Arbuscular mycorrhizae reduce the response of important plant functional traits to drought and salinity. A meta-analysis study

We aimed at exploring the plant functional traits whose responses to drought or salinity are altered by the presence of arbuscular mycorrhiza (AM). We performed a meta-analysis across 114 articles spanning 110 plant species or cultivars. We quantified the size effect of AM symbiosis on the stress response of several functional traits, using linear mixed model analysis (LMM). Correlation analysis between functional traits and total biomass responses to stresses were also performed through LMM. The literature search and further selection yielded seven functional traits, extracted from 114 laboratory studies, including 888 observations and 110 plant species/cultivars. Evidence for significant effects of predictor variables (type of stress, AM symbiosis and/or their interaction) on functional trait response were found for leaf area ratio (LAR), root mass fraction (RMF) and root-shoot (R:S) ratio. Our results provided evidence to accept the hypothesis that AM fungal inoculation may reduce the stress response of these plant functional traits by decreasing its magnitude. We also found a weak correlation between stress responses of these traits and total biomass variation. Although our literature search and data collection were intensive and our results robust, the scope of our conclusions is limited by the agronomical bias of plant species targeted by the meta-analysis. Further knowledge on non-cultivable plant species and better understanding of the mechanisms ruling resources allocation in plants would allow more generalised conclusions.

Modelling relative abundance of Oligoryzomys flavescens, an Orthohantavirus reservoir, in an endemic hantavirus pulmonary syndrome zone

Hantavirus pulmonary syndrome (HPS) is a zoonotic emerging infectious disease caused by New World orthohantaviruses (family Hantaviridae) hosted by rodents of the family Cricetidae. In Argentina, one of its main hosts is the sigmodontine rodent Oligoryzomys flavescens, a widely distributed mouse of the Pampas, Delta and Espinal ecoregions of central-east Argentina. Because the abundance of the reservoir and its proportion in the rodent community affects both virus prevalence and human exposure risk, its estimation throughout its known geographical distribution is of key importance for the design of public health strategies to prevent HPS. The aim of this study was therefore to model the relative abundance of O. flavescens in most of the Pampas ecoregion within Buenos Aires Province, Argentina, where hantavirus pulmonary syndrome is endemic. To do this we used owl-pellet samples collected between 2006 and 2008 from 51 sites distributed throughout most of Buenos Aires province. Mammalian prey in each pellet was identified to the lowest possible taxonomic level by examination of the skulls, dentaries and molars. We modelled the frequency of O. flavescens found in each sample as a function of climatic, environmental, and topographic data of each site. The two best models were applied to a Geo referential Information System to build maps of estimated frequency (as a proxy of relative abundance) within Buenos Aires province. Estimated relative abundance of O. flavescens in Buenos Aires province was significantly associated with annual mean temperature, annual precipitation and presence of freshwater bodies, and varied among sub-regions, with the Inland and Rolling Pampas being the regions with highest frequencies. Knowing in which areas O. flavescens abundance is expected to be higher can be used to concentrate limited sanitary efforts in those areas that are most needed in order to reduce transmission and increase detection.

Spatial arrangement of silo bags is key to mitigate damage by wildlife

BACKGROUND

Silo bag is a major harvest storage option in many countries worldwide. Wildlife interacts with this new element in the rural landscape. As a result, wildlife activity could generate breaks in silo bag lining, causing losses to the stored content. The aim of this study was to analyze the damage in silo bags by large hairy armadillos (Chaetophractus villosus) according to different spatial arrangements of silo bags, in order to propose a management strategy to reduce the damage. Our prediction was that silo bags arranged in a cluster would have less damage by large hairy armadillos than bags arranged in a row or than single (isolated) bags at a certain plot. In addition, we expected that in a cluster the exposed outside of the bags would show increased damage compared to the inside of the cluster.

RESULTS

We measured 294 silo bags. Damage intensity (number of breaks/100 m silo bag perimeter) in silo bags arranged in a cluster was 72% lower than in bags arranged in a row (P = 0.03), and 77% lower than in single bags (P = 0.001). Moreover, we detected that damage intensity inside was 75% lower than outside of a cluster (P = 0.001).

CONCLUSION

We propose grouping in a cluster of parallel bags instead of installing them in a row or isolated bags at plot as a strategy that could be adopted and implemented by farmers in order to reduce the damage by large hairy armadillos, the most harmful wildlife species to silo bags in Argentina. © 2021 Society of Chemical Industry.

