Pampas Region Of Argentina Research Articles

How much carbon do Argentine Pampas Pinus radiata plantations store?

Aim of study: To quantify the biomass and carbon stored in the main ecosystem components in Pinus radiata D. Don plantations across an age sequence in the Pampean region of Argentina.
 Area of study: Plantations were established on non-agricultural land, southeast of the province of Buenos Aires.
 Material and methods: Fourteen sites were selected of Pinus radiata plantations, 9-, 13-, 15-, 19- and 21-years-old, in a first forest rotation. Forty-two trees were destructively sampled, allometric functions were set and biomass was estimated for the different compartments (needles, branches, stem). Root biomass was estimated from equations adjusted by the sampling of twenty-four trees. At 4 sites, C-stock was determined in the tree component, in the forest floor and understory, and soil organic carbon (SOC) was determined to a 50 cm depth.
 Main results: C-stock in the tree component increased with stand age, whereas SOC and C-stock in the forest floor and understory were not related to stand age. The system-level C-stock was 273.1, 263.7, 269.7 and 324.1 Mg ha-1 for the 9-, 13-, 19- and 21-year-old stands. On average, 69% of the total system-level C-stock was in the soil, while 28% was in the tree biomass and 3% was in the forest floor and understory.
 Research highlights: The forestry component contributed to C sequestration with no changes in SOC-stocks reserves for the age range studied.

Landscape configuration is an important predictor of sunflower yield in the Argentinean Pampas Region

Conventional agriculture is frequently associated with large-scale environmental degradation andlandscape homogenization. In contrast, ecological intensification incorporates natural habitat conservationand landscape complexity to improve important ecosystem services such as pollination and crop yields. Inan observational study of 105 fields in the Argentinean Pampas Region, we explored whether sunfloweryields were related to landscape composition (percentage of natural habitat) and configuration (field size andedge density), and covariates of agricultural management practices such as nitrogen fertilizer addition, seeddensity, sowing date and crop cultivar. Our mixed-effects models revealed that field size and edge densitiesbetween crop and natural habitat are important predictors of yield. For example, a doubling of edge densityfrom 40 m/ha to 80 m/ha predicted an 11.3% (269 kg/ha) yield increase, while a doubling in the field size from40 ha to 80 ha predicted a 6.1% (149 kg/ha) yield decrease. We suggest that pollination is an important driverof both effects as higher edge densities and smaller field sizes reduce wild pollinator flight distances to cropflowers and thus increases the chances for effective crop pollination. This study provides key information forsustainable management of sunflower agroecosystems.

Monitoring Corn Nitrogen Concentration from Radar (C-SAR), Optical, and Sensor Satellite Data Fusion

Corn (Zea mays L.) nitrogen (N) management requires monitoring plant N concentration (Nc) with remote sensing tools to improve N use, increasing both profitability and sustainability. This work aims to predict the corn Nc during the growing cycle from Sentinel-2 and Sentinel-1 (C-SAR) sensor data fusion. Eleven experiments using five fertilizer N rates (0, 60, 120, 180, and 240 kg N ha−1) were conducted in the Pampas region of Argentina. Plant samples were collected at four stages of vegetative and reproductive periods. Vegetation indices were calculated with new combinations of spectral bands, C-SAR backscatters, and sensor data fusion derived from Sentinel-1 and Sentinel-2. Predictive models of Nc with the best fit (R2 = 0.91) were calibrated with spectral band combinations and sensor data fusion in six experiments. During validation of the models in five experiments, sensor data fusion predicted corn Nc with lower error (MAPE: 14%, RMSE: 0.31 %Nc) than spectral band combination (MAPE: 20%, RMSE: 0.44 %Nc). The red-edge (704, 740, 740 nm), short-wave infrared (1375 nm) bands, and VV backscatter were all necessary to monitor corn Nc. Thus, satellite remote sensing via sensor data fusion is a critical data source for predicting changes in plant N status.

