If you’ve wandered through a forest, you’ve probably dodged dead, rotting branches or stumps scattered on the ground. This is Deadwoods.
Deadwoods provides habitat for small mammals, birds, amphibians and insects. And as deadwood decomposes it contributes to the ecosystem’s cycle of nutrients, which is important for plant growth. But there’s another important role we have little understanding .
Of on a global scale: the carbon Deadwoods releases as it decomposes, with part of it going into the soil and part into the atmosphere. Insects, such as termites and wood borers, can accelerate this process.
The world’s deadwood currently stores 73 billion tones of carbon. Our new research in Nature has, for the first time, calculated that 10.9 billion tonnes of this (around 15%) is released into the atmosphere and soil each year.
But this amount can change depending on insect activity, and will likely increase under climate change. It’s vital deadwood is considered explicitly in all future climate change projections.
An extraordinary, global effort
Forests are crucial carbon sinks, where living trees capture and store carbon dioxide from the atmosphere, helping to regulate climate. Deadwood — including fallen or still-standing trees, branches and stumps — makes up 8% of this carbon stock in the…
Our aim was to measure the influence of climate and insects on the rate of decomposition — but it wasn’t easy. Our research paper is the result of an extraordinary effort to co-ordinate a large-scale cross-continent field experiment. More than 30 res…
Wood from more than 140 tree species was laid out for up to three years at 55 forest sites on six continents, from the Amazon rainforest to Brisbane, Australia. Half of these wood samples were in closed mesh cages to exclude insects from the decompos…
Our research showed the rate of deadwood decay and how insects contribute to it depend very strongly on climate. We found the rate increased primarily with rising temperature, and was disproportionately greater in the tropics compared to all other cooler climate region.
In fact, deadwood in tropical regions lost a median mass of 28.2% every year. In cooler, temperate regions, the median mass lost was just 6.3%.
More deadwood decay occurs in the tropics because the region has greater biodiversity (more insects and fungi) to facilitate decomposition. As insects consume the wood, they render it to small particles, which speed up decay. The insects also introduced fungal spices
Of the 10.9 billion tonnes of carbon dioxide released by deadwood each year, we estimate insect activity is responsible for 3.2 billion tonnes, or 29%.
Let’s break this down by region. In the tropics, insects were responsible for almost one-third of the carbon released from deadwood. In regions with low temperatures in forests of northern and temperate latitudes — such as in Canada and Finland — insects had little effects.
Source Deccan Herald