Monte Ecoregion Research Articles

Distinct morphophysiological responses of the native C4 grasses Axonopus siccus and Eragrostis polytricha to shading

Light, an important abiotic factor that shapes plant growth, is explored here in its impact on two native C4 grasses of campo rupestre, an important and unique montane ecoregion in Brazil that occurs across the biomes Cerrado, Atlantic Forest and Caatinga. Axonopus siccus and Eragrostis polytricha seedlings were subjected to two light conditions: (i) artificial shading and (ii) full sun. The evaluations included growth, nutrition, photosynthesis, leaf anatomy, and metabolism. Shading influenced most of the growth parameters of E. polytricha but left A. siccus morphology almost unchanged. The parameters of leaf anatomy, nutrient content, and chlorophyll a fluorescence exhibited consistent patterns between species. In particular, A. siccus showed higher Amax and light compensation point in shaded conditions, while E. polytricha revealed distinctive changes in carbon metabolism (soluble sugars, sucrose, and starch content), explaining its increased shade growth. These findings underscore various light stress responses in these native C4 grasses.

Patterns, drivers, and implications of postfire delayed tree mortality in temperate conifer forests of the western United States

AbstractConifer forest resilience may be threatened by increasing wildfire activity and compound disturbances in western North America. Fire refugia enhance forest resilience, yet may decline over time due to delayed mortality—a process that remains poorly understood at landscape and regional scales. To address this uncertainty, we used high‐resolution satellite imagery (5‐m pixel) to map and quantify delayed mortality of conifer tree cover between 1 and 5 years postfire, across 30 large wildfires that burned within three montane ecoregions in the western United States. We used statistical models to explore the influence of burn severity, topography, soils, and climate moisture deficit on delayed mortality. We estimate that delayed mortality reduced live conifer tree cover by 5%–25% at the fire perimeter scale and 12%–15% at the ecoregion scale. Remotely sensed burn severity (1‐year postfire) was the strongest predictor of delayed mortality, indicating patch‐level fire effects are a strong proxy for fire injury severity among surviving trees that eventually perish. Delayed mortality rates were further influenced by long‐term average and short‐term postfire climate moisture deficits, illustrating the impact of drought on fire‐injured tree survival. Our work demonstrates that delayed mortality in conifer forests of the western United States can be remotely quantified at a fine grain and landscape scale, is a spatially extensive phenomenon, is driven by fire–climate–environment interactions, and has important ecological implications.

Serological survey reveals enzootic circulation of St. Louis encephalitis and West Nile viruses in semiarid Monte ecosystem of Argentina

St. Louis encephalitis virus (SLEV) and West Nile virus (WNV) are arboviruses transmitted by Culex mosquitoes and amplified in avian hosts. The present study aimed to investigate the presence and seasonal circulation of SLEV and WNV in La Rioja province, within the semiarid ecoregion of the Monte, Argentina. Over a two-year period, avian sera were collected and tested for neutralizing antibodies against SLEV and WNV. Our results reveal the enzootic activity of both viruses in this challenging environment. SLEV seroprevalence was 4.5% (35/778), with higher activity in spring (2016) and autumn (2017). WNV seroprevalence was 3.5% (27/778), peaking during the summer 2016–2017. Greater seroprevalence for SLEV in 2016 was detected for the Lark-like Brushrunner (Coryphistera alaudina) and the Short-billed Canastero (Asthenes baeri) and in 2017 for the Black-crested Finch (Lophospingus pusillus) and Lark-like Brushrunner, whereas for WNV greater seroprevalence in 2016 was detected for the Picui Ground Dove (Columbina picui) and in 2017 for the Lark-like Brushrunner and Band-tailed Seedeater (Catamenia analis). Additionally, five avian individuals experienced seroconversion during the sampling period, namely the Lark-like Brushrunner and White-fronted Woodpecker (Melanerpes cactorum) for SLEV, and the Lark-like Brushrunner, Greater Wagtail Tyrant (Stigmatura budytoides) and Many-colored Chaco Finch (Saltatricula multicolor) for WNV. The study highlights the persistence and circulation of these viruses in a semiarid ecosystem, raising questions about overwintering mechanisms and transmission dynamics. This research contributes to understanding arbovirus ecology in diverse environments. Further investigations are needed to assess the specific mechanisms facilitating virus persistence in the Monte ecoregion.

