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Nature_and_Environment.122 |
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Forests/trees |
{Nature_and_Environment.122.16}: Jay Hoffman {resist} Sun, 06 Dec 2020 12:38:26 CST (82 lines)
Trees appear to communicate and cooperate through subterranean networks of fungi Trees and fungi form partnerships known as mycorrhizas: Threadlike fungi envelop and fuse with tree roots, helping them extract water and nutrients like phosphorus and nitrogen in exchange for some of the carbon-rich sugars the trees make through photosynthesis. Research had demonstrated that mycorrhizas also connected plants to one another and that these associations might be ecologically important, but most scientists had studied them in greenhouses and laboratories, not in the wild. By analyzing the DNA in root tips and tracing the movement of molecules through underground conduits, Suzanne Simard has discovered that fungal threads link nearly every tree in a forest even trees of different species. Carbon, water, nutrients, alarm signals and hormones can pass from tree to tree through these subterranean circuits. Resources tend to flow from the oldest and biggest trees to the youngest and smallest. Chemical alarm signals generated by one tree prepare nearby trees for danger. Seedlings severed from the forests underground lifelines are much more likely to die than their networked counterparts. And if a tree is on the brink of death, it sometimes bequeaths a substantial share of its carbon to its neighbors. Before Simard and other ecologists revealed the extent and significance of mycorrhizal networks, foresters typically regarded trees as solitary individuals that competed for space and resources and were otherwise indifferent to one another. Simard and her peers have demonstrated that this framework is far too simplistic. An old- growth forest is neither an assemblage of stoic organisms tolerating one anothers presence nor a merciless battle royale: Its a vast, ancient and intricate society. There is conflict in a forest, but there is also negotiation, reciprocity and perhaps even selflessness. The trees, understory plants, fungi and microbes in a forest are so thoroughly connected, communicative and codependent that some scientists have described them as superorganisms. Recent research suggests that mycorrhizal networks also perfuse prairies, grasslands, chaparral and Arctic tundra essentially everywhere there is life on land. Together, these symbiotic partners knit Earths soils into nearly contiguous living networks of unfathomable scale and complexity. Depending on the species involved, mycorrhizas supplied trees and other plants with up to 40 percent of the nitrogen they received from the environment and as much as 50 percent of the water they needed to survive. Below ground, trees traded between 10 and 40 percent of the carbon stored in their roots. When Douglas fir seedlings were stripped of their leaves and thus likely to die, they transferred stress signals and a substantial sum of carbon to nearby ponderosa pine, which subsequently accelerated their production of defensive enzymes. Forests function as some of the planets vital organs. The colonization of land by plants between 425 and 600 million years ago, and the eventual spread of forests, helped create a breathable atmosphere with the high level of oxygen we continue to enjoy today. Forests suffuse the air with water vapor, fungal spores and chemical compounds that seed clouds, cooling Earth by reflecting sunlight and providing much-needed precipitation to inland areas that might otherwise dry out. Researchers estimate that, collectively, forests store somewhere between 400 and 1,200 gigatons of carbon, potentially exceeding the atmospheric pool. When a seed germinates in an old-growth forest, it immediately taps into an extensive underground community of interspecies partnerships. Uniform plantations of young trees planted after a clear-cut are bereft of ancient roots and their symbiotic fungi. The trees in these surrogate forests are much more vulnerable to disease and death because, despite one anothers company, they have been orphaned. Diverse microbial communities inhabit our bodies, modulating our immune systems and helping us digest certain foods. The energy- producing organelles in our cells known as mitochondria were once free-swimming bacteria that were subsumed early in the evolution of multicellular life. Through a process called horizontal gene transfer, fungi, plants and animals including humans have continuously exchanged DNA with bacteria and viruses. From its skin, fur or bark right down to its genome, any multicellular creature is an amalgam of other life-forms. Wherever living things emerge, they find one another, mingle and meld. "https://www.nytimes.com/interactive/2020/12/02/magazine/tree- communication-mycorrhiza.html"
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