Browsing by Autor "Quentin Struelens"

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Glacier influence on bird assemblages in habitat islands of the high Bolivian Andes
(Wiley, 2021) Tatiana Cárdenas; Kazuya Naoki; Carlos Miguel Landivar; Quentin Struelens; María Isabel Gómez; Rosa Isela Meneses; Sophie Cauvy‐Fraunié; Fabien Anthelme; Olivier Dangles
Abstract Aim Climate projections for the upcoming decades predict a significant loss of ice mass particularly critical for glaciers in tropical mountains. In the dry landscapes of the southern Andes (from Southern Peru to Chile), this global trend has strong ecological impacts on high‐altitude wetlands that support a unique avifauna for feeding, roosting and nesting. As glacier runoffs are expected to affect the area and the quality of wetland habitats, these changes may potentially affect bird communities. To address this issue, we studied the structural and functional diversity of bird assemblages in glacier‐fed high‐altitude wetlands (>4500 m). Location Five valleys of the Cordillera Real, Bolivia. Methods We surveyed bird communities during dry, wet and intermediate seasons in 40 wetlands (total of 27,720 observations of birds and habitats from 540 transects) showing different degrees of dependence on glacial meltwater. We examined the potential effect of glacier retreat on bird communities through changes in wetland area and environmental quality and heterogeneity. Results We found strong relationship between wetland area and taxonomic and functional diversity, but not on phylogenetic diversity. Generalized additive models revealed that avian diversity was influenced by wetland's productivity and elevation and maximized at intermediate levels of glacier influence. Multivariate analysis further showed that habitat productivity and humidity, both potentially influenced by future glacial retreat trends, are the main drivers of bird community composition, with the wettest habitats being crucial for aquatic birds and uncommon species. Main conclusions Glacier retreat may significantly affect bird community diversity and composition through changes in both area and quality of high‐altitude wetlands, with a particular concern for aquatic birds.
Market access and community size influence pastoral management of native and exotic livestock species: A case study in communities of the Cordillera Real in Bolivia's high Andean wetlands
(Public Library of Science, 2017) Quentin Struelens; Karina Gonzales Pomar; Susi Loza Herrera; Gaby Nina Huanca; Olivier Dangles; François Rebaudo
Grazing areas management is of utmost importance in the Andean region. In the valleys of the Bolivian Cordillera Real near La Paz, pastoralism constitutes the traditional way for people to insure food security and economical sustainability. In these harsh mountains, unique and productive wetlands sustained by glacial water streams are of utmost importance for feeding cattle herds during the dry season. After the colonization by the Spanish, a shift in livestock species has been observed, with the introduction of exotic species such as cows and sheep, resulting in a different impact on pastures compared to native camelid species-llamas and alpacas. Here we explored some of the social-economical and environmental drivers that motivate Bolivian pastoralists to prefer exotic over native livestock species, based on 36 household surveys in the Cordillera Real. We constructed a Partial Least Squares Structural Equation Model in order to assess the relationships between these drivers. Our results suggest that the access to market influenced pastoralists to reshape their herd composition, by increasing the number of sheep. They also suggest that community size increased daily grazing time in pastures, therefore intensifying the grazing pressure. At a broader scale, this study highlights the effects of some social-economical and environmental drivers on mountain herding systems.
Modelling temperature‐dependent development rate and phenology in arthropods: The <scp>devRate</scp> package for <scp>r</scp>
(Wiley, 2017) François Rebaudo; Quentin Struelens; Olivier Dangles
Abstract Thermal biologists are interested in generating paired data on development rates and temperatures, but they are in need of automated tools to accurately analyse this data. Fed with a database of more than 30 existing development models, the devRate package provides tools for plotting and visualizing data, selecting the most appropriate model, and mapping and forecasting ectotherm phenology using temperature time‐series data. Most proposed models are for arthropods, mainly insects (e.g. Lepidoptera, Coleoptera, Hemiptera, Diptera, Hymenoptera). This paper presents the main functions of the package and provides an example using an empirical dataset. The devRate package provides investigators with a unique set of tools and a database that allows them to fit development rate models, and to compare arthropod response to temperature.
Pesticide misuse among small Andean farmers stems from pervasive misinformation by retailers
(Public Library of Science, 2022) Quentin Struelens; Marco Rivera; Mariana Alem Zabalaga; Raúl Ccanto; Reinaldo Quispe Tarqui; Diego Mina; Carlos Carpio; María Rosa Yumbla Mantilla; Mélany Osorio; Soraya Román
A critical issue in the context of sustainable agriculture is the reduction of pesticides. Despite well-known adverse effects, farmers around the world continue using pesticides with mostly inappropriate ways. Relevant policies have assumed that farmers themselves are primarily responsible for pesticide misuse. However, the responsibility of pesticide retailers has never been quantified due to the difficulty in obtaining reliable data. An empirical study was conducted with smallholder farmers who collected 9,670 pesticide retailers’ recommendations from 1489 surveys in the highlands of Bolivia, Ecuador and Peru. This original design allowed obtaining for the first time genuine responses about pesticide recommendations from retailers at a large scale. When comparing retailers’ recommendations with product datasheets, the results suggest that 88.2% of recommendations standards were incorrectly followed resulting in dosing recommendations that were either excessive or insufficient and accurate less than 12% of the time. An in-depth analysis also showed that 79.2% of recommended products pertained to only 6 modes of action, thus increasing the risks of pest resistance. An expert retailer model further showed that all highly toxic pesticides could be replaced by less-toxic ones. Several ways to alleviate these detrimental consequences are proposed, by acting at the root of pesticide misuse–at the retailer’s recommendation stage.
Relationship between temperature and development rate of Copitarsia incommoda (Lepidoptera: Noctuidae) in the Bolivian Andes
(Springer Science+Business Media, 2017) François Rebaudo; Quentin Struelens; Franz Callizaya Condori; R. Quispe
Thermal pace-of-life strategies improve phenological predictions in ectotherms
(Nature Portfolio, 2018) Quentin Struelens; François Rebaudo; Reinaldo Quispe; Olivier Dangles