Grazing exclusion-induced changes in soil fungal communities in a highly desertified Brazilian dryland.

Soil desertification poses a critical ecological challenge in arid and semiarid climates worldwide, leading to decreased soil productivity due to the disruption of essential microbial community processes. Fungi, as one of the most important soil microbial communities, play a crucial role in enhancing nutrient and water uptake by plants through mycorrhizal associations. However, the impact of overgrazing-induced desertification on fungal community structure, particularly in the Caatinga biome of semiarid regions, remains unclear. In this study, we assessed the changes in both the total fungal community and the arbuscular mycorrhizal fungal community (AMF) across 1. Natural vegetation (native), 2. Grazing exclusion (20 years) (restored), and 3. affected by overgrazing-induced degradation (degraded) scenarios. Our assessment, conducted during both the dry and rainy seasons in Irauçuba, Ceará, utilized Internal Transcribed Spacer (ITS) gene sequencing via Illumina® platform. Our findings highlighted the significant roles of the AMF families Glomeraceae (∼71% of the total sequences) and Acaulosporaceae (∼14% of the total sequences) as potential key taxa in mitigating climate change within dryland areas. Moreover, we identified the orders Pleosporales (∼35% of the total sequences) and Capnodiales (∼21% of the total sequences) as the most abundant soil fungal communities in the Caatinga biome. The structure of the total fungal community differed when comparing native and restored areas to degraded areas. Total fungal communities from native and restored areas clustered together, suggesting that grazing exclusion has the potential to improve soil properties and recover fungal community structure amid global climate change challenges.

Seasonal Hair Glucocorticoid Fluctuations in Wild Mice (Phyllotis darwini) within a Semi-Arid Landscape in North-Central Chile.

Mammals in drylands face environmental challenges exacerbated by climate change. Currently, human activity significantly impacts these environments, and its effects on the energy demands experienced by individuals have not yet been determined. Energy demand in organisms is managed through elevations in glucocorticoid levels, which also vary with developmental and health states. Here, we assessed how anthropization, individual characteristics, and seasonality influence hair glucocorticoid concentration in the Darwin's leaf-eared mouse (Phyllotis darwini) inhabiting two areas with contrasting anthropogenic intervention in a semi-arid ecosystem of northern Chile. Hair samples were collected (n = 199) to quantify hair corticosterone concentration (HCC) using enzyme immunoassays; additionally, sex, body condition, and ectoparasite load were recorded. There were no differences in HCC between anthropized areas and areas protected from human disturbance; however, higher concentrations were recorded in females, and seasonal fluctuations were experienced by males. The results indicate that animals inhabiting semi-arid ecosystems are differentially stressed depending on their sex. Additionally, sex and season have a greater impact on corticosterone concentration than anthropogenic perturbation, possibly including temporal factors, precipitation, and primary production. The influence of sex and seasonality on HCC in P. darwini make it necessary to include these variables in future stress assessments of this species.

Shifts in plant functional groups along an aridity gradient in a tropical dry forest.

Increasing aridity associated with climate change may lead to the crossing of critical ecosystem thresholds in drylands, compromising ecosystem services for millions of people. In this context, finding tools to detect at early stages the effects of increasing aridity on ecosystems is extremely urgent to avoid irreversible damage. Here, we assess shifts in plant community functional structure along a spatial aridity gradient in tropical dryland (Brazilian Caatinga), to select the most appropriate plant functional groups as ecological indicators likely useful to predict temporal ecosystem trajectories in response to aridity. We identified seven plant functional groups based on 13 functional traits associated with plant establishment, defense, regeneration, and dispersal, whose relative abundances changed, linearly and non-linearly, with increasing aridity, showing either increasing or decreasing trends. Of particular importance is the increase in abundance of plants with high chemical defense and Crassulacean Acid Metabolism (CAM) photosynthetic pathway, with increasing aridity. We propose the use of these functional groups as early warning indicators to detect aridity impacts on these dryland ecosystems and shifts in ecosystem functioning. This information can also be used in the elaboration of mitigation and ecological restoration measures to prevent and revert current and future climate change impacts on tropical dry forests.

A temporal analysis of the consequences of the drought regime on the water footprint of agriculture in the Guadalupe Valley, Mexico.