Habitats and parasitoid abundance influence spatial density dependence patterns, rendering an asilid fly as a potential biological controller of white grubs

The behavioral response of a parasitoid shows the effect on host parasitism patterns at a given host distribution. As a result, an increase or decrease in parasitism intensity according to local host densities is found. This relationship could be proportional, positive, or negative, as a consequence of host foraging.Mallophora ruficaudais a parasitoid fly that parasitizesCyclocephala signaticollisscarab beetle larvae. Females search and place egg clusters overground in open grasslands. Larvae actively search hosts underground following chemical cues arising from the host itself. The parasitism patterns are a result of this complex host-searching strategy that is shared between both stages of the fly. In this work, we carried out a study at four spatial scales in apiaries located in the Pampas region of Argentina. We aimed to assess the potential ofM. ruficaudaas a control agent of white grubs. We found that parasitism has an inverse density-dependent in relation to low female activity and a direct density-dependent in relation to high female activity at the larger spatial scale. We found an inverse density-dependent pattern at the intermediate spatial scale. Parasitism is inversely density-dependent at both smaller spatial scales, associated with oviposition substrate availability and distance. Additionally,M. ruficaudadoes not select the oviposition substrates according to the abundance ofC. signaticollisinhabiting underground. We determined thatM. ruficaudacould act as a natural biological controller ofC. signaticollis. This work shows the importance of a proper scale for the analysis of factors that influence population dynamics of entomophagous insects and for evaluating their potential as biological control agents, and how environmental characteristics mold the parasitism patterns of this dipteran parasitoid.

Large-scale ecologically-based farming systems foster earthworm communities and their contribution to ecosystem processes

In the Pampean region of Argentina, large-scale ecologically-based farming systems (EBS) are proposed as a more sustainable alternative to the conventional systems (CS). EBS rely on soil biological functioning, where earthworms are essential by their contribution to ecosystem processes such as nutrient cycling and soil aggregation. Our aim was to assess the effect of EBS, compared to CS and undisturbed grasslands (GS), on earthworm communities and their contribution to the process of soil structure formation, evaluated through direct sorting and quantification of earthworm casts. EBS and GS had similar earthworm richness and abundance, in both cases significantly higher than in CS. Earthworm biomass was higher in GS than in both farming systems and higher in EBS than in CS. Cast production was higher in EBS compared to CS, and similar in EBS and GS. Cast production was linearly related to earthworm abundance and to a greater extent to earthworm biomass. We conclude, in the first direct assessment of earthworm contribution to soil structure formation in EBS of the Pampean region, that this farming system provides better conditions for earthworm development compared to CS, enhancing their role in the soil ecosystem processes. Thus, we confirmed the ability of EBS to increase soil biological fertility replacing chemical inputs by ecosystem processes thus achieving more resilient and sustainable farming systems.

Cation nutrient reserves decline markedly under intensive cropping of Pampas Mollisols

The availability of exchangeable cationic nutrients in soils, such as calcium (Cae), magnesium (Mge), and potassium (Ke), is vital for crops growth and development. However, the concentration of these nutrients can be diminished by land use and management practices. The objectives of this study were i) to determine the concentration of Cae, Mge, and Ke in uncropped soils or soils under continuous agriculture, ii) to determine the Cae, Mge and Ke decrease rate due to agriculture (dCae, dMge, and dKe, respectively), iii) to evaluate the relative contribution of edaphoclimatic and farming variables on dCae, dMge, and dKe, and iv) to evaluate the spatial variability of Cae, Mge, and Ke. Surface soil samples (0–20 cm layer) were taken in 2011 and 2018 at geo-referenced sampling locations within 507 agricultural production fields (AGR2011 and AGR2018) from the Argentinean Pampas region (PR). Additionally, surface soil samples were taken from areas under gramineous vegetation that had never been cropped at each sampling point. Path analysis explained 58, 42, and 56 % of the variability on dCae, dMge and dKe between 2011 and 2018, respectively. The main factors determining the depletion of these nutrients were the soybean relative harvested area for dCae, magnesium concentration in 2011 for dMge, and rainfall for dKe. The spatial variation of Cae, Mge, and Ke increased with the history of agricultural use of soils, particularly in the case of Ke and Mge. If the depletion of exchangeable cationic nutrients in the PR continues at current rates, their deficiencies for the main crops could become evident in the medium/short term, depending on the area. For this reason, it is necessary to continue surveying the evolution of soil Cae, Mge and Ke over time in the PR and other areas in the world with similar edaphoclimatic conditions.

