Dynamics of arid desert coastal ecosystem in response to tsunami, tropical cyclone, and drought: A pollen and geochemical study from Baja California Sur, Mexico

Abstract

The long-term ecological responses to natural disturbances in arid desert coastal ecosystems are crucial for understanding and predicting ecosystem dynamics, yet there is a notable scarcity of studies addressing these responses in such regions. Through microfossil and geochemical analyses of sediment cores from Lake Santispac and Lake Cocos, we exam the impacts of tsunamis, tropical cyclones, and droughts on vegetation dynamics and biodiversity in Baja California sur. Our findings reveal critical insights aligned with the Intermediate Disturbance Hypothesis (IDH). Tropical cyclones, acting as intermediate disturbances, enhance biodiversity by creating habitat heterogeneity, while extreme events like tsunamis reset ecological stages, facilitating species colonization and boosting biodiversity. Conversely, prolonged droughts reduce biodiversity by favoring drought-tolerant species. Future climate projections indicate higher temperatures, more frequent intense tropical cyclones, and prolonged droughts, further influencing these dynamic ecosystems. Mangroves, essential for maintaining biodiversity and ecosystem resilience, are expected to expand due to increased storm activity and sediment deposition. However, the combined effects of these disturbances create a nonequilibrium state, fostering high biodiversity and resilience in Baja California's ecosystems. Additionally, evidence of historical human activities, such as cave arts and arrow artifacts, underscores the importance of further study into human-environment interactions in this region. This study highlights the significance of long-term paleoecological studies in deciphering ecosystem dynamics and provides a crucial foundation for future research aimed at unraveling the complex dynamics of disturbances in maintaining biodiversity and ecosystem health in arid coastal regions, emphasizing the vital role of palynology in understanding ecosystem transformations.