Plant Biology on EARTH Magazine

Rising carbon dioxide may raise risk of nutrient deficiencies in humans

Fri, 21 Dec 2018 10:54:40 -0500

In a new study, researchers found that levels of zinc, iron and protein in some grains and legumes will drop as atmospheric carbon dioxide concentrations rise. Credit: public domain.

Plants absorb carbon dioxide to fuel their growth. As humans increase the amount of the greenhouse gas in the atmosphere, more will be available to vegetation around the world. But according to a new study, too much carbon dioxide might eventually lead to plants that are deficient in key nutrients for humans, which could be especially detrimental in the developing world.

Algae ate themselves to death and caused a global extinction

Fri, 12 Oct 2018 13:14:37 -0400

A new study suggests that enhanced burial of carbon from eukaryotic algae drew down atmospheric carbon dioxide levels during the Ordovician, resulting in a diminished greenhouse effect that triggered an ice age and a mass extinction. Credit: Callan Bentley, 2018.

Errant asteroids and toxic emissions from volcanic eruptions are the usual suspects in mass extinctions. But during the Ordovician, it was a million-year stretch of cooling ushered in by proliferating algae that triggered a worldwide glaciation and extinction event, according to a new study.

Globe-trotting kelp set new world record

Fri, 12 Oct 2018 13:03:55 -0400

Kelp grows in underwater forests in shallow regions of temperate, tropical and polar oceans. Air bladders in the leaves enable the seaweed to travel vast distances on currents across oceans. Credit: public domain.

When marine biologist Erasmo Macaya, from University of Concepción in Chile, found a piece of kelp washed up on a beach in Antarctica, he suspected the scrap of seaweed had come a long way.

A rocky source of nitrogen

Tue, 03 Jul 2018 11:38:51 -0400

Calculations of the planet’s nitrogen balance have always been off: plants and soils seem to sequester far more nitrogen than expected. The atmosphere has long been thought of as the only major source of nitrogen, but a new study indicates an additional source: as much as a quarter of Earth’s terrestrial nitrogen may be supplied by eroding bedrock.

Mountaintops get less lonely for alpine plants

Tue, 03 Jul 2018 11:08:50 -0400

It takes a hardy plant to live on top of a mountain, but new research shows that summits in the Alps are hosting more species of plants than ever before. Long-term botany surveys conducted on 302 European mountaintops over the past 145 years show that the variety of plant species living on the harsh summits has markedly increased over the last 10 years due to climate change.

Beavers preserve wetlands in water-stressed areas

Wed, 10 Jan 2018 10:44:23 -0500

Once considered detrimental to ecosystems and nuisances where, for example, dams flooded farmland, beavers have been rhetorically touted in recent years as a potential boon for wetland health and water conservation. Anecdotal accounts and qualitative findings have suggested beavers improve water quality and availability in drought-stressed ecosystems, but just how much influence they have was not known. In new research, scientists have examined two creeks in Nevada to directly measure how effective beaver dams are at slowing water flows and storing water through the dry summer months.

A flammable planet: Fire finds its place in Earth history

Tue, 09 Jan 2018 07:07:24 -0500

For hundreds of millions of years, wildfires have shaped the planet. Credit: Naomi Kelly.

We owe Earth as we know it to fire. Fire-prone ecosystems cover 40 percent of the land surface today, and fires play a key role in maintaining many of the world’s major biomes, including grasslands, savannas, shrublands and boreal forests. It’s thought that global forests would double in extent in the absence of fire.

Mangroves sprouted in Arctic during Eocene

Fri, 13 Oct 2017 13:51:03 -0400

Evidence of ancient mangrove plants was found in lignite seams, such as in this outcrop on Faddeevsky Island. Credit: Guillaume Suan.

Mangrove trees, which today thrive in tropical and subtropical climates in the low and midlatitudes, grew in the high Russian Arctic about 56 million years ago, scientists reported in Geology. It’s the northernmost occurrence of mangrove trees ever documented.

Chemical clues illuminate fossil plant relationships

Fri, 13 Oct 2017 09:35:59 -0400

To reconstruct relationships among extinct plants and animals, paleontologists often compare genetic sequences from distinct organisms or analyze differences in fossil shapes. But both techniques have limitations: DNA does not last more than about a million years in the rock record, so genetic comparisons are typically limited to relatively recent species; and finding fossils intact enough to use for shape comparisons can be difficult. In a recent study, scientists describe a new technique that could help get around these issues — for some plants at least — using molecular remnants that are more robust than DNA and are preserved in fossil leaves.