Phylogeography and ecological niche modelling of the South American cricetid rodent Graomys griseoflavus, with insights into its chromosomal evolution

Abstract The rodent Graomys griseoflavus has a wide geographical distribution in the Arid Diagonal of South America, showing variation in the diploid number (2n = 33–38) caused by three different Robertsonian (Rb) translocations. Two contrasting hypotheses have been proposed to explain the origin and evolution of this polymorphism: (i) unique and sequential events; or (ii) multiple and independent origins of Rb translocations. Here, we combined phylogeography and ecological niche modelling to elucidate the evolutionary history of G. griseoflavus and help to contrast these hypotheses. The results indicated a demographic increase that would have begun ~150 kya from the High Monte ecoregion. The spatial distributions of these populations were coincident with the areas of highest habitat suitability. The palaeoclimatic projections suggested the presence of two main glacial refugia coincident with the main genetic clusters. Graomys griseoflavus underwent two pulses of southward expansion at ~220 and ~210 kya. More recently (~20 kya), there was a secondary contact between the southern populations (Low Monte ecoregion) expanding northwards and the northern populations (High Monte ecoregion) expanding into marginal areas of the Chaco ecoregion. Combined with the cytogenetic evidence, our results support the multiple and independent origins of Rb translocations.

Space-time mapping of soil organic carbon stock and its local drivers: Potential for use in carbon accounting

The measurement and tracking of changes in soil organic carbon (SOC) stocks and its underpinning drivers are important in greenhouse gas accounting and carbon trading schemes. While repeated direct measurement of a location over time is the ‘gold standard’ for SOC stock change estimation, this is currently unfeasible at scale due to sample collection and analysis costs. Here, we used a data-driven, space–time digital soil mapping modelling approach (ST-DSM) coupled with an interpretive machine learning (IML) technique to both predict and quantify the relative contributions of covariates to annual SOC stocks and their uncertainty at 0–30 cm depth and at a 90 m spatial resolution for Australia between 1990 and 2018. A quantile regression forest model was calibrated using data from a datacube comprising of SOC stock values collected over the prediction years and a suite of dynamic and static environmental covariates. The evaluation of the ST-DSM model on a test set was satisfactory. Long-term annual mean (Mg C/ha), and total (Pg C) topsoil SOC stock were 37.6 (12.3 – 101.1, 90 % PI) and 28.3 (9.25 – 83.1, 90 % PI) respectively. The mean annual rate of SOC stock change over the Australian continent was 0.11 (±0.22) Mg C/ha yr−1 and the total net change was 23.5 Tg C yr−1, indicating Australia’s soils were a net sink of SOC over the 29-year period. However, SOC stocks declined in the montane ecoregion, a great concern given its fragility and high SOC stock. The long-term mean fraction of photosynthetic vegetation was the most important individual local contributor to SOC stock prediction in many parts of Australia. The aggregated effect of covariates based on the soil forming factors indicates vegetation as the principal local driver of SOC stock across most of the Australian continent, followed by climate. The evaluation of our results against independent, temporally paired field data and estimates from a nationally accepted SOC process-based model yielded promising results. Our approach demonstrates the use of readily available and inexpensive covariates to estimate SOC stock changes, as well as the underlying drivers over a larger area but at a spatial resolution suitable for decision making. This approach presents a new monitoring and verification possibility for carbon projects and national carbon accounting especially with the growing number of existing profile observations in soil databases.

Las comunidades criptógamas como potenciales indicadores de recuperación post-fuego en el pedemonte

