Browsing by Autor "Jhazel Quispe"

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Global population size and conservation priority areas for the endangered Titicaca grebe
(Wiley, 2024) D. A. Villar; Paola Velásquez‐Noriega; Edwin R. Gutiérrez Tito; Anahi Cosky Paca‐Condori; Edmundo G. Moreno Terrazas; Ronald Hinojosa Cárdenas; Alfredo Balcón Cuno; Carmen Villanueva; Patrick F. Chapman; Jhazel Quispe
Abstract The Titicaca grebe ( Rollandia microptera ) is a poorly studied endangered species, only found in the Lake Titicaca watershed of Peru and Bolivia. Population surveys undertaken in the early twenty‐first century suggested that the species had declined in number by >70%. We conducted a population survey of the grebe between March and August 2022 in Peru and Bolivia, using both maximum entropy and Bayesian occupancy models to estimate factors affecting habitat suitability for the grebe. We conducted surveys between March and August 2022 in Peru and Bolivia. Contrary to the International Union for Conservation of Nature (IUCN) population estimates of <1,000 individuals, there are likely tens of thousands of individual grebes. The population estimation was sensitive to the type of model used. Distance from shore and fishing intensity were the most significant factors influencing grebe populations. The Reserva Nacional del Titicaca, the only protected area in the lake, covers some of the most suitable Titicaca grebe habitat across its entire range. The population of the Titicaca grebe is significantly higher than previous estimates, but we do not recommend a change to its conservation status because of the lack of conservation efforts for this species, and the long‐term risks associated with global warming and fisheries bycatch.
Modeling forest dynamics along climate gradients in Bolivia
(Wiley, 2014) Christian Seiler; Ronald Hutjes; Bart Kruijt; Jhazel Quispe; S. Añez; Vivek K. Arora; Joe R. Melton; Thomas Hickler; P. Kabat
Abstract Dynamic vegetation models have been used to assess the resilience of tropical forests to climate change, but the global application of these modeling experiments often misrepresents carbon dynamics at a regional level, limiting the validity of future projections. Here a dynamic vegetation model (Lund Potsdam Jena General Ecosystem Simulator) was adapted to simulate present‐day potential vegetation as a baseline for climate change impact assessments in the evergreen and deciduous forests of Bolivia. Results were compared to biomass measurements (819 plots) and remote sensing data. Using regional parameter values for allometric relations, specific leaf area, wood density, and disturbance interval, a realistic transition from the evergreen Amazon to the deciduous dry forest was simulated. This transition coincided with threshold values for precipitation (1400 mm yr −1 ) and water deficit (i.e., potential evapotranspiration minus precipitation) (−830 mm yr −1 ), beyond which leaf abscission became a competitive advantage. Significant correlations were found between modeled and observed values of seasonal leaf abscission ( R 2 = 0.6, p <0.001) and vegetation carbon ( R 2 = 0.31, p <0.01). Modeled Gross Primary Productivity (GPP) and remotely sensed normalized difference vegetation index showed that dry forests were more sensitive to rainfall anomalies than wet forests. GPP was positively correlated to the El Niño–Southern Oscillation index in the Amazon and negatively correlated to consecutive dry days. Decreasing rainfall trends were simulated to reduce GPP in the Amazon. The current model setup provides a baseline for assessing the potential impacts of climate change in the transition zone from wet to dry tropical forests in Bolivia.