A new species of Plohophorus Ameghino (Cingulata, Glyptodontidae) from the latest Pliocene–earliest Pleistocene of the Pampean Region (Argentina): the last survivor of a Neogene lineage

Within xenarthrans, two large groups are recognized, Pilosa (anteaters and sloths) and Cingulata (armoured xenarthrans). The latter contains Glyptodontidae, one of the most bizarre and enigmatic groups of animals that ever lived. Recent phylogenetic proposals show an early Miocene divergence into two clades, one of northern origin (Glyptodontinae) and the other with its oldest records in the early–middle Miocene of southern South America, which groups most of the recognized diversity. Although knowledge of the ‘austral clade’ has increased recently, several taxa need urgent taxonomic and phylogenetic studies to understand their evolutionary history. One case is represented by the ‘Plohophorini’, a tribe that traditionally included several genera (Plohophorus, Pseudoplohophorus, Phlyctaenopyga, Stromaphorus and Stromaphoropsis), from the late Miocene–Pliocene of the Pampean and North-Western regions of Argentina, and Uruguay. A new and terminal species of Plohophorus, P. avellaneda sp. nov., coming from the El Polvorín Formation (Pampean region of Argentina) is here reported and described, and represents the first case of a Neogene genus of glyptodont crossing the Plio–Pleistocene boundary (c. 2.53 Ma). In addition, the palaeohistological analysis on the osteoderms (the first for ‘Plohophorini’) reveals some characters not observed in other glyptodonts, highlighting its potential phylogenetic importance. The phylogenetic analysis corroborates that the well-characterized species of ‘Plohophorini’ of Uruguay and the Pampean region of Argentina (‘eastern Plohophorini’) constitute a natural group within the austral clade, since both species of Plohophorus (P. avellaneda + P. figuratus) cluster together, and are the sister taxa of Ps. absolutus + Ps. benvenutti. Along the evolutionary history of Plohophorini an increase in body mass is observed, reaching its maximum with P. avellaneda sp. nov. (c. 471 ka). Despite the high frequency of late Pliocene records, Plohophorini disappear completely from the fossil record during the Pleistocene, suggesting that this character was negatively selected. http://zoobank.org/urn:lsid:zoobank.org:pub:FF11606C-2F27-4309-9DFD-FA74E769E639

Gastrointestinal parasite assemblages from the wild rodent capybara (Hydrochoerus hydrochaeris) inhabiting a natural protected area from Argentina

Abstract Knowledge about parasitic diseases of wildlife will help us to understand the dynamics of parasites and their effects on host populations. The capybara (Hydrochoerus hydrochaeris) is the largest living rodent in the world, and its distribution is associated with the presence of tropical and subtropical wetlands in South America. The Los Padres Lake Integral Reserve (LPLIR) is an important conservation zone in the pampean region of Argentina. One of the emblematic species found within the reserve is the capybara. The objective of this study was to determine the gastrointestinal parasites present in wild capybaras of the LPLIR and to compare different coprological methodologies. Free-ranging capybara fresh feces from 57 individuals were randomly collected from the area of LPLIR in the summer of 2022. Three different techniques were applied: spontaneous sedimentation technique (SS), INTA modified McMaster technique (MM), and Mini-FLOTAC (MF) technique. Fifty-six samples from all samples analysed (56/57, 98%) were found to be positive for gastrointestinal parasites. Two species of Strongylida, Protozoophaga obesa, Echinocoleus hydrochaeris, one unidentified nematode, one unidentified spirurid, and at least two morphotypes of Eimeria spp. oocysts were recorded. There were found significant differences in the proportion of positive samples and in richness by technique, but no significant differences were found in parasite counting. In conclusion, the choice of methodology depends on the specific objectives of the study. This is the first parasitological study of capybaras from the LPLIR and represents an exploration of parasite communities present in these wild rodents at their southernmost distribution.

Nutrient dynamics in water resources of productive flatland territories in the Pampean region of Argentina: evaluation at a watershed scale.

