Bark Beetles and Wildland Fire Behavior

With all the science surrounding bark beetles in western states, I have come to learn that bark beetles can cause serious mortality in western forest and some urban environments. All though bark beetles are a natural part of a functioning ecosystem, under undesirable conditions, bark beetles may actually come in conflict with land management objectives. Many interactions between bark beetles and fire suggest that these relationships are not good. Bark beetles can change the forest environment by influencing forest structure and transforming fuels. If beetles are linked to tree mortality, it's no secret that disturbed stands will likely burn threw hotter and faster. The magnitude of recent outbreaks and large wildfires has resulted in a flurry of research attempting to quantify bark beetle/fire/fuel/ interactions. Conventional science is pointing to the fact that large scale beetle outbreaks are altogether altering fuel complexes resulting in an increased potential for high-intensity, high-severity fires. Conversely, some scientist believe fire damaged trees may predispose western stands to initial bark beetle attacks in the first place. These phenomena together present land mangers with formidable challenges in regards to bark beetles, fuels, and future fire hazards.

http://www.ucsusa.org/

Invasive Medushead in Western States

http://www.sagegrouseinitiative.com/wp

Medusahead ( Taeniatherum caput-meduse) is native to the Mediterranean region and is an important member of a group of grasses that includes wheat, barley, and ceral rye. Medusahead was first recorded in the United States near Roseburg, Oregon, in 1887 (Howell 1903). Herbarium records indicate that the plant spread concentrically – north into Washington, south into California, and east into the Great Basin, Idaho, and other western states. It is not known how medusahead was introduced to the United States, however, it has been suggested that medusahead arrived as a contaminant in cereal grain seed, while others (George 1992; Hilken and Miller 1980) suggest it may have arrived clinging to the fur of imported livestock. Once introduced to the western US, medusahead spread rapidly in low-elevation annual grasslands, woodlands, and chaparral communities. These west coast plant communities have a similar climate to the Mediterranean region: hot and dry summers, and cool, moist falls. In both lowland rangelands and in high-elevation semiarid systems, medusahead is considered to be an ecosystem transformer species (Richardson et al. 2000; Wells et al. 1986). This places it among the worst weeds: not only does medusahead compete for resources with more desirable species, but it changes ecosystem function to favor its own survival at the expense of the entire ecosystem. Displacement of natural vegetation by medusahead has substantial impacts on the structure, organization and functioning of western ecosystems.

deseretnews.com

It's no secret that extensive stands of pinyon juniper and sagebrusg steppe exist across the American West. In semiarid big sagebrush steppe and woodlands, medusahead acts as a fire promoter. Like other annual grasses, medusahead fills in between the native vegetation, creating a continuous fuel corridor that accelerates the fire cycle,  posing a risk of fire during any season. Because of these the mean fire return interval on disturbed sites is greatly reduced.

http://bugwoodcloud.org/

It can be difficult to selectively remove an invasive grass such as medusahead from a grassland, steppe, or woodland community. For this reason, medusa is often burned during late spring at high temperatures when the seeds are still present on the plant to promote mortality.Following a burn, other control techniques such as grazing, revegetation, and preemergence herbicides are often used as appropriate land managment tools for medusahead in areas with high annual grass biomass production.






George MR (1992) Ecology and Management of Medusahead. Davis, CA: University of California Range Science Report 31:1-3

Hilken TO, Miller RF (1980) Medusahead (Taeniatherum asperum Nevski): A review and annotated bibliography. Oregon State University Agricultural Experiment Station Bulletin 644, Corvallis, Oregon, USA

Howell TJ (1903) A Flora of Northwest America. Self-published. Portland, Oregon.

Richardson DM, Pysek P, Rejmanek M, Barbour MG, Panetta FD, West CJ (2000) Naturalization and invasion of alien plants: concepts and definitions. Divers Distrib 6:93-107

Bark Beetles: What Role Do They Play In Fire Ecology?

After reading into bark beetles I see why they can be a big factor on how detrimental fire is to an area. Bark beetles feed mostly on dead or dying trees but have been known to eat living trees as well. 

There are two main reasons that bark beetles can increase risk and severity of fire. For one bark beetle brake down timber leaving gabs that aerate the logs and make them dry more quickly. This leaves tinder that can catch much more easily allowing crown fires to destroy huge amounts of forest.

The second reason that they can lead to higher rates of fire is they can feed off of and kill living tree. This also increases tinder for fires to use as accelerant.

With climate change effecting forests everywhere and dry hot weather increasing the risk of fire, bark beetles give one more risk to forest in warmer climates. 

https://www.google.com/search?q=bark+beetle+damage&espv

Future of Grasslands

Global change defines how every abiotic and biotic factor along with ecological process's on our planet can or is changing, some of these changes may include increasing CO2 levels, wildlife and vegetation migration, transitioning of ecosystems into new alternate stable states and phases, and many more factors. Basically its how all of our planets systems can or are changing. I think global changes biggest affect on grasslands will be increasing temperatures or changes in the precipitation regime. Basically any type of change that is going to alter a site and possibly better support other vegetation. For example, say the precipitation regime changes and the grasslands are getting more rain than average, decreasing the fire frequency. The change in fire regime could allow woody encroachment or provide a habitat for non-native species, causing the ecosystem to start to shift to a tree, shrub, or non-native dominated ecosystem. Another impact on global change is that land managers cannot do anything about a changing temperature or precipitation regime, so the change would not be preventable in that case. Temp and precip are just two of the many examples that come with global change and its possible affects on grassland ecosystems. Feel free to comment down below if you guys think of other examples!

Bark Beetles and Wildfire

Bark beetles feed off of living trees. 

 

 Once the tree is infested, it dies, leaving it dry and susceptible to fire. Bark beetles and trees have had a symbiotic relationship in the past where the beetles would feed off a few trees and those trees would release seed for regrowth. That relationship is no longer the same as the climate is getting warmer, the bark beetle have been spreading to higher elevations and attacking trees that have not had a symbiotic relationship with them, leaving them vulnerable.

 In any case, once the trees are dead, they become fuel for fire.  If the bark beetle just left the remnants (saw dust) on the forest floor, the forest may be able to survive as the fuel would be just enough for a low-severity ground fire.

 However, the bark beetle can kill a tree, and the tree will still be standing, getting drier as it dies.  If there were a fire with many standing dead trees, these trees will ignite and cause high-severity crown fires, killing the entire forest.  

Managing Invasive Species with Fire

Non native spices can cause stressful conditions to native species in an environment. There are many ways to remove invasive species from an ecosystem. One technique that works well in some situations is prescribed burns. This can be effective when native plants are resilient to fire and non native are not.

Although fire management works well in some situations it is not always the best way to rid invasive species depending on the fire regimes you may have to continue to set prescribed burns every several years.

Other methods such as pulling non-native species and using chemicals and herbicides work better in some ecosystems with invasive species such as cheatgrass actually thrive after burns. In cases like this fire is not a good option when it comes to ways of managing invasive species.

When using fire as a management against non-native and invasive species it is important to make sure you know what effects fire will have on the ecosystem it can be a very effective tool yet it also can cause more problems then you had to begin with.