Changes in water availability have a substantial impact on the sustainability and maintenance of agriculture, with water footprint (WF) being a robust methodology to assess these transformations. The Guadalupe Valley is one of the places with the highest agricultural production in Mexico. Despite its semi-arid climatic conditions, it provides high-quality crops that are well-positioned in the world. The historical trend of rainfall and temperatures between 1987 and 2017 was analyzed to identify climatic patterns in the territory. Through the calculations of the water footprint of Grapevine and Olive crops, the sensitivity of the crops to recurrent water deficit and their adaptation in their yields to drought episodes was identified. The reduction in precipitation and occurrence of extreme temperatures have contributed significantly towards augmenting crop evapotranspiration and, consequently, intensifying crop irrigation demands. As a result, there has been an apparent increase in the consumption of WFagricultural since 2007. Thus, the period of highest WFagricultural consumption was 2014 (Extremely dry), as opposed to 2011 (Very wet). In particular, the lowest WFgreen consumptions were observed in extremely dry years, that is, > 20% of the WFagricultural intensifying drought events. Therefore, these periods were compensated with higher uses of WFblue and WFgray, which are inversely correlated with precipitation, where vine crops consume 73% more WFagricultural compared to olive plantations, showing greater interannual variability. These results contribute to analyzing the temporal evolution of water consumption for agriculture, providing a basis for rational water use strategies.

Carcass yield, non-carcass components, and economic viability of licuri oil addition to the diet of Santa Ines ewes / Rendimiento de la canal, componentes ajenos a la canal y viabilidad económica de la adición de aceite de licuri en la dieta de ovejas Santa Inés / Rendimento de carcaça, componentes não carcaça e viabilidade econômica do uso do óleo de licuri na dieta de ovelhas Santa Inês

Abstract Background: The production of biofuels has caused an increase in the prices of agricultural commodities. Thus, the ecological footprint, social inclusion and profitability of production systems have encouraged the use of agro-industrial products as an alternative in ruminant feeds. Objective: To evaluate carcass yields, non-carcass components, and the economic viability of including licuri oil in diet of Santa Ines ewes. Methods: A total of 32 Santa Ines ewes (multiparous, non-lactating, 2-4 years old, and 36.7±0.87 kg of body weight-BW) were allotted to a randomized block design with four treatments (diets containing 0, 2, 4 or 5% licuri oil) with eight replicates per treatment, and confined for 77 days. Results: The incremental inclusion of licuri oil promoted a quadratic response on slaughter BW, carcass and true yields, chest widths, heart fat, pancreas, omental fat, and ribeye area (p<0.05). Carcass, heart and loin weight, shank yield, fat thickness and loin fat were reduced (p<0.05); while cooling losses, left half-carcass weight, saw blade yield, and proportion of meat in the loin increased (p<0.05) with increasing dietary levels of licuri oil. The control diet resulted in the best gross revenue (USD$609.39); however, there was a loss (USD$50.96) regarding economic performance indicators. Conclusion: The use of up to 2% licuri oil in the diet increased carcass yield of discard ewes.

Resumen Antecedentes: La producción de biocombustibles ha provocado un aumento en los precios de los productos agrícolas básicos. Por lo tanto, la huella ecológica, la inclusión social y la rentabilidad de los sistemas productivos han incentivado la busqueda de productos agroindustriales como alternativa para la alimentación de rumiantes. Objetivo: Evaluar el rendimiento en canal, los componentes ajenos a la canal, y la viabilidad económica de incluir aceite de licuri en dietas para ovejas de raza Santa Ines. Métodos: Un total de 32 ovejas Santa Ines (multíparas, no lactantes, de 2 a 4 años y de 36,7±0,87 kg de peso corporal-PC) fueron asignadas a un diseño de bloques al azar con cuatro tratamientos (dieta basal adicionada con 0, 2, 4 o 5% de aceite de licuri) con ocho repeticiones por tratamiento, y confinadas por 77 días. Resultados: Los niveles incrementales de aceite de licuri tuvieron un efecto cuadrático sobre el PC al sacrificio, el rendimiento real y de la canal, el ancho del pecho, la grasa del corazón, el páncreas, la grasa del epiplón y el área del ojo del lomo (p<0,05). Se redujo (p<0,05) el peso de la canal, el corazón y el lomo, el rendimiento del jarrete, el grosor de la grasa y la grasa del lomo; y aumentaron las pérdidas por enfriamiento, el peso de media canal restante, el rendimiento de la hoja de sierra y la proporción de carne en el lomo (p<0,05) con niveles incrementales de aceite de licuri. La dieta control resultó en el mejor ingreso bruto (USD$609,39); sin embargo, hubo una pérdida (USD$50,96) en los indicadores de desempeño económico. Conclusión: El uso de hasta un 2% de aceite de licuri en la dieta incrementa el rendimiento en canal de las ovejas de descarte.

