The Beetles' Invasion: A Tiny Terror for Forests

            Winter of 2015 has been one of the hottest winters on record for a significant portion of northern United States (1).  The warmer winter is likely a result of the increase in climate change caused by the emission of carbon dioxide into the atmosphere.  As a result from the warm winter, beetles have not been killed from the cold and have traveled north into Canada (1, 2).  Similarly, beetles are attacking forests worldwide such as Poland, China, and Nepal (3, 4, 5).  Beetles pose a significant threat to forests due to several forests dying off causing a huge environmental impact.  Beetles are a serious threat to the forest ecology because some of them are highly invasive while others are overfeeding due to densely packed forests and warmer conditions.

            Beetles are a severe problem for forests worldwide.  Beetles feed on the resins beneath the tree’s bark, which is one of the tree’s first defenses against predators, and make distinct S-shaped patterns below (2).  If the tree senses there are invaders, the tree will activate cell death, where the beetle is burrowing, releasing a toxin (2, 5).  In the meantime, the female beetle is feasting and laying eggs beneath the bark (5).  Although the toxin is enough to kill the female beetle and her offspring, if there are large swarms of beetles, the tree is certain to die (2).  Once the tree experiences death, the eggs will hatch into the larvae and they will continue to burrow during the winter until they grow to adulthood (5).  The cycle can then begin anew and infect several other trees, effectively killing the forest.  An infestation can be called an epidemic when at least one percent of the total growing population is afflicted (5).  An epidemic can easily wipe out an entire forest destroying both homes for several animals and renewable resources for people.

            Scientists have several explanations are to what is fueling the beetle invasion. Firstly, warmer temperatures and humid conditions have contributed to the increase of beetles (1, 2, 3, 4, 5).  The forest density being overcrowded is also lending for more trees to be infected (1, 2, 3, 4, 5).  Overcrowding is when there are too many trees all in a small amount of space which can allow for the transmission of disease and especially beetles to ravage the forest.  Tree health and age are other factors that allows for trees to be more susceptible (3, 4, 5).  Aside from the common explanations as noted above, “arid climate, strong winds, low rainfall, sparse vegetation” and human interference have created favorable conditions for species to survive and carry disease (4).  In addition, little attention has allowed the species to boom and quickly extinguish forests (3, 4).  A lack of natural enemies for both native and invasive species has also contributed to the tree death (5).

Mountain Pine Beetle

Source: http://media.graytvinc.com/

images/pine+beetle.png

            Invasive species have been a significant issue for several forests.  These species choke out native species due to competition and a lack of predators.  The southern pine beetle is an invasive species that originated in southern United States (1).  Typically, the northeastern winters have kept the beetles at bay due to them not being able to survive a temperature of negative eight

degrees Fahrenheit (1, 2).  The beetles are closely related to the mountain pine beetle, which is also destroying forests in northern United States and even extending into Canada and the boreal forest (1, 2).  The mountain pine beetle is native to the United States but an invasive species for British Columbia.  The beetle is slowing gnawing its way through the forests and causing a great deal of damage to the timber industry in Canada (2). Since the 1990s, approximately 60 million acres of British Columbian forest has been destroyed by the mountain pine beetle (2).

            Not all beetles have been invasive.  In fact, a number of native species have drastically

Bird's eye view of Bialowieza Forest. 

The browned trees are attacked by beetles

Source: http://www.bialystok.lasy.gov.pl/image/

journal/article?img_id=28501307&t=1454674855574

increased and have been the culprit of tree death.  A primeval forest, the Bialowieza Forest, located on the border of Poland and Belarus, has been ravaged by the bark beetle which has chewed through several spruce trees affecting over 4,000 hectares (3).  Currently, people are petitioning to cut down affected trees to stop the spread of beetles, which is the worst infestation on record (3).  However, the forest is a national park barring the cutting of trees and local environmentalists are fiercely fighting against the petition (3).  There is also a beetle epidemic in China.  The Asian longhorned beetle is one of the most destructive species of beetle has destroyed 80% of poplar stands planted in the Three North region of China (4). Sadly, the life of the poplar stand was slashed to a ten year average in areas infested with the Asian longhorned beetle (4).  Finally, in Nepal, the heartwood borer has been attacking Sal trees (5).  Despite being a native species, Nepal’s forests are on the decline (5).

 There are several proposed ideas in order to remedy the beetle epidemic. Firstly, cutting down infected trees would prevent the beetles from moving to another tree.  In addition, thinning the forest will reduce the amount of spaces the beetles can spread to and less competition increase the health of the forest (3, 5). China has suggested using biopesticides to control the beetles without harming the forest and pheromones to deter the beetles from finding potential trees (3). 

Beetles are pose a serious threat to the health of forests worldwide.  The increase in temperature, humidity, and overcrowded forests created conditions for beetles to thrive.  In doing so, forests around the world are declining.  However, there are conservation possibilities to control beetles from feasting on forests.  Although there is a looming invasion for the US, efforts are being made to save the forests.

