The Compost Creatures Helping Us Battle Climate Change

The role of tiny decomposers within the soil food web, and the link between climate change & species extinction.

Remember the last time you enjoyed a walk in a forest? Do you remember the species you saw? If you were lucky, you might answer that you saw deer, squirrels, or even a bear in the distance. The more botanically-minded might mention the trees, shrubs, flowers, moss, even mushrooms.

However, we may need to pay more attention to something as important as those easy-to-spot species. Beneath our feet is a hidden world teeming with tiny creatures that break down fallen leaves and other forest “waste.” Nature’s recycling system. This process, called decomposition, is crucial for healthy ecosystems. It recycles nutrients back into the soil, where plants can use them to grow. And they also play a vital, and lesser known, role in shaping our climate.

If you are interested in the science of climate change, you have probably heard this multiple times: Climate change and species extinction crises go hand in hand. We know that fighting one and ignoring the other will take us nowhere. Yet conservation efforts too often focus on the big, charismatic species or megafauna. Everything in an ecosystem serves a function, and removing any species — no matter how small — can have rippling consequences we may not be prepared to adapt to. Starting with decomposition.

The overlooked decomposer ecosystem

Different organisms can perform decomposition (See Figure 1). From single-cell prokaryotes to big vertebrates, the different associations create a complex ecosystem of well-integrated species and functions. They all rely on one another to complete the decomposition process.

Unfortunately, climate change threatens this delicate system (See Figure 2 for examples). Anyone trying to compost at home knows decomposers like bacteria and insects are very sensitive to heat and humidity. If the climate gets too hot or dry, the decomposing organisms slow their processes or die altogether. Dead plant matter starts piling up, never returning to the system, plants run out of nutrients, and the ecosystem collapses. The ecosystem starts experiencing an ecological “famine.”

In addition, different soil ecosystems are adapted to decomposing specific plant species. As climate changes, forests are experiencing a shift in plant community composition, which could affect this delicate decomposer ecosystem (See Figure 3). The plants they are used to decompose may not be present anymore; other species could also replace these plants, which decomposers can’t process.

We need to understand how all these events play out to design cost-effective conservation programs that help us adapt to and mitigate the effects of global climate change. Thus, researchers are examining how decomposer communities help ecosystems cope with different climatic events, such as droughts.

In a recent study led by Dr. Junwei Luan, researchers set up experiments across different forest biomes ranging from the temperate to the tropical climate zone in China. They controlled the amount of rain falling on the forest floor to simulate different degrees of drought conditions. They also examined how the biodiversity of decomposing creatures and different plant species affected the process. Their goal was to see if a more diverse system could better handle drought.

Data from the study shows that having a wider range of decomposers, especially larger creatures like millipedes and isopods, can help counteract the slowing down of decomposition caused by drier conditions. Additionally, having a variety of leaves on the forest floor (more diverse forests) can also improve decomposition to some extent, but this effect is weaker than having a diverse decomposer community.

The researchers set up plots in five different forest types, some with reduced rainfall and some with normal rainfall. They also looked at plots with different combinations of decomposers, from tiny bacteria to larger creatures. They measured how quickly leaves decomposed in each plot.

Their results showed that drier conditions slowed down decomposition, as expected. However, this slowdown was less pronounced in plots with a wider range of decomposers, particularly when larger creatures were present.

The study also found that having a variety of leaves on the forest floor can slightly improve decomposition rates. Different types of leaves decompose at different rates, and having a mix provides decomposers with a more balanced food source, allowing them to work more efficiently. However, this effect was less strong than the benefit of having a wider range of decomposers.

Decomposers, biodiversity, and climate change

This study highlights a finding that, while expected by the researchers, might well be surprising to some, namely that:

A higher biodiversity of decomposers and fallen leaves (litter) in forests can help counteract the negative effects of climate change-driven drier conditions.

Why? Because decomposition is a crucial process for healthy forests. It recycles nutrients back into the soil, where trees can use them to grow. Growing forests capture atmospheric carbon dioxide, a powerful greenhouse gas. If decomposition slows down, it can harm the entire ecosystem, further accentuating the effects of climate change.

The research shows that we can help forests cope with future droughts if we consider soil and plant biodiversity in forest management practices. This could involve planting different tree species together and protecting decomposer populations. Forests with various decomposers and fallen leaves can be more resilient to drier conditions.

The delicate balance of life in an ecosystem relies on a complex web of interactions. Each species is necessary, from trees to insects, fungi, and bacteria. Rapidly changing climatic conditions disrupt this balance, pushing some species to the brink of extinction. But the loss goes beyond the majestic animals we easily adore. For instance, the hidden world of decomposers silently cleans up our forests, a seemingly small task with huge consequences. Their extinction can slow down nutrient recycling, impacting plant growth and entire ecosystems.

This domino effect highlights the interconnectedness of nature. Conservation efforts must look beyond the charismatic megafauna. Every species contributes to a healthy planet, big or small, visible or unseen. Protecting this biodiversity is not just about saving individual animals; it’s about safeguarding ecosystems as a whole. By protecting biodiversity, we give our ecosystems a fighting chance to adapt and survive the challenges of a changing climate. So, next time you walk in a forest — remember to look down, and underneath, as well as up.