This year our beech trees are dropping all of their seeds again. Why?
A bellbird or korimako feeds on mountain beech honeydew (Wikimedia Commons)
Tawai or beech trees do a thing called “masting” to help them survive. Masting usually happens every 4 years or so, when the beech trees produce HEAPS more seeds than usual.
It’s a good strategy because most of the beech seeds usually get gobbled up by seed-eating bugs and birds.
But in a ‘mast’ year, there are too many seeds for these critters to eat and so those left over can grow into trees! Genius.
The problem for our forests is that more seeds means healthier seed-eating animals, who then have more babies. Good news, right? Nope, it’s not as great as you’d think…
More seeds means more food for pests like rats, mice and stoats, and this leads to a population explosion of these predators.
Once the seeds are gone, these nasties will turn on our birds, bats, geckos and insects. The last time we had a masting season, our mohua or yellowhead birds nearly went extinct. Eek!
Lucy Forgan, who lived on D’Urville island when the 2014 beech mast happened, made this great comic about the mast. Imagine if bats could fight back against pests in this way – it would solve a lot of problems!
Why are the beech trees masting again this year though? Haven’t they just done it?
Scientists know that masting happens when there is an increase in average temperature between the last two summers. This summer has been one of our hottest on record so another increase means another mast. And with climate change comes more extreme weather, so this could keep happening more often which is pretty exhausting for all our beech trees!
Fighting Back
The Department of Conservation has told us that it is armed and ready. They’re going to continue their pest-control program called Battle for our Birds (PDF).
But controlling these pests costs money. DoC’s funding to protect our wildlife is nowhere near enough and so Forest & Bird has asking the Minister for Conservation to increase their spending on pest control so we can protect our birds – especially as more and more of these seed drops could happen in the future.
Our Northland forests are now in big trouble and need at least $10 million of pest control to have a fighting chance against these predators.
This video explains the beech mast in more detailed – but be warned, watching these pests in action can be gruesome!
Photo of a kākāpō feeding one of its chicks (Kākāpō Recovery Project).
Is it all bad news?
Not yet!… One bird that benefits the most from a mast year is the kākāpō, but not just from the beech trees. The kākāpō’s favourite food is rimu berries and rimu trees are part of the ‘podocarp’ family of trees.
This year is a podocarp mast year too and luckily for kākāpō, they live on predator free islands so don’t have to worry about nasty pests like rats, stoats and possums. They get all those delicious rimu berries to themselves and that means they will have a good breeding year. In 2016, 38 new chicks have hatched!
Ka pai kākāpō!
