Sustainable Consumption

Many people think [without actually “thinking”, near as I can tell] that easy paths to sustainability run down the Vegetarian Road and the Local Produce Highway. Seems like a no-brainer, no? You don’t feed produce to animals, you eat it instead and you save something like 75% to 90% of the calories that would otherwise vaporize metabolically. You grow your food locally, you save all the fuel, infrastructure, and carbon footprint invested in getting it your store from Chile or Mexico or Morocco or wherever.

Milkweed bug nymphs. These

babies (literally babies) suck

liquid from the plant without

doing it any real injury.

Like most easy answers, a lot of this is complete bullshit. If you’ve ever been to arid parts of the Middle East, eastern Asia, or North America, or alpine territory anywhere, you’re looking at a lot of real estate that ain’t growing edible plants at all, much less at a scale that would help support human life. But it CAN grow goats, sheep, cattle, hares, rabbits, camels (including Andean species like lama, alpaca, etc.), cui (cavy or guinea pig, eaten spiced and deep fried in the Andes), swine, armadillos, poultry…oh hell, you can grow all sorts of animal biomass on such ground. Converting otherwise unproductive land into a real contributor.

Short-horned grasshopper. The

quintessential chewing herbivore.

These do indeed cause overt damage

to the plants, but the plants don’t

necessarily mind.

Similarly, the belief that local production nets sustainability is simply wacky until you account for differences in the inputs of time, matter and energy needed to produce in different areas. In other words, if you are going to grow meaningful quantities of wheat in Switzerland, or grapefruit in New Jersey, or rice in England, you’re going to have to input a SHITLOAD of matter and energy to get it done. I’m guessing, in these cases and others, that you’re going to have to input more time, matter and energy than the total needed to Indonesia plus ship it. Sustainable? I don’t think so. Net sustainable? No smeggin’ way.

Here’s a cool one. These are the

tracks of leaf miners. Mostly these are

moth and fly larvae that burrow through

the leaf tissue, feeding (and defecating)

as they go.

Anyway. Back in the days when Ecologists were Systems Ecologists, we tended to discount herbivory. Except for the grassland steppe ecosystems of central Asia and North America and the open oceans, most of the energy action—from half to over 90%--went down via decomposer food webs.

Some insect—I have no idea

beyond that—set up this nifty

little rolled up ball of Christmas

fern fronds and defecated all

the hell inside it. And kept it

rolled up in there until I

split it and photographed it.

Cool!

All that structural material in forests (tough, leathery oak leaves, stiff, spiky bark, hard and mostly hollow wood) had to be processed through invertebrate guts and slathered with extracellular digestive enzymes by microbes to make it amenable.  

Nectar-feeding butterfly. No

nutrition problems here, at least once you find the sugary stuff and get your mouthparts into it. Easy to digest, massive energy content? Recipe for trophic success!

It’s not completely clear to me why more energy isn’t shunted down the road of liquid-feeders. It really is on the order of 10% or so. Not much more even under the best circumstances. I’ve seen people claiming that it’s an evolutionary problem—too much water and not enough physiological adaptation. But I’m not sure that makes sense Hell, if a few organisms can adapt to do it, more could. I must be missing something.

Oh. Here’s the real key to the

herbivory shunt on the food web. This katydid turned up dead under the porch light one afternoon. Note

it’s intact and complete.

The late Richard G. Wiegert, guy who had life licked and spent summers in Yellowstone, spring and autumn on Sapelo Island, and winters (only) teaching in Athens, Georgia, had a problem. His energy flux models of Sapelo tidal marshes couldn’t account for 19 grams of carbon per square meter per year. This was a hell of an issue for Dick. Pissed him off for his entire career.

And the next morning? This katydid carcass was sliced and diced. Carved, sauced and served. Now THAT is a food

web in action!!!

Bill and I found the answer. One warm afternoon on Sapelo, we were out in the marsh for some reason, just kind of enjoying the sun and the smell of the grass and the mud and the water. It was quiet. Too quiet. And along with the sound of the breeze and the scent of the air moving gently up from the sediment surface, there was a clearly audible “Crunch. Crunch. Crunch.” We looked around to investigate.

One last photo. A monarch

butterfly larva chomping 

away in an Eastern Shore

garden in late summer. All is

good in the food web!

And were shocked. This was the second place we found where big legless lizards—genus Ophisaurus—seemed to be ecologically important (the other was the pine scrub behind the dunes on the Outer Banks). The lizards were out on the warm mud at low tide in the Sapelo marsh, wolfing down fiddler crabs, crunching them noisily at a great rate. I’m pretty sure at just about 19 grams of carbon per square meter per year.

Wiegert never did buy our thinking on this point. Let the record show that he died still missing 19 grams of carbon. And that Bill and I know where it goes!