Resumo Antecedentes: A produção de biocombustíveis tem causado um aumento nos preços das commodities agrícolas. Assim, a pegada ecológica, a inclusão social e a rentabilidade do sistema de produção têm incentivado o uso de produtos agroindustriais como alternativa alimentar para ruminantes. Objetivo: Avaliar os rendimentos de carcaça, componentes não carcaça e a viabilidade econômica da inclusão do óleo de licuri em dietas para ovelhas Santa Inês. Métodos: Um total de 32 ovelhas Santa Inês (multíparas, não lactantes, 2-4 anos e 36,7±0,87 kg de peso corporal-PC) foram distribuídas em delineamento em blocos casualizados com 4 tratamentos (dietas contendo óleo de licuri a 0, 2, 4 e 5% de matéria seca) com 8 repetições por tratamento e confinadas por 77 dias. Resultados: A inclusão de óleo de licuri promoveu efeito quadrático no PC de abate, rendimentos de carcaça e verdadeiros, largura de peito, gordura do coração, pâncreas, gordura omental e área de olho de lombo (p<0,05). Os pesos de carcaça, coração e lombo, rendimento de pernil, espessura de gordura e gordura do lombo foram reduzidos (p<0,05), e as perdas por resfriamento, peso de meia carcaça esquerda, rendimento de lâmina de serra e proporção de carne no lombo aumentaram (p<0,05) com um aumento nos níveis de óleo de licuri. A dieta controle resultou na melhor receita bruta (USD$609,39); no entanto, houve uma perda (USD$50,96) em relação aos indicadores de desempenho econômico. Conclusão: O uso de até 2% de óleo de licuri na dieta proporcionou aumento nos rendimentos de carcaça de ovelhas de descarte.

Climate change should drive mammal defaunation in tropical dry forests.

Human-induced climate change has intensified negative impacts on socioeconomic factors, the environment, and biodiversity, including changes in rainfall patterns and an increase in global average temperatures. Drylands are particularly at risk, with projections suggesting they will become hotter, drier, and less suitable for a significant portion of their species, potentially leading to mammal defaunation. We use ecological niche modelling and community ecology biodiversity metrics to examine potential geographical range shifts of non-volant mammal species in the largest Neotropical dryland, the Caatinga, and evaluate impacts of climate change on mammal assemblages. According to projections, 85% of the mammal species will lose suitable habitats, with one quarter of species projected to completely lose suitable habitats by 2060. This will result in a decrease in species richness for more than 90% of assemblages and an increase in compositional similarity to nearby assemblages (i.e., reduction in spatial beta diversity) for 70% of the assemblages. Small-sized mammals will be the most impacted and lose most of their suitable habitats, especially in highlands. The scenario is even worse in the eastern half of Caatinga where habitat destruction already prevails, compounding the threats faced by species there. While species-specific responses can vary with respect to dispersal, behavior, and energy requirements, our findings indicate that climate change can drive mammal assemblages to biotic homogenization and species loss, with drastic changes in assemblage trophic structure. For successful long-term socioenvironmental policy and conservation planning, it is critical that findings from biodiversity forecasts are considered.

Biochar as a carbonaceous material to enhance soil quality in drylands ecosystems: A review.

Drylands are fragile environments that should be carefully managed to improve their quality and functions to achieve sustainable development. Their major problems involve low availability of nutrients and soil organic carbon content. Biochar effect on soil is a joint response of micro to nano sized biochar and soil characteristics. In this review, we attempt to carry out a critical analysis of biochar application to enhance dryland soil quality. Correlating the effects identified from its soil application, we explored the subjects that remains open in the literature. The relation of composition-structure-properties of biochar vary among pyrolysis parameters and biomass sources. Limitations in soil physical quality in drylands, such as low water-holding capacity, can be alleviated by applying biochar at a rate of 10 Mg ha-1 also resulting in beneficial effects on soil aggregation, improved soil porosity, and reduced bulk density. Biochar addition can contribute to the rehabilitation of saline soils, by releasing cations able to displaces sodium in the exchange complex. However, the recovery process of salt-affected soils might be accelerated by the association of biochar with another soil conditioners. This is a promising strategy especially considering the biochar alkalinity and variability in nutrients bioavailability to improve soil fertilization. Further, while higher biochar application rate (>20 Mg ha-1) might change soil C dynamics, a combination of biochar and nitrogen fertilizer can increase microbial biomass carbon in dryland systems. Other aspect of biochar soil application is the economic viability of scale-up production, which is mainly associate to pyrolysis process being biochar production the costliest stage. Nevertheless, the supplying of feedstock might also represent a great input on biochar final costs. Therefore, biochar-based technology is a big opportunity to improve fragile environments such as drylands, integrating sustainable technologies with regional development. Considering the specificity of application area, it might be a model of sustainable agricultural practices protecting the environment in a bioeconomic perspective.

