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  • Take a look outside a window.

  • What is the season where you are?

  • How do you know?

  • Most likely, you looked at a tree or plant

  • and noticed details about its leaves

  • and assessed the qualities of sunlight streaming outside.

  • Observing the timing of biological events

  • in relation to changes in season and climate

  • is called "phenology".

  • When you notice the daffodil buds are poking through the snow

  • and think spring is on its way,

  • you're using phenology.

  • When you see leaves turn from green to red,

  • and watch migrating birds fly past,

  • and realize that summer is over, autumn is here,

  • you're using phenology.

  • Literally meaning, "the science of appearance",

  • phenology comes from the Greek words

  • "pheno," to show or appear,

  • and "logos," to study.

  • Humans have relied on phenology

  • since the time of hunters and gatherers.

  • We've watched changes in seasons

  • to know when to plant and harvest food

  • and when to track migrating animals.

  • Scientists observe and document seasonal changes in nature

  • and look for patterns in the timing of seasonal events.

  • Timing of these natural signs has remained consistent until recently.

  • Increasing global temperature is causing rhythms of nature to shift.

  • Bud burst, the day when a tree or plant's leaf or flower buds open,

  • is occurring earlier in the year for some species.

  • For every one degree Celsius rise in temperature,

  • bud burst happens five days earlier than usual.

  • Differences in timing affect not only plants,

  • but the insects and birds that depend on the plants for food.

  • For example, oak trees in the Arnhem Forest of the Netherlands

  • now experience bud burst ten days earlier,

  • as compared to twenty years ago.

  • New oak leaves are a favorite food of winter moth caterpillars.

  • To survive, the caterpillars adapted

  • to the change in the tree's timing,

  • and now hatch 15 days earlier than before.

  • Migrating pied flycatcher birds, however,

  • aren't doing as well.

  • The birds prefer to feed their chicks winter moth caterpillars.

  • The caterpillars are now hatching earlier,

  • but the birds' chicks are not.

  • This delay is costing the birds a food source.

  • The pied flycatcher population has decreased

  • by up to 90% in some areas as a result.

  • Changes to a seemingly simple event,

  • leaves opening,

  • has ripple effects throughout a food web.

  • Earlier bloom times can also have an economic impact.

  • The famed cherry blossoms in Washington D.C.

  • are blooming five days earlier than before.

  • Since the cherry trees are blooming earlier,

  • the blossoms also fade earlier,

  • frustrating thousands of tourists who visit

  • for the Cherry Blossom Festival.

  • High school marching bands plan

  • all year to attend the parade

  • and perform, surrounded by a majestic white canopy.

  • How disappointing for them to find, well, trees

  • rather than the famous cherry blossoms!

  • Plants and animals react to changes in natural light and temperature.

  • Increasing temperatures cause plants to bloom earlier than before,

  • and become out of sync with the insects and birds in a food web.

  • So, the next time you look out your window

  • and notice what season it is,

  • you may be fooled by those blooming trees.

  • Think of phenology,

  • then think of how you can play a part to slow climate change.

Take a look outside a window.

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B2 TED-Ed earlier timing cherry migrating blooming

【TED-Ed】Phenology and nature's shifting rhythms - Regina Brinker

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    wikiHuang posted on 2014/01/19
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