Alexandra Orrego

Alexandra Orrego

Years participated in RESESS:

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An Overview

Major: Geoscience
Academic Affiliation: Georgia State University
Research Mentor: Brian Harvey
Communications Mentor: Daniel Nothaft


Growing up in the forested areas of North Georgia, Alexandra always maintained an appreciation for the Earth and its environment. During her first year as an undergraduate she realized that her love for the environment could become a career. Since solidifying her studies in Geoscience she is interested in technologies such as GIS, remote sensing, and applying these technologies to investigate changes in the environment that may have hazardous consequences to the Earth, ecology, and humans. She hopes to pursue a graduate degree in GIS and remote sensing of forest ecosystems. This summer Alexandra analyzed spatial and temporal patterns of interacting biotic disturbances in Western U.S. forests. In a warming and drying climate increased occurrences of hotspots- spatiotemporally overlapping biotic disturbances, may be an indication of a lowered ability for ecological compensation in affected forests and therefore hinder forest resilience. Her results promote further investigations of the mechanisms behind hotspots and will help in forecasting the future of forest ecosystems globally.


Are Hotspots of Biotic Disturbances Increasing in Western U.S. Forests (1997-2016)?

In recent decades, unprecedented outbreaks of biotic disturbances such as insects and pathogens across Western U.S. forests have raised concerns on how a warming climate may continue to affect and alter forest ecosystems. While much research has focused on the dynamics of single biotic disturbances, less is known about the spatial patterns and temporal trends of interacting biotic disturbances in these forests. It is important to understand spatiotemporal trends of co-occurring biotic disturbances, as it may be an indication of a lowered ability for ecological compensation, which may hinder affected forests ability to survive biotic disturbances in the future. More specifically, this study analyzes spatial and temporal patterns of biotic disturbances in western U.S forests and the occurrence of “hotspots” - two or more spatially and temporally intersecting biotic disturbances. Using geographic information systems (GIS) and the United States Forest Service (USFS) Aerial Detection survey (ADS) data from 1997-2016 we ask if hotspots of biotic disturbances are increasing over time, and we assess the spatial distribution of hotspots across western U.S. forests. We found that hotspots of intersecting biotic disturbances in the same year have been increasing exponentially over the past 2 decades. Overall, 30% of affected forested area in the western U.S. is experiencing hotspots. Spatially, hotspots tend to be along mountainous areas of middle to high elevations along The Cascade, The Rocky Mountain, and Sierra Nevada ranges whereas, cold spots occur generally along the Pacific coast and in arid, inland regions. Identifying hotspots is important in order to aid in further investigation of the mechanisms that drive interacting biotic disturbances in an increasingly warming and drying climate.