Aughh! They're coming. . . the plants!

You may wonder why the hell I'm putting up a summary of my class lecture--well, this rewrite helps some of the information stick in my cranial folds.

Tonight's lecture was "Pathways and Dynamics of Plant Invasions." Yes, it was not that exciting. Before the first break I had trouble staying awake--less the prof's fault than perhaps low blood sugar.

Anyway, plant species move to new areas by two primary means: natural pathways (which always existed) i.e. atmospheric, oceanic, and river currents and, of course, us. Natural pathways usually deposited plants along coastlines whereas humans can move them much further in an interior.
Human dispersal has two ways as well--deliberate e.g. commerce, taking the pretty flowers and planting them in our garden 3,500 miles away (now how did that loosestrife end up way over here?), and using species like kudzu to halt soil erosion. That did stop the erosion, but caused other problems. The other method is accidental.
Worldwide New Zealand has the highest percentage of non-indigenous plant species with a total of 50 (holy shite!)% of their present species originating elsewhere. In the U.S. Hawaii has the highest percentage and California the highest absolute number of invasive plant species.

Invasives can be successful (see the rule of tens in a previous post) because they can make use of resources that the natives can't.
There are several theories for plant invasions: species-area relationship, equilibrium theory (put forth by Mr. Berry's buddy E.O. Wilson), metapopulations, and landscape ecology. Obviously, I'm not going in to detail, suffice it to say the more invasives the more success you'll have. There are also three barriers plants have to make it through to successfully colonize a new area: the biological, the physical (like road use, for instance), and environmental (soil conditions, climate, etc.)

What is the largest single factor in plant invasions? Disturbances. So back off with the freakin' bulldozer when you're landscaping, will ya?