Among the disturbances affecting terrestrial ecosystems, fire is one of the most important in the Monte ecoregion of Argentina. In the foothills, recurrent fires generate changes in the composition of the vegetation and the physiognomy of the landscape, without knowledge of the effects of fire on cryptogams. Cryptogams include biological soil crusts (BSC), corticolous and saxicolous lichens, and mosses. These communities are crucial in degraded ecosystems and in arid zones by fixing nitrogen and stabilizing the soil. Furthermore, some of the organisms of BSC develop quite slowly and are sensitive to disturbances, which makes them potentially useful as indicators of disturbance or recovery. In this work, we evaluate the cover and frequency of functional types of cryptogams, as well as the environmental factors that favor their development in sites with different fire histories, in order to identify potential indicators of post-fire recovery. We found that saxicolous and corticolous lichen frequency, BSC cover and cyanobacterial-dominated BSC frequency varied as a function of post-fire recovery time. Their cover and frequency were also affected by the cover of vascular plants, bare soil, rocks and mounds generated by animals. These variations in abundance can be used as indicators of the success of passive ecological restoration strategies. Corticolous and saxicolous lichens may function as indicators of post-fire recovery as they are only present on sites with +40 years since the latest fire and showed a greater response than vascular plants. On the other hand, CBS dominated by cyanobacteria —being more abundant in sites with recent fires— would be good indicators of more recent soil recovery processes. The wide distribution of BSC dominated by mosses, and the development of cyanobacteria in recently disturbed places, highlight the potential of these two groups of organisms to actively and more quickly restore arid ecosystems degraded by fires.

Dominant source areas shift seasonally from longitudinal to lateral contributions in a montane headwater stream

Montane ecoregions are important vehicles for downstream hydrologic function, but their dynamics are relatively understudied compared to alpine and subalpine catchments in the western United States. Montane catchments experience shifts in precipitation inputs seasonally, which results in spatiotemporal differences in source area contributions to the stream. We collected hydrometric and geochemical data between 2018 and 2021 from a 2.65 km2 semi-arid headwater catchment in the Front Range of Colorado, USA. Using a combined approach of hydrometric monitoring, geochemical characterization, and end-member mixing analysis (EMMA), we assess hydrologic connectivity between areas with high upslope accumulation and the stream. Within our study area, high upslope accumulation area corresponded to alluvial/ colluvial fans wherein we focused instrumentation and water sample collection. Using observed rainfall, and multiyear measurements of groundwater levels, soil moisture, and streamflow, we observed distinct hydrologic seasons within our catchment characterized by snowmelt during the spring, rainstorms during the summer, and a return to baseflow during the fall. Within this framework, we found that source areas to streamflow shift with longitudinal distance downstream, and among hydrologic seasons. Notably, our EMMA results indicate that contributions from upstream source areas become less important than lateral inputs from spring snowmelt into the fall return to baseflow. This was most pronounced at the upper catchment where upstream contributions to streamflow decreased up to 33.3% between spring and fall. These results suggest that streamflow is maintained by local source areas contributing laterally and vertically. Our results reflect dynamic shifts in hydrologic connectivity in space and in time, which are increasingly important to land and water resource management given rapid climate changes within the western United States.

Key sites for seedling emergence in degraded areas of the monte ecoregion of the Rio Negro Province, Argentina

In disturbed shrublands of the Monte ecoregion in the Rio Negro province, herbaceous vegetation occurs in patches of high plant cover beneath shrubs, interspersed with patches of low cover between them, which leads to the existence of differential microsites in the environment. The protected understory in the shrub patches is occupied by other functional groups that conform this system: perennial grasses, annuals and biological crusts. The areas between the shrubs may be more or less degraded by grazing, and may exhibit physical impediments to the germination and establishment of seeds and to seedling emergence and survival, in the form of vesicular crusts that develop on the soil surface and contribute to desertification in those systems where they appear. The objective of our study was to relate the presence of seedlings in three microsites of the environment: a) beneath shrubs, and in the open spaces between them discriminated into b) flat and c) rough places, with different covers of the soil surface (biological crust, litter, perennial grasses and gravel), and with the presence and thickness of vesicular crusts, in a semi-arid shrubland of the south-eastern Monte ecoregion. We found that the presence of seedlings differed between the microsites and was related to the different soil cover in each microsite. In flat microsites, that presence was positively related with litter and biological crust covers and negatively related to vesicular crust thickness and gravel cover; in rough places we only found a positive influence of litter, and beneath shrubs, there were beneficial effects due to perennial grass cover and scarce negative effects due to vesicular crusts.

Low genetic variation of foliar traits among Prosopis chilensis (Leguminosae) provenances.