Bet-hedgers commit to the hedge: Zooplankton in ephemeral semiarid wetlands of tropical Brazil that widely spread risk.

Bet-hedging is an ecological risk-aversion strategy in which a population does not commit all its effort toward a single reproductive event or specific environmental condition, and instead spreads the risk to include multiple reproductive events or conditions. For aquatic invertebrates in dry wetlands, this often takes the form of some propagules hatching in the first available flood, while remaining propagules hatch in subsequent floods (the "hedge"); this better ensures that a subset of propagules will hatch in a flood of sufficient duration to successfully complete development. Harsh environmental conditions are believed to promote an increased reliance on bet-hedging. Bet-hedging studies have typically been restricted to single sites or single populations. Community-level assessments may provide more robust support for the range of hatching strategies that exist in nature. Here, we tested whether freshwater zooplankton assemblages inhabiting ephemeral and unpredictable wetlands of a semiarid zone of tropical Brazil employ hatching strategies suggestive of bet-hedging; few efforts have addressed bet-hedging in the tropics where the unique conditions may influence the strategy. We collected dry sediments from six ephemeral wetlands, and flooded them across a sequence of three hydrations under similar laboratory conditions to assess whether hatching patterns conform to some of the predictions of the bet-hedging theory. We found that taxa showing hatching patterns akin to bet-hedging associated with delayed hatching numerically dominated the assemblages that emerged from dry sediments, although there was large heterogeneity in the hatching rate among sites and across taxa. While some populations distributed their hatching across all three floods and committed most of their hatching fraction to the first hydration, others committed as much or more effort to the second hydration (the "hedge") or the third hydration (another substantial "hedge"). Thus, in the harsh study wetlands, hatching patterns akin to bet-hedging associated with delayed hatching were common and occurred at multiple temporal scales. Our community assessment found that a commitment to the "hedge" was greater than the current theory would predict. Our findings have broader implications; bet-hedger taxa seem especially well equipped to tolerate stress if conditions become harsher as environments change.

Blood biochemical parameters of lambs fed diets containing cactus cladodes / Parâmetros bioquímicos sanguíneos de cordeiros alimentados com dietas contendo palma forrageira

This study aimed to evaluate the effects of partial replacement (750g/kg) of Tifton hay by two cactus cladodes (Nopalea or Opuntia) on the metabolic profile of lambs. Thirty-six uncastrated male Santa Inês lambs (22.0±2.9kg initial body weight) were distributed in a completely randomized design, with three treatments and 12 repetitions. The animals were fed a control diet (Tifton hay as exclusive roughage), Miúda cactus cladodes-based diet or Orelha de Elefante Mexicana (O.E.M.) cactus cladodes-based diet. Blood samples were collected one day before (baseline) and 45 days after the introduction of the tested diets. The Miúda cactus cladodes caused an increase (P=0.055) in the serum activity of the gamma-glutamyl transferase enzyme (53.66U/L) and in the blood content of glucose and fructosamine. The O.E.M. cactus cladodes caused lower (P=0.038) serum cholesterol content (41.33mg/dL). Regardless of the variety, there was a decrease (P=0.001) in the serum content of indirect bilirubin, urea, and sodium, and increase in the serum magnesium concentration. The partial replacement of the Tifton hay by Miúda or O.E.M. cactus cladodes in lamb feeding increases the enzyme activity, indicating liver and/or kidney changes, but does not cause relevant damage to energy, protein, and mineral metabolism.

