March 9, 2018
By Liz Clift
It’s not always easy to know what’s happening in a landscape—or why it’s happening. This can be especially true if you’re not familiar with the native (or invasive) plants in your area, with natural local variations in topography, or with the presence/absence of certain animal species seasonally and generationally (among many other variables), although all of these factors offer clues.
However, the landscape frequently offers many clues as to its overall health—and potentially what has happened in its history, especially if you become familiar with plant species (which, unlike animals, can’t run away, swim away, or fly off when they hear you approaching).
One recent weekend, I was hiking through a park located in Washington state and noticed an abundance of blackberry (Rubus armeniacus) and English ivy (Hedera helix), both of which are listed as noxious weeds by the state of Washington. The rest of the park, by comparison, had very few noxious weeds present, and was instead dominated in the understory layer by sword fern (Polystichum munitum), snowberry (Symphoricarpos albus), thimbleberry (Rubus parvilorus), and assorted mosses, lichens, and liverworts.
This localized invasion of noxious species was a curious thing—and indicative of some sort of ecosystem disturbance. Later that evening, I began to research the history of that park. As it turns out, the park does have a history of ecological disturbance—namely a pipeline spill that resulted in a fire that tore down the creek channel for more than a mile (and at a fairly wide swath). Although this happened nearly two decades ago, the landscape is still recovering, and it shows. In fact, the sources I was reading specifically called out the invasion of blackberry as one of the lasting consequences of the fire.
Ecological disturbances, like fire, can make it easier for opportunistic species (such as blackberries, yellow star thistle [Centaurea solsitialis], or cheatgrass [Bromus tectorum]) to move into an area previously dominated by native plants. However, it’s important to note that the disturbance doesn’t have to be dramatic, such as a fire or scouring flood. These species will also take advantage of lands that have been grazed, worn down through unauthorized uses, or developed, where they are often able to outcompete native plants.
You can learn more about the noxious weeds in your area by looking at your state’s noxious weed control board, using the US Department of Agriculture noxious weed list for your state, or through your local department of agriculture. By becoming familiar with these species (especially those listed as Class B or Class C), you’ll find that you start to notice more of them in the landscapes and ecosystems around you. At times, this may even feel disappointing (I’ve definitely said, “that plant is pretty, it must be invasive”) as you begin to recognize how many plants you enjoy greeting are, in fact, not so healthy for your local ecosystem.
If that’s how you find yourself feeling about a particular plant, remember that all of these plants also have a place where they are native and that, in many cases, the reason that we have local problems with invasive plants is precisely because they’re beautiful—and so someone planted them ornamentally, only to have the plants go rogue. Instead, we should focus on the fact that plants in their native ecosystems aren’t typically invasive; their numbers are kept in check by a variety of environmental factors, including predators, disease, and rainfall.
Learning to read the landscape—as well as understand how to tell when things in a particular landscape seem generally (even if not specifically) off can yield clues to the health of the landscape, the history of the landscape, and perhaps even ecological reclamation or restoration work that has taken place.
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