The Pampean plains in South America are well-known for their livestock and agricultural productivity. The peri-urban watershed of El Pescado Creek (Central-Eastern Argentina) has been significantly modified in the last few years due to local land-use changes. This work aims to analyze the dynamics of nutrient content associated with the surface water-groundwater relationship in this watershed and to define the trophic state of the watercourse. Sampling sites were selected for both surface water and groundwater analyses, and field surveys were carried out during the spring and summer of 2017. Handmade shallow groundwater wells were installed along the floodplain of the watercourse. Deep groundwater was analyzed in agricultural and livestock farms. In situ determinations included dissolved oxygen (DO), pH, electrical conductivity (EC), turbidity, transparency, and temperature measurements. Laboratory analyses included NO3--N, total nitrogen (TN), soluble reactive phosphorus (SRP), total phosphorus (TP), and phytobenthonic and phytoplanktonic chlorophyll-a. Results showed an increase in EC and nutrient concentration in the summer samples (both in surface water and shallow groundwater), along with higher turbidity of the surface water. Water flow was dissimilar between samplings (spring: 1.735 m3/s, summer: 0.065 m3/s), showing contrasting hydrological scenarios. Low wash-out conditions enhanced phytobenthonic algae biomass growth, turning most of the sites towards a eutrophic state in summer. Our results showed that the dynamics of nitrogen and phosphorus compounds in the watershed of El Pescado Creek depend on the hydrodynamic processes of the watershed, the different land-uses, and the chemical characteristics of these compounds. In order to develop sustainable management strategies, further understanding of nutrient concentrations effects, and the factors affecting them, must be done in this area of the Pampean region.

Drivers of planktonic chlorophyll a in pampean shallow lakes

Although agricultural intensification has been linked with the increment of lake eutrophication and shallow lake research has demonstrated the importance of submerged macrophytes for maintaining water clarity, less is known about the role of macrophytes and the effects of agriculture on shallow lakes of the global south. Shallow lakes in the Pampean region of Argentina are subjected to high anthropic pressure and are classified as eutrophic and hypereutrophic and, in spite of most of them are turbid and dominated by phytoplankton biomass, some remain in a clear-vegetated regime with profuse submerged macrophytes. We studied the potential drivers of phytoplankton biomass (estimated as Chlorophyll-a - Chla) by applying a regional approach and a model selection process for a dataset of 58 shallow lakes that represent the variability of the Pampean region. For the 58 lakes, the presence of submerged macrophytes, total nitrogen, and nearby agriculture of each lake were the main drivers of Chla with −1.55, 0.19 and 0.02 coefficient values, respectively. Moreover, a high proportion of the variance in this dataset (37.7 %) was explained by the regional location of each lake (hydrographic systems). For lakes with macrophytes (N = 8), Chla exhibited a positive relationship with total phosphorus (coefficient value = 3.05), whereas for lakes without macrophytes (N = 50) Chla showed a positive relationship with nearby agricultural development (coefficient value = 0.02) and 36.4 % of variance explained by the hydrographic system. Our regional approach highlighted the importance of submerged macrophytes in shaping phytoplankton biomass in Pampean shallow lakes. Our results support the idea that the conservation of submerged macrophytes, as well as the control of agriculture in the riparian zones of lakes, will help to stabilize the shallow lakes in clear regime, even in regions highly impacted by agriculture and in lakes under eutrophic conditions.

Contribution of Integrated Crop Livestock Systems to Climate Smart Agriculture in Argentina

Integrated crop-livestock system (ICLS) is a useful practice to enhance soil organic carbon (SOC) compared to continuous cropping systems (CC). However, robust data from different regions around the world remain to be collected. So, our objectives were to (i) compare SOC and its physical fractions in ICLS and CC, and (ii) evaluate the use of δ13C to identify the source of C of SOC in these systems in the Pampas region of Argentina. For that, we compared two farms, an ICLS and a CC having the same soil type and landscape position. The ICLS farm produces alfalfa grazed alternatively with soybean and corn, and the CC farm produces the latter two crops in a continuous sequence. Soil samples (0–5, 5–20, 20–40, and 40–60 cm) were collected and analyzed for SOC, its physical fractions, and their isotopic signature (δ13C). Soils under ICLS showed an increment of 50% of SOC stock compared to CC in the first 60 cm. This increase was related to 100–2000 µm fractions of SOC. The shift in δ13C signature is more in ICLS than in CC, suggesting that rotation with C3 legumes contributed to C sequestration and, therefore, climate-smart agriculture. The combination of on-farm research and isotopic technique can help to study deeply the effect of real farm practices on soil carbon derived from pasture.

