Sep 14, 2020 09:48 PM
(This post was last modified: Sep 14, 2020 09:53 PM by C C.)
Q&A: La Nina may bring more Atlantic storms, western drought
https://apnews.com/8e547d1f6c20e5f529b6d80d4ec84462
Solving a mystery from the Dust Bowl to help plan for climate change
https://natsci.source.colostate.edu/solv...te-change/
EXCERPTS: Almost 100 years ago, there was a strange, slow-motion takeover of the Great Plains. During the Dust Bowl of the 1930s, as a historic heatwave and drought swept the middle of the United States, there was a dramatic shift in the types of plants occupying the region. Grasses more common in the cooler north began taking over the unusually hot and dry southern plains states that were usually occupied by other native grasses.
At the time, of course, this shift in plant cover was not the top concern during a disaster that displaced some 2.5 million people and caused at least $1.9 billion in agricultural losses alone. And, in fact, it didn’t seem all that strange - until scientists started learning more about these types of plants.
[...] During the 1960s, researchers found that there was a distinct ecological difference between these two types of what were thought of as warmer- and cooler-climate grasses (one group, known as “C4” use photosynthesis to produce a compound with four carbon atoms, compared to the other, known as “C3,” whose first photosynthesis compound is composed of just three carbon atoms). The C4 grasses grow best in warm temperatures and are more efficient at using water. The C3 grasses tend to be most abundant in cooler and wetter climates.
Which raised the question: Why, during an infamous drought and heatwave, would C3 grasses suddenly invade some 135,000 square miles of the south-central U.S.? Thus was born the “Dust Bowl paradox.”
[...] Why would these cool-loving, less-water-efficient C3 grasses have come to dominate the central U.S. during a historic heatwave and drought? Knapp and his colleagues discovered that it had less to do with the amount of precipitation and much more to do with when that precipitation falls.
During a normal growing year in the southern U.S. plains, the bulk of the moisture falls in the summer, during the growing season. But in the northern grasslands, precipitation patterns are more even throughout the year. It turns out that this is also what happens during extreme drought - precipitation is much less tied to the warm months, occurring more evenly through the year. So, with precipitation falling in patterns more like the northern plains during a drought in the south, C3 grasses found the bounds of their preferred rainfall dynamics extending southward. And they proliferated.
The researchers also found that the encroachment of C3 plants has a sort of self-fueling power. Because they start growing earlier in the year, “they can preemptively use soil water before C4 plants become active, further reducing the growth of C4 species..."
The paper, “Resolving the Dust Bowl paradox of grassland responses to extreme drought,” appeared Aug. 24 in PNAS, along with a paper by a fellow Department of Biology faculty member, University Distinguished Professor Diana Wall, who coauthored a paper titled, “Genetic diversity of soil invertebrates corroborates timing estimates for past collapses of the West Antarctic Ice Sheet.” (MORE - details)
https://apnews.com/8e547d1f6c20e5f529b6d80d4ec84462
Solving a mystery from the Dust Bowl to help plan for climate change
https://natsci.source.colostate.edu/solv...te-change/
EXCERPTS: Almost 100 years ago, there was a strange, slow-motion takeover of the Great Plains. During the Dust Bowl of the 1930s, as a historic heatwave and drought swept the middle of the United States, there was a dramatic shift in the types of plants occupying the region. Grasses more common in the cooler north began taking over the unusually hot and dry southern plains states that were usually occupied by other native grasses.
At the time, of course, this shift in plant cover was not the top concern during a disaster that displaced some 2.5 million people and caused at least $1.9 billion in agricultural losses alone. And, in fact, it didn’t seem all that strange - until scientists started learning more about these types of plants.
[...] During the 1960s, researchers found that there was a distinct ecological difference between these two types of what were thought of as warmer- and cooler-climate grasses (one group, known as “C4” use photosynthesis to produce a compound with four carbon atoms, compared to the other, known as “C3,” whose first photosynthesis compound is composed of just three carbon atoms). The C4 grasses grow best in warm temperatures and are more efficient at using water. The C3 grasses tend to be most abundant in cooler and wetter climates.
Which raised the question: Why, during an infamous drought and heatwave, would C3 grasses suddenly invade some 135,000 square miles of the south-central U.S.? Thus was born the “Dust Bowl paradox.”
[...] Why would these cool-loving, less-water-efficient C3 grasses have come to dominate the central U.S. during a historic heatwave and drought? Knapp and his colleagues discovered that it had less to do with the amount of precipitation and much more to do with when that precipitation falls.
During a normal growing year in the southern U.S. plains, the bulk of the moisture falls in the summer, during the growing season. But in the northern grasslands, precipitation patterns are more even throughout the year. It turns out that this is also what happens during extreme drought - precipitation is much less tied to the warm months, occurring more evenly through the year. So, with precipitation falling in patterns more like the northern plains during a drought in the south, C3 grasses found the bounds of their preferred rainfall dynamics extending southward. And they proliferated.
The researchers also found that the encroachment of C3 plants has a sort of self-fueling power. Because they start growing earlier in the year, “they can preemptively use soil water before C4 plants become active, further reducing the growth of C4 species..."
The paper, “Resolving the Dust Bowl paradox of grassland responses to extreme drought,” appeared Aug. 24 in PNAS, along with a paper by a fellow Department of Biology faculty member, University Distinguished Professor Diana Wall, who coauthored a paper titled, “Genetic diversity of soil invertebrates corroborates timing estimates for past collapses of the West Antarctic Ice Sheet.” (MORE - details)