Op-Ed: Will we ever have to ask, ‘Where have all the flowers gone?’
Searching California’s wildlands for native plants has been likened to treasure hunting, for good reason. More than most places, our state is endowed with a flora that is both fabulously rich and alluringly evasive. As everyone who observed the recent desert super blooms or poppy apocalypse knows, botanical bonanzas sometimes appear where they haven’t been seen for years and then vanish in a few weeks.
Those of us who are addicted to looking for our state’s thousands of native plants become used to frequent disappointment. If the winter was too dry or the grass is too long or we are just not in exactly the right place at the right time, we won’t find the colorful gem we are seeking. Plants are no dummies. Over evolutionary time, our fickle climate pattern with its brief growing season, nearly endless summer, intermittent droughts and landscape-transforming fires has honed their abilities to hide from adversity. Biding their time in the soil, waiting for the happy promise of enough sunlight and water at the right time, seeds or bulbs may remain dormant for many years.
Hiding and waiting is a great strategy as long as droughts are temporary. But as our climate becomes warmer, increased evaporation will make it effectively ever drier, and rainfall will arrive ever less predictably at the right time of year. Native plants will thus face long-term increases in water stress, often exacerbated by intensified fire and shifts in their delicate coexistence with exotic species. My research has aimed to understand how well Californian native plants are coping with these changes.
Growing up in Sonoma Valley in the 1960s, I used to hear my mother sigh about the beautiful poppy- and lupine-covered hillsides she saw a decade earlier. Suburbs and vineyards had since consumed them, as has been the case in so much of our state.
But as a field ecologist working at relatively remote field sites, and becoming increasingly climate-conscious, I found myself asking questions like: Are the foothill poppy displays as intense after a 2017 chaparral fire as they were after a nearby fire in 1999? Are the grasslands less solidly blue with sky lupines in the wet winter of 2018-19 as they were in the winter of 2005-06? Is this landscape just a little less flowery than when I first saw it 30-plus years ago, or have I been tricked into imagining that by nostalgia and the ever-shifting backdrop of the seasons and years?
Those of us with the good fortune to be employed as field ecologists sometimes find ourselves with valuable long-term data sets, usually at around the same life stage when our hair turns fully gray. Many of these studies began decades ago for totally different reasons and later metamorphosed into climate change analyses. Since the 1990s, my collaborators and I began to study how Californian plant diversity was shaped by fire, grazing and soils. Five years ago, we began to see signs that diversity was being affected by climate.
In a Northern Californian grassland landscape, we found that the diversity of native annual plants declined over a 15-year (now 20-year) period in which most winters were drier than the long-term average. Wet winters toward the beginning of this period caused upward spikes in native plant diversity, but wet winters in later years did not. Statistical and experimental evidence suggested that the dry winters caused high seedling mortality, depleting the all-important supply of dormant seeds in the soil, in turn lessening the resilience of diversity in these native plant communities to yearly climate fluctuations. At the same time, although invasive species hadn’t increased as a whole, some of them had become more common and others less so. While still vibrant, this grassland landscape lost some of its botanical color and variety even during my brief time studying it. Our results suggest that its recovery would require a rather unlikely long spell of wet and not-too-warm years, but I’ll keep watching and hoping for the best.
Of course, my grassland study is only one small case of modern ecological change among so many. Moderate shifts in the diversity of plant communities have been found in my study and others, but the terrifying mega-fires and drought-caused tree die-offs in Sierra forests are far harsher manifestations of what warming and drying (combined with other factors) can do to Californian vegetation.
In the largest picture, California and the world are entering a time of what ecologists call “vegetation-climate disequilibrium,” otherwise known as the environment changing faster than plants are likely to keep up.
Pessimists among us fear that the ensuing rapid changes will mainly benefit fast-moving, already abundant and ecologically flexible invasive species, to the still further detriment of native plants. But we could be wrong. And some ecosystems may resist change more than others. For instance, although California’s chaparral vegetation is at risk from too-frequent fire and warmer post-fire weather, another Northern Californian study we conducted found chaparral plant diversity to recover just as well after a 2017 fire as a 1999 fire — foothill poppies included.
Faced with rapid environmental change, all those who love nature will need to broaden that love to embrace future landscapes much different from those of our childhoods. Whatever conservation means in the future, it will be less about yearning for an idealized past and more about identifying what elements of nature we most value and think we can save. At the end of such conversations, my standard half-joking advice is to learn to love activities like hiking in burned forests and admiring the woodpeckers hard at work recycling the dead trees.
Susan Harrison is a professor in the Department of Environmental Science and Policy at UC Davis and a member of the National Academy of Sciences.
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