Soil acidity changes quickly from place to place

Wed, 29 Mar 2017 14:46:24 -0400

This global soil acidity map shows acidic areas in red and alkaline areas in blue. Credit: University of California, Santa Barbara.

The acidity of soils, which affects soil fertility, depends largely on a region’s climate. What has been less clear is just how abrupt — or gradual — shifts in acidity are at the boundaries between adjacent regions with different climates. In a new study in Nature, scientists report that acidity transitions are indeed abrupt, and the results may provide a glimpse into how plant communities will evolve as the planet’s climate continues to change.

Liverworts, not moss, dominated Earth's early terrestrial ecosystems

Wed, 25 Jan 2017 13:58:56 -0500

Moss carpets colonize recent lava flows in southern Iceland. Credit: Ria Mitchell.

Moss, the springy green plant that blankets forest floors, has been heralded as the generator of large amounts of oxygen to Earth’s atmosphere during the Paleozoic. In a new study, however, researchers suggest that it could have been the overlooked relative of moss — liverworts — that dominated early terrestrial ecosystems and thus had more to do with reducing high carbon dioxide levels in the atmosphere at the time and cooling climate globally.

Lack of fungi did not lead to copious Carboniferous coal

Thu, 19 May 2016 16:27:03 -0400

The majority of the world's coal dates to the Carboniferous Period. Credit: Mary Caperton Morton.

The Carboniferous Period is famous for supplying Earth with an abundance of coal deposits. According to one hypothesis, the formation of all this coal is explained by a proposed 60-million-year gap, or lag, between the spread of the forests globally about 360 million years ago and the rise of wood-eating microbes and fungi that could break down tough plant matter. But a new study refutes this idea, instead attributing the Carboniferous’ copious coal to the consolidation of the supercontinent Pangea.

Fossil leaves provide clues to ancient Australian habitat

Tue, 19 Apr 2016 15:29:35 -0400

Heath and scrubland vegetation cover this part of Stirling Range National Park in southwestern Australia. In the Late Cretaceous, central Australia may have looked similar, with a mosaic of low-growing and open vegetation and woody thickets. Credit: Raymond Carpenter.

Researchers have long thought that the scrublands of Australia developed over the last 25 million to 30 million years as part of a global trend toward colder and drier climates in which rainforests yielded ground to more open, fire-prone environments.

Land plants came prepared for terrestrial life

Thu, 07 Jan 2016 10:54:54 -0500

Nitella hyalina is a stonewort and a member of the charophyte green algae family. No known charophyte alga has symbiotic associations with mycorrhizal fungi, but N. hyalina and other stoneworts do develop root-like rhizoids that anchor the thallus in sand and mud, and probably frequently interact with fungi. The frame is about 5 millimeters tall. Credit: Charles F. Delwiche, University of Maryland, all rights reserved.

Plants colonized land between 450 million and 420 million years ago, and, once there, they drastically altered terrestrial landscapes and provided resources for animals leaving the oceans around the same time. One adaptation that helped plants gain a foothold on land is a symbiosis with fungi known as arbuscular mycorrhizae (AM), which help plants acquire water and key nutrients from the soil and are still associated with most land plants today. In return, plants provide the fungi with bioavailable carbon produced during photosynthesis. When this symbiosis evolved has remained unclear, but researchers recently discovered that it likely has roots in a group of freshwater algae ancestral to land plants.

Thorny plant marks West African diamond deposits

Thu, 06 Aug 2015 10:24:56 -0400

Credit: ©Callan Bentley.

Editor’s note: This story was updated on Oct. 9, 2015, to fix an error in the size of the kimberlite pipe. West Africa is famous for diamonds, brought up from the depths of Earth’s mantle eons ago during explosive volcanic eruptions. On the surface, the eroded remains of these eruptions, known as kimberlite pipes, are infamously hard to find under the thick jungles of Guinea, Sierra Leone and Liberia, and only a few of the deep, narrow pipes contain profitable diamonds. Now, a researcher has identified an unusual feature that might point the way toward such pipes, and possibly revolutionize the search for diamond-rich deposits: a tall, thorny palm-like plant that seems to only grow atop kimberlites.

