Land-use change is a root cause of the extinction crisis, but links between habitat change and biodiversity loss are not fully understood. While there is evidence that habitat loss is an important ...extinction driver, the relevance of habitat fragmentation remains debated. Moreover, while time delays of biodiversity responses to habitat transformation are well-documented, time-delayed effects have been ignored in the habitat loss versus fragmentation debate. Here, using a hierarchical Bayesian multi-species occupancy framework, we systematically tested for time-delayed responses of bird and mammal communities to habitat loss and to habitat fragmentation. We focused on the Argentine Chaco, where deforestation has been widespread recently. We used an extensive field dataset on birds and mammals, along with a time series of annual woodland maps from 1985 to 2016 covering recent and historical habitat transformations. Contemporary habitat amount explained bird and mammal occupancy better than past habitat amount. However, occupancy was affected more by the past rather than recent fragmentation, indicating a time-delayed response to fragmentation. Considering past landscape patterns is therefore crucial for understanding current biodiversity patterns. Not accounting for land-use history ignores the possibility of extinction debt and can thus obscure impacts of fragmentation, potentially explaining contrasting findings of habitat loss versus fragmentation studies.
•We explored tradeoffs between meat production and avian diversity in the Dry Chaco.•Two land use gradients were described, starting from forest and natural grasslands.•Avian richness sharply ...declined from semi-natural covers to intensive systems.•Most guilds decreased rapidly on the forest gradient favoring land sparing strategy.•Natural grasslands distinctive avifauna shows their value to conservation planning
Studies to assess the relationship between agriculture production and biodiversity conservation usually focus on one gradient ranging from a natural reference land cover type (typically forest) to an intensive productive land use. However, many semi-arid ecoregions such as the dry Chaco are characterized by a mosaic of different land covers, including natural grasslands and woody vegetation with different degrees of transformation, frequently aimed at meat production. We analyzed the associations between avian biodiversity and meat productivity of forest, natural grasslands, three types of livestock production systems, and soybean crops in northern Argentina dry Chaco; an area of c. 19 millionha characterized by high conservation value and rapid land use change. A Generalized Lineal Model analysis of reports and publications quantified a meat productivity range in which soybean (the less diverse land cover type) doubles the most efficient livestock systems, and is eight times more productive than the widespread puestos system. A multidimensional scaling ordination identified two independent gradients of bird's response to increasing land use intensity, respectively from protected forests and from natural grasslands, to highly transformed systems. Along both gradients avian richness and density sharply declined in the transition from semi-natural land covers to planted pastures and similarity to native grasslands and protected forests decreased exponentially. Along the “grasslands gradient”, bird richness and density presented a unimodal response. Maximum likelihood-fitted curves of bird's guilds response to the productivity gradients showed that in the “forest gradient” most guilds decreased exponentially or linearly, whereas in the “grasslands gradient” most guilds peaked at intermediate levels of meat yield. Our results suggest that land sparing strategies can be more efficient to balance agriculture production with the conservation of forest avian diversity, but also that the prevailing “forest oriented” conservation schemes (e.g. Argentine Forest Law) do not capture the complexity of the system and both forests and grassland gradients should be considered in land use planning, possibly including a combination of conservation strategies.
1. The fruit-tracking hypothesis predicts spatiotemporal links between changes in the abundance of fruit-eating birds and the abundance of their fleshy-fruit resources. 2. While the spatial scale of ...plant—frugivore interactions has been explored to understand mismatches between observed and expected fruit—frugivore patterns, methodological issues such as the consequences of measuring fruit and frugivore abundance rather than fruit availability and fruit consumption have not been evaluated. 3. Here, we explored whether predicted fruit—frugivore spatiotemporal links can be captured with higher accuracy by proximate measurements of interaction strength. We used a 6-ha grided plot in an Andean subtropical forest to study the link between (i) fruit and fruit-eating bird abundances; (ii) fruit availability and frequency of fruit consumption; and (iii) covariation between frugivore abundance and frequency of frugivory. We evaluated these links for the entire frugivore assemblage and for the four most important species using data gathered bimonthly along a 2-year period. 4. Fleshy-fruit availability and abundance varied sharply temporally and were patchily distributed in mosaics that differed in fruit quantity. Fruit availability and abundance also varied along spatial gradients extended over the whole study plot. We found a strong response of the entire frugivorous bird assemblage to fruit availability over time, and a weakly significant relationship over space at the local scale. The main frugivore species widely differed in their responses to changes in fruit abundance in such a way that response at the assemblage level cannot be seen as the sum of individual responses of each species. Our results suggest that fruit tracking in frugivorous—insectivorous birds may be largely explained by species-specific responses to changes in the availability of fruits and alternative resources. 5. In agreement with our prediction, more accurate measurements of interaction strength described fruit—frugivore relationships better than traditional measurements. Moreover, we show that covariation between frugivore abundance, frequency of fruit consumption and fruit availability must be included in the fruit-tracking hypothesis framework to demonstrate (or reject) spatiotemporal fruit tracking. We propose that estimation of nutrient and energy availability in fruits could be a new frontier to understanding the forces driving foraging decisions that lead to fruit tracking.
