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Post-fire forest regeneration in a changing climate - Final Report to the Joint Fire Science Program

Author(s): Derek J. N. Young, Andrew Latimer
Year Published: 2017

Severe disturbance such as wildfire may create important opportunities for plant communities to reorganize in response to environmental change, including climate change. Disturbance may be particularly important in forests where the foundational plant species (trees) are long-lived and usually establish soon after disturbance. The response of post-fire tree establishment to post-fire weather conditions could therefore provide useful information about how forest communities will respond to climate change. We examined the effect of post-fire weather conditions on regenerating vegetation in fire-adapted forests in northern California, USA by surveying plots 4-5 years after 14 different wildfires that burned between 2004 and 2012. This time period (2004-2016) encompassed a wide range of annual weather conditions, including a period of extreme drought as well as relatively wet years. We related post-fire establishment patterns of trees, shrubs, and graminoids at 535 severely burned plots to the average climate at each plot and to departures from the average during the first 3 years after fire. For the most common tree species, we observed either (a) decreased establishment under unusually dry postfire conditions or (b) low sensitivity of regeneration to post-fire weather. However, in general, post-fire regeneration patterns were explained more strongly by long-term climate and topography variables and local adult tree species abundance than by post-fire weather conditions. This observation suggests that surviving adult trees may contribute to a “biological inertia” that restricts the extent to which tree community composition will track changes in climate through post-disturbance regeneration. In contrast to our observations in trees, we observed substantial increases in shrub and graminoid cover under post-fire drought, suggesting that fire-driven forest-to-chaparral type conversion may become more common with increasing aridity resulting from climate change. Taken together, our conclusions imply that managers may need to allocate more resources to post-fire management (e.g., tree planting and shrub control) if they wish to (a) facilitate forest tree community in tracking shifts in climate and/or (b) maintain historical tree growth and survival rates given the potential for increasing shrub competition.

Citation: Young, Derek J. N.; Latimer, Andrew M. 2017. Post-fire forest regeneration in a changing climate. Joint Fire Science Project 15-2-01-34. Davis, CA: University of California-Davis. 32 p.
Topic(s): Fire Ecology, Fire Effects, Fire & Climate
Ecosystem(s): None
Document Type: Technical Report or White Paper
NRFSN number: 17003
FRAMES RCS number: 25049
Record updated: Mar 7, 2018