Este trabalho teve como objetivo avaliar os efeitos da substituição parcial (750g/kg) do feno de Tifton por duas variedades de palma forrageira (Nopalea ou Opuntia) no perfil metabólico de cordeiros. Trinta e seis cordeiros Santa Inês, machos, não castrados (22,0 ± 2,9kg de peso corporal inicial), foram distribuídos em delineamento inteiramente ao acaso, com três tratamentos e 12 repetições. Os animais foram alimentados com dieta controle (feno de Tifton como volumoso exclusivo), dieta à base de palma forrageira Miúda ou dieta à base de palma forrageira Orelha de Elefante Mexicana (OEM). Amostras de sangue foram coletadas um dia antes (baseline) e 45 dias após a introdução das dietas testadas. A palma Miúda causou aumento (P=0,055) na atividade sérica da enzima gamaglutamiltransferase (53,66U/L) e no teor sanguíneo de glicose e frutosamina. A palma OEM causou menor teor (P=0,038) de colesterol sérico (41,33mg/dL). Independentemente da variedade, houve diminuição (P=0,001) do teor sérico de bilirrubina indireta, ureia e sódio, e aumento na concentração sérica de magnésio. A substituição parcial do feno de Tifton por palma Miúda ou por OEM na alimentação de cordeiros aumenta a atividade enzimática, o que indica alterações hepáticas e/ou renais, mas não causa danos relevantes nos metabolismos energético, proteico e mineral.

Evolutionary importance of the relationship between cytogeography and climate: New insights on creosote bushes from North and South America.

Relationships between genome size and environmental variables suggest that DNA content might be adaptive and of evolutionary importance in plants. The genus Larrea provides an interesting system to test this hypothesis, since it shows both intra- and interspecific variation in genome size. Larrea has an amphitropical distribution in North and South American deserts, where it is most speciose. Larrea tridentata in North America shows a gradient of increasing autopolyploidy; while three of the four studied South American species are diploids, Larrea divaricata, Larrea nitida, Larrea ameghinoi, and the fourth is an allopolyploid, Larrea cuneifolia. We downloaded available focal species' georeferenced records from seven data reservoirs. We used these records to extract biologically relevant environmental variables from WorldClim at 30 arc seconds scale, to have a broad characterization of the variable climatic conditions of both regions, and a climatic envelope for each species. We estimated relative DNA content index and relative monoploid genome values, by flow cytometry, of four most abundant Larrea species throughout their respective ranges. Then we winnow the bioclimatic dataset down to uncorrelated variables and sampled locales, to analyse the degree of association between both intra- and interspecific relative DNA content and climatic variables that are functionally relevant in arid environments using Pearson correlations, general linear and mixed effects models. Within the genus Larrea, relative DNA content increases with rising temperature and decreases with rising precipitation. At the intraspecific level, all four species show relative DNA content variation across climatic conditions. Larrea is a genus that shows genome size variation correlated with climate. Our results are also consistent with the hypothesis that extreme environmental pressures may have facilitated repeated whole genome duplication events in North America, while in South America, reticulate evolution, as allopolyploidization, and speciation might have been climate-dependent since the Oligocene.

Feeding restriction in the pre and postpartum period of hair ewes raised in the semi-arid region: implications on performance and carcass traits of the progeny.

Feed restriction (FR) occurs commonly in sheep production systems in the Brazilian semi-arid region and can cause physiological changes in the progeny. We assessed the effects of the FR pre and postnatal on the performance and carcass traits of Morada Nova lambs. Twenty-four lambs born from a group of 68 ewes were distributed in three treatments of 8 replicates as follows: ewes fed ad libitum pre and postnatal (AL-AL); postnatal restriction (POSTN-R): included lambs born from ewes fed ad libitum in the last third of pregnancy with FR postnatal; and prenatal feeding restriction (PREN-AL): comprised lambs born from ewes subjected to FR in the last third of pregnancy but ad libitum postnatal. Slaughter body weight (20.96 kg); total weight gain (11.34 kg); average daily weight (0.096 kg); fasting carcass weight (19.45); hot carcass weight (9.33 kg); and cold carcass weight (9.11 kg) were smaller (P < 0.05) in POSTN-R but similar between AL-AL and PREN-AL. Rib (0.47 kg), shoulder (0.85 kg), loin (0.50 kg), and chest-flank (0.97 kg) had lower weight in lambs under POSTN-R (P < 0.05). The treatments did not affect the tissue composition of the 12th rib. The non-carcass components and carcass traits are the variables that best discriminate animals under FR plans. The postpartum FR in native lambs has an impact on the performance and carcass weight of the progeny, unlike lambs submitted to prepartum FR, which demonstrates the adaptation to intrauterine nutritional deficiency in Morada Nova ewes to produce lambs with heavy carcasses in regions semi-arid.

Arbuscular mycorrhizal fungi community in soils under desertification and restoration in the Brazilian semiarid.