Seed dormancy and germination of native and invasive alien woody species of an endangered temperate forest in the Argentine Pampas

Forest restoration plans can benefit from knowledge of seed ecophysiology. Naturally, seeds respond to environmental clues to trigger germination or persist in the seed bank. Controlling dormancy and germination moment in native species will allow more efficient seed management, both for direct seeding (in situ restoration) and for native plant cultivation in nurseries (ex situ restoration). In addition, the differences in germination conditions of native and alien invasive trees can be used as control windows of the alien species in the seed bank. The aim of this study was to identify the environmental factors regulating seed dormancy and germination of native and alien trees of the Talares, an endangered temperate forest of the Argentine Pampas region. Seeds of the native trees Schinus longifolius, Jodina rhombifolia, Celtis tala and the alien trees, Ligustrum lucidum, Ligustrum sinense and Gleditsia triacanthos were collected and the presence of dormancy was determined exposing the seeds to standard germination protocols. In case of dormancy presence, a post-maturation experiment was carried out in two conditions: i) cold and wet (stratification) and ii) dry and warm (after-ripening). The native species J. rhombifolia and C. tala showed seed dormancy but S. longifolius did not. For C. tala germination it was necessary a previous post-maturing process; however, environmental conditions for J. rhombifolia germination were not attained. Alien species showed a high germination, reaching up to 100% in at least one of the evaluated conditions, and displayed different emergence windows compare to natives. Since alien species germinated at lower temperatures than natives, a temporal window for chemical or mechanical control is proposed. Ecophysiology of seed dormancy and germination facilitates strategies for decision makers, as it can make native seeds use and aliens control more efficient to meet global restoration goals.

Modeling drought stress impacts under current and future climate for peanut in the semiarid pampas region of Argentina

In the semiarid pampas region of Argentina, peanut ( Arachis hypogaea L.) crop undergoes frequent and unpredictable drought stress periods, with high probability of occurrence under future climate change projections. However, the overall frequency of occurrence and timing of different drought stress patterns under current and future climates has not been well investigated for the main peanut region in central Argentina. The aims of this study were to: (i) define the main peanut drought stress patterns and their occurrence (frequency) during the peanut growing season, via a crop growth modeling approach, (ii) test seed yield stability of the formerly defined (in i) drought stress patterns under future climate scenarios, and (iii) analyze the effect of sowing dates on peanut seed yield as a management strategy to mitigate the impact of future climate scenarios for peanut seed yield in the semiarid pampas region of Argentina. The APSIM-peanut growth model was calibrated and validated for local genotypes and production environments. Our study simulated seasonal drought stress patterns at five representative locations across the region under current and future climate scenarios, and tested six sowing dates as a practice to mitigate the impact of climate change. Clustering analysis identified two contrasting environment types (ETs). The high stress ET showed greater frequency of occurrence (>50%) at the southern locations. Future climate conditions increased the frequency of high stress ET by roughly 6% and reduced peanut seed yield by 12%, as average across locations. For both current and future climates, earlier sowing dates maximized peanut seed yield, regardless the locations. Changing sowing date was not an effective practice to mitigate the negative impact of climate change on peanut seed yield. The defined ETs allowed identifying a target population of environments (TPE) having implications for optimizing peanut breeding and management strategies. The projected increase in the frequency of drought stress for all tested locations provides a challenging scenario for sustaining peanut productivity in this region. • The aims were to determine drought patterns under current and future climate, and to test sowing date as a mitigation tool • The defined drought stress patterns changed the frequency across locations, identifying a target population of environments • ·Future climate increased the frequency of drought stress by ~6% and reduced peanut seed yield by ~12% • Sowing date did not mitigate climate change impact. • This study provides insights to optimize breeding and management, and assists policy makers to address climate change.

A New Species of Sprentascaris (Nematoda: Raphidascarididae) in Hypostomus commersoni (Pisces: Loricariidae) from Argentina.

To report a new species: Sprentascaris pampayensis, a Raphidascarididae parasite from the Neotropical region. During a parasitological survey, specimens were collected of a new species of Sprentascaris from Hypostomus commersoni Valenciennes from urban lakes in Santa Fe City, Santa Fe Province, in the Pampean region of Argentina. Morphological and morphometric descriptions, and molecular analyses were performed. The new species, S. pampayensis n. sp., is characterized by having slightly extended lateral wings in both sexes, oral structure with three well-developed lips with double papillae, ventrolateral lips with an amphidial pore. Triangular buccal opening with three well-developed lips with flattened extensions at their bases, which end in a pointed manner towards the back. Males have 17 pairs of preanal papillae, 1 pair of adanal papillae, 3 pairs of postanal papillae and 1odd median postanal papilla located between the first and second pairs, unusual shape of caudal papillae with the central tubular part conspicuously elevated. Females have pre-equatorial vulva, smooth-shelled eggs, and mature embryonated eggs. Sprentascaris pampayensis n. sp. differs morphologically and genetically from S. manherti Petter and Cassone, 1984, S. lanfrediae Melo, Santos, Giese, Santos and Santos, 2011 and S. andersoni Malta, Paiva, Elisei, Tavares and Pereira, 2018. Morphological and morphometric comparison also distinguishes it from S. pimelodi Petter and Cassone, 1984, S. hypostomi Petter and Cassone, 1984, S. marano Ramallo, 2009, and S. saltaensis Ailán-Choke, Ramallo and Davies, 2017. Sprentascaris pampayensis n. sp. is a new parasitic nematode of Hypostomus commersoni.