Nonnative plants not a problem in Britain

Thu, 16 Jul 2015 12:14:04 -0400

Japanese knotweed has been classified as a destructive invasive species in several countries, including the U.K. and the U.S. Credit: ©MdE, CC BY-SA 3.0 de.

In many places in the world, nonnative plants are epidemic, outcompeting local flora for space and resources and sometimes leading to extinctions of native plants. But a new study finds that, in Britain at least, foreign plants don’t seem to be negatively impacting the natives after all.

Tiny plant fossils offer big view of ancient ecosystems

Mon, 01 Jun 2015 10:12:55 -0400

Fossil plant phytoliths, like this 49-million-year-old example found in an ancient soil horizon in Patagonia, Argentina, may offer clearer views of past ecosystems. (Scale bar is 10 micrometers.) Credit: Regan Dunn.

A key part in understanding a terrestrial ecosystem is analyzing its vegetation structure: How dense is the foliage? Is its canopy open or closed? How much sunlight reaches the ground? Answering these questions about a modern plant community is relatively easy, but for paleoecosystems, such analysis has not been possible until recently. Now, a new study published in Science reports a novel way to create what lead author Regan Dunn calls a “3-D look” at ancient ecosystems.

Amber-encased plant could be oldest known grass: Specimen may also preserve a Cretaceous-aged hallucinogen

Mon, 04 May 2015 12:52:54 -0400

This 100-million-year-old amber-encased specimen contains what could be the oldest grass fossil known, and the only fossilized specimen of the fungus ergot (dark material at top) ever found. Credit: Oregon State University.

Delicate grasses don’t preserve well in the fossil record, and evidence for grasses coexisting with dinosaurs is scant. But according to a new study, a chunk of 100-million-year-old amber recently discovered in Myanmar appears to contain the world’s oldest grass fossil — far more ancient than any fossil grasses previously found. What’s more, the specimen seems to be topped with the world’s oldest known ergot — a fungus containing ingredients used to make lysergic acid diethylamide, better known as LSD. But while the image of a 100-metric-ton sauropod grazing on hallucinogen-laced grass is intriguing, not everybody is convinced that the specimen is the real deal.

Ancient moss reveals tsunami timing

Mon, 20 Apr 2015 11:54:15 -0400

The moss found in the tsunami deposit, called Hylocomium splendens, sprouts a new growth segment in the spring that grows until autumn. Credit: Knut Rydgren.

Fishermen trawling Norway’s waters have long known of a place where the seafloor drops precipitously into the abyss. It’s called Storegga — or “great edge” — and it’s actually the steep headwall of the largest undersea landslide in recent geologic history. The slide triggered a tsunami that flooded the shores of the North Sea, reaching as far as Greenland, and likely affecting the Stone Age people that inhabited Northern Europe at the time.

Fossil leaves reveal effect of "impact winter"

Fri, 30 Jan 2015 14:29:58 -0500

In an analysis of fossil leaves from the Cretaceous-Paleogene boundary, when the Chicxulub impact occurred, scientists saw an increase in vein density (A to B) and a decrease in leaf mass per area (C to D). Credit: B. Blonder et al., 2014, PLOS Biol. 12(9): e1001949.

When the Chicxulub bolide struck the Yucatán Peninsula at the end of the Cretaceous about 66 million years ago, widespread extinctions of land and marine animals resulted. However, the blast’s lasting effects on plants, which tend to be more resilient against impact-related fallout, have been less clear. Now, a new analysis of fossil leaves dating to around the end-Cretaceous offers some of the first quantitative evidence of a substantial shift in plant communities — toward more deciduous plants — following the impact.

Why red leaves remain elusive in Europe

Thu, 05 Jan 2012 06:41:58 -0500

As leaves change color every fall, the North American landscape transforms from a rolling verdure to a collage of vibrant yellows, oranges and reds. The autumn foliage in Europe, however, is rather bland, composed of mostly yellow leaves with red-leafed trees few and far between. Why this is the case has remained a mystery for years. But discovering why Europe’s leaves don’t turn red is only half of the battle; determining why the trees’ leaves turn yellow in the first place is the other.