Global warming is changing our plant communities

Date:
August 17, 2020
Source:
University of Miami
Summary:
In a comprehensive study of nearly 20,000 species, research shows
that plant communities are shifting to include more heat-loving
species as a result of climate change.



FULL STORY ========================================================================== Although Live Oak trees are common in South Florida today, Ken Feeley,
a University of Miami biology professor, said their time here may be
fleeting.

With climate change pushing up temperatures, the oaks, which favor cooler conditions, could soon decline in the region and be replaced with more tropical, heat-loving species such as Gumbo Limbo or Mahogany trees.


========================================================================== "Live Oaks occur throughout the southeast and all the way up to coastal Virginia, so down here we are in one of the very hottest places in its
range," said Feeley, who is also the University's Smathers Chair of
Tropical Tree Biology. "As temperatures increase, it may simply get too
hot in Miami for oaks and other temperate species." Likewise, in Canada,
as temperatures increase, sugar maple trees -- which are used to produce
maple syrup -- are losing their habitats. And in New York City, trees that
are more typical of the balmy South, such as Magnolias, are increasing
in abundance and blooming earlier each year, news reports indicate.

These are just a few examples of a larger trend happening across the
Americas - - from Hudson Bay to Tierra del Fuego -- as plant communities
shift their ranges and respond to changing climates, Feeley pointed
out. In his newest study, published in Nature Climate Change, Feeley,
along with three of his graduate students and a visiting graduate student
from the Nacional University of Colombia, analyzed more than 20 million
records of more than 17,000 plant species from throughout the Western Hemisphere. They found that since the 1970s, entire plant ecosystems have changed directionally over time to include more and more of the species
that prefer warmer climates. This process is called thermophilization.

"Almost anywhere you go, the types of species that you encounter now
are different than what you would have found in that same spot 40 years
ago, and we believe that this pattern is the direct result of rising temperatures and climate change," Feeley said.

The research of Feeley and his students demonstrates that entire
ecosystems are consistently losing the plant species that favor
cold temperatures, and that those plants are being replaced by more heat-tolerant species that can withstand the warming climate. Plants
favoring cool temperatures are either moving to higher elevations and latitudes, or some species may even be going locally extinct. Feeley
and his students are now exploring key focal species that may offer more insight into these processes.

"Some of these changes can be so dramatic that we are shifting entire
habitat types from forests to grasslands or vice versa -- by looking
at all types of plants over long periods of time and over huge areas,
we were able to observe those changes," he explained.

In addition to the effects of rising temperatures, the researchers
also looked at how plant communities are being affected by changes in
rainfall during the past four decades. Feeley and his team observed
shifts in the amounts of drought-tolerant versus drought-sensitive plant species. But in many cases, the observed changes were not connected to
the changes in rainfall. In fact, in many areas that are getting drier,
the drought-sensitive species have become more common during the past
decades. According to Feeley, this may be because of a connection between
the species' heat tolerances and their water demands.

Heat tolerant species are typically less drought-tolerant, so as rising temperatures favor the increase of heat-tolerant species, it may also indirectly prompt a rise in water-demanding species. Feeley stressed
that this can create dangerous situations in some areas where the plant communities are pushed out of equilibrium with their climate.

"When drought hits, it will be doubly bad for these ecosystems
that have lost their tolerance to drought," he said, adding that
"for places where droughts are becoming more severe and frequent --
like in California -- this could make things a lot worse." But the implications of thermophilization go far beyond just the loss of certain plants, according to Feeley. Plants are at the base of the food chain
and provide sustenance and habitat for wildlife -- so if the plant
communities transform, so will the animals that need them.

"All animals -- including humans -- depend on the plants around them,"
Feeley said. "If we lose some plants, we may also lose the insects,
birds, and many other forms of wildlife that we are used to seeing in
our communities and that are critical to our ways of life. When people
think of climate change, they need to realize that it's not just about
losing ice in Antarctica or rising sea levels -- climate change affects
almost every natural system in every part of the planet."

========================================================================== Story Source: Materials provided by University_of_Miami. Original written
by Janette Neuwahl Tannen. Note: Content may be edited for style and
length.


========================================================================== Journal Reference:
1. K. J. Feeley, C. Bravo-Avila, B. Fadrique, T. M. Perez, D. Zuleta.

Climate-driven changes in the composition of New World plant
communities.

Nature Climate Change, 2020; DOI: 10.1038/s41558-020-0873-2 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200817124912.htm

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