According to Mississippi State University, live oaks are salt-resistant and stand up to strong coastal winds and hurricane-force winds. The growing season of a live oak runs from late February until late September. In the spring, this "near" evergreen grows new leaves rapidly, replacing those lost during the winter. Pollen is spread by the wind between the male yellow flowered clusters and red, thin clustered female sections found on each single tree.
This type of pollination, with both male and female parts on one tree, is called "monoecious. In late September, acorns begin forming clusters at the tips of the branches, typically with three to five acorns on each cluster.
Acorns are green at first, later turning a shiny, dark chestnut brown. Each acorn is hidden in a cap one-third to one-quarter of an inch deep. Live oaks continue to produce acorns until December. If you would like to propagate live oaks in your yard, gather acorns only after they fall from the tree. If an acorn rattles when you pick it up, the seed will not grow.
Place the acorns in water, then heat the water until you can barely stand placing your hand in it. Unfortunately, plants and animals are no better at predicting the future than we are. Strangely, mast years are not simply resource-driven. Sure, a wet, cool spring can affect pollination and a hot, dry summer can affect acorn maturation.
But annual rainfall and temperature fluctuations are much smaller in magnitude than acorn crop sizes. In other words, weather variables cannot account for the excessive nutty production of acorns in a mast year. So what does trigger a mast year? Scientists have proposed a range of explanations—from environmental triggers to chemical signaling to pollen availability—but our understanding is not clear. Years of lean acorn production keep predator populations low, so there are fewer animals to eat all the seeds in a mast year.
Ultimately, a higher proportion of nuts overall escape the jaws of hungry animals. Whatever the reasons and mechanisms behind acorn cycles, mast years do have ecological consequences for years to come.
More acorns, for example, may mean more deer and mice. Unfortunately, more deer and mice may mean more ticks and consequently more Lyme disease. Many animals depend upon the highly nutritious acorn for survival. Oak trees, meanwhile, depend upon boom and bust cycles, and a few uneaten acorns, for theirs.
Amazing Acorn Facts. Why would someone in one area see an unusually heavy mast — that's the fruit and seed volume of forest trees — while someone else in the same general region might not? When it comes to the boom-and-bust cycles of nut production, blame Mother Nature and not the trees, said Kim Coder, a professor of tree biology and health care in the Warnell School of Forestry and Natural Resources at the University of Georgia.
They are also very localized. The primary weather factors influencing nut production are spring frosts, summer droughts and fall rains, Coder said.
And the most important of these are spring frosts. Trees have what Coder calls "inside timers" that tell them to do different things at different times, such as when to flower and hold fruit. Just how many acorns any single tree produces depends on many things. A common term for those good years is "a big mast year.
While it means a bountiful harvest of tree seeds and fruit, he stressed that it's important that people understand two things about what causes a big mast. One is that the weather, not the tree, is the driving force behind the harvest. The second is that the same harvest is not necessarily happening in equal proportions across a large blanket of the landscape.
Here's Coder's take on how nature doesn't play fairly from one year to the next. It begins with the oak tree's flowers:. The female flowers on oak and walnut trees are itty-bitty.
The internal timers tell the trees to open their buds in the spring after the danger of frost has passed. Once the buds flower, the blooms are open for only a week, during which time they are pollinated by the wind. However, a late frost when the flowers are open stops the flowering process. If that happens, the results show up in the fall with greatly limited nut production regardless of what happens with the weather in the summer and autumn. On the one hand, even if there's a good spring fruit set, summer droughts can cause acorn fungal problems that can limit production.
0コメント