New well-preserved materials of Glossotherium chapadmalense (Xenarthra, Mylodontidae) from the Pliocene of Argentina shed light on the origin and evolution of the genus

ABSTRACT Fossil remains of extinct mylodontine sloths have been discovered in numerous localities throughout the American supercontinent, but knowledge of them is still mainly centered on the Pleistocene forms rather than their Neogene relatives. In this contribution, previously unpublished cranial and postcranial materials herein ascribed to Glossotherium chapadmalense (Kraglievich), coming from the Pliocene Chapadmalal Formation (Province of Buenos Aires, Argentina), are presented. These remains are described and compared with those of other mylodontine species from South and North America, providing an exhaustive characterization of cranial morphology in G. chapadmalense and some preliminary insights into its postcranial anatomy. The results have revealed a unique combination of differences and similarities of this enigmatic species with the larger-sized representatives of Glossotherium. In addition, these materials allowed shedding light on the long-standing uncertainties regarding its taxonomic status, as this form has been alternately considered to belong to the genera Glossotherium or Glossotheridium over the last century. As a result, the genus Glossotherium was present, at least, at the Early–Late Pliocene transition in the Pampean region of Argentina, and is recorded by the Upper Pleistocene throughout the entire South American continent. The radiation of the Pleistocene species is associated with a consistent body mass increase that was probably a response to the cooling temperatures and higher predation pressure in South America during the Late Pliocene–Early Pleistocene. These phenomena were probably driven by the stable emergence of the Panamanian Isthmus around 3 Ma and the successive faunal turnover pulses of the Great American Biotic Interchange.

Statistically based soil-climate exposure scenarios for aquatic pesticide fate modeling and exposure assessment in the Pampa Region of Argentina.

Although pesticides are used intensively in Argentina's Pampa region, the possibility of performing an environmental risk assessment (ERA) remains limited due to the absence of readily available databases to run pesticide fate models and the lack of standardized realistic worst-case scenarios. The aim of the present study was to further advance capacities for performing probabilistic ERAs in the Pampa region by dividing and parameterizing the region into functional soil-climate mapping units (SCU) and defining statistically based, worst-case soil-climate exposure scenarios. Results obtained demonstrate that the SCU selected for a specific modeling exercise should depend on the dissociation constant (Kd ) of the pesticide evaluated and whether short- or long-term pesticide fate modeling and risk assessment are needed. Four regionally representative SCUs were specifically identified for modeling the fate of pesticides with low, high, and intermediate values of Kd . Fate modeling of pesticides with an intermediate Kd requires the use of a different SCU for short- versus long-term pesticide modeling, whereas this distinction is not necessary for pesticides with both low and high Kd . The current definition of realistic, worst-case, soil-climate scenarios represents a crucial step toward better pesticide fate modeling and exposure assessment in Argentina's Pampa region. Integr Environ Assess Manag 2023;19:626-637. © 2022 SETAC.

Avian Biodiversity and Frugivory in an Agroecological Cherry Orchard in The Pampas Region of Argentina

