Browsing by Author "Alaniz, Alberto J."

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    Increasing importance of heat stress for cattle farming under future global climate scenarios
    (2021) Carvajal, Mario A.; Alaniz, Alberto J.; Gutierrez-Gomez, Constanza; Vergara, Pablo M.; Sejian, Veerasamy; Bozinovic, Francisco
    In the last decades, livestock species have been severely affected by heat stress because of increasing temperatures, which has threatened animal welfare and decreased production. Based on thermal comfort indices and ensemble climate projections, we analyzed the current and future global spatiotemporal patterns of the heat exposure of cattle in 10 agroclimatic zones. The results show that similar to 7% of the global cattle population is currently exposed to dangerous heat conditions. This percentage is projected to increase to similar to 48% before 2100 under a scenario of growing emissions. Tropical agroclimatic zones are expected to face an early increase in the exposure to intense heat before 2050. Heat exposure was negatively correlated with the socioeconomic variables, showing that poor and livestock-dependent tropical countries are the most affected. Our results demonstrate the near future consequences of heat stress on livestock, emphasizing the limited time available to implement effective abatement strategies. (C) 2021 Elsevier B.V. All rights reserved.
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    Linking sedimentological and spatial analysis to assess the impact of the forestry industry on soil loss: The case of Lanalhue Basin, Chile
    (2021) Alaniz, Alberto J.; Abarzua, Ana M.; Martel-Cea, Alejandra; Jarpa, Leonora; Hernandez, Marjorie; Aquino-Lopez, Marco A.; Smith-Ramirez, Cecilia
    Soil loss has become one of the main problems associated with global change over the last decades. New assessments are needed in order to improve our understanding of the real impacts of human productive activities on the natural dynamics linked to erosion in lake basins. We analyzed the recent and historical dynamics of soil loss in a coastal lake basin of central Chile (Lanalhue lake), evaluating land use impacts and proposing management changes to control erosion and restore the soil. We implemented two approaches: A) Using a high-resolution sedimentological proxy and a high-accuracy chronology of cores to determine the sediment accumulation rate, organic/inorganic matter and granulometry for the last 120 years; and B) applying the Universal Soil Loss Equation to estimate erosion of soil from hills during the last 32 years, considering a combination of satellite, climate, soil, and land-cover topographic data. We found that the sedimentation rates, as well as the concentration of organic matter in lake sediments, were relatively constant from 1900 to 1950; after that, they experienced a significant increase. The same pattern of rapid increase was found for sand content. We found that erosion during the last 30 years has been high and constant, especially in bare soil (mainly clear-cutting areas) and exotic forest plantations. Erosion has been significantly higher within exotic forest plantations, reaching 31 ton/ha/yr in clear-cutting areas. Three industrial forestry companies accounted for 61.5% of the basin surface where urgent erosion control is needed. Our findings support the indication that industrial forestry is the main activity affecting erosion dynamics in the basin; secondarily, earthquakes have been important modulators of the sediment dynamics in Lanalhue during these last 120 years.
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    Perspectives on the timing of ecosystem collapse in a changing climate
    (2024) Alaniz, Alberto J.; Marquet, Pablo A.; Carvajal, Mario A.; Vergara, Pablo M.; Moreira-Arce, Dario; Muzzio, Miguel A.; Keith, David A.
    Climate change is one of the most important drivers of ecosystem change, the global-scale impacts of which will intensify over the next 2 decades. Estimating the timing of unprecedented changes is not only challenging but is of great importance for the development of ecosystem conservation guidelines. Time of emergence (ToE) (point at which climate change can be differentiated from a previous climate), a widely applied concept in climatology studies, provides a robust but unexplored approach for assessing the risk of ecosystem collapse, as described by the C criterion of the International Union for Conservation of Nature's Red List of Ecosystems (RLE). We identified 3 main theoretical considerations of ToE for RLE assessment (degree of stability, multifactorial instead of one-dimensional analyses, and hallmarks of ecosystem collapse) and 4 sources of uncertainty when applying ToE methodology (intermodel spread, historical reference period, consensus among variables, and consideration of different scenarios), which aims to avoid misuse and errors while promoting a proper application of the framework by scientists and practitioners. The incorporation of ToE for the RLE assessments adds important information for conservation priority setting that allows prediction of changes within and beyond the time frames proposed by the RLE.
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    Scale-dependent habitat use from an individual-based perspective: the case of the endangered Darwin's fox living in heterogeneous forest landscapes
    (2021) Moreira-Arce, Dario; Cabello, Javier; Meneses, Luis O.; Norambuena, Katherine; Perez-Hernandez, Christian G.; Hidalgo-Hermoso, Ezequiel; Alaniz, Alberto J.; Vergara, Pablo M.
    Context Understanding how rare and threatened species respond to habitat heterogeneity at different spatial scales requires unbiased population-level parameters incorporating individual variability in occurrence and detection probabilities.
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    The Impact of a Lack of Government Strategies for Sustainable Water Management and Land Use Planning on the Hydrology of Water Bodies: Lessons Learned from the Disappearance of the Aculeo Lagoon in Central Chile
    (2022) Valdes-Pineda, Rodrigo; Garcia-Chevesich, Pablo A.; Alaniz, Alberto J.; Venegas-Quinones, Hector L.; Valdes, Juan B.; Pizarro, Roberto
    Several studies have focused on why the Aculeo Lagoon in central Chile disappeared, with a recent one concluding that a lack of precipitation was the main cause, bringing tremendous political consequences as it supported the argument that the government is not responsible for this environmental, economic, and social disaster. In this study, we evaluated in detail the socio-economic history of the watershed, the past climate and its effects on the lagoon's water levels (including precipitation recycling effects), anthropogenic modifications to the lagoon's water balance, the evolution of water rights and demands, and inaccurate estimates of sustainable groundwater extraction volumes from regional aquifers. This analysis has revealed novel and undisputable evidence that this natural body of water disappeared primarily because of anthropogenic factors (mostly river deviations and aquifer pumping) that, combined with the effects of less than a decade with below-normal precipitation, had a severe impact on this natural lagoon-aquifer system.
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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.