Alejandro Guarín, MS student
The influence of climate and topography in the spatial and temporal patterns of tree mortality in mixed conifer forests, Yosemite National Park, California, USA
Tree mortality is a key process in forest vegetation dynamics. It is regulated both by biotic (e.g. competition, disease) and abiotic processes (e.g. climate) mediated by topography that operate at nested scales. I study tree mortality in mixed conifer forests in Yosemite National Park (California, USA) to determine if climate has triggered tree dieback at large scales, and what has been the modifying influence of topography in producing variable temporal and spatial patterns across the landscape. I use dendrochronology (tree-rings) to determine date of death, and relate it to annual and seasonal climatic variability. Identification of tree mortality under the influence of contrasting topographic conditions (slope aspect) provides information about variations in finer-scale water availability. Given that fire suppression practices have generated dense forests that may amplify water stress and disease outbreak, these results provide important information on how human-induced change may have affected climate-time mortality patterns, and are useful for developing the Park’s management and conservation strategies.
A sampling site with extensive tree mortality
Detail of some bark-beetle galleries
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