Prosopis chilensis (Molina) Stuntz (Leguminosae) is a valuable native species in Argentina that has been proposed to be used in reforestation, afforestation and restoration programmes. Natural provenances show important differentiation in height, shape, spine size, fruits and foliar traits throughout their distribution in the semiarid Monte ecoregion. The goal of this work was to characterize the genetic basis of the leaf variation in P. chilensis aiming to contribute to the improvement management program. We analyzed morphological variation and estimate narrow sense heritability for ten quantitative traits from a provenance-progeny trial founded from open pollinated families. We assessed the variance components by a generalized linear mixed model. Differences among provenances were quantified through univariate QST statistics and multivariate discriminant analysis of principal components. Finally, univariate and multivariate neutrality test were conducted to unveil the evolutionary forces that shape the variation. Univariate and multivariate analysis showed low genetic variation in foliar traits among provenances grown in the common garden. Consistently, the QST estimates for each trait were low. Both, the univariate (QST-FST comparison) and the multivariate neutrality test suggest that the leaf variation among provenances may be shaped by genetic drift rather than selective forces. Heritability estimates were significant only for leaflet apex and leaflet apex/leaflet area. Since genetic variation for most foliar traits among provenances estimated under controlled environmental conditions were very low or absent, the variation described in the wild would be explained merely by plastic response to varying environments. These results are discussed in terms of adaptive strategies and the use of different provenances as seed sources within the framework of the improvement program. It is expected that P. chilensis seeds or seedlings from trees selected under economical criteria will be able to develop in different areas thanks to the phenotypic plasticity of leaf traits.

Molecular phylogeny of the “salty” Liolaemus species (Reptilia: Squamata): anomalus group, endemic of the Argentina Monte Desert

In Argentina, the Monte ecoregion extends for more than 2,000 km from NW Argentina to borealPatagonia, and includes many salt-pans and barren flatlands colonized by the monophyleticLiolaemus anomalus group that includes seven species. Some of their external morphologicalcharacteristics and behaviors are very unusual for the genus, and this has led to a complextaxonomic history. The group is very poorly known except for a recent paper with descriptionsof three species and morphological-based phylogenetic hypotheses. Of the four recognizedspecies, two are threatened and one is vulnerable, and while the conservation status of thethree recently described species is unknown, they are suspected to also be under some degreeof threat. We reviewed all georeferenced localities known to produce a distribution map, andsequenced two mitochondrial and four nuclear genes, for representatives of all species. Weinferred a time-calibrated species tree showing that the evolutionary history of this clade occurredentirely during the Pleistocene, with most of the divergences very recent. The climaticand geomorphological changes driving this divergence started during the Great PatagonianGlaciation, initially separating the two northwestern-most distributed species (L. pipanaco +L. pseudoanomalus) from the rest. Given the very recent evolutionary history of the group andtheir unique and conserved morphology, incongruent topologies among datasets are expected; adetailed genome-wide dataset will be needed to fully assess and resolve their speciation history.

Propolis from the Monte Region in Argentina: A Potential Phytotherapic and Food Functional Ingredient.

The aim of this review is to provide overall information on Argentine propolis and to shed light on its potential, especially the one from the Monte region so as to support future research in the field. Around 1999, the Argentine propolis began to be chemically and functionally characterized to give it greater added value. Because Argentina has a wide plant biodiversity, it is expected that its propolis will have various botanical origins, and consequently, a different chemical composition. To date, five types have been defined. Based on their functionality, several products have been developed for use in human and veterinary medicine and in animal and human food. Because the Argentine propolis with the greatest potential is that of the Monte eco-region, this review will describe the findings of the last 20 years on this propolis, its botanical source (Zuccagnia punctata Cav.), its chemical composition, and a description of markers of chemical quality (chalcones) and functionality. Propolis can regulate the activity of various pro-inflammatory enzymes and carbohydrate and lipid metabolism enzymes, as well as remove reactive oxygen and nitrogen species. Consequently, it can modulate metabolic syndrome and could be used as a functional ingredient in food. Furthermore, hydroalcoholic extracts can act against human and animal pathogenic bacteria and human yeast, and mycelial pathogenic fungi. The ability to stop the growth of post-harvest pathogenic bacteria and fungi was also demonstrated. For this reason, Argentine propolis are natural products capable of protecting crops and increasing the lifespan of harvested fruit and vegetables. Several reports indicate the potential of Argentine propolis to be used in innovative products to improve health, food preservation, and packaging. However, there is still much to learn about these natural products to make a wholesome use of them.

