A few rare California grasslands have a unique quality–the soil contains the mineral serpentinite. That unusual trait has a surprising advantage for such grasslands. Serpentine soil is low in calcium and other common plant nutrients, while rich in elements toxic to plants. Very few plants, some of which are found nowhere else in the world, can grow in serpentine soil. The endemic plants that do manage to survive benefit from the adverse soil conditions, which make the region highly resistant to invasive plant species. Serpentine grasslands are ecologically stable, however, even these hardy grasslands are not immune to destructive human activities. California native grasslands are in danger of fading into nondescript amalgams due to invasive species.

Invasive grasses choking native California Poppies. Photo by John Fellner

Researchers at University of California, Santa Cruz discovered that nitrogen pollution has changed the soil composition in these unusual grasslands–making the Earth more fertile and livable for the average plant. Invasive plants are capitalizing on the increased soil fertility, taking root and altering the landscape in an unprecedented way. Native plants, having never previously had to cope with competitors, are defenseless against the invaders. The ecological identity of these grasslands is now in question, and researchers are working hard to restore their uniquely Californian, self-protective compositions.

This is one of countless stories of the the destruction brought on by environmental degradation and invasive species. On islands, native species often evolve free of predators and competitors. They are protected by the conditions of their home–remote, isolated, inaccessible–and so they have no evolutionary pressure to develop defenses. When an invasive species is suddenly introduced to an island, the results can be devastating. Rare species that are adapted to very specific conditions become highly vulnerable when even a small change to those conditions occurs. That small change can have huge consequences: it can–and has–driven rare species to extinction, and threatens many more.

Read the full article at UC Santa Cruz NEWSCENTER

Learn more about the research at the Zavaleta Lab