Damage to silo bags by mammals in agroecosystems: a contribution for mitigating human–wildlife conflicts

Abstract ContextDamage to harvest storage systems by mammals and associated postharvest losses generate human–wildlife conflicts. Silo bags have been widely adopted worldwide as a type of temporary harvest storage for agricultural crops. The basis of silo-bag technology is the hermetic condition of the plastic lining. Breaks in this silo-bag lining by mammals generate damage of stored content and are a serious concern for farmers, who generally take actions against wildlife with consequent impacts on the environment. AimsWe described the incidence and intensity of breaks in silo-bag linings by different mammal groups (armadillos, canids and rodents) in agroecosystems of central Argentina, and we analysed the influence of extrinsic and intrinsic factors on patterns of breakage of silo bags, and propose management options based on cultural methods tending to prevent damage and reduce human–wildlife conflicts. MethodsSampling was conducted during the austral summer and winter of 2018, at three sites in the Pampas of Argentina. At each site, we chose farms that were using at least one silo bag, described silo-bag characteristics, and recorded the number of breaks in silo bags generated by mammals. Key resultsWe sampled a total of 306 silo bags from 38 farms. Damage incidence by mammals comprised 49% of silo bags sampled. Statistical analyses (GLMMs) revealed that damage intensity generally increased with storage time. Seasonality played a key role, with breakage being higher during summer for armadillos, when they are most active, and in winter for rodents, when they are most abundant. Damage by armadillos exhibited geographic variation and also decreased significantly with increasing distance to the nearest plot edge in which the silo bag was placed. Damage by rodents was higher for bags containing grains rather than forage. ConclusionsDamage to silo bags by mammals was affected by both extrinsic (seasonal and geographical) and intrinsic (stored content, storage time and distance to nearest edge) factors; however, these effects varied according to the mammal group considered. ImplicationsRelocation of silo bags away from plot edges could significantly reduce damage by armadillos, the most harmful mammals to silo bags.

The seasonal role of field characteristics on seed-eating bird abundances in agricultural landscapes

In temperate agroecosystems, avian responses in abundance and distribution to landscape attributes may be exacerbated by the coupling of natural seasons and farming practices. We assessed the seasonal roles of field type, field use in the surroundings, and distance from a field to the nearest woodlot on the abundance of seed-eating birds in a 225,000 km² study area in the Pampas of central Argentina. During spring-summer and autumn of 2011–2013, we randomly selected 392 fields and used transect samples to collect data on abundance and presence of seed-eating bird species. We recorded a total of 11,579 individuals belonging to 15 seed-eating bird species. We used generalized lineal mixed models to relate bird abundance to field type, field use in the surroundings, and distance to the nearest woodlot. In spring-summer (breeding season) most bird responses were associated with their nesting requirements. Species that build their nests in trees, such as eared doves Zenaida auriculata, picazuro pigeons Patagioenas picazuro, and monk parakeets Myiopsitta monachus, were more abundant in fields closer to woodlots, whereas grassland yellow-finches Sicalis luteola, which nest at areas with tall grasses, were more abundant in fields with livestock use patches in the field surroundings. In autumn (non-breeding season), most bird responses were associated with foraging and refuge needs. The high abundance of eared doves in crop stubbles and the association of pigeons at field surroundings dominated by croplands or at crop stubbles surrounded by livestock use fields revealed the intimate association of these species to sites with high availability of food resources. In addition, both picazuro pigeons and spot-winged pigeons Patagioenas maculosa were associated with woodlots, which provide suitable roosting sites. Our results show that in temperate agroecosystems, the relationships between field characteristics and seed-eating bird abundances vary with season.

Amphibians of northwestern Buenos Aires province, Argentina: checklist, range extensions and comments on conservation

Northwestern Buenos Aires province is located within the Pampas region of Argentina. Agricultural practices have extensively modified native grasslands in a relatively short period, leaving no intact pristine areas. Based on data collected between 2006 and 2015 at 153 ponds in agricultural landscapes, we compiled an annotated list of the amphibians of northwestern Buenos Aires province. We report 13 extant species of amphibians, which represent 43% of the known amphibian diversity in Buenos Aires province, and extend the ranges of three species. Three species found only in herpetological collections extend the list to 16 species. Our study is the first long-term survey of amphibians conducted in this part of Argentina and provides valuable information for future conservation actions across agricultural landscapes.

Salt effects on functional traits in model and in economically important Lotus species

A common stress on plants is NaCl-derived soil salinity. Genus Lotus comprises model and economically important species, which have been studied regarding physiological responses to salinity. Leaf area ratio (LAR), root length ratio (RLR) and their components, specific leaf area (SLA) and leaf mass fraction (LMF) and specific root length (SRL) and root mass fraction (RMF) might be affected by high soil salinity. We characterised L. tenuis, L. corniculatus, L. filicaulis, L. creticus, L. burtii and L. japonicus grown under different salt concentrations (0, 50, 100 and 150 mm NaCl) on the basis of SLA, LMF, SRL and RMF using PCA. We also assessed effects of different salt concentrations on LAR and RLR in each species, and explored whether changes in these traits provide fitness benefit. Salinity (150 mm NaCl) increased LAR in L. burtii and L. corniculatus, but not in the remaining species. The highest salt concentration caused a decrease of RLR in L. japonicus Gifu, but not in the remaining species. Changes in LAR and RLR would not be adaptive, according to adaptiveness analysis, with the exception of SLA changes in L. corniculatus. PCA revealed that under favourable conditions plants optimise surfaces for light and nutrient acquisition (SLA and SRL), whereas at higher salt concentrations they favour carbon allocation to leaves and roots (LMF and RMF) in detriment to their surfaces. PCA also showed that L. creticus subjected to saline treatment was distinguished from the remaining Lotus species. We suggest that augmented carbon partitioning to leaves and roots could constitute a salt-alleviating mechanism through toxic ion dilution.