Soil desertification has a significant social, economic, and environmental impact worldwide. Mycorrhizal diversity remains poorly understood in semiarid regions impacted by desertification, especially in Brazilian drylands. More importantly, positive impacts of grazing exclusion on mycorrhizal communities are still incipient. Here, we hypothesized that overgrazing changes the structure of Arbuscular Mycorrhizal Fungi (AMF) community compared to native areas and, grazing exclusion is effective to restore the AMF community. Thus, we analyzed the status of AMF community in soils under desertification (overgrazing) and restoration (twenty-years of grazing exclusion) in the Brazilian semiarid. AMF-spores were extracted via humid decantation methodology, morphologically classified, and alpha diversity metrics were calculated. Soil samples were chemically, and physically characterized and multivariate statistical analyses were applied to verify the impact of soil degradation and restoration on AMF-community. Briefly, native, and restored areas presented higher contents of organic matter, phosphorus, microbial carbon, and ß-glucosidase activity. However, degraded soil showed higher Al3+, Na+, and bulk soil density values. The abundance of AMF spores was higher in restored soil, followed by degraded and native vegetation, and Shannon's diversity index was significantly higher in restored soils, followed by native vegetation. AMF-spores were classified into four families (Gigasporaceae > Acaulosporaceae > Glomeraceae > Ambisporaceae). Ambisporaceae was closed correlated with degraded soil, mainly with Al3+, Na+, and bulk soil density properties. On the other hand, Acaulosporaceae and Glomeraceae were positively correlated with native vegetation and restored soil, respectively, thereby improving Shannon index, richness, enzyme activity, and soil respiration. Thus, grazing exclusion, in long term, can be a good strategy to restore AMF-diversity in soils in the Brazilian semiarid.

Microbial Biogeochemical Cycling of Nitrogen in Arid Ecosystems.

Arid ecosystems cover ∼40% of the Earth's terrestrial surface and store a high proportion of the global nitrogen (N) pool. They are low-productivity, low-biomass, and polyextreme ecosystems, i.e., with (hyper)arid and (hyper)oligotrophic conditions and high surface UV irradiation and evapotranspiration. These polyextreme conditions severely limit the presence of macrofauna and -flora and, particularly, the growth and productivity of plant species. Therefore, it is generally recognized that much of the primary production (including N-input processes) and nutrient biogeochemical cycling (particularly N cycling) in these ecosystems are microbially mediated. Consequently, we present a comprehensive survey of the current state of knowledge of biotic and abiotic N-cycling processes of edaphic (i.e., open soil, biological soil crust, or plant-associated rhizosphere and rhizosheath) and hypo/endolithic refuge niches from drylands in general, including hot, cold, and polar desert ecosystems. We particularly focused on the microbially mediated biological nitrogen fixation, N mineralization, assimilatory and dissimilatory nitrate reduction, and nitrification N-input processes and the denitrification and anaerobic ammonium oxidation (anammox) N-loss processes. We note that the application of modern meta-omics and related methods has generated comprehensive data sets on the abundance, diversity, and ecology of the different N-cycling microbial guilds. However, it is worth mentioning that microbial N-cycling data from important deserts (e.g., Sahara) and quantitative rate data on N transformation processes from various desert niches are lacking or sparse. Filling this knowledge gap is particularly important, as climate change models often lack data on microbial activity and environmental microbial N-cycling communities can be key actors of climate change by producing or consuming nitrous oxide (N2O), a potent greenhouse gas.

A Systematic Review on Opuntia (Cactaceae; Opuntioideae) Flower-Visiting Insects in the World with Emphasis on Mexico: Implications for Biodiversity Conservation.

Opuntia spp. are cacti with high ecological, economic and conservation interest in semiarid environments, particularly in Mexico. We conducted a systematic search of the existing peer-reviewed literature about the state of knowledge of pollination ecology on these plants. We documented the most studied Opuntia species worldwide with an emphasis on Mexico. We found that only 15% of Opuntia species described have been investigated so far, and studies were mainly focused on comprehension of the biology of a single species. Despite the economic and cultural importance of Opuntia, there is a significant lack of knowledge about the flower-visiting insects and their taxonomic identity. We provide a checklist of the insect species associated with Opuntia spp. Through a circular network, we visualize the complex Opuntia flower-visiting insect relationship, and we detected a set of key species constituting the generalist core of the networks constructed. Since pollination is crucial for crop production, a better understanding of ecological interactions would inform management measures to strengthen biodiversity and agriculture sustainability as well as productivity in arid and marginal lands. Further research on pollination ecology is needed to improve the conservation status of the insects associated with Opuntia species.

Inoculation with Native Actinobacteria May Improve Desert Plant Growth and Survival with Potential Use for Restoration Practices.

