The red, orange, and spotted mushrooms that appear after rain do more than just add colour to the landscape. According to a new study, the fungi that produce them may be keeping the natural world productive and stable. Indeed, they may be crucial to the health of the Earth's ecosystems, according to Matthias Rillig, a soil ecologist at the Free University of Berlin who was not involved in the research.
Findings of Study:
Fungi are classified into 70,000 different species. Molds, lichens, mushrooms, toadstools, and puffballs are among the organisms that can be found in the environment. Pathogens ranging from those that cause athlete's foot in humans to those that cause billions of dollars in damage to wheat, maize, and other crops are also included.
Many of these fungi live underground, but researchers have traditionally ignored them. However, ecologists have discovered that some, such as soil fungi known as mycorrhizae, form vast underground networks that connect trees and supply them with nutrients, allowing a forest to thrive.
Could other soil fungi be performing a similar function aboveground? To find out, Manuel Delgado-Baquerizo, an ecosystem ecologist at the Spanish National Research Council, collaborated with colleagues from around the world who had collected and analyzed local soil samples—and the fungi they contained—for various projects. The researchers examined nearly 700 samples from tropical, temperate, and polar climates.
Delgado-team Baquerizo's used DNA to determine how many soil fungi were pathogens, mycorrhizae, decomposers (such as mould), and fungi that live inside plant roots at each site. The researchers also looked at satellite images to see how much photosynthesis was happening in each area, and thus how productive the vegetation was, and how much that productivity had changed over the last two decades. "It's a clever data combination," Rillig says.
A distinct pattern emerged. Delgado-Baquerizo and colleagues report today in Nature Ecology & Evolution that the more species of decomposers there were, the more plant productivity remained constant over time across a wide range of ecosystems, from grasslands to forests to deserts. The authors discovered that having a diverse population of decomposers and, to a lesser extent, root fungi helped keep vegetation growing even during dry spells.
This diversity may ensure that no matter how conditions change, some fungi will still be able to supply nutrients to the plants above them. "Their role may be greater than that of mycorrhizal fungi," says Sarah Sapsford, a fungal disease ecologist at New Zealand's Ministry of Primary Industries who was not involved in the research.
A diverse set of pathogens, on the other hand, appeared to jeopardize the health of the aboveground ecosystem. Plants grew slower and performed less photosynthesis, reducing the productivity that feeds the rest of the ecosystem's organisms. Pathogens can weaken plants and make them less resistant to environmental stresses.
"It's fascinating that these patterns stand out despite all the other variables changing from site to site," Rillig says. However, he cautions that the study does not prove that fungal diversity causes stability (or vulnerability). Other factors, such as the diversity of other types of microbes in the soil, he believes, could also be significant.
Nobody knows how to promote soil fungi diversity, but Sapsford believes that by assessing it, "we may be able to pinpoint the ecosystems that may be 'unstable' and less resilient to disturbance." "It's a thrilling time."
(Source: Science.org)
