Although autumn leaves have mostly fallen by this time of year, you may have noticed that a few are still hanging on–especially on our native oak trees (Quercus spp). As with so many things, there’s actually a word for that!
Leaf marcescence is the term for the tendency of certain trees (notably oak, beech and chestnut) to keep many of their leaves firmly attached well into winter.
As with many natural phenomena, ecologists are still unsure as to why this happens–but there are several theories:
- Retention of leaves around the nutritious new buds discourages large mammals from browsing–who wants a mouthful of dead leaves instead of tasty new growth?
- Browsing on these rustly branches makes too much noise for predator-conscious mammals to risk
- Marcescent leaves trap more snow, increasing the moisture of the soil below the tree, and giving it a head start in spring
- Leaves falling in late winter or spring provide nutrient-rich mulch, just when the tree needs it most
Of course, it’s probably not an either-or proposition either; a combination of these and other factors may have combined to encourage this unusual trait.
So it would seem that in nature, reluctance to let go can sometimes be an asset. Hang in there, oaks–your time is coming!
