Patterns of woodboring beetle activity following fires and bark beetle outbreaks in montane forests of California, USA

Ray, Chris; Cluck, Daniel R.; Wilkerson, Robert L.; Siegel, Rodney B.; White, Angela M.; Tarbill, Gina L.; Sawyer, Sarah C.; Howell, Christine A.

doi:10.1186/s42408-019-0040-1

Fire Ecology

Table 1 Non-exclusive, alternative hypotheses (H_A) regarding processes expected to affect the activity (abundance) of larval or adult woodboring beetles that colonize trees killed or weakened by wildfire or bark beetle outbreak (BBO). These hypotheses were addressed with respect to five BBO sites and 11 burned sites that were sampled in the greater Sierra Nevada region of California, USA, during the summers of 2015 and 2016

From: Patterns of woodboring beetle activity following fires and bark beetle outbreaks in montane forests of California, USA

H_A	Process
T	Type of disturbance: Woodborer activity is higher in burned than BBO stands because heat and smoke attract some woodborer taxa and because fire can create a pulse of resources (dead and weakened trees) not previously exploited by bark beetles.
M	Magnitude of disturbance: Woodborer activity is higher where dead trees are more abundant, due to the attractiveness of a large resource base.
S	Severity of disturbance: Woodborer activity is higher in stands burned at higher severity because more severe fires produce more smoke and heat as well as more dead and dying trees. Outbreak severity also affects woodborer activity, through positive effects on resource production and negative effects of increased interspecific competition.
A	Age of disturbance: Woodborer activity eventually declines with time after a disturbance, as the resource is depleted. Conversely, the activity of larval woodborers increases within the first year or two after a disturbance, as eggs continue to be deposited and larvae grow.
P	Phenology: Woodborer activity is lower in stands that ignite early or late in the fire season, if most adults disperse during the middle of the fire season when ignitions are most frequent.
H	Host quality: Woodborer activity varies by tree taxon due to taxon-specific differences in the quality of trees as a host resource.
G	Growth rate: Woodborer activity is higher on the southern sides of smaller snags (standing dead trees) in locations where diurnal warming can facilitate larval growth.
C	Competition: At scales appropriate to each life stage, woodborer activity varies inversely with bark beetle activity, due to adult host preferences and larval competition for phloem.

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