Study tracks decades of life cycle changes in nonwoody plants
One biologist made 600,000 observations over the course of the study


Date:
June 9, 2020
Source:
University of Illinois at Urbana-Champaign, News Bureau
Summary:
For 25 years, Carol Augspurger visited a patch of ancient woods
near Urbana, Illinois to look at the same 25 one-square-meter plots
of earth she first demarcated for study in 1993. Her 600,000+
observations revealed that herbaceous plants are shifting their
schedules in response to climate change, with distinct patterns
for early- and late-spring- emerging plants.



FULL STORY ==========================================================================
For 25 years, Carol Augspurger visited a patch of ancient woods near
Urbana, Illinois to look at the same 25 one-square-meter plots of earth
she first demarcated for study in 1993. She surveyed the plots once a
week in spring and summer, tracking the major life events of each of
the herbaceous plants that grew there. In fall, she visited every other
week. In winter, once a month.


==========================================================================
Over the course of her study, Augspurger made nearly 600,000 observations
of 43 plant species in Trelease Woods, a 60.5-acre remnant of old-growth
forest in central Illinois. She noted 10 distinct developmental stages in
the plants' lives, including when they emerged in spring, how long it took
them to mature, when the flowers opened and died, when the leaves began
to lose their greenness and when the plants went dormant. Augspurger
is a professor emerita of plant biology at the University of Illinois
at Urbana-Champaign.

By tracking these events and their relationship to average daily
temperature and precipitation records, Augspurger and her colleague,
Illinois Natural History Survey statistician and plant ecologist David
Zaya, found that some shifts in the timing of plant seasonal life cycle
events correlated with temperature trends.

The findings appear in the journal Ecological Monographs.

"We marked every major life cycle event in our plants from emergence
until they went dormant," Augspurger said. "And we did it for an intact community, a natural forest community." The analysis revealed that
by the end of the study in 2017, the first spring plants were emerging
almost four days later in March than they had in the early 1990s. But
their growing seasons were getting shorter: Dormancy was occurring six
days earlier. March average temperatures got slightly cooler over the
same time period, but April temperatures were rising.



========================================================================== Plants that emerged in late spring -- typically after April 1 --
were undergoing even more dramatic shifts. Their growing seasons were lengthening: The period from emergence to dormancy lasted more than
40 days longer for these plants at the end of the study than at the
beginning.

"For the early species, the growing season was a little bit shorter,"
Zaya said. "But for the late species, the growing season was 20 days
longer per decade." The duration of leaf expansion and flowering was
shorter for the late-spring plants, while senescence, their period
of aging, got longer. During senescence, plants gradually decline in
making sugar and transfer their energy stores underground, but they do
not produce new leaves, flowers or fruit. The increasing duration of
senescence corresponded with higher average temperatures in the fall.

"It may be that the late-spring species are benefiting from changing temperature trends by being able to grow and get carbon for a longer
period of time in the fall," Zaya said. "This suggests that there may
be winners and losers in the plant community as a result of climate
change, where some plants can respond more, some can respond less."
Many of the changes seen in the plants paralleled the temperature trends,
but the researchers caution that the study does not prove that changing temperatures are driving the seasonal life cycle shifts in plants. Tying
any specific trend in plants to climate change is tricky, Augspurger said.

"If you look at these 25 years of Illinois weather, climate change is
not happening uniformly every month of the year," she said. "The minimum temperatures are changing more than the maximums, for example, and March
is not changing as much as May. It's not only that the different plant
species may respond in different ways to the changes, but the weather
itself is changing differently." Regardless of the cause, the shifting patterns among plant species likely influence their interactions with herbivores, pollinators and each other, Augspurger said.

"What they do developmentally ultimately affects their ability to survive,
grow and reproduce," she said. "If they're changing their period of
activity, they're either going to have a shorter or longer time to gain
carbon, to absorb nutrients and to put it together into making flowers,
seeds and offspring. This can affect species' abundance and survival,
and the health of the overall ecosystem."

========================================================================== Story Source: Materials provided by University_of_Illinois_at_Urbana-Champaign,_News_Bureau.

Original written by Diana Yates. Note: Content may be edited for style
and length.


========================================================================== Journal Reference:
1. Carol K. Augspurger, David N. Zaya. Concordance of long‐term
shifts
with climate warming varies among phenological events and herbaceous
species. Ecological Monographs, 2020; DOI: 10.1002/ecm.1421 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/06/200609122916.htm

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