Nature Notes - Spring is in the air

ONE of my favourite trees is now signposting that spring is on the way. Hazel is a tree that after its moment of glory then sort of