Soil microorganisms, together with water, play a key role in arid ecosystems, being responsible for the nutrient cycle, facilitating nutrient incorporation into plants, influencing plant drought tolerance, and enhancing their establishment. Therefore, their use for restoration practices is promising. We tested the potential of native strains of Actinobacteria from Monte Desert as growth promoters of native vegetation, isolating them from two substrates from their habitat (bare soil and leaf-cutting ant refuse dumps). Strains were inoculated into the soil where seedlings of three native plant species (Atriplex lampa, Grindelia chiloensis, Gutierrezia solbrigii) were growing. Seedlings were grown following a full factorial design experiment under greenhouse and field conditions comparing native Actinobacteria effects with a known growth-promoting strain, Streptomyces sp. (BCRU-MM40 GenBank accession number: FJ771041), and control treatments. Seedlings survived greenhouse condition but species survival and growth were different among treatments at field conditions, varying over time. The highest survival was observed in a native soil strain (S20) while the lowest in MM40. The low survival in MM40 and in the other treatments may be explained by the higher herbivory observed in those seedlings compared to control ones, suggesting a higher nutritional status in inoculated plants. Strains from refuse dumps were the best at enhancing seedling growth, while strains from soil were the best at maintaining their survival. Native Actinobacteria studied may increase plant species survival and growth by improving their nutritional status, suggesting their potential to facilitate vegetation establishment and, therefore, being good candidates for restoration practices. Furthermore, plant species respond differently to different strains, highlighting the importance of microorganism diversity for ecosystem functioning.

Long-term effects of grazing on the biological, chemical, and physical soil properties of the Caatinga biome.

Soil degradation is a global issue that affects both plant productivity and human life. Intensive grazing practices can accelerate this process, mainly due to rapid removal of biomass from the soil surface. However, the long-term effects of grazing on biological, chemical, and physical properties remain poorly understood, particularly in tropical drylands, such as the Caatinga biome. Our aim was to evaluate the soil properties and combine both culture-dependent and -independent analyses to assess metabolic activity and bacterial community structure. We collected samples (0-20 cm) of three different types of soil in the Caatinga biome: secondary Caatinga forest (NC), grazing exclusion (GE), and degraded areas by overgrazing (OG). We sought to investigate how grazing affects soil properties to determine the effectiveness of grazing exclusion in the restoration of soil fertility/functions. Redundancy analysis demonstrated NC were positively correlated with organic carbon (λ = 0.18, p = 0.0012) and total nitrogen (λ = 0.16, p = 0.0011), while OG was correlated with harmful soil parameters such as Na+ (λ = 0.08, p = 0.0400), electric conductivity (λ = 0.13, p = 0.0060) and exchangeable acidity (λ = 0.11, p = 0.0030). In addition, GE showed lower aluminum content and saturation, reducing these harmful parameters by 48 % and 34 %, respectively. Also, GE showed the highest values for the ß-glucosidase (63.62 mg ρ-nitrophenol kg-1 h-1) and arylsulfatase (5.8 mg ρ-nitrophenol kg-1 h-1) activities. Changes in bacterial community structure were significant (p = 0.0096), with a higher difference comparing GE and OG (p = 0.0135). The GE area showed 20 % more phosphate solubilizers than OG, but there were no differences for siderophores production. All isolates were halotolerant and had at least 60 % nitrogen fixers. Our findings indicate that while soil recovery is slow, with grazing-exclusion areas presenting 18 years of implantation, it seems to improve in subsequent years. Finally, our results provide evidence that microbe-based technologies can mitigate soil degradation in the Caatinga biome.

Impact of irrigation with fish-processing effluents on nitrification and ammonia-oxidizer abundances in Patagonian arid soils.

This study aimed to evaluate the short-term effects of irrigation with diluted fish-processing effluents on soil pH, electrical conductivity, nitrification rate and abundance of ammonia oxidizers. To accomplish that, we constructed microcosms of soil from an undisturbed arid ecosystem of Patagonia, and irrigated them for 2 months with diluted effluents from a fish-processing factory or with water as control. In the initial soil sample, and along the experiment, we determined soil pH, electrical conductivity, and the concentration of inorganic nitrogen forms, which we used to calculate the net nitrification rate. We further estimated the abundances of ammonia-oxidizing archaea and bacteria in the initial soil sample and at the end of the experiment, by qPCR of amoA genes. Soil pH decreased and electrical conductivity increased in both irrigation treatments, although the effect was higher in effluent-irrigated microcosms. Soil nitrate + nitrite concentration, and thus the nitrification rate, was higher in effluent than in water-irrigated microcosms. The abundance of archaeal amoA genes was higher under effluent than water-irrigation, but that of bacterial amoA genes did not vary significantly between treatments. Neither ammonia-oxidizing archaea nor bacteria were influenced by the changes in soil pH and electrical conductivity induced by effluent irrigation.

