chaco. Here, we compile data from the field and collections to report new presence records of the Pampas cat from the Dry Chaco of Argentina, which update to the distribution of this felid in the region. We discuss the need of further assessments for the species distribution in the light of ongoing land-use changes in the area.

ModellingChloris virgatagermination and emergence under different temperature and light quality conditions

AbstractChloris virgatais a problematic weed around the world. Prediction of weed germination rates could be a useful strategy to optimise timing of weed control actions. We studied the germination and emergence ofC. virgatacollected seeds under different after‐ripening treatments and different exhumation dates after seed dispersal, to estimate seed dormancy level and predict weed emergence dynamics under field conditions. Three experiments were conducted under controlled conditions to determine base, optimum and maximum germination temperatures (Tb,ToandTmrespectively) and comprised: (a) exposure of seeds to gradually increasing and decreasing temperatures between 5 and 35°C; (b) exposure of seeds to different constant temperatures; and (c) exposure of seeds to different light quality conditions (red – far red ratio) and temperature regimes (constant and alternating temperatures). To explore genuine environmental conditions, a field experiment was performed to determine weed emergence under different shading levels. Finally, with the data obtained, a thermal time model for dormancy release was used to predictC. virgataseedling emergence in the Argentine Pampas region. Seeds after‐ripened in cold and wet conditions and constant 25°C showed the highest germination percentages. The values ofTb(7°C),To(28°C) andTm(40°C) remained constant at all exhumation dates. Neither light quality nor thermal regime modified the final germination percentages. However, shading delayed seedling emergence under field conditions, even when it was adjusted by thermal time. These results may allow predictingC. virgataemergence in temperate regions and help to improve weed control in integrated weed management strategies.

Runoff response of a small agricultural basin in the argentine Pampas considering connectivity aspects

AbstractOur manuscript analyses the surface runoff variability, and its controlling factors in a small basin with gentle slopes, at the headwaters of a flat catchment, to improve the knowledge of the hydrology of plain areas under agriculture. We study runoff, rainfall and antecedent conditions in the argentine Pampas region. We use correlations, regressions and quantitative and qualitative descriptive information of the system: erosion signs, ground cover by crops, groundwater depth data and temporal changes in the drainage network, to discuss and understand the complexity of the runoff process by frameworks to study (dis)connectivity. The analysis of 56 events evidenced a nonlinear rainfall–runoff relationship. In contrast with other works, we identified clear upper limit events, under which hydrological responses emerge, as a result of combinations of antecedent wetness, rainfall erosivity, ground cover and preferential drainage paths. We separated the nonlinear rainfall–runoff response in three linear relationships according to differences in antecedent wetness conditions. We found differences in runoff responses under wet and dry antecedent conditions, but complex responses under medium antecedent conditions. The analyses of the inputs, the structural and the functional elements of the (dis)connectivity frameworks, were key in the understanding of the temporal changes of runoff, and its complex responses. Temporal coincidences of connectivity components and their feedbacks appear to be strongly associated with the runoff dynamics. High‐magnitude hydrological responses occur with complete coincidences, while partial coincidences between the components reduce connectivity and low magnitude and/or heterogeneous responses prevail. Thus, these analyses suggest that runoff is controlled by (dis)connectivity in this basin with gentle slopes. Our work contributes to the understanding of the process of surface runoff in the context of humid flatlands under agricultural land use, by the identification of the complex combinations of factors which regulate/control the (dis)connectivity that helps to interpret the nonlinearities of runoff.

Field assay using a native entomopathogenic nematode for biological control of the weevil Phyrdenus muriceus in organic eggplant crops in Argentina

The weevil Phyrdenus muriceus Germar (Coleoptera: Curculionidae) is an emergent pest of eggplant (Solanum melongena L.) crops in the humid Pampa of Argentina. Entomopathogenic nematodes (EPNs) constitute an effective and environmentally safe strategy within integrated pest management. The efficacy of a native EPN Heterorhabditis bacteriophora SUP isolate for the control of P. muriceus was evaluated. Larvae and adults were susceptible to the nematode in laboratory assays. Field evaluations indicated a slight reduction of P. muriceus populations, evidenced after a second application by a decrease of the foliar damage in the eggplant crops. Adults of P. muriceus parasitized by H. bacteriophora were observed in the field one month after the second application. The present study is the first assessment of EPNs against P. muriceus under field conditions, and the first report of their use in the humid Pampa, one of the major agricultural areas of Argentina.

Enhancement of palatable perennial grasses by disturbance and seed addition in degraded native grasslands of the dry pampas in Central Argentina

Land use has changed the original composition of the natural grasslands in the dry pampas of central Argentina, to the detriment of palatable perennial grasses (PPG). Long-term elimination of anthropogenic disturbances has not been enough to effectively recover the PPG, which suggests that availability of seeds and/or habitats may be limiting their recruitment. Therefore, our objectives in a degraded grassland site were to assess: (1) the germinable soil seed bank and (2) changes in botanical composition after addition of PPG seed following canopy disturbance. In autumn 2015, we randomly selected 10-paired plots, measured the aboveground biomass and took soil samples to assess the germinable soil seed bank. Afterwards, we disturbed the resident vegetation in each paired plot and either added PPG seeds or left the plot without any seed addition as a control. We quantified the seedling density of seeded and spontaneous species in the spring of 2015 and 2016, and the aboveground biomass at the end of 2017. Annual grasses and forbs (AGFS) dominated the soil seed bank, while PPG and unpalatable perennial grasses (UPG) occurred at low seed density and richness. Addition of PPG seeds resulted in the successful establishment of one key seeded PPG (Poa ligularis). In the spring 2017, the aerial biomass of PPG was highest in the seeded plots, where P. ligularis accounted for 94%. Our results showed that PPG were poorly represented in the soil seed bank of the degraded grassland and that disturbance of the resident vegetation combined with PPG seed addition enabled successful recruitment of a key PPG. So, enhancement of the pastoral value of degraded dry pampas grasslands would be possible through disturbance of the resident vegetation and addition of PPG seed.

