Holocene Fire-Climate-Vegetation Linkages in the Western Mid-latitude Forests of North and South America

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This award will help researchers understand the interplay of climate, vegetation, and fire dynamics in the mid-latitude forests of western North and South America. The two regions offer important comparisons in terms of their present climate, vegetation, and fire regime and their environmental history. Both regions feature different vegetation types but broadly similar climate histories. The varying climate histories arise from distinct responses to large-scale climate forcing mechanisms in the Holocene (i.e., variations in summer insolation). This research will play each region's similarities and differences against each other to provide a set of natural experiments not possible in a single region. This is important because climate, fire, and vegetation are closely related components of forest ecosystems in western North and South America. The strength and nature of the linkages among these components vary depending on the time scale of interest. On intra-annual time scales, weather conditions determine the likelihood of fire events by influencing fuel moisture and ignition sources within a given season. On inter-annual to decadal time scales, climate variability is important because the sequence of wet and dry periods indirectly promotes fire occurrence. Vegetation changes on inter-annual and decadal scales also affect fire activity by determining the character and distribution of fuels. Fire events, in turn, shape forest succession and create landscape patterns that set the stage for subsequent disturbance events. On centennial-to-millennial time scales, climate governs the long-term variations in fire frequency, size, and severity as well as vegetation composition and species distributions. Vegetation characteristics on long time scales also exert a positive feedback to fire regimes by determining the nature of the fuel biomass.This research will develop a high-resolution fire-history network in western North America and Patagonia comparable to existing vegetation-history networks, discern the hierarchy of climate controls that either promote or suppress fire, and examine modern climate data to determine the large-scale climate anomalies that influence fire regimes in the study areas. This approach of developing a fire-history database and analyzing climate anomalies associated with fire at present and in the past, will allow the researchers to understand climate-fire-vegetation linkages on multiple scales.The researchers will share their data with the larger scientific community through shared databases (including the National Geophysical Data Center) and publications. In addition, the researchers will forge strong collaboration with South American colleagues to enable technology transfer between North and South American researchers. This will be accomplished, in part, through the support of foreign scientist's travel to the United States to share data and analytical techniques.