Thursday, July 09, 2015
Complex Nature in a Parking Lot
Tended urban landscapes can be categorized as simple or complex. Simple landscapes are composed of lawn, trees, hedges and mulch. Care of this sort of landscape requires mowing grass and trimming the hedge--both of which keep plants in a stunted, infantile state. The plants play the role of something nonliving: the lawn a living rug, the hedge a living wall. This outdoor space is managed more like it were indoors, with the accompanying cleaning requirements, cheating nature of its well-honed modus operandi of recycle-in-place. Whatever the trees drop is alien to this landscape and must be hauled away. Application of broadleaf herbicide simplifies the lawn further, foiling nature's inclination to diversify with a host of weeds. The enforcers of simplified landscapes cruise around town in rigs that can approach the size of semis, to hold all the cleaning and grooming machinery required to keep nature from being natural.
Now and then there's an exception to this rule. A homeowner may plant a perennial border, or a memorial garden is planted in a park, or the idea of a raingarden appeals.
At Westminster Choir College, these vegetated swales, essentially raingardens, were planted because the concept of native swales filtering polluted parking lot runoff penetrated into the regulatory framework controlling new development. Regs dictate a vegetated swale, the landscape architect chooses what plants are to be put in, and a complex urban landscape is born.
And who will take care of this landscape? Typically, it will be crews that, if they had ever encountered switchgrass or cardinal flower or milkweed before, would have thought them a weed to pull out. If you mow lawns and trim hedges all day, the idea that a plant could mature, flower and go to seed is entirely alien.
There is, then, a disconnect between installation and maintenance. To maintain such a landscape requires not a trailer full of machinery but knowledge, not only of the twenty intended species but also the twenty or thirty species of weeds that will happily spring up and compete for space.
The maintenance crew finds itself in a game of botanical To Tell the Truth, where the mystery guest speaks a foreign language of opposite or alternate branching, dentated or entire leaves, stigmas and styles, lemmas and paleas. Each plant must be known not only by its flowers, but also by other characteristics so one doesn't pull it out by mistake after the flowers fade. So, will the real intended plant please stand up?
Is this plant (velvet leaf) intended? It looks distinctive.
How about this (pigweed)?
This vine (bindweed) has a nice flower, but it's climbing over something else (curly dock). Is any of this intended or not? It's almost certain the person told to visit this site with a weed whipper now and then hasn't a clue.
How about these (smartweed on the left, lambs quarters on the right)?
Finally, a flower (crown vetch)! It looks intended, but if one wants to maintain a balanced, diverse planting, it would be the first one to be pulled out.
Finally, an intended plant, swamp milkweed, but chances are 50/50 it will be pulled out by mistake. It's got "weed" in its name, after all.
The appearance of these particular vegetated swales is being saved by switchgrass, which is filling in nicely with its luxuriant mass that shrugs off the weedy wannabes, and the blackgum and redbud trees are flourishing in this inverted, naturally watered space. But until the knowledge that went into its planting also informs the maintenance, these complex landscapes will not be nearly as attractive as they could be.