Abstract Detail

Conservation Biology

McIntyre, Patrick [1], Thorne, James [2], Kelly, Maggi [3], Dolanc, Christopher [4], Flint, Alan [5], Flint, Lorrie [5], Ackerly, David [6].

Eighty years of change in California's forests: climate, fire and land use.

We compared forest structure between a historical (1930’s) survey of California vegetation and contemporary (2000’s) U.S. Forest Service surveys. Across California, tree density in forested regions increased by ~30% in the contemporary dataset, while forest biomass in the same regions declined, as indicated by a ~ 20% reduction in total basal area. These changes reflect a demographic shift in forest structure: larger trees (>60cm dbh) have declined, while smaller trees (10 – 30cm dbh) have increased. Similar changes have previously been documented in Sierra Nevada and transverse range forests, but here we extend these findings to a statewide level, including coastal ranges. Demographic shifts were driven largely by declines in Pinus and Abies trees in larger size classes in montane regions. These large tree declines were associated with regional changes in climatic water deficit driven in part by temperature increases since the 1930’s. Contemporary plots in areas that have burned since the 1950’s were more similar to historic plots, with a lower density of small trees, suggesting a signal of altered fire regime on forest structure. Additional drivers of change such as shifts in land use and timber harvesting are explored. We also present preliminary analyses of repeat photographs from forested areas in California from the 1930's as a partially independent means of documenting forest change.

Broader Impacts:

1 - UC Berkeley, Museum of Vertebrate Zoology, 3101 Valley Life Sciences, Berkeley, CA, 94720, USA
2 - UC Davis, Department of Environmental Science and Policy, Davis, CA, 95616
3 - UC Berkeley, Enviornmental Science and Policy, Berkeley, CA, 94720, United States
4 - UC Davis, Enviornmental Science and Policy, Davis, CA, 95616
5 - USGS California Water Science Center, 6000 J St, Sacramento, CA, 95819, USA
6 - University of California Berkeley, 1005 Valley Life Sci Building, Berkeley, CA, 94720-3140, USA

Keywords:
global change
Forest Inventory and Analysis
water stress
fire
drought
California.

Presentation Type: Oral Paper:Papers for Topics
Session: 20
Location: Marlborough A/Riverside Hilton
Date: Tuesday, July 30th, 2013
Time: 10:45 AM
Number: 20009
Abstract ID:639
Candidate for Awards:None