How to optimize your taxa: switch away from grass

How to optimize your taxa: switch away from grass

I’ll bet you didn’t know anything about taxa. Join my club.

They’re a good thing, as seen in this scientific sentence: “Short mown grassland designed for recreational use is the dominant form of urban greenspace in temperate regions but requires considerable maintenance and typically provides limited habitat values for most taxa.”

Scientists, bless their hearts, do amazingly useful stuff. But sheesh, they need help communicating things. This latest study, from which the quote above is taken, makes the case for ditching grass and replacing it with meadows to encourage healthier and more biodiverse urban spaces. But of course they don’t say it like that. They say it like this: “Our results suggest that diversification of urban greenspace by planting urban meadows in place of some mown amenity grassland is likely to generate substantial biodiversity benefits, with a mosaic of meadow types likely to maximize such benefits.”

Or put another way: Instead of reflexively planting grass everywhere, we should think of other options, try different things, see what takes, encourage the growth of flowers, moss, shrubs, more flowers, etc., on public spaces and everywhere else we can think of and see what happens to the local population of bugs, birds and beasties. Where it’s important to keep vegetation from growing too tall for safety reasons (say, on the median between lanes of traffic, because visibility), aim for plants that naturally grow short. That way you won’t have to mow it; you might just need to clip it once or twice a year instead of using loud smelly disgusting two-stroke engines every few weeks to keep the grass from looking unkempt.

As I wrote in the Ottawa Citizen a few months back, Montreal is currently studying various possibilities to replace grass on medians. Me, I’m no scientist. I don’t know which plants are likely to work. They have to be tough, not just to survive winter but to survive constant trampling to say nothing of air pollution. Ideally they are pretty, too, and attract bees, insects and whatnot.

But you still want to know about taxa, so I looked it up for you. Taxa (clears throat) is the plural form of taxon.

Yeah, some days I hate Google too.

Taxon is a fancy word for ‘species’. The bigger the taxa, the more biodiverse your little patch of nature is. That’s a good thing.

Grass, you’ll learn if you can manage to sift through this latest scientific study, does not encourage a big taxa. For one thing, most grass is just one or very few species (John Green did a fun episode on the Kentucky Bluegrass for his podcast, the Anthropocene Reviewed that’s a lot easier to digest than just about any scientific study). Grass, in other words, is a big giant monoculture, and in general monocultures are bad for the environment because by their nature they discourage biodiversity. We’re so used to grass it doesn’t bother us very much at all, but that doesn’t make it a healthy or environmentally sensible thing to have around.

Or, as the scientists put it:

Cumulatively across urban areas, parks can harbor significant numbers of plant species (Thompson et al. 2004, Stewart et al. 2009, Bertoncini et al. 2012), and, per unit area, lawns support species richness similar to those of seminatural grasslands, although composition is often dominated by a small number of grass species (Thompson et al. 2004, Bertoncini et al. 2012, Wheeler et al. 2017). However, the limited vegetation structure provided by short grass shards leads to reduced diversity of many invertebrate taxa relative to more structurally complex grasslands (Morris 2000, Jerrentrup et al. 2014). This results from direct effects of reduced habitat availability and complexity and other effects such as microclimate alteration (Gardiner and Hassall 2009), trampling by humans (Duffey 1975), and mowing limited forb flowering and seed set (Garbuzov et al. 2015) and causing direct mortality (Humbert et al. 2010). As a result, there is growing interest around the world in finding more structurally and botanically diverse alternatives to mown amenity grassland (Bormann et al. 2001, Klaus 2013, Blackmore and Goulson 2014, Hwang et al 2017, Jiang and Yuan 2017).

Introducing areas of “meadow” vegetation, broadly defined as infrequently mown grassland, usually with flowering forbs to replace park grass is thought to ameliorate some of these effects.

You gotta love people who put “meadow” in quotation marks but leave “forb” all naked and unexplained. A forb, incidentally, is a herbaceous flowering plant that is not a graminoid. Like, say, a sunflower. Thanks, Wikipedia!

I like to poke fun at scientists but the work they do is important. You can’t just yank out your Kentucky Bluegrass and sprinkle whatever seeds you have on hand and hope for the best. I mean, you, in your own personal backyard, are free to do that. But it would be irresponsible for the city to try the same method. There are plants that do better than others, and it’s important to experiment and document and do all the things people with clipboards do. That’s why I’m urging the City of Ottawa to look at the Montreal experiment and take inspiration from their results. Plants that do well in urban Montreal are likely to do well in urban Ottawa.

Instead of bickering over who’s got the best hockey team, we could compete to see who’s got the biggest taxa. And wouldn’t that be neat.

Nature: Use it to keep it

Nature: Use it to keep it

How many plastic straws can you pick up on your jog?

How many plastic straws can you pick up on your jog?

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