Phylogenetic signal and climatic niche of stem photosynthesis in the mediterranean and desert regions of California and Baja California Peninsula.

PREMISE: Woody plants with photosynthetic stems are common in the drylands of the world; however, we know little about the origin(s) and geographical distribution of photosynthetic stems. Therefore, we set to answer the following questions: (1) Is stem photosynthesis phylogenetically conserved? (2) Do green-stemmed and fleshy-stemmed species have identifiable climatic niches? METHODS: We mapped the photosynthetic stem trait onto a phylogeny of 228 mediterranean and desert species and calculated indices of phylogenetic signal and created climatic niche models of 28 species belonging to three groups: green, fleshy, and green-and-fleshy stemmed species. RESULTS: We found phylogenetic signal in the fleshy stem trait, but not in the green stem trait. Fleshy-stemmed species occupy areas associated with high isothermality, high precipitation seasonality, and high mean temperature of the wettest quarter, whereas green-stemmed species occupy areas associated with high precipitation of driest month, high precipitation of coldest quarter, high mean diurnal temperature range and high maximum temperature of the warmest month. CONCLUSIONS: Despite the fact that both photosynthetic stem types help cope with water shortage, having fleshy stems allows plants to cope with greater precipitation seasonality than is possible with green stems. Green stems require a lot of water to be stored in the soil to maintain net photosynthesis during the dry season, so they inhabit areas with higher and more predictable precipitation.

First record of Moenkhausia costae (Steindachner 1907) in the Paraíba do Norte basin after the São Francisco River diversion / Primeiro registro de Moenkhausia costae (Steindachner 1907) na bacia da Paraíba do Norte após a transposição do rio São Francisco

Abstract: Construction of water diversions in drylands is boosted by increasing demands for freshwater often due to prolonged droughts. Even though these mega-enterprises result in benefits to society, it also poses a threat to freshwater biodiversity. In Northeastern Brazil, for instance, the São Francisco River Integration Project already supplies water for millions of people, but over time it will also favor the introductions of multiple aquatic species in the river basins of the Northeastern Caatinga and Coastal Drainages ecoregion. These introductions can cause unprecedented impacts in the native ichthyofauna, such as homogenization of freshwater faunas, transmission of pathogens and loss of native species. This study compares the composition and relative frequency of fish species from Poções reservoir using data obtained by gillnetting and trawling before and after the São Francisco diversion in the dry and rainy seasons, and reports the first detection of Moenkhausia costae introduction in the Paraíba do Norte basin, through the São Francisco River channel. Our results show some evidences that M. costae may become dominant and invasive in Poções reservoir. The introduction of M. costae adds a new component of disruption for these freshwaters and may pose a serious threat to the endemic ichthyofauna in lentic and lotic systems from the Paraíba do Norte basin.

Resumo: Obras para transposição de rios em regiões secas do mundo têm sido impulsionadas pelo aumento da demanda por água doce, muitas vezes associadas às secas prolongadas que são intrínsecas a essas regiões. Embora tais megaempreendimentos possam trazer benefícios para a sociedade, também representam uma ameaça para a biodiversidade aquática. No Nordeste do Brasil, por exemplo, o Projeto de Integração do Rio São Francisco já fornece água para milhões de pessoas, mas com o tempo também contribuirá com a introdução de várias espécies aquáticas nas bacias hidrográficas da ecorregião Nordeste da Caatinga e Drenagem Costeira. Essas introduções podem causar impactos sem precedentes, tais como homogeneização da ictiofauna nativa, transmissão de patógenos e perda de espécies nativas. Este estudo compara a composição e frequência relativa de espécies de peixes do açude Poções usando dados coletados com redes de espera e de arrasto antes e depois da transposição do rio São Francisco, nos períodos seco e chuvoso, e relata o primeiro caso de introdução de Moenkhausia costae na Bacia do Rio Paraíba do Norte, através do canal do rio São Francisco. Nossos resultados mostram que M. costae poderá se tornar dominante e invasora no açude Poções. A introdução de M. costae adiciona um novo componente de perturbação para esse açude e pode representar uma séria ameaça à ictiofauna endêmica de sistemas lênticos e lóticos da bacia do rio Paraíba do Norte.