The bark of a single tree can host trillions of bacteria, playing a surprising role in managing greenhouse gases. Earth’s tree bark covers about 143 million square kilometers, nearly the size of all land combined. Despite its extensive area, scientists have largely ignored the microbes living on tree bark.
Bob Leung, a researcher at Monash University, points out that it seems obvious now; bacteria thrive almost everywhere. If they exist in soils and on leaves, why not on bark? Leung and his team studied the paperbark tree, scientifically known as Melaleuca quinquenervia, and found over 6 trillion bacteria per square meter—similar amounts to what’s found in soil.
Through genetic tests on 114 bacteria, researchers identified three main families: Acidobacteriaceae, Mycobacteriaceae, and Acetobacteraceae. Excitingly, these species are completely new to science. A key finding is that these microbes can use hydrogen, carbon monoxide, and methane for energy. Hydrogen isn’t a greenhouse gas itself, but it can amplify the warming effects of methane, a worrying climate change factor.
The research expanded to include seven other Australian tree species, including gum trees and banksias. They observed that tree bark absorbs hydrogen, carbon monoxide, and methane when oxygen is present. Yet, in waterlogged conditions where oxygen is scarce, these microbes switch to producing greenhouse gases.
Estimates suggest that global hydrogen absorption by bark microbes ranges from 0.6 to 1.6 billion kilograms annually, potentially accounting for about 2 percent of the atmospheric hydrogen removed. This study represents the first attempt to quantify the contribution of tree bark to atmospheric hydrogen.
Luke Jeffrey from Southern Cross University emphasizes the importance of this discovery. “Trees do more than just capture carbon dioxide; they actively cycle other gases too.” He notes that hydrogen consumption in bark could help manage methane levels, a significant global concern.
Yet, current data remains limited. The research only sampled eight species in Eastern Australia. “More studies are needed across various climates and tree types to get a clearer picture,” Jeffrey states.
Brett Summerell from the Botanic Gardens of Sydney highlights the need to explore microbial diversity in bark, especially in drier regions. Understanding the interactions between fungi and bacteria could also shed light on their ecological roles.
As our knowledge expands, the role of tree microbes may become crucial in tackling climate change. While we are just beginning to uncover these hidden contributors, their significance is becoming increasingly clear.
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microbiology,climate change,trees