Strix (Strigidae) is a worldwide genus of 17 owl species typical of forested habitats, including Rusty-barred Owls (S. hylophila), Chaco Owls (S. chacoensis), and Rufous-legged Owls (S. rufipes) in ...South America. These species are distributed allopatrically, but the ecological traits that determine their distributions remain largely unknown and their phylogenetic relationships are unclear. We used species distribution models (SDMs) to identify variables explaining their distribution patterns and test hypotheses about ecological divergence and conservatism based on niche overlap analysis. For Rusty-barred Owls and Chaco Owls, climatic factors related to temperature played a major role, whereas a rainfall variable was more important for Rufous-legged Owls. When niche overlaps were compared, accounting for regional similarities in the habitat available to each species, an ecological niche divergence process was supported for Chaco Owl-Rusty-barred Owl and Chaco Owl-Rufous-legged Owl, whereas a niche conservatism process was supported for Rusty-barred Owl-Rufous-legged Owl. Different ecological requirements support current species delimitation, but they are in disagreement with the two main hypotheses currently envisaged about their phylogenetic relationships (Chaco Owls as the sister taxa of either Rufous-legged Owls or Rusty-barred Owls) and support a new phylogenetic hypothesis (Rufous-legged Owls as sister taxa of Rusty-barred Owls). Our findings suggest that speciation of Rusty-barred Owls and Rufous-legged Owls was a vicariant event resulting from Atlantic marine transgressions in southern South America in the Miocene, but their niche was conserved because habitat changed little in their respective ranges. In contrast, Chaco Owls diverged ecologically from the other two species as a result of their adaptations to the habitat they currently occupy. Ecological and historical approaches in biogeography can be embedded to explain distribution patterns, and results provided by SDMs can be used to infer historical and ecological processes in an integrative way. Strix (Strigidae) es un género mundial de 17 especies de lechuzas típicas de hábitats boscosos, incluyendo S. hylophila, S. chacoensis y S. rufipes en América del Sur. Estas especies se distribuyen de forma alopátrica, pero las condiciones ambientales que determinan sus distribuciones permanecen en gran parte desconocidas y sus relaciones filogenéticas no están claras. Utilizamos modelos de distribución de especies (MDEs) para identificar variables que expliquen sus patrones de distribución y poner a prueba hipótesis sobre la divergencia ecológica y el conservatismo basado en análisis de superposición de nichos. Para S. hylophila y S. chacoensis, los factores climáticos relacionados con la temperatura desempeñaron un papel importante, mientras que una variable relacionada con las precipitaciones fue la más importante para S. rufipes. Cuando se compararon los solapamientos de nichos teniendo en cuenta las similitudes regionales en el hábitat disponible para cada especie, se apoyó un proceso de divergencia de nicho ecológico para S. chacoensis y S. rufipes, mientras que un proceso conservador de nicho fue apoyado S. chacoensis and S. hylophila y para S. hylophila y S. rufipes. Los requerimientos ecológicos identificados apoyan la delimitatión actual de las especies, pero están en desacuerdo con las dos principales hipótesis actualmente consideradas acerca de sus relaciones filogenéticas (S. chacoensis como especie hermana de S. rufipes de S. hylophila) y apoyan una nueva hipótesis filogenética de S. rufipes como especie hermana de S. hylophila. Nuestros resultados sugieren que la especiación de S. hylophila y S. rufipes fue un evento de vicarianza que resultó de las transgresiones marinas del atlántico en el Sur de Sudamérica durante el Mioceno, pero su nicho se conservó porque el hábitat cambió poco en sus rangos correspondientes. Por el contrario, S. chacoensis divergió ecológicamente de las otras dos especies como resultado de sus adaptaciones al hábitat que ocupa en la actualidad. Los enfoques ecológicos e históricos en la biogeografía pueden complementarse para explicar los patrones de distribución de los organismos, y los resultados proporcionados por los MDE pueden ser utilizados para inferir procesos históricos y ecológicos de una manera integrada.