Simple regression models to estimate light interception in wheat crops with Sentinel‐2 and a handheld sensor

AbstractCapture of radiation by crop canopies drives growth rate, grain set, and yield. Since the fraction of photosynthetically active radiation absorbed by green area (fAPARg) correlates with normalized difference vegetation index (NDVI), remote sensors have been used to monitor vegetation. With a 10‐m spatial resolution and 5‐d revisiting time, the recently launched Sentinel‐2 satellite is a promising tool for fAPARg monitoring. However, the available algorithm to estimate fAPARg is based on simulations of canopy interception of several vegetation types and was never tested in field crops. Handheld sensors, such as GreenSeeker, are another alternative to estimate fAPARg. Our objectives were (a) to test the ability of indices derived from Sentinel‐2 and GreenSeeker NDVI to capture fAPARg of wheat (Triticum aestivum L.) crops, (b) to compare these sensors’ performance against the moderate resolution imaging spectroradiometer (MODIS), and (c) to compare our Sentinel‐2 model estimations with the available algorithm. In wheat fields in the southwest Argentinean Pampas, on several sampling dates, we measured fAPARg with a quantum light sensor and NDVI with a GreenSeeker. We regressed fAPARg measurements with vegetation indices from the different sources and selected the best models. Sentinel‐2 and GreenSeeker NDVI precisely estimated fAPARg, with a performance similar to MODIS (p < .05; RMSD = 0.09, 0.11, and 0.08; R2 = .89, .88, and .95, respectively). The available algorithm to estimate fAPARg with Sentinel‐2 yielded biased estimations, mainly in the lower range of fAPARg. These results suggest that simple models may provide fAPARg estimations with Sentinel‐2 and GreenSeeker in wheat crops with an accuracy suitable for agricultural applications.

Modelling L band backscattering of wheat in Argentinean Pampas and its application to soil moisture retrieval

ABSTRACT In this paper a data base of L band backscattering simulations, based on the application of a discrete scattering model and detailed ground truth collected over Argentinean wheat fields, is tested. The simulations are directly compared against backscattering measurements collected over single fields. Then the scattering model is used to tune a semi empirical and manageable model function. Finally this function, jointly with a multi-temporal algorithm, is used for soil moisture retrieval and results are tested against an independent set of measurements. The site used for training and validation is located in the Pampas region, which will be continuously monitored in the framework of the SAOCOM (SAtélite Argentino de Observación COn Microondas) programme. In general, both the direct model and the retrieval algorithm produce consistent results. However, variation in the azimuth angle of observation produces appreciable effects, and some discrepancies are observed for radar observations collected just after a rainfall. These issues deserve further investigation with a larger amount of experimental data.

Crop rotations in the Rolling Pampas: Characterization, spatial pattern and its potential controls

One of the most important decisions made by farmers every year involves land allocation to different crops. Accurate information on crop sequences over large areas is a key prerequisite to address social concerns as soybean monoculture, to map good agronomic practices and to assess farmers' adaptive capacity among others. Here we aimed to characterize crop sequences and describe the crop rotation patterns in an area of the Rolling Pampas in Argentina. We performed annual supervised classifications for the 2010/2011 to 2016/2017 growing seasons using high resolution satellite images and in situ data. Classification's accuracies were always higher than 85%. Analysis of crop sequences showed that the most common practice was alternating periods of continuous planting of early soybean with periods where maize and/or wheat were included in the rotation. In addition, during the period analyzed nearly 10% of the study area exhibited continuous soybean monoculture, and 6% of the area showed a strict crop rotation of maize, soybean, and wheat-soybean double crop. Changes in early soybean planted area were significantly associated (p < 0.1) to its previous year's international price, and were probably affected by political economy regulations. The inclusion of maize or wheat in the rotation was more frequently observed at larger cadastral units, while soybean monoculture was more frequent in smaller cadastral units. This suggests that farmers’ capitalization may be associated to different crop rotation decisions through a different long term planning capacity.

Vegetation in rural roadsides of the Pampa region (Argentina): an opportunity for grassland conservation?

ABSTRACTIn many areas of the agriculturalized Pampas of Argentina, rural roadsides (RRS) are the only relics of the grassland biome that originally dominated the region. Nowadays, no policies regulate the use and preservation of these environments. We assessed plant species diversity in 28 RRS in a representative area of the Southern Pampean region, and investigated the degree to which some RRS variables (width, slope, type, and density of RRS in a circular area of 2000 m in diameter) explain their floristic assemblages and species richness. We listed 107 species belonging to 25 families. The most species-rich families were Poaceae (33 species) and Asteraceae (22 species). Fifty percent of the species were native to the region and 58% perennial. There was a predominance of herbaceous dicots (68%), and 12 species (11%) were endemic to the region. A canonical correspondence analysis showed that the density of neighboring RRS significantly explained plant species assemblages. Exotic species richness decreased with the width of the RRS. We expect that this information and proper management will promote the potential of RRS for nature conservation as we consider RRS important refuge for grassland plants.