Altitudinal gradient of plant diversity patterns in the Sierra de Quilmes (Monte desert – Argentina)

The Monte Desert is the most arid rangeland in Argentina. Its northern portion, the High Monte ecoregion, is a geomorphologically complex area, characterized by mountain and bolsons landforms. Yet, most studies about plant diversity in the area have disregarded the altitudinal gradient. We examined the patterns of species richness, composition, and diversity along an altitudinal gradient in the Sierra de Quilmes (High Monte ecoregion), through the deconstruction of biodiversity into growth forms. We sampled vegetation from eight sampling sites in each of five altitudinal bands ranging from 1650 to 2550 m a.s.l. We found 123 species belonging to 33 families. Community composition changed with altitude. The abundance of shrubs increased with altitude, while the abundance of trees decreased. Both alpha and beta diversities peaked in the lowest and intermediate altitudes (1700 and 2300 bands). This pattern was particularly consistent for woody plants. The higher beta diversity in the 1700 band might result from geomorphology and soil features variation. The remaining gradient conformed to a hump-shaped pattern with a peak in the 2300 band, which may present more suitable climatic conditions. This study contributes to a broader understanding of the causes determining vegetation diversity patterns in the High Monte Desert.

Solanaceae diversity in South America and its distribution in Argentina.

Solanaceae is one of the most diverse families in the Americas, particularly in Argentina where it represents the fourth family in terms of species number. Although checklists for most South American countries have been published, some are outdated and there has been no analysis of Solanaceae diversity at country level. We present an updated summary of Solanaceae diversity in South America, an analysis of its distribution in Argentina, and preliminary conservation assessments for all species endemic to Argentina. Regression analyses were used for evaluating the ratio between taxa/area and endemic/total species, multivariate ordering methods were used to analyze the relationships between Argentine ecoregions, and the IUCN criteria were applied for conservation assessments. Results show that Solanaceae comprises 1611 species in South America. The highest diversity is in Peru, which, together with Ecuador, possesses more diversity than expected for the area; Chile and Brazil have the greatest percentage of endemic species. In Argentina, the Chaco ecoregion hosts the highest number of taxa, but largest number of endemic species is found in the Monte ecoregion. According to the IUCN criteria, 28 endemic species from Argentina are considered threatened. We discuss South American countries and Argentine ecoregions in terms of conservation priorities.

Occurrence of domestic and intrusive triatomines (Hemiptera: Reduviidae) in sylvatic habitats of the temperate Monte Desert ecoregion of Argentina

The eco-epidemiology of Triatominae and Trypanosoma cruzi transmission has been little studied in the Argentinean Monte ecoregion. Herein, we provide a comprehensive description of domestic and intrusive triatomines to evaluate the risk of reinfestation of rural dwellings. Triatoma infestans, T. patagonica, T. garciabesi and T. eratyrusiformis were collected by active searches or light traps. None were infected with T. cruzi. One T. infestans male was collected at 1.3 km from the nearest infested house. The finding of intrusive and domestic triatomines in sylvatic foci emphasizes the need of implementing an effective vector surveillance system.

Seed Availability Does Not Ensure Regeneration in Northern Ecosystems of the Endangered Limber Pine

Research Highlights: When biotic interactions such as disease alter both the seed production capacity of stands, and seedling survivorship, the relative importance of seed availability versus substrate specificity may alter future regeneration opportunities for plant populations. Background and Objectives: We investigated the importance of disease severity, seed availability, and substrate limitation to the regeneration dynamics of the endangered limber pine, Pinus flexilis, in two ecosystems with varying forest composition, and different histories of white pine blister rust infection (WPBR; Cronartium ribicola). Materials and Methods: A total of 17 stands from the montane ecoregion (Alberta, Canada) were sampled for seed production between 2007–2010, seedling density, and age structure. Model selection using an information theoretic approach compared a series of a priori models and their combinations, based on our hypotheses on the role biotic variables play in the regeneration process. Results: Despite higher rates of WPBR infection, 2.3 times more seed was available for avian dispersers in the southern ecosystem. Recent seedling regeneration did not correspond to seed production (83 versus 251 seedlings/ha, in southern versus northern ecosystems, respectively), resulting in a seven-fold difference in seed to seedling ratios between ecosystems. Models suggest that disease and vegetation cover were important factors explaining the absence of regeneration in 79.4% of the plots sampled, while basal area (BA) of live limber pine, rocky substrates, ecosystem, South aspects, and slope enhanced limber pine regeneration. Seedling age structures suggest that recent regeneration is less likely in more diseased landscapes, than it was historically (40% versus 72.8% of seedlings < 20 years old, respectively, in southern versus northern ecosystems). Conclusions: At the northern limits of limber pine’s range, seed availability does not ensure regeneration, suggesting that other environmental or biotic factors hinder regeneration. Regeneration was consistently predicted to be lower in the southern ecosystem than in the northern ecosystem, suggesting that natural regeneration and the potential for population recovery are ecosystem dependent. We recommend that monitoring recent seedlings will aid the identification of biotic and abiotic factors affecting regeneration.