La agroecología tiende a beneficiar a la biodiversidad mientras que toma provecho de algunos de los servicios ecosistémicos, como por ejemplo el control natural de plagas. Sin embargo, cuando la biodiversidad y la producción agrícola entran en conflicto, es necesario determinar las causas de las pérdidas previo a tomar medidas de control. Nuestro estudio tuvo como objetivo evaluar la diversidad de aves en un cultivo de cerezas ubicado en Argentina, y analizar las tasas de consumo de frutos de las diferentes especies de aves. Se realizó un total de 82 horas de observación en 35 cuadrantes de 3 m × 3 m durante las cuales se registró la riqueza de aves, el número de individuos por especie y el total de cerezas consumidas por especie. Se consideró la posición de los cuadrantes dentro del cultivo, la forma del árbol y la hora del día. Además, se contabilizó el número total de cerezas en cada cuadrante de 3 m × 3 m y se las clasificó en cerezas con marcas de agua, atacadas por hongos, dañadas por pájaros o sanas. Se observaron un total de 21 especies de aves. El consumo de cerezas fue mayor durante la mañana y en el borde del cultivo. La proporción de cerezas afectadas por hongos fue mayor que la cantidad afectada por aves y agua. Nuestros hallazgos respaldan la idea de que los sistemas agroecológicos brindan refugio a muchas especies de aves con costos bajos para el productor. —O'Connor, T., García, G.Ó. e Isacch, J.P. (2022). Biodiversidad de aves y eventos de frugivoría en un cultivo agroecológico de cerezas en la región Pampeana de Argentina.

Validation and correction of satellite-estimated precipitation using ground observations in the Pampean region of Argentina

Validation and correction of satellite-estimated precipitation using ground observations in the Pampean region of Argentina

The Pampean region (Argentina) underwent larger variation in aridity than in temperature during the late Pleistocene: New evidence from the isotopic analysis of mammalian taxa

During the Pleistocene intense climatic changes occurred corresponding with the alternation of interglacial and glacial periods. By means of stable isotope analysis on fossil mammals, this research allows the assessment of the palaeoecological and palaeoclimatic conditions, including the possible scenarios for the atmospheric circulation pattern during three key phases of the late Pleistocene in the Pampean region of Argentina: Last Interglacial (LIG, MIS 5e; unpublished data), Last Glacial Maximum (LGM; 28,170–19,849 cal BP yrs), and post-Last Glacial Maximum (post-LGM, 17,281–11,500 cal BP yrs). Tooth enamel δ13C values of mammals from the Last Glacial Maximum showed an increase in C4 plants consumption compared to the other two phases studied, which may be related to a reduction in forest cover due to a combination of environmental factors such as decreased pCO2atm and increased aridity. We evaluated mean annual precipitation (MAP) and mean annual temperature (MAT) variability from tooth enamel δ13C and δ18O values, which showed a greater variation in precipitation between phases than in temperature. This result enabled us to propose two climate regimes for the studied temporal sequence, an arid-temperate regime, and a humid-temperate regime, which were mostly regulated by variations in atmospheric circulation.

Maize genetic progress in the central Pampas of Argentina: effects of contrasting sowing dates

Delayed sowing date of maize (Zea mays L.) has become a broadly adopted practice in the Pampas region of Argentina, because late-sown crops frequently experience a more favorable water balance around flowering and a reduction in the year-to-year yield variation. However, breeding efforts in this region have been focused on early sowing date environments. In addition, there has been no research on genetic progress of grain yield and the underlying attributes under late-sowing conditions. The aim of this study was to compare genetic progress in grain yield and secondary traits for hybrids released between 1980 and 2016 when grown in early- versus late sowing environments in the central Pampas region. Grain yield, its components (kernel number and kernel weight), and its physiological determinants (total shoot biomass and harvest index) were assessed in two contrasting sowing dates during three years. Biomass at silking (BR1) and during the post-silking period (BR1-R6), plant growth rate and source-sink ratios during the critical and the effective kernel-filling periods were also analyzed. Grain yield genetic progress was similar for early (0.9% y-1) relative to late sowing dates (0.8% y-1). Kernel number increase with the year of release (YOR) was more important in early (0.6% y-1) than in late (0.4% y-1) sowings, whereas the opposite trend was documented for kernel weight (0.2% and 0.3% y-1, respectively). Newer hybrids showed greater biomass production in both sowing dates (0.8% y-1 for early, 0.6% y-1 for late) and a slight increase in harvest index in late sowings (0.2% y-1). Breeding effects on shoot biomass production were exclusively attributed to the post-silking period (1.2% y-1 for early and 0.9% y-1 for late), as BR1 remained unchanged with YOR. Assimilate availability per kernel during the effective kernel filling increased with YOR in both sowing dates (1.0% y-1 for early and 0.9% y-1 for late), promoting a longer kernel filling duration. Results demonstrated that breeding efforts focused on early sowings as the main target environment, have also impacted yield gains in late sowings. However, the enhanced importance of kernel weight on grain yield determination among late- than among early sowings will demand future breeding strategies to pay special attention to unfavorable photothermal conditions during kernel filling.