Twentieth-century shifts in forest structure in California: Denser forests, smaller trees, and increased dominance of oaks
Proceedings of the National Academy of Sciences
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Abstract
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 (>61 cm diameter at breast height) have declined, whereas smaller trees ( < 30 cm) have increased. Large tree declines were found in all surveyed regions of California, whereas small tree increases were found in every region except the south and central coast. Large tree declines were more severe in areas experiencing greater increases in climaticwater deficit since the 1930s, based on a hydrologicmodel of water balance for historical climates through the 20th century. Forest composition in California in the last century has also shifted toward increased dominance by oaks relative to pines, a pattern consistent with warming and increased water stress, and also with paleohistoric shifts in vegetation in California over the last 150,000 y.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Twentieth-century shifts in forest structure in California: Denser forests, smaller trees, and increased dominance of oaks |
| Series title | Proceedings of the National Academy of Sciences |
| DOI | 10.1073/pnas.1410186112 |
| Volume | 112 |
| Issue | 5 |
| Year Published | 2015 |
| Language | English |
| Publisher | National Academy of Sciences |
| Contributing office(s) | California Water Science Center |
| Description | 6 p. |
| First page | 1458 |
| Last page | 1463 |
| Country | United States |
| State | California |
| Google Analytic Metrics | Metrics page |