Assessing drivers of soil properties and classification in the West Usambara mountains, Tanzania

Improved soil information in tropical montane regions is critical for conservation, sustainable agricultural management, and land use planning, but is often challenged by topographic and land-use heterogeneity. The West Usambara mountains are a part of the Eastern Arc chain of mountains of Tanzania and Kenya, a globally important tropical montane ecoregion made up of isolated fault-block mountain complexes characterized by high biological endemism, population density, and agronomic productivity. We synthesized novel and legacy soil data from published and unpublished studies to better understand the drivers of soil property distributions and soil diversity in the West Usambaras, and to serve as a foundation for improved soil mapping efforts across the Eastern Arc. Analysis of the resulting dataset of 468 sites (ranging in elevation from 1040 to 2230m.a.s.l.) revealed that soil properties varied more significantly by land use and topography than by soil type, suggesting that future mapping efforts in the region should focus primarily on soil property prediction and secondarily on soil classification. Sites under cultivated land uses had the lowest topsoil soil organic carbon (SOC) concentrations and highest pH values, and SOC generally increased with increasing elevation. Valley soils had significantly lower surface SOC concentrations but higher exchangeable bases and pH values than all other landscape positions. Soil pH decreased by an average of 3.5units across the entire elevation gradient and decreased by 1 unit with elevation even after SOC, land use and landscape position were included in multiple regression models. The relationship of cation exchange capacity (CEC) to SOC and clay content varied by landscape position. Therefore, particularly in montane regions where soils can vary significantly over short distances, multiple functions may be necessary to produce improved estimates of parameters such as CEC. Soil classification was driven most strongly by topography, with Acrisols (WRB Reference Group) and Ultisols (U.S. Soil Taxonomy (ST)) as the dominant soil types, located primarily on mid slope, upper slope and crest landscape positions, making up 47% and 75% of observed profiles, respectively. However, five ST Orders and seven WRB Reference Groups were present in the dataset, with the highest soil diversity occurring at lower slope landscape positions. Conclusions drawn from this large dataset support previous work in the West Usambaras and provide a conceptual foundation from which to build improved soil maps across the Eastern Arc and in other tropical montane systems throughout the world.

Phylogenetic and divergence time analysis of the Chelonoidis chilensis complex (Testudines: Testudinidae)

We present a phylogenetic and divergence time analysis of the Chelonoidis chilensis complex (the southernmost tortoises of South America) within crown Testudinidae. We compiled a dataset of 1118 bp cytochrome b (cyt b) sequences derived from 111 individuals sampled across the known geographic range of the species, and performed a phylogenetic analysis employing Maximum Parsimony, Maximum Likelihood and Bayesian Inference methods. The resulting trees showed similar topologies and support values. The C. chilensis complex was always recovered as a monophyletic group composed by two major clades (i.e. haplogroups). The biogeographic distribution of one of these clades overlaps with the Dry Chaco eco–region, while the biogeographic distribution of the other overlaps with the Monte eco–region. In order to date the origin and diversification time of these two clades, we employed a previously published two-step molecular clock method. In the first step we dated the time of origin of C. chilensis as a clade within the Testudinidae family using new and previously published sequences, extinct testudinid taxa for age calibration and the Fossilized Birth-Death (FBD) model. In the second step we dated the divergence between the haplogroups of C. chilensis based on the time of origin estimated in the first step and a coalescent evolution model. Our results suggest that divergence between Dry Chaco and Monte tortoises may have occurred about 2.47 million of years ago. We interpret these results in the light of the environmental and geological changes that occurred during the late Pliocene to Middle Pleistocene of South America.

Resiliency in masting systems: Do evolved seed escape strategies benefit an endangered pine?