Interaction Between Rainforests and Climate Change

(Photo cred linked)

There are a few factors that can be seen in the relationship between the rainforests of the world and climate change. The amount of carbon dioxide in the air is 40% higher than what plants were taking up about 100 years ago. (Schiermeier) From my previous blog, we know that global climate change is the increase of the Earth’s atmospheric temperature due to the increased emission of carbon dioxide that is released into the air. We took a look at what climate change can do to the world’s oceans, but the focus of this blog is to see what’s happening on land, and specifically in the rainforests of the world.

Rainforests, both tropical and temperate, are actually very beneficial to us in the fight to decrease carbon dioxide into the air. In the carbon cycle, the trees of the rainforest are known to pull the main greenhouse gas (CO2) out of the air and hold the carbon in their wood as well as the soil that they are rooted in; carbon is then turned into sugar for the plant. (Gillis) The stored carbon is what’s helpful. Sounds like the perfect picture, right? So why do we have a problem? Not only are people getting rid of the one source that can help in capturing the carbon in the atmosphere, but they are re-releasing carbon back into the atmosphere when they go into rainforests and destroy the land. Climate change is the one thing that is making it harder for rainforests to help slow down… well… climate change. Due to the increase in carbon dioxide in the air, this is causing the atmosphere to become warmer and the environment to become drier; the change in these conditions is what is killing off the trees and other plants in the rainforest. Studies suggest that by the year 2050, “temperatures in the Amazon will increase by 2-3°C. At the same time, a decrease in rainfall during dry months will lead to widespread drying.” (Pratginestos) Dead trees don’t absorb CO1, and their stored carbon is released as their biomass is decomposed.

   

Loss/Gain forest cover in the last decade (Gillis) 

Rising temperatures and dryer conditions aren’t the only things killing off the rainforests and affecting climate change. Another major factor that goes into the relationship between rainforests and climate change is deforestation. “Over time, humans have cut down or damaged at least three-quarters of the world’s forests, and that destruction has accounted for much of the excess carbon that is warming the planet.” (Gillis) Cleared forest lands also have the potential to absorb more heat energy than the forest lands that were there before. A farmland in Europe that practices “no-till” farming has come to realize that the plants that grow from their no-till technique (seeding before plowing) have the potential to decrease the atmospheric temperature in the area. This is because the “effect is driven by the increased fraction of sunlight that the soil reflects back into space… which reduces the amount of the Earth’s surface absorbed from the Sun.” (Morello) Knowing that more plants on the ground can reduce the amount of heat that the Earth is absorbing is a strong argument as to why the rainforests need to not be destroyed; the more rainforests there are, the cooler the environment/atmosphere will be, and it will decrease the affects of climate change.

It is now evident how we’re losing the rainforests: deforestation, temperature increasing, drier atmosphere, and other factors of climate change including climate change, itself. If these effects continue to happen at the scale that they are currently happening at: 

•  Coast redwood could lose up to 23% of its current distribution as the climate changes more drastically in the southern rainforest region. 
• Alaska yellow-cedar could lose up to 21% of its current distribution and already is experiencing extensive dieback from warming and reduced snow pack. (SitNews) 

Some countries have made the effort to make sure that they are cutting back on greenhouse gas emissions. Others have even proposed protection laws, and have pushed regrowth of the rainforests. According to a New York Times article (Gillis), Brazil has done more than any other country to limit the emissions leading to global warming. In the same article, it is started that leaders of other countries encourage forest regrowth in attempts to balance out the human impact on global climate change. I don’t think proposing protection laws on the rainforests as well as attempting to regrow the regions that have lost the rainforests are such bad ideas. For the amount of work the trees do for the planet in reducing the effects of climate change, it’s evident why the rainforests need to be preserved. The more rainforests that we lose, the worse the global climate change issue will get. 

RESOURCES: 

Gillis, Justin. "Restored Forests Breathe Life Into Efforts Against Climate Change." The New York Times. The New York Times, 23 Dec. 2014. Web. 17 Mar. 2015.

Morello, Lauren. "Unploughed Fields Take Edge off Heatwaves." Nature.com. Nature Publishing Group, 23 June 2014. Web. 17 Mar. 2015.

Pratginestos, Juan. "Climate Change in the Amazon." WWF. WWF, n.d. Web. 09 Mar. 2015.

Schiermeier, Quirin. "Climate Change Crisis for Rainforests." Nature.com. Nature Publishing Group, 5 Mar. 2009. Web. 17 Mar. 2015.

"Scientists Warn Climate Change Is Threatening World's Most Expansive Temperate Rainforests." SitNews. Ed. Mary Kauffman. SitNews, 3 Mar. 2015. Web. 17 Mar. 2015.