A HIDEOUS PATTERN: INVASIVE SPECIES


Let us introduce you to Amanda James; a PhD student in environmental sciences at the University of California, and a Descience participant. We asked Amanda to tell us about her research involving plant species that are outcompeting and destroying native ecosystems. How can we prevent this from happening? Read and learn.

--“You study plants in school right?”

--“Yeah…that’s pretty much my entire graduate project Dad. Why do you ask?”

--“Well, why are all the plants so ugly here during the summer? I mean, are all these plants brown because they’re dead?”

Many Southern California residents don’t know that the brown painted hills are actually not Californian at all. On the contrary, our native coastal sage scrub communities are beautifully diverse with colors ranging from silvery sea greens to deep evergreen hues.

Having been born and raised in beautiful Southern California, I am thankful for living in such a biologically diverse region where an hour drive can take you to the beach, to the snow in the mountains, to the desert, and down to the valley.

--“Diverse? Where? Isn’t it like… paved everywhere?”

While this is true for a large portion of Southern California, we do have remnant swathes and parcels of land that are undeveloped or conserved as biological “islands.” Given our unique and very habitable climate of Mediterranean warm summers and relatively mild winters, there is a wide breadth of organisms that call Southern California home. However, living in such a warm and comfortable environment not only lures mobs of vacationers to our inviting beaches and pleasant environs, but it also rolls out the welcome mat for another unwanted and unexpected invasion… exotic species!

Exotic species, such as invasive annual plants introduced in the early 18th

Spanish exploration, replace native coastal sage shrubland. Invasive annuals do this quickly, when the winter rains arrive or after fires, by choking out native perennial seedlings. By rapidly outcompeting California natives, they hoard valuable resources such as nutrients and water. Just as soon as they appear, they are gone; leaving behind a sea of dead plant material, hence the “ugly” my Dad refers to. The proliferation of fast growing, and dying, inasives further drives the loss of native California plant communities through increased fire stress and suitable habitat loss.

With invasives being detrimental to the environment in which they permeate, I often compare them to poorly constructed fabric. An example would be in constructing a shirt from scratch. To begin this endeavor one needs to begin with a good quality fabric. However, small defects, such as broken threads, degrade the quality and life of the garment, just as exotics degrade the quality of the ecosystem that they invade. The more defects you have, or invasives, the more the fabric will fail with increased use. As one thread breaks, others follow suit. This is similar to the demands on natural systems to support increased pressures, such as increased pedestrian and recreational traffic or increased pollution input. Eventually with enough weak points, the shirt falls apart, unable to withstand the stresses of being worn. In terms of ecosystem functioning, exotics perform the same, eventually breaking down order and synergy in the system; creating disruptions (i.e. holes in the shirt) that prevent native plant growth. Ultimately, changes in plant community composition lead to large scale vegetation type conversions that disrupt ecosystem services such as clean air and a fresh water supply.

All regions of California are vulnerable to the invasion. However, we can all engage in

preventive actions! It all starts with education; knowing what is and what isn’t native in your region is a good start. There is no need to be a Botanist in order to distinguish the characteristic features of native plants, such as a leaf shape, flower color, and growth pattern. Something as simple as a visit to your local arboretum, botanical garden, natural history museum or a quick internet search can accomplish this. The next step is to learn how you can take personal actions.

For instance; do you see invasive kudzu growing in your yard? Do you see exotic iceplants encroaching on a public space? By making sure that your own property is clear of invasives and encouraging your neighbors to do the same are great ways to curb the spread of exotics.

In addition, sending a letter, or speaking with your local representatives about how invasion reduces your right to clean air and water is another small, yet important step. Some communities even have group action days where members can help remove pests in addition to getting a great workout! Lastly but not least, is to simply support native plant growth. This can be done by selecting native plants for your landscaping, or by encouraging your city to promote native “green spaces” in order to slowly replace invasive plants. For additional tips and ideas on making a native plant garden, please refer to this region-specific guide presented by the National Wildlife Federation.

(http://www.nwf.org/Garden-For-Wildlife/About/Native-Plants.aspx)

To conclude, Californian’s can all do something about the dead annual wastelands of summer, and you can make a difference in your own community as well! A step in the right direction, no matter how small, makes for great strides as we all make them together. We are all capable of resisting the invasion.


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