20th-century shifts in forest structure in California - evidence from the VTM dataset
Tuesday, January 20, 2015 at 10:05AM McIntyre, P. J., J. H. Thorne, C. R. Dolanc, A. L. Flint, L. E. Flint, M. Kelly and D. D. Ackerly. 2015. Twentieth-century shifts in forest structure in California: Denser forests, smaller trees, and increased dominance of oaks. Proceedings of the National Academy of Sciences 112(5): 1458-1463
change in climate water deficit (left) and change in large trees (right)We document changes in forest structure between historical (1930s) and contemporary (2000s) surveys of California vegetation through comparisons of tree abundance and size across the state and within several ecoregions. Across California, tree density in forested regions increased by 30% between the two time periods, whereas forest biomass in the same regions declined, as indicated by a 19% reduction in basal area. These changes reflect a demographic shift in forest structure: larger trees (>60 cm diameter at breast height) have declined, whereas smaller trees (<30 cm) have increased. Large tree declines were more severe in areas experiencing greater increases in climatic water deficit since the 1930s, based on a hydrologicmodel of water balance for historical climates through the 20th century.
