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A new international study including researchers from Western Sydney University has revealed that termites play a critical role in the world’s ecosystems, particularly in the tropics, and they are expected to become increasingly important as temperatures rise globally.
Published in Science, the study indicates that termite activity is 3.5 times as sensitive to temperature increases than that of microbes (bacteria and fungi) so as temperatures heat up around the globe, the important role that termites play in wood decay will likely expand beyond the tropics.
The results suggest that regions with high termite activity should increase as the earth becomes warmer and drier. As a result, they could soon be moving closer toward the North and South poles as global temperatures warm from climate change.
Co-author Professor Jeff Powell from the University’s Hawkesbury Institute for the Environment said the study offers insight into the contributions termites make to the functioning of natural ecosystems, despite them being known as pests.
“The findings have shown us that the impact of termites is often underappreciated, particularly in the dry tropics where microbial decay of wood is slow. We can expect to see substantial increases in termite activity by mid-century,” said Professor Powell.
While microbes require water to grow and consume wood, termites can function at relatively low moisture levels. They can look for their next meal, carry what they require back to their mounds or move their colony into the wood they are consuming, even if the conditions are dry.
Termites release carbon from the wood as methane and carbon dioxide, which are two of the most important greenhouse gases. Therefore, termites may increasingly contribute to greenhouse gas emissions with climate change.
Led by researchers from the University of Miami, the study measured termite and microbial decay of wood at more than 130 sites around the globe, including the eucalypt woodland where Western Sydney University’s EucFACE experiment is located. The site is part of Australia’s Terrestrial Ecosystem Research Network (TERN).
“This is a great example of what a relatively simple experiment can achieve when the research community gets behind it in a coordinated way. Without this, it would not have been possible to uncover the massive extent to which the climate impacts termite activity.”
The study titled, ‘Termites sensitivity to temperature affects global wood decay rates,’ is available to download here.
Expert Reaction
These comments have been collated by the Science Media Centre to provide a variety of expert perspectives on this issue. Feel free to use these quotes in your stories. Views expressed are the personal opinions of the experts named. They do not represent the views of the SMC or any other organisation unless specifically stated.
Cate Macinnis-Ng and Tynan Burkhardt (University of Auckland), and Tim Curran and Md Azharul Alam (Lincoln University), study authors
Decomposition of woody biomass is an important part of the carbon cycle of forests, woodlands and savannas. As wood breaks down, carbon is returned to the atmosphere. Microbes that contribute to decomposition are sensitive to changing temperature and rainfall but less is known about termites. Termites are important decomposers of dead wood but their role changes in different parts of the world depending on the abundance of termites and environmental conditions. Before this study, it was unclear how climate change might influence the contribution termites make to decomposition processes.
This global study covering 133 sites across six continents and a range of ecosystem types provides an opportunity to explore what influences decomposition rates under different conditions. Over 100 researchers from around the world used the same method at local sites, leaving wood blocks to rot for a two-year period. Wood blocks were weighed at the beginning and end of the experiment with more weight loss indicating more decomposition of wood. Blocks were enclosed in mesh to exclude termites with half the blocks having holes punched in the mesh to allow exposure to termites.
We had three study sites in Aotearoa New Zealand, two forests in west Auckland and a third on the Banks Peninsula. The study found termites are most important in tropical seasonal forests, tropical savannas, and subtropical deserts but overall, increasing temperatures increased decomposition rates substantially. There are only three native species of termites so very few of our wood samples had termites in them but as the climate warms, we expect decomposition rates to increase, even without termites. Introduced termite species may further accelerate decomposition as they become more widespread.
Being part of a global collaboration like this is an opportunity to do exciting science that answers big picture questions. We have very little information about the potential impacts of climate change on carbon storage and cycling in forests of Aotearoa and this global study gives us some insights into the potential changes due to increased temperatures, decreased water availability and interactions with invasive species. By including local sites from Aotearoa in global studies, we can understand where our ecosystems fit in the global carbon cycle and this helps us better predict changes under future climates.
Tripti Singh, Senior Scientist/Team Leader (Wood Science Design), Scion Research
Termites and wood decay fungi are ubiquitous in nature. They contribute to the carbon cycle by inhabiting and feeding on a wide range of living, dead, and decaying plant matter.
Termites are insects generally in tropical, subtropical, and warm temperate regions and play an important role in ecosystems. Despite the ecological benefits of termites, they are also significant pests causing damage to timber used in the built environment. There are over 400 different species of termites, however, only a few cause damages of economic importance. Broadly, termites can be divided into four types; 1) The subterranean termites including Coptotermes cause the most economic damage. Nest usually under ground or at ground level, with access to soil moisture. 2) Mastotermes darwiniensis under the second group is most difficult to control, this species is very similar to certain cockroaches, the termites' closest relatives. 3) Drywood termites, nest in the wood. They do not need mud-tube link to soil, can derive all water needs from wood. 4) Dampwood termites, live and reproduce in damp wood, they are of special importance in the forest.
Worldwide, approximately 30 termite species are considered invasive and have spread beyond their native ranges, some with significant economic consequences. This study suggests that termites are temperature and rainfall-dependent and with increasing temperature around the world, the presence of termites will likely expand beyond the topical and subtropical reasons of the world.
Currently, termites are not considered economically important in New Zealand and only three exotic termites are considered to have been established in New Zealand and none of these established species are of economic significance. However, with continuing climate cycling (whether anthropogenically forced or not) a warming habitat is conducive to successful colonisation by species like Coptotermes and has the potential to cause considerable harm to the economy, environment, and trade.
The ecological consequences of termite invasions remain poorly understood, however, as suggested by this study, the widespread invasion by termites could release more carbon dioxide and methane into the atmosphere and contribute further to climate change.
Predictive studies on termites such as our ability to pinpoint the species that are most likely to spread are necessary for proactive approaches to invasive termite management.