•Linear fragments are native dry forest with potential to provide ecosystem services.•Pollination to soybean was study near and far from linear forest fragments (LFFs).•The open pollination treatment ...increased pods, seeds and yields by more than 30%.•The proximity to LFFs was not directly related to a larger difference in production.
The delivery of ecosystem services, such as biotic pollination is a benefit that nature provides us. Pollinators increase the quantity, quality and stability of crops for food production. Previous works show that proximity to natural habitats increases crop production through the delivery of pollination services. However, similar researches in subtropical regions is largely lacking. In this study we evaluated the role of linear forest fragments (LFFs) on the provision of biotic pollination service to soybean crops (Glycine max) and explored whether this service changes with increasing distance to LFFs in subtropical dry Chaco (Argentina). In three agricultural farms and testing two soybean varieties, we covered plots of 0.75m2 with soybean plants and compared them with equally sized open plots. Plots were placed near (60m) and far (600m) from LFFs. We found that plants from the open treatment produced 32% more pods, 41% more seeds and had 42% higher yield (kg/ha) than plants from the covered plots. The difference between open and covered plots in seeds and yield did not change significantly with the distance to LFFs, but the number of pods, contrary to what we expected, was higher far from LFFs. Our findings highlight the possible impact of pollinators on soybean yield in both varieties tested here; but the proximity to LFFs was not directly related to a larger difference in production. Observed patterns are explained by edge effects and competition between soybean plants and trees near LFFs, combined with an underestimation of the distance from the natural hives to which honeybees can efficiently exploit the crops. In this subtropical region, soybean expansion is the most important driver of land cover change and this study represents a first step towards a better understanding of the functioning of these remnants of natural areas within the agricultural land in the region of dry Chaco forests.
Los bosques son esenciales para el bienestar humano ya que proporcionan múltiples bienes y servicios (de regulación, provisión, culturales) que benefician la salud humana. Los insectos polinizadores ...representan uno de los componentes más importantes de la diversidad forestal porque tienen un papel importante tanto en la conservación de la biodiversidad de especies de plantas como en la producción agrícola. En un monitoreo plurianual de colonias silvestres de Meliponini en un bosque del Chaco Seco, hemos utilizado un método simple para encontrar colonias silvestres dentro de los árboles, incluso cuando las condiciones impedían la actividad de forrajeo de las abejas (frío, calor extremo). Describimos brevemente este método y discutimos su utilidad para los ecólogos y las comunidades campesinas. PALABRAS CLAVE. Ecorregión Chaqueña. Nidificación. Neltuma. Tribu Meliponini. Forests are essential for human wellbeing since they provide multiple goods and services (of regulation, provision, cultural) that benefit human health. Insect pollinators represent one of the most important components of forest diversity because they have a significant role both in the plant species biodiversity conservation and agricultural production. In a multiannual monitoring of Meliponini wild colonies in a Dry Chaco forest, we have used a simple method to find colonies inside trees, even when conditions prevented foraging-activity of bees (cold, extreme heat). We briefly describe this method here and discuss its utility for ecologists and peasant communities. KEYWORDS. Chacoan ecoregion. Meliponini tribe. Neltuma. Nesting.
Los bosques son esenciales para el bienestar humano ya que proporcionan múltiples bienes y servicios (de regulación, provisión, culturales) que benefician la salud humana. Los insectos polinizadores ...representan uno de los componentes más importantes de la diversidad forestal porque tienen un papel importante tanto en la conservación de la biodiversidad de especies de plantas como en la producción agrícola. En un monitoreo plurianual de colonias silvestres de Meliponini en un bosque del Chaco Seco, hemos utilizado un método simple para encontrar colonias silvestres dentro de los árboles, incluso cuando las condiciones impedían la actividad de forrajeo de las abejas (frío, calor extremo). Describimos brevemente este método y discutimos su utilidad para los ecólogos y las comunidades campesinas.
