Tag Archives: climate change

Plants vs. the World

A stinging nettle.

The world is a rough place to grow up. Just ask a stinging nettle. Credit: Ashley Braun/All rights reserved.

Life as a plant can be stressful. Once, or rather, if, you sprout where you’re planted, you’re faced with some immediate limitations. Let’s hope you have just the right exposure to sunlight, water, and nutrients. Maybe not too much wind or competition for space. And watch out for herbivores.

But that’s about all plants can do, right? Just watch.

While plants do have some obvious defenses (thorns, toxins, tannins, and the like), we humans often think of plants as being passive. We don’t give them much credit for taking a stand against the world. “Vegging out” means sitting around doing nothing, unaware and unresponsive. Yet researchers are finding many examples of plants actively responding to the world around them and in a variety of ways.

Yo, Romeo: Smell Ya Later

Tall goldenrod plant with fly-induced gall.

I forgot to mention that gall fly larvae spit causes huge galls (ball-shaped masses) to form on the goldenrod’s stem. They then live inside the gall all winter, sucking nutrients out of the plant from the inside. No wonder the plant is pissed. Credit: Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor/Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License.

Take smelling, for example. In 2012, entomologists at The Pennsylvania State University documented both in the field and in the lab evidence of a plant that, when exposed to the smelly male sex hormones of a long-time enemy, is able to beef up its chemical defenses against it.

It seems that once the tall goldenrod plant, Solidago altissima, gets a whiff of a romantically inclined male goldenrod gall fly, Eurosta solidagini, it begins releasing the defense hormone, jasmonic acid, which is a real turn-off to lady flies. Particularly, as it turns out, when they’re looking for a place to lay their eggs, which hatch into hungry little caterpillars and only have a stomach for tall goldenrod.

Male flies release clouds of this pheromone “perfume” when they’re in the mood for love, sitting on the leaves of a tall goldenrod plant and waiting to attract a female. After they mate, the female flits away to find a suitable nursery plant for her bug babies. In this search, she goes from plant to plant, sticking her egg-laying organs into goldenrod buds and getting a “taste” for the plant with her feet and ovipositor. If she likes the taste, she lays her eggs. If not, on to the next plant.

However, once a plant is exposed to the male flies’ odor, not only are they less likely to have female flies inject their eggs into them, but to a large extent they also avoid being eaten by other hungry insects. Jasmonic acid must taste terrible to a would-be mother goldenrod gall fly. But the musk of a male fly apparently smells like heaven to a nervous goldenrod.

Beating the Heat

Another very real concern for plants is heat stress, which is only going to get worse as the global climate warms. The United Nations Intergovernmental Panel on Climate Change is in the process of releasing its latest series of reports on global warming and its impacts on the natural and human worlds. A part of one of their reports was leaked before being published, but it apparently has dire warnings for agriculture.

According to the New York Times:

In a departure from an earlier assessment, the scientists concluded that rising temperatures will have some beneficial effects on crops in some places, but that globally they will make it harder for crops to thrive—perhaps reducing production over all by as much as 2 percent each decade for the rest of this century, compared with what it would be without climate change.

And, the scientists say, they are already seeing the harmful effects in some regions.

Heat waves have already taken a toll on crop production in recent years (see Europe in 2003). A growing body of research suggests that important crops such as corn and soybeans are more sensitive to extreme heat than previously thought.

What does “extreme heat” mean? The mid-80s. Having grown up with sticky Midwestern summers, that doesn’t even sound that hot, but it translates to a sudden drop in production for these plants.

Even so, plants do have ways to cope with heat stress. Researchers at Iowa State University have recently uncovered some of the molecular pathways that plants use to deal with stress. From a press release:

The research takes a close look at what happens to the model plant Arabidopsis at a molecular level when faced with environmental stress. It involves a process called unfolded protein response, which can act as an alarm system when the plant senses harsh conditions. When the alarm goes off, the plant activates survival measures that can protect crops from succumbing to weather extremes.

Considering the warming world facing plants, they’re going to need these kind of defenses to stay alive. And why should we expect them to just sit back and watch?

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A World Without Ice

Iceberg Lake, Glacier National Park.

Iceberg Lake, Glacier National Park. Ashley Braun/All rights reserved.

Ice asks no questions, presents no arguments, reads no newspapers, listens to no debates. It is not burdened by ideology and carries no political baggage as it crosses the threshold from solid to liquid. It just melts.

— University of Michigan geophysicist Henry Pollack, A World Without Ice

Arctic Sea Ice Breaks 2007 Record Low

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I take my World Oceans Day marinated in oil

Or, at least, that’s the way it seems this year for the new U.N.-declared holiday, in light of the crude catastrophe in the Gulf of Mexico.

While the salty seas off of Louisiana could definitely use some lovin’, the rest of the oceans aren’t faring much better. The following issues wouldn’t mind it at all if you started throwing out some life preservers:

  • Life in plastic, it’s gone gastric: That is, for this albatross chick and other sea animals that mistake tiny bits of discarded plastic in the water for food. Unfortunately, some of that little plastic debris adds up to a huge, floating Pacific garbage patch about twice the size of Texas. And there’s another one in the North Atlantic too.

    Claire Fackler, NOAA National Marine Sanctuaries

  • Bleach out and touch someone: One of the first sure signs of climate change was warming ocean temperatures which started bleaching coral reefs. Which means they — and many of the tiny organisms at the bottom of the food chain — die.

    Bleached staghorn coral ... the water ain't fine here. Photo: Matt Kieffer via Flickr Creative Commons

  • On acid: A neat trick of what’s known as the “carbon cycle” is that the oceans absorb about 25% of the carbon dioxide pumped into the atmosphere by, for example, burning fossil fuels. However, when it dissolves into sea water, a weak acid known as “carbonic acid” forms, which disintegrates the shells of sea life. This less-than-neat phenomenon is known as ocean acidification. Get more info from Sigourney Weaver and the Natural Resources Defense Council:
  • Go fish: Actually, don’t. My good-natured environmental policy professor, Dr. Bill Evans used to work with the International Whaling Commission, and I believe, also the National Oceanic and Atmospheric Administration. And one thing I learned from his class was that there are now waaaay too many boats — rather than fish — in the sea. According to scientists, if fishing continues at the same rate, most of the world’s seafood stocks will collapse by 2048. (Source: Impacts of biodiversity loss on ocean ecosystem services. Worm et al. Science 2006;314:787–90)
  • Bluefin tuna is blue to the albacore over its threatened status. Photo: bzibble via Flickr Creative Commons

Now, for some good news: The collapse of the world’s fisheries can be avoided. The same doomsaying scientist published a more optimistic outlook last year, but it has lots of big ifs, including the effects of fisheries management, climate change, and ocean acidification. So don’t think you’re off the hook quite yet! (Source: Rebuilding Global Fisheries, Worm et al. Science 31 July 2009: 578-585)

And here’s a little Gristy advice for how to help the oceans by eating more kindly: How to choose sustainable seafood. Or, like me (even in pre-vegetarian days), you could skip the seafood altogether. Happy World Oceans Day!

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