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"There isn't much out there for them to eat," said Randy Tucker, a biologist for the state Division of Natural Resources. "When animals have to travel to find food, they sometimes cross roads. When they cross roads, they sometimes get hit."
A serious shortage of mast -- nuts, fruits and other wildlife foods -- promises to make the road-kill situation worse than it otherwise might be. DNR biologists recently completed their Mast Index Survey, an annual assessment of the state's wild food production. Tucker said this year's mast crop is the worst in the survey's 40-year history.
"There's always some mast out there, and there are always some areas of relative mast abundance," he explained. "But what is out there this year is really spotty. Overall, the food situation is dismal."
In a normal year, shortages in one type of mast would be compensated for by abundances in another. Last year, for example, acorns were relatively scarce but hickory nuts and beechnuts were plentiful. Sassafras and greenbrier were hard to find, but crabapples and hawthorn were present in abundance.
This year, every wildlife food item except dogwood is running below the Mast Survey's long-term average. Beechnuts, for example, are running 46 percent under their long-term average; walnuts, 23 percent; hickory nuts, 22 percent; white oak acorns, 48 percent; chestnut oak acorns, 64 percent; black and red oak acorns, 42 percent; scarlet oak acorns, 32 percent; black cherry, 30 percent; apples, 66 percent; and crabapples, 39 percent.
"Ordinarily, you don't get shortages of hard mast items and soft mast items in the same year," Tucker said. "This year we did. It's kind of a double whammy."
Not even dogwood, the lone mast item that exceeded its long-term average, can be considered abundant. It's up exactly 1 percent from normal.
"The problem with dogwood, too, is that there isn't nearly as much of it as there used to be," Tucker said. "A disease, dogwood anthracnose, has killed off a lot of trees. So even a relative abundance of dogwood isn't exactly good news."
Biologists expect the shortage to have short-term and long-term effects on Mountain State wildlife. Squirrels and other small mammals will suffer on the highways. So, to a lesser extent, should deer and bears. But wildlife officials' main concerns are for what might happen during the upcoming winter and the following spring.
"Wildlife use mast to store up energy reserves for the winter," Tucker explained. "With food so scarce this fall, animals will enter the winter on a lower nutritional plane. First of all, they'll have to expend more energy simply to find the little bit of food that's available. And even when they find it, they won't have as much to eat as they usually do.
"If we have a really hard winter, some animals won't have the energy reserves they need to survive harsh weather conditions. If we get a late freeze or a big snowstorm in March or April, there's a good chance we might get some winterkill, especially among deer."
Tucker also expects the mast shortage to reduce animals' breeding success.
"Ultimately, the condition in which animals come through the winter affects breeding," he said. "Animals that enter the winter on a low nutritional plane are going to have very low reserves when the breeding season comes along the following spring."
Female bears and deer, which become pregnant in the fall and deliver their young in the spring, also stand to suffer from the current food shortage. Malnourished sow bears sometimes reabsorb their fetuses while in hibernation rather than give birth. Doe deer might bear one fawn instead of two.
"A lot of the outlook for deer will depend on how early the trees 'green up' next spring," Tucker said. "Those fawns are getting ready to drop by mid-May. If we don't get an early green-up, it will affect the does' carrying of fawns."
DNR officials generally avoid using the term "mast failure," but Tucker said there's no other way to describe the current situation.
"The grocery store [for wildlife] is pretty empty right now," he said. "It's hard to look at the situation and not call this a mast failure. A winter with really bad weather will only elevate the seriousness of what we're starting to see now."
Plants take in the carbon dioxide they need for photosynthesis through microscopic breathing pores in the surface of leaves. But for each molecule of the gas gained, they lose hundreds of water molecules through these same openings. The pores can tighten to save water when CO2 is abundant, but scientists didn't know how that worked until now.
A team led by Julian Schroeder, professor of biology at the University of California, San Diego, has identified the protein sensors that control the response. Enzymes that react with CO2 cause cells surrounding the opening of the pores to close down they report in the journal Nature Cell Biology online December 13.
The research isn't really about whether high levels of CO2 might damage plants, but rather about how to harness this mechanism to genetically modify crops - so that's why it has been suggestive but not definitive for my purpose of trying to understand what is killing trees. However having listened to RPauli's lecture, I am wondering if CO2 levels are actually the root cause because they are rising at much higher rates than plants can adapt to by limiting the number of stomata in their leaves. So perhaps trees are dying because their leaves are losing water because they have too many stomata for the current level of CO2 in the atmosphere! That is certainly how they have looked the last two summers - wilted.
Here's another provocative study, which has this to say:
“As human activity continues to raise atmospheric carbon dioxide levels, a better understanding of how plants respond to carbon dioxide is becoming imperative,” said Julian Schroeder, a professor of biology at UCSD who directed the project. “Our results provide new insights into how an increased concentration of atmospheric carbon dioxide leads to changes within a plant cell that trigger the closing of the stomata—the breathing or gas exchange pores in the leaf surface.”
And, as usual, concludes we just don't know much:
“These molecular mechanisms are like fundamental parts of machinery,” explained Young. “It's hard to predict what an instrument will do, if you don't even know anything about the parts that it is made from.
Similarly, this tantalizing report also examines, tangentially, the relationship between CO2 and the behavior of stomata, as it affects the nitrogen and water cycles, where a co-author concludes:
"Our environment and quality of life depend on less uncertainty on this front."
On the other hand:
“When ozone enters the leaf through the stomatal pores, it damages the plants photosynthetic machinery and basically causes green leaves to lose their color, a process called chlorosis,” said Julian Schroeder, a professor of biological sciences at UC San Diego and one of the principal authors of the recent study. “Plants have a way to protect themselves and they do that by closing the stomatal pores when concentrations of ozone increase.”
While this protective mechanism minimizes the damage to plants, he adds, it also minimizes their ability to photosynthesize when ozone levels are high, because the stomatal pores are also the breathing holes in leaves through which carbon dioxide enters leaves. The result is diminished plant growth or at least less than one might expect given the rising levels of carbon dioxide.
Some scientists assessing the impacts of rising greenhouse gases had initially estimated that increased plant growth generated from extra carbon dioxide in the atmosphere could sequester much of the excess atmospheric carbon in plant material. But in a paper published last July in Nature, researchers from Britain’s Hadley Centre for Climate Prediction and Research concluded that the damage done to plants by increasing ozone pollution would actually reduce the ability of plants to soak up carbon from the atmosphere by 15 percent which corresponds to about 30 billion tons of carbon per year on a global scale---a dire prediction given that humans are already putting more carbon into the atmosphere than plants can soak up.
"Heat waves, droughts and fuel prices are just a few reasons for the current global food crisis that is making headlines around the world. Research by William Manning of the University of Massachusetts Amherst indicates that rising background levels of ozone in the atmosphere are a likely contributor to the problem, lowering the yield of important food crops, such as wheat and soybeans.'Plants are much more sensitive to ozone than people, and a slight increase in exposure can have a large impact on their productivity,' says Manning, a professor of plant, soil and insect sciences. 'The new ozone standard set by the U.S. EPA in March 2008 is based on protecting human health, and may not be strict enough to protect plants.'"




















