Researcher discovers threshold that triggers drought response in forests


Date:
February 21, 2023
Source:
University of Missouri-Columbia
Summary:
Missouri is home to an array of natural resources, with forests
among the state's most valuable ecosystems. As warmer temperatures
fueled by climate change affect ecosystems globally, forests are
under stress to adapt to these changes and ensure their survival
in a warmer world.

Researchers now introduce the 'ecosystem wilting point' concept,
which explains how whole forests respond to drought.


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FULL STORY ========================================================================== Missouri is home to an array of natural resources, with forests among
the state's most valuable ecosystems. As warmer temperatures fueled by
climate change affect ecosystems globally, forests are under stress to
adapt to these changes and ensure their survival in a warmer world.


==========================================================================
In a new study, University of Missouri researcher Jeffrey Wood introduces
the "ecosystem wilting point" concept, which explains how whole forests
respond to drought. Wood and his research team found that when forests
reach their ecosystem wilting point, they are less able to function
properly, which includes their ability to absorb carbon dioxide. To
learn how the forest behaved during periods of drought, Wood combined measurements of evapotranspiration (the loss of water to the air) and
ecosystem water status, which indicates how hydrated the forest is.

"The motivating reason for being able to understand the drought response
of forests is that, globally, drought is important now, and it's not
expected to get better," said Wood, an assistant professor in the College
of Agriculture, Food and Natural Resources. "We wanted to develop a
better way to understand and characterize these ecosystems, so we can
use that information to help with modeling the dynamics of vegetation
over time and better understand the future impact on these ecosystems."
In pursuit of understanding the nuances of forests' stress, Wood and
his co- authors reanalyzed data collected during an extreme drought
event that took place in 2012 in Baskett Forest, an outdoor laboratory
of 2,266 acres located five miles east of Ashland, Missouri. This study
uses a method that was initially developed to understand the interaction between water and an individual cell. That method was later applied to
leaves, and then Wood extended it in this study to analyze a whole forest.

In this study, this oak-hickory forest in central Missouri reaches its ecosystem wilting point between 2-4 weeks of extreme drought. At that
point, the forest would need soaking rainfall to rejuvenate.

"The ecosystem wilting point is functionally significant in that when
the forest passes that threshold, there is a noticeable change in how
the forest is behaving," Wood said. "When you get into that highly
stressed state, the forest is quite unresponsive to changes in the
environment. So, when the sun comes up, you would tend to think that
the forest turns on and starts to photosynthesize, but if the forest
is past its ecosystem wilting point, it has a very limited capacity
to respond to the changes in light in terms of carbon dioxide uptake
because it's under so much stress." This study offers insight into
the water relations of whole forests, a useful tool for researchers
exploring how forests across the globe handle temperature variations -- something Wood emphasizes is important as scientists manage forests in
a way that prepares them to better withstand climate change.

"Forests are pretty important; they're connected to weather and the
climate in ways that we still don't fully understand," Wood said.

* RELATED_TOPICS
o Plants_&_Animals
# Ecology_Research # Drought # Trees # Nature
o Earth_&_Climate
# Forest # Ecosystems # Ecology # Rainforests
* RELATED_TERMS
o Forestry o Forest o Conservation_ethic o Deforestation
o Marine_conservation o Slash_and_burn o Water_scarcity
o Biodiversity

========================================================================== Story Source: Materials provided by University_of_Missouri-Columbia. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Jeffrey D. Wood, Lianhong Gu, Paul J. Hanson, Christian Frankenberg,
Lawren Sack. The ecosystem wilting point defines drought response
and recovery of a Quercus‐Carya forest. Global Change Biology,
2023; DOI: 10.1111/gcb.16582 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/02/230221180113.htm

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