Browsing by Author "Macias Fauria, Marc"

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  • Macias Fauria, Marc (Helsingin yliopisto, 2008)
    Ecological processes are controlled to varying degrees by climate. Large-scale climatic patterns (teleconnections) control the frequency of local weather phenomena over large regions (continents to hemispheres) and at different timescales (days to decades). This Ph.D. aims to explain how large-scale climate patterns synchronize a set of ecological processes northern coniferous forests (tree-ring growth, large area burnt by wildfire, and tree-mortality caused by mountain pine beetle) through controlling the frequency, duration, and spatial correlation of key local weather variables over large areas. Methodology was based on obtaining long complete ecological and climatic records and applying a variety of timeseries analyses in order to find out if climate and populations were related, and the nature and extent of such relationships, within a framework defined by knowledge on both the biological and the physical characteristics of the studied interactions. The description of the mechanisms through which such teleconnections control population traits is essential in these studies. Research on timeseries allowed the development of new methods to deal with highly autocorrelated data. Overall, the studied processes were strongly related with and synchronized by large-scale climate. Mountain ranges played a major role in creating regional climatic gradients and thus strongly influenced relationships between climate and the ecological processes. Moreover, land use (grazing in this case) strongly affected the relationships between ecological processes (tree-growth) and climate. Relationships between climate and ecological processes were found to be highly dynamic and to have changed during the 20th century, driven in part by long-term climatic changes and by internal variability of large-scale climate patterns. Finally, an environmental multi-proxy reconstruction is presented using regional relationships between climate and proxy records.