Last Updated on March 12, 2024 by Forest-Master-Sales
You may have noticed a couple of things happen over the last couple of weeks. It’s not dark by 3pm, it’s fractionally warmer (sometimes) and there’s a hint of colour with the first bloom of spring flowers. But you may have also noticed that the trees are starting to slowly peek through with fresh, new leaves – as if they are waking up from their winter slumber.
But why do most of the 60,000 different pieces of trees wake up in spring? What triggers this dramatic transformation?
Understanding why trees wake up after winter involves how they’re built, the seasons, and where they live. Trees are tough and can live in lots of places, from super cold to super hot. They’re good at feeling and dealing with changes around them, especially when it’s time to wake up from winter.
This process revolves around finding the right balance between growth and rest. In the winter, when it’s cold and there’s not much sunlight, trees go into a sleep-like state called dormancy. This helps them save energy and shield themselves from tough weather. During dormancy, trees slow down their metabolism and stop growing
As the days get longer and the weather gets warmer, trees have an internal clock called the circadian rhythm that starts working. This clock controls a lot of the tree’s functions, like, for example, how it grows. When the days get longer, the circadian rhythm tells the tree to start making a hormone called auxin.
Auxin is a hormone in plants that helps control how they grow and change. It’s made at the tips of growing parts of the plant and moves throughout it, making cells divide and stretch. When there’s more auxin around, the buds on branches get bigger, getting ready to grow more.
There’s more to growth than just auxin. Another hormone, gibberellin, also helps things grow. Gibberellin is made in the tree’s roots and travels up to the rest of the tree. It makes cells divide and stretch out. When there’s lots of gibberellin, the buds on the tree’s branches get longer, and the leaves start to come out.
When trees come out of their winter rest, it’s not just due to hormones. They also respond to factors like temperature and sunlight to fuel their growth. As the weather warms up and days lengthen, trees ramp up their metabolism, giving them the energy to grow. More sunlight also aids in photosynthesis, converting sunlight into energy for new growth.
Besides various factors inside and outside a tree, like its environment and genetics, trees also need the right mix of nutrients and water to grow well – they can redistribute up to 95% of the water they absorb (there are more stats below!). Even when trees aren’t actively growing in winter, their roots keep soaking up nutrients and water from the soil. These are stored in the trunk and branches. When spring arrives and the tree starts growing again, it uses up these stored nutrients and water to grow new leaves, branches, and roots.
Waking up after being dormant is a complex process for trees. It involves a mix of hormones, internal clocks, and outside signals. Trees are great at adapting to their surroundings to stay alive and grow. As we enjoy the green leaves of spring, let’s take a moment to admire the incredible biology behind it all.
