Alders by the Pond 1
Tree Diaries ~ Feb 2021
So this is the first in a new series of posts called ‘Tree Diaries’, where I’ll be focussing in on just one tree, or a small group. I’ve gained a lot of scrappy, ad-hoc knowledge about the trees we have here over the last couple of years, but these posts will give me a space and an incentive to get up close and personal, really get to know individual trees – as one of a species, but also as individuals with their own life history, health, habitat and so on.
So, to begin I am starting with two young alder trees that we planted a few months ago in November 2020. I have decided they need names (‘the one on the ash tree side of the pond’ isn’t much fun is it?), and I’ve come up with Al and Glute, playing with their Latin name, Alnus Glutinosa.
So here they are…meet Al (on the left) and Glute (on the right). They’re both right by the pond, not together but able to give each other a wave, as you can see with my little purple drawings (otherwise they’re too hard to make out on the photo)
Left – Al, with Glute in purple in the distance, Right – Glute, and there’s Al waving at him from the other side
Alnus Glutinosa is the Latin name, so I’ve nicknamed mine Al and Glute. In old English the name was Alor. The ‘glutinosa’ part comes from the fact that the young twigs can be sticky. This type of alder is on the Woodland Trust ‘native tree list‘, growing in the UK since the last ice age, 10,000 years ago.
Age and Size
They are both about two and half metres high at the moment. They are fast growing trees – about 60cm a year – so this means they’re probably about 4-4.5 years old. Alders are relatively short-lived trees, tending to live to around 100 years old, and getting to a height of about 20 metres. Here’s how they may look in 30 years or so….
Alder tree by the Tanyard Bridge, in January cc-by-sa/2.0 – © Stefan Czapski – geograph.org.uk/p/3826842
Stats as of 18 Feb ’21
Height: Al – 2.7 m, Glute – 2.5 m
Girth at 1m: Al – 7cm, Glute – 6 cm
Flowers and Fruit
Alders are ‘monoecious’, meaning that they have both male and female flowers on one tree. I had this in mind when I was thinking of names for them – I toyed with Alan and Alice for a while but decided if I was going to anthropomorphise, I’d at least try to be accurate, hence the gender-free Al and Glute.
Al (on the right below) only has its winter leaf buds at the moment, but Glute (on the left) is getting ahead, with several clusters of these purple catkins. The long, hanging catkins are where the male flowers will grow over the next couple of months. The smaller ones growing behind are where the female flowers will grow, forming into cones (alder are the only native deciduous tree to have cones). I’ll update with more pics as they develop.
‘Glute’ (left) has male and female catkins already growing, ‘Al’ (right) is behind, with only on the leaf buds visible so far.
The thing to know about alder is that they like to grow in wet and boggy places – so they’re hopefully loving having their roots in the wet soil around our pond. Sometimes the water level rises almost to their trunks, but as far as I know, that’s just fine with the alders. Out of the water, their wood is soft and spongey, but in the water the wood becomes rock hard. It’s because of this that historically alder has been used to make underwater structures such as bridge foundations, sluice gates and boats.
Alder has a symbiotic friend called Frankia Alni. Here it is….
Frankia alni modules on alder roots (Image from Wikimedia Commons)
Frankia alni is a bacteria that creates these nodules on alder roots. It’s a good thing – a beneficial partnership – as the tree provides the bacteria with sugars and the bacteria provides the tree with nitrogen. This process also enriches the soil around the tree with nitrogen, benefiting the nearby plants too. So a good set of neighbours to have if your soil is a bit poor. I’m not sure how I’ll know if Frankia alni has turned up and is doing it’s thing without digging around the roots, but I’ll keep an eye out.
Wildlife and Alders
The alder invites an exciting range of wildlife. The leaves are plant food for the caterpillars of the alder kitten moth, the pebble hook tip moth and the blue-border carpet moth. The catkins are an early source of nectar and pollen for bees, and the seeds are eaten by siskin, redpoll and goldfinch. Except for the goldfinch, which are already very familiar visitors here, these others are all new to me. I hope we can attract a few of them!