Browsing by Author "Quiroz, Madelaine"

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    Multiple environmental drivers for the Patagonian forest-dwelling beetles: Contrasting functional and taxonomic responses across strata and trophic guilds
    (2022) Vergara, Pablo M.; Fierro, Andres; Carvajal, Mario A.; Alaniz, Alberto J.; Quiroz, Madelaine
    changes in forest-dwelling beetle communities. However, the effects of multiple environmental factors can be complex to detect in ecosystems that offer a broad variety of microhabitats for a great variety of beetle species. This is the case in Patagonian temperate forests, where the use of remote sensing provides an opportunity to evaluate the sensitivity of beetle species to environmental changes. Here, we identified the environmental drivers of forest-dwelling beetle communities in the ground and canopy of 34 north Patagonian-forest landscapes. We analyzed the associations of the taxonomic and functional diversity of five trophic guilds with 30 remote-sensing variables of landscape structure, composition, and disturbances; vegetation and soil properties; and climate and physical variables. Hierarchical clustering analysis was used to identify trophic guilds responding similarly to predictors. Segmented regression analysis was used to evaluate functional redundancy from taxonomic-functional richness relationships. A total of 583 species (23,848 individuals) of beetles were recorded for both strata. The effects of environmental variables were heterogeneous across strata and guilds. Canopy beetles were especially sensitive to early successional conditions, and canopy attributes, but also benefited from the canopy openness. Forest specialists of the ground and canopy responded differently to environmental variables. Ground-dwelling beetles were mostly affected by fires, human modifications, edge closeness, high temperatures, and soil properties, responding weakly to canopy properties. Functional redundancy
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    Unravelling the cavity-nesting network at large spatial scales: The biogeographic role of woodpeckers as ecosystem engineers
    (2024) Alaniz, Alberto J.; Carvajal, Mario A.; Quiroz, Madelaine; Vergara, Pablo M.; Marquet, Pablo A.; Fierro, Andres; Sieving, Kathryn E.; Moreira-Arce, Dario; Hidalgo-Corrotea, Claudia; Rodriguez-San Pedro, Annia; Allendes, Luis; Machuca, Katerine
    AimPrimary cavity nesters (e.g. woodpeckers) act as ecosystem engineers by providing tree cavities to several vertebrates that use them as nests or refuges. Although diverse assemblages of primary excavators are assumed to increase the number of tree cavities, environmental factors can limit populations of primary excavators, thus weakening their ecological function. We aim to test the biogeographical-scale relationships between primary excavators and cavity users by distinguishing the contribution of environmental variables.LocationSouthern South America.Materials and MethodsWe used species distribution models, which combine bioclimatic and remote sensing derived variables, to map the richness of vertebrates composing the cavity-network of temperate and Mediterranean forests of South America. Based on a resampling procedure for ensuring spatial independence, we fitted structural equation models to estimate relationships between forest characteristics and cavity user vertebrates.ResultsRichness of secondary cavity users (mammals, obligated, habitat generalists and forest specialists) were positively and strongly influenced by the richness of primary excavators. Environmental variables affected differently the richness of primary and secondary cavity users. The richness of primary cavity users responded to tree richness and height while that of habitat specialist secondary users was positively affected by primary productivity and negatively by sclerophyll forests.Main ConclusionsOur results confirm the role of primary excavators as ecosystem engineers but highlight the importance of considering large spatial scales when analysing cavity-nesting networks. Biogeographical patterns of tree diversity and forest structure can be important drivers of cavity nesting networks that remain hidden when studies are conducted over fine spatial scales.