Facultad de Ciencias Naturales y Exactas

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http://dpl-repositorio.upla.cl/handle/20.500.15012/285
Facultad de Ciencias Naturales y Exactas, cultiva y difunde con espíritu crítico y creativo, el saber científico y tecnológico, formando profesionales de excelencia, responsables innovadores tolerantes pluralistas con compromiso social y ambiental y con competencias profesionales dispuestos a integrar un mundo globalizado.

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Browsing Facultad de Ciencias Naturales y Exactas by Subject "Biodiversity"

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    Evaluación de la recuperación post-incendio a corto plazo en bosques mediterráneos de Chile central bajo diferentes niveles de sequía utilizando teledetección
    (Universidad de Playa Ancha Ciencias de la Educación, 2024) Hernández Duarte, Ana Guadalupe; Saavedra Pimentel, Freddy Alejandro; Femenino; Facultad de Ciencias Naturales y Exactas; Universidad de Playa Ancha Ciencias de la Educación
    Vegetation recovery in Mediterranean ecosystems after fires has become a topic of great relevance, particularly in the context of climate change. These ecosystems, characterized by high biodiversity and adaptations to extreme climatic conditions, face significant challenges due to the intensification of natural disturbances like fires and droughts. Understanding forest recovery processes is crucial not only for biodiversity conservation but also for maintaining essential ecosystem services, such as carbon sequestration and hydrological cycle regulation. This doctoral thesis focuses on analyzing how various environmental factors influence the short-term (5-year) productivity recovery of the Mediterranean forest in central Chile following fires, assessed using the Normalized Difference Vegetation Index (NDVI) derived from satellite imagery. For this purpose, the research begins with a general introduction to the effects of climate change on disturbance regimes and their impact on the recovery of Mediterranean ecosystems. It seeks to test a model proposing that interactions between prolonged droughts and forest fires significantly reduce forest recovery, potentially reaching ecological tipping points. The third chapter examines productivity response differences among three Mediterranean forest types under three drought conditions (No Drought, Mega Drought, and Hyper Drought) and two fire severity levels (moderate and high). Results indicate significant differences in the recovery of the three forest types across drought gradients during the Hyper Drought period. The xeric forest, primarily composed of Quillaja saponaria and Lithrea caustica, showed significant interaction effects between drought levels and fire severity, while the thorny forest and shrubland showed no significant interactions. The mesic forest, dominated by Cryptocarya alba and Peumus boldus, exhibited additional significant recovery differences between the Hyper Drought and Mega Drought periods, as well as significant interaction effects. These findings highlight the critical role of prolonged and severe droughts in shaping forest recovery dynamics and underscore the IX need to understand these patterns to enhance future forest resilience under increasingly arid conditions. The fourth chapter addresses the relative importance and effect of both firerelated and post-fire climatic conditions on vegetation recovery in the three main types of Mediterranean sclerophyllous forest in Chile. For this, predictive Random Forest models were developed with two response variables: a relative NDVI recovery metric (NDVIrec) and absolute NDVI. The mean R-squared values obtained for these models ranged from 0.7 to 0.9, depending on the forest type. Results underscore that drought severity is the main limiting factor for post-fire recovery in the NDVIrec models, negatively impacting vegetation recovery. In contrast, pre-fire vegetation greenness emerged as the main factor in the NDVI models, positively influencing productivity recovery capacity. Consequently, this research contributes to a deeper understanding of the effects of prolonged and severe droughts, as well as other driving factors, on the recovery and potential regenerative capacity of Mediterranean forests. Improving knowledge of how different vegetation formations respond to these postdisturbance recovery drivers can aid in developing more effective and efficient conservation and management strategies to promote resilience in these highly pressured forests. These findings are an integral part of the PhD in Environmental Sciences within the research line "Global Environmental Challenges, Environment, Society, and Organisms," providing valuable insights to address the challenges facing forest management in a climate change context. Keywords: Climate change, natural disturbances, drought, wildfire, Mediterranean forest, remote sensing.