AbstractSatiation of predispersal seed predators by mast years has been demonstrated in many intact ecosystems. When disease causes mortality of seed‐bearing trees in an ecosystem, the abundance of food sources may alter seed predator behavior and abundance, and the ecosystem services derived from mutualistic seed dispersers. We used the endangered limber pine (Pinus flexilis) to examine whether the benefits of interannual variation in cone production vary depending on the severity of white pine blister rust (Cronartium ribicola) infections, the abundance of seed predator populations, and stand characteristics. We compared infection level, cone production, cone predation, and abundance of red squirrels (Tamiasciurus hudsonicus) in 17 stands over two mast years and two nonmast years. Stands were selected from a southern and northern ecosystem within Alberta's montane ecoregion, with varying forest composition and history of blister rust infection. Considerable variability in interannual cone production, and proportionately greater cone escape (those remaining in stands) in the 2010 mast year led to 10 times greater cone escape overall in the mast year than in nonmast years. Model selection using Akaike's information criterion (AIC) suggests that both cone escape and proportion cone escape from seed predators depended primarily on temporal variability in cone production among mast vs. nonmast years, basal area of canopy trees within stands, squirrel abundance, and ecosystem differences. Several two‐way and three‐way interactions between masting, ecosystems, and predator abundance were selected by AIC for inclusion into the best model of the a priori candidate set for both the cone escape model and proportion cone escape model. Our study suggests that masting confers temporal resiliency in seed escape in declining limber pine ecosystems, even under varying disease and seed predator threats. These findings also suggest that evolved seed escape strategies may be resilient to a variety of ecological conditions, including low reproductive capacity. Nonetheless, proximate ecological conditions may determine the fate of declining species, as predator behavior differed between ecosystems, and greater net cone escape in favorable stands may be necessary to attract mutualistic seed dispersers.

Effects of climatic oscillations on the faunas. The Holocene Thermal Maximum and the displacement of armadillos in Argentina: Anatomical features and conservation

The Dasypodidae (commonly known as armadillos) are exclusively from the Americas and have a long evolutionary history on the continents. They were frequently consumed by hunter-gatherers in the past and they are consumed by native people in the modern age along their distributional area. Both paleontological and archaeological records show that they inhabited areas in which they do not inhabit in the present-day. The study conducted on faunal remains at the Alfar site (southeast Buenos Aires Province, Argentina) allowed the determination of two different species (Zaedyus pichiy and Tolypeutes matacus) based on the ornamentation of the osteoderms that compose the animal's carapace. Radiocarbon dating of Unit II (fossil bearing level, 5700yBP) locates the human exploitation during a warm and arid climate period known as the Holocene Thermal Maximum. The armadillos found at Alfar site are absent in the area nowadays. Instead, they are distributed in arid/semiarid environments of the Patagonia and Central regions of Argentina, where the association is characteristic of the Monte ecoregion, 1000km northwest far from Alfar site. The results here presented serve to support the hypothesis of the Dasypodidae as paleoenvironmental proxies and also to confirm the importance of paleozoology studies to apply in conservation biology.

Are owl pellets good estimators of prey abundance?

Some ecologists have been skeptics about the use of owl pellets to estimate small mammal’s fauna. This is due to the assumptions required by this method: (a) that owls hunt at random, and (b) that pellets represent a random sample from the environment. We performed statistical analysis to test these assumptions and to assess the effectiveness of Barn owl pellets as a useful estimator of field abundances of its preys. We used samples collected in the arid Extra-Andean Patagonia along an altitudinal environmental gradient from lower Monte ecoregion to upper Patagonian steppe ecoregion, with a mid-elevation ecotone. To test if owls hunt at random, we estimated expected pellet frequency by creating a distribution of random pellets, which we compared with data using a simulated chi-square. To test if pellets represent a random sample from the environment, differences between ecoregions were evaluated by PERMANOVAs with Bray–Curtis dissimilarities. We did not find evidence that owls foraged non-randomly. Therefore, we can assume that the proportions of the small mammal’s species in the diet are representative of the proportions of the species in their communities. Only Monte is different from other ecoregions. The ecotone samples are grouped with those of Patagonian steppes. There are no real differences between localities in the small mammal’s abundances in each of these ecoregions and/or Barn owl pellets cannot detect patterns at a smaller spatial scale. Therefore, we have no evidence to invalidate the use of owl pellets at an ecoregional scale.