Eriophyllum lanosum, one of the desert winter annuals that Larry Venable, an ecologist at the University of Arizona in Tucson, and his collaborators monitored for 26 years. The photo was taken in March 2008.
Click on image for full size
Image Courtesy of Jonathon Horst
Even in the Desert, Plants Feel the Heat of Global Warming
Scientists who study plants in the Sonoran Desert are worried about global warming.
While desert winters have become warmer and drier over the years, climate changes have pushed the arrival of winter rains later in the winter season, forcing some winter annual plants to come out when temperatures are colder.
In 1982, Larry Venable, an ecologist at the University of Arizona (UA) in Tucson, began an investigation on "bet-hedging" in plants. Bet-hedging is an adaptation seeds make that allows them to remain dormant for a period of time if conditions in the environment make germination and survival less likely. This delay can be caused by lack of rainfall, lack of nutrients, temperatures that are too hot or too cold, or any other condition that would affect the survival of a seed. Bet-hedging allows a plant to improve chances of survival.
The later arrival of Sonoran desert winter rains pushes the germination of the winter annuals later into the year and has affected the types of winter annuals that do well there. Researchers measure carbon and nitrogen in the plants' leaves to learn how well the various species grow at winter's lower temperatures. The amount of carbon in a plant's leaves tells scientists how well a plant has adapted to water storage in cold weather. Higher amounts of nitrogen can mean that the plant is better at gathering light in cold weather and is better able to photosynthesize.
If plants are better at photosynthesis, they are more able to use energy from sunlight and convert it into food, which improves the plant's chances for survival. They also found that plants that are better at storing water do better in colder environments.
If the later arrival of winter rains continues, the germination of the winter annuals will continue to occur later in the year, and the plant community will continuously change and favor plants that do well in colder environments.
Shop Windows to the Universe Science Store!
Our online store
includes fun classroom activities
for you and your students. Issues of NESTA's quarterly journal, The Earth Scientist
are also full of classroom activities on different topics in Earth and space science!
You might also be interested in:
Over 100 years ago, people worldwide began burning more coal and oil for homes, factories, and transportation. Burning these fossil fuels releases carbon dioxide and other greenhouse gases into the atmosphere....more
Rain is precipitation that falls to the Earth in drops of 5mm or more in diameter according to the US National Weather Service. Virga is rain that evaporates before reaching the ground. Raindrops form...more
There is more nitrogen gas in the air than any other kind of gas. About 4/5ths of Earth's atmosphere is nitrogen gas! A molecule of nitrogen gas is made up of two nitrogen atoms. There are other molecules...more
Photosynthesis is the name of the process by which autotrophs (self-feeders) convert water, carbon dioxide, and solar energy into sugars and oxygen. It is a complex chemical process by which plants and...more
Scientists have learned that Mount Hood, Oregon's tallest mountain, has erupted in the past due to the mixing of two different types of magma. "The data will help give us a better road map to what a future...more
The Earth's mantle is a rocky, solid shell that is between the Earth's crust and the outer core, and makes up about 84 percent of the Earth's volume. The mantle is made up of many distinct portions or...more
Some geologic faults that appear strong and stable, slip and slide like weak faults, causing earthquakes. Scientists have been looking at one of these faults in a new way to figure out why. In theory,...more