Trillions of trees are growing on Earth, though how many kinds there are has been underestimated, a new study finds.
Earth hosts roughly 64,100 known tree species. But there could be at least 73,300 — about 14 percent more than previously thought — a global collaboration of researchers reports in the Feb. 8 Proceedings of the National Academy of Sciences.
More than a third of the 9,200 undiscovered species are probably rare and hiding out in South America’s biodiversity hot spots, such as the Amazon and the tropical Andes, biologist Roberto Cazzolla Gatti of the University of Bologna in Italy and colleagues say.
To estimate the number of Earth’s existing tree species, the team analyzed global forest data from two databases — the Global Forest Biodiversity Initiative and TREECHANGE. The researchers used a statistical analysis to account for the number of rare, infrequent trees that could be overlooked, revealing the new difference between documented species and novel ones.
If more than 9,000 types of stationary, comparatively massive trees remain undetected, Cazzolla Gatti says, then the number of much smaller and more mobile animal species that are still unknown must be even greater.
The research could help scientists target conservation efforts amid accelerating biodiversity loss worldwide (SN: 4/22/20). Invulnerable places such as the Amazon, where deforestation and fires are quickly erasing habitat, many plants and animals could be being wiped off the map before they are ever documented (SN: 9/1/21).
Continuing to invest in conservation and preserving biodiversity is vital, Cazzolla Gatti says. Without it, “we have not many chances to keep our planet alive.”
Gleaming, gluey, deathtrap hairs have betrayed the secret identity of a well-known wildflower: It’s a carnivore.
A species of false asphodel (Triantha occidentalis) uses enzyme-secreting hairs on its flowering stem to snare and digest insects, researchers report in the Aug. 17 Proceedings of the National Academy of Sciences. Scientists have known about T. occidentalis since the 19th century, but its taste for meat has gone undetected until now.
Sticky hairs by themselves aren’t unusual — many noncarnivorous plants use them to defend against pests. But T. occidentalis has qualities that some meat-eating plants share: a love of bright, boggy, nutrient-poor habitats and the absence of a gene that fine-tunes how plants get energy from light. Together, those features felt like pieces of a jigsaw puzzle hinting at carnivory, says botanist Sean Graham of the University of British Columbia in Vancouver.
To solve the puzzle, Graham and colleagues needed to know if the wildflower pulls nutrients from insect corpses. Luckily, T. occidentalis grows along North America’s West Coast, from Alaska to California, and can be found on hikes near Vancouver. “They’re right on our doorstep,” Graham says.
The team attached fruit flies fed with nitrogen-15, an isotope that can be used to track changes in nitrogen levels, to the flowering stems of bog-dwelling T. occidentalis plants in British Columbia’s Cypress Provincial Park. Over half of the wildflowers’ nitrogen came from the fruit flies, the team found. Those levels are comparable to known carnivorous plants. What’s more, the wildflowers’ sticky hairs oozed phosphatase, a digestive enzyme that many carnivorous plants secrete to consume prey.
Most of the world’s roughly 800 meat-eating plant species set traps and flowers far apart to avoid killing pollinating visitors (SN: 2/6/18). T. occidentalis bucks that trend. “Putting your traps close to your flowers is, on the surface, a really big conflict,” Graham says. But the plant’s hairs maybe just sticky enough to catch small flies and beetles without entrapping bigger pollinators such as bees and butterflies.
T. occidentalism sticky hairs might also hint at how some meat-eating plants evolved. In nutrient-poor soils, it may have been advantageous for some plants to co-opt hairs for carnivory, Graham says. “The insects are being trapped anyway, so might as well use them.”
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