Northern California Is Already Losing Wildflowers Because of Climate Change

A study of a reserve near Davis finds a decline in wildflower diversity since 2000.

California is in the middle of a severe drought now, with more likely on the way, as a result of climate change. One potential consequence of this water shortage? Some of California’s native wildflower species may vanish, according to a new study—and, in fact, that’s happening already.

Between 2000 and 2014, environmental researchers sampled wildflowers at dozens of sites throughout the McLaughlin Natural Reserve outside of Davis, California. The researchers found that the number of wildflower species living in different patches has declined steadily throughout the reserve. Native wildflowers took the biggest hit, but some introduced species fell off, too. The decline is steep enough that it’s noticeable to a “relatively casual observer,” the researchers write in their paper, published this week in the Proceedings of the National Academy of Sciences.

A California grassland with less plant diversity might be one that’s less productive and resilient against problems.

With statistics, the research team was able to link the disappearing flowers to diminishing wintertime rainfall in the area and not to other stresses, such as wildfires, or munching cattle. Some, but not all, climate models predict that global warming will cut the amount of rain California receives. So what’s happening now could be a predictor for the future, as global warming increases in severity.

The trend is worrisome because other studies have found that having many plant species in an environment helps that area retain nutrients, resist invading non-native species, and support more life. A California grassland with less plant diversity might be one that’s less productive and resilient against problems.

This isn’t the first study to notice that places’ plant populations are already changing because of global warming. One previous study found that Mediterranean mountains lost plant species between 2001 and 2008; boreal European mountains, meanwhile, actually gained species. The difference, the authors of that study hypothesize, is that boreal mountains were colder to begin with, so those mountains’ warmer temperatures, particularly on their higher slopes, may have encouraged more plants to grow. Meanwhile, Mediterranean mountains were warmer to start and have only gotten drier and hotter since 2001, like California is expected to.

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