Summary
1.
The fruit‐tracking hypothesis predicts spatiotemporal links between changes in the abundance of fruit‐eating birds and the abundance of their fleshy‐fruit resources.
2.
While the spatial ...scale of plant–frugivore interactions has been explored to understand mismatches between observed and expected fruit–frugivore patterns, methodological issues such as the consequences of measuring fruit and frugivore abundance rather than fruit availability and fruit consumption have not been evaluated.
3.
Here, we explored whether predicted fruit–frugivore spatiotemporal links can be captured with higher accuracy by proximate measurements of interaction strength. We used a 6‐ha grided plot in an Andean subtropical forest to study the link between (i) fruit and fruit‐eating bird abundances; (ii) fruit availability and frequency of fruit consumption; and (iii) covariation between frugivore abundance and frequency of frugivory. We evaluated these links for the entire frugivore assemblage and for the four most important species using data gathered bimonthly along a 2‐year period.
4.
Fleshy‐fruit availability and abundance varied sharply temporally and were patchily distributed in mosaics that differed in fruit quantity. Fruit availability and abundance also varied along spatial gradients extended over the whole study plot. We found a strong response of the entire frugivorous bird assemblage to fruit availability over time, and a weakly significant relationship over space at the local scale. The main frugivore species widely differed in their responses to changes in fruit abundance in such a way that response at the assemblage level cannot be seen as the sum of individual responses of each species. Our results suggest that fruit tracking in frugivorous–insectivorous birds may be largely explained by species‐specific responses to changes in the availability of fruits and alternative resources.
5.
In agreement with our prediction, more accurate measurements of interaction strength described fruit–frugivore relationships better than traditional measurements. Moreover, we show that covariation between frugivore abundance, frequency of fruit consumption and fruit availability must be included in the fruit‐tracking hypothesis framework to demonstrate (or reject) spatiotemporal fruit tracking. We propose that estimation of nutrient and energy availability in fruits could be a new frontier to understanding the forces driving foraging decisions that lead to fruit tracking.
In El Salvador end-stage renal disease (ESRD) was the first cause of hospital mortality overall, the first cause of hospital deaths in men, and the fifth cause of hospital mortality in women in 2013. ...In agricultural communities, chronic kidney disease (CKD) occurs predominantly in male agricultural workers, but it also affects women to a lesser degree, even those who are not involved in agricultural work. Internationally, most epidemiological CKD studies emphasize men and no epidemiological studies focused exclusively on women.
To describe the epidemiological characteristics of CKD in females in agricultural communities of El Salvador.
A cross-sectional epidemiological study was carried out in 2009 - 2011 based on active screening for CKD and risk factors in women aged ≥ 18 years in 3 disadvantaged populations of El Salvador: Bajo Lempa (Usulután Department), Guayapa Abajo (Ahuachapán Department), and Las Brisas (San Miguel Department). Epidemiological and clinical data were gathered through personal history, as well as urinalysis for renal damage markers, determinations of serum creatinine and glucose, and estimation of glomerular filtration rates. CKD cases were confirmed at 3 months.
Prevalence of CKD was 13.9% in 1,412 women from 1,306 families studied. Chronic kidney disease of nontraditional causes (CKDu), not attributed to diabetes mellitus, hypertension, or proteinuric primary glomerulopathy (proteinuria > 1 g/L) was 6.6%. Prevalence of chronic renal failure was 6.8%. Prevalence of renal damage markers was 9.8% (microalbuminuria (30 - 300 mg/L) 5.7%; macroalbuminuria (> 300 mg/L) 2%; and hematuria, 2.1%. Prevalence of chronic kidney disease risk factors was: diabetes mellitus, 9.3%; hypertension, 23%; family history of CKD, 16%; family history of diabetes mellitus (DM), 18.7%; family history of hypertension (HT), 31.9%; obesity, 21%; central obesity, 30.7%; NSAID use, 84.3%; agricultural occupation, 15.2%; and contact with agrochemicals, 33.1%.
CKD in women of Salvadoran agricultural communities is associated with disadvantaged populations, traditional (DM, HT, obesity) and non-traditional causes (environmental and occupational exposure to toxic agents and inadequate working conditions). Our results reinforce the hypotheses emerging from other studies, suggesting a multifactorial etiopathology including environmental and occupational nephrotoxic exposure.
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