Deep South Texas is unique. It feels vast and nomadic, sprawling in all directions with hundreds of thousands of acres of ranchland and – if you don’t count the cows or the main thruways along the Rio Grande – sparsely populated. It’s a diverse region, thanks to the confluence of semi-arid and subtropical climates that meet in central South Texas to form a mixture of grasslands and extremely dry uplands.
The Zapata bladderpod is aptly named. It inhabits the Tamaulipan thornscrub, also known as mezquital, a dry ecoregion defined by shrubs and desertlike conditions, with seasonal marshlands and intermittent streams. As we search the dense thickets of shrubs and enormous prickly pear, Opuntia lindheimeri, I begin to think these plants don’t want to be found.
At a time when plants could help solve global environmental problems, scientists warn we must become more in touch with botanical education
The lack of botanical education and knowledge has become a problem, exacerbated by schools and universities in the UK reducing their teaching of basic plant science, including plant identification and ecology.
Researchers describe the lack of public knowledge as a self-accelerating cycle which risks “…the extinction of botanical education,” where biology is taught predominantly by people with research interests in animal science.
California’s giant sequoias have faced particularly fierce wildfires since 2015, the result of climate change and a lack of frequent fire over the prior century, according to the National Park Service. The imminent threat — which has now reached some of the state’s most exalted trees — has prompted scientists and firefighters to take exceptional steps to save them.
City lights that blaze all night are profoundly disrupting urban plants’ phenology – shifting when their buds open in the spring and when their leaves change colors and drop in the fall. New research I coauthored shows how nighttime lights are lengthening the growing season in cities, which can affect everything from allergies to local economies.
We found that artificial light alone advanced the date that leaf buds broke in the spring by an average of about nine days compared to sites without nighttime lights. The timing of the fall color change in leaves was more complex, but the leaf change was still delayed on average by nearly six days across the lower 48 states. In general, we found that the more intense the light was, the greater the difference.
We also projected the future influence of nighttime lights for five U.S. cities – Minneapolis, Chicago, Washington, Atlanta and Houston – based on different scenarios for future global warming and up to a 1% annual increase in nighttime light intensity. We found that increasing nighttime light would likely continue to shift the start of the season earlier, though its influence on the fall color change timing was more complex.
Why it matters
This kind of shift in plants’ biological clocks has important implications for the economic, climate, health and ecological services that urban plants provide.
On the positive side, longer growing seasons could allow urban farms to be active over longer periods of time. Plants could also provide shade to cool neighborhoods earlier in spring and later in fall as global temperatures rise.
A longer active season for urban plants also suggests an earlier and longer pollen season, which can exacerbate asthma and other breathing problems. A study in Maryland found a 17% increase in hospitalizations for asthma in years when plants bloomed very early.
What still isn’t known
How the fall color timing will change going forward as night lighting increases and temperatures rise is less clear. Temperature and artificial light together influence the fall color in a complex way, and our projections suggested that the delay of coloring date due to climate warming might stop midcentury and possibly reverse because of artificial light. This will require more research.
How urban artificial light will change in the future also remains to be seen.
Urban plants’ phenology may also be influenced by other factors, such as carbon dioxide and soil moisture. Additionally, the faster increase of temperature at night compared to the daytime could lead to different day-night temperature patterns, which might affect plant phenology in complex ways.