Wildfires and bark beetles have interacted for centuries—and even millennia—to shape diverse and resilient forest ecosystems. However, the record-breaking wildfires of recent years in western North America have raised concerns that the vast areas of damaged and dead trees—essentially easily exploitable resources—might promote the growth of insect populations.
The Douglas-fir beetle, the primary mortality agent of Douglas-fir trees, often experiences population increases following wildfires. The same applies to many other phloem-feeding insects, such as various woodboring beetles, which are attracted to burned areas and colonize fire-injured trees.
In a recent study, Canadian researchers investigated the interactions between Douglas-fir beetles and woodboring beetles that exploit the phloem of fire-injured trees. More specifically, their hypothesis was that the rapid colonization of bark beetle niches by woodborers following wildfires might restrict Douglas-fir beetle population growth through interspecific competition beneath the bark.
The hypothesis was tested in three mature Douglas-fir forests in British Columbia that burned in 2017. The researchers found that both Douglas-fir beetles and woodborers preferentially colonized mature stands containing large-diameter trees with moderate fire damage.
When woodborers were absent, the Douglas-fir beetle’s reproductive rate was sufficient to cause a local population outbreak. In contrast, in stands where woodborers were abundant (more than 50% of trees infested), Douglas-fir beetles were unable to reproduce at outbreak levels.
These results indicate that competition from woodboring beetles can significantly limit Douglas-fir beetle outbreaks in fire-injured forests. From a forest management perspective, this suggests that forests should be managed in ways that support the success of economically harmless phloem-feeding insects—such as many woodboring beetle species—since their presence may help reduce the risk of bark beetle outbreaks following wildfires.
Previous thoughts on the same topic:
The EU Needs Innovations That Drive Climate Neutrality
Forests in Indonesia and Finland
Why are boreal forest fires on the rise everywhere but in Finland?
If one is using the forests for an economical gain, one should not let the forests to grow over aged.
ReplyDelete