Graduation Date
Fall 2019
Document Type
Thesis
Program
Master of Science degree with a major in Natural Resources, option Forestry, Watershed, & Wildland Sciences
Committee Chair Name
John-Pascal Berrill
Committee Chair Affiliation
HSU Faculty or Staff
Second Committee Member Name
Martin Ritchie
Second Committee Member Affiliation
Community Member or Outside Professional
Third Committee Member Name
Kevin Boston
Third Committee Member Affiliation
HSU Faculty or Staff
Fourth Committee Member Name
Christa Dagley
Fourth Committee Member Affiliation
HSU Faculty or Staff
Keywords
Populus tremuloides, Northeastern California, Northern California
Subject Categories
Forestry
Abstract
Quaking aspen (Populus tremuloides) is a valued, minor component on western landscapes. It provides a wide range of ecosystem services, and has been in decline for the last century. This decline may be explained partially by the lack of fire on the landscape as aspen benefit from fire that eliminates conifer competition and stimulates reproduction through root suckering. Managers are interested in aspen restoration but have a lack of knowledge about their spatial dynamics in response to fire. Improving our understanding of aspen stand spatial changes over time may be important for maintaining their presence on landscapes where their role is unique from neighboring ecotypes. Our study area in northeastern California on the Lassen, Modoc and Plumas National Forests has experienced recent large mixed-severity wildfires where aspen was present, providing an opportunity to study the re-introduction of fire. We observed two time periods; a 54-year absence of fire from 1941 to 1993 preceding a 24-year period of wildfire activity from 1993 to 2017. We utilized historical (1941, 1993) and current (2017) aerial photos to delineate aspen stand size, location and succession to conifers. We chose aspen stands in areas where wildfires overlapped (twice burned), where only a single wildfire burned, or areas that did not burn within the recent 24-year period. We looked at these same stands within the first period of fire exclusion for comparison (i.e., 1941-1993). In the absence of fire, all aspen stand areas declined and all stands experienced increases in conifer composition. After wildfire, stands that burned experienced a release from conifer competition and increased in stand area. Stands that burned twice or at high severity experienced a larger removal of conifer competition than stands that burned once at low severity, promoting aspen recovery and expansion. Stands with less edge:area ratio also expanded more with fire present. Across both time periods, stand movement, where aspen stand footprints were mostly in new areas compared to footprints of previous years, was highest in smaller stands. In the fire exclusion period, smaller stands exhibited greater changes in area and location (movement), highlighting their vulnerability to loss in the absence of disturbances that provide adequate growing space for aspen over time.
Citation Style
APA
Recommended Citation
Brewen, Cerena, "Multidecadal change in Aspen experiencing long-unburned, mixed-severity wildfire, and reburn disturbance regimes" (2019). Cal Poly Humboldt theses and projects. 353.
https://digitalcommons.humboldt.edu/etd/353