Plant growth is good or bad, "colonial" root bacteria also have the right to decide

in electron microscopic photos, the fungus (bright gray) penetrates the root cells, where the fungus provides water and nutrients in exchange for carbon.
: Science Source
In the future, the world's flora may be as dependent on underground community as it is on aboveground community, or even more. Beneath 90 per cent of plants, there is an invisible support system, an underground fungal partner, forming a silky network that connects plants and brings nutrients and water to their roots. In return, plants provide a stable carbon supply for fungi. Now, researchers have found that these hidden partners can influence the ecosystem's response to climate change.
, according to a study presented at the American Society for Ecology's online annual meeting in early August, suitable fungal partners can help plants survive in warmer, drier environments. Other studies at the conference showed that climate change could also disrupt these "root fungi", thus accelerating the death of their host plants. Mattias Rillig, an ecologist at the Free University of Berlin in Germany, said: "It is becoming increasingly clear that we cannot ignore the response of germ fungi to climate change. There
two forms of these fungi. Plescobacteria roots (AM) are common in tropical and tempered forests, as well as in fields and grasslands, invading root cells and extending fine hairs called mycelium into the soil. In contrast, exogenetic root (EM) fungi are associated with conifer trees, oak trees, pecans,and beech. They grow outside the root system, and their network of mycelium forms mushrooms that suddenly emerge from the wet forest floor.
both types absorb phosphorus and other nutrients, absorb nitrogen from decaying organic matter, and help store carbon in the soil. "Because of their importance to plant productivity, the root community is arguably the most important symblosis in terrestrial ecosystems." Christopher Fernandez, a soil ecologist at the University of Minnesota in the United States, said.
but climate change may change these links. Fernandez's study is part of the B4WARMED (Northern Warming Forest at Risk) project, which aims to monitor the effects of warming and drying on northern forests across the northern latitudes. The study also artificially warmed and dried forests, and Fernandez simulated the effects of climate change on hidden fungi by sequencing soil and root samples.
Fernandez reported at the meeting that as the environment becomes warmer and drier, the diversity of EM fungi decreases and the "weed" EM fungus will take its place. These "weeds" don't put a lot of effort into building an extensive underground network, causing their connections to be disrupted. If the same damage occurs with climate change, there will be fewer critical partnerships with fungi, which could deprive trees of nutrients.
" B4WARMED results suggest that significant changes are likely to occur in both ground and subterranean community in the future. Sarah Sapsford, an ecologist at the University of Canterbury in New Zealand, said: "What we're seeing now may never be seen again. The
a different ecosystem, the pine forests of the southwestern United States, suggest that existing variations in the roots can also affect the resilience of trees. Decades ago, a moth rampage left some pine nuts growing near the National Monument at Sunset Crater in Arizona stunted. Severely injured trees have different EM fungi than their higher neighbors, suggesting that the two trees may be genetically different.
2002 and 2003, when a major storm hit the area, high trees killed twice as many people. To see if the roots would have an impact, Catherine Gehring, an ecologist at the University of Northern Arizona at Flagstaff, and colleagues in the greenhouses, in different ways, bred seedlings from two plants with and without fungi.
Gehring and colleagues are working with local researchers to re-plant pine trees in the Navajo Nation, not far from the sunset crater. Genetic differences between trees seem to determine which of the two groups of EM fungi "colonizes" them, and the team carefully planted seedlings with the correct genotypes to attract drought-resistant fungi. This, Gehring says, "can mean the difference between life and death in times of drought."
third study has shown that roots can affect not only trees, but also the entire ecosystem's response to environmental change. Since AM and EM fungi are associated with different tree species, Colin Averill, an ecologist at the Federal Institute of Technology in Zurich, Switzerland, wondered if the fungus itself helped determine which forest was growing in a particular area.
early researchers were skeptical, and Averill and colleagues looked for evidence from a wealth of data from the U.S. Forest Service that documented the species, growth and death of each tree larger than a sapling in 6,965 forests in the eastern United States. They found that many plots were either dominated by AM-related tree species or by EM-related tree species;
statistical analysis found that fungi are the key to this serious division. The researchers found one possible reason: dominant germs can help keep forests stable. Measurements of trees in each plot every five years show that AM trees are at least 10 times more likely to take root in AM forests and twice as likely to survive as EM forests. At the same time, EM trees are more likely to thrive in EM forests.
can strengthen their monopoly by altering the soil to its benefit to specific species, such as controlling nitrogen levels in the soil. A more mature network of fungi can also help small trees endure dense shadows that interfere with photocodying, or help older trees fight drought or disease. "If you are an EM tree, you can access an EM network, which can help you survive." Averill said.
control of these fungi may slow forest responses to external pressures such as climate change. Trees associated with AM survive better at warmer temperatures, but as the climate warms, they may grow more slowly than expected in EM-led forests, Averill said. "These types of dynamics can become very important as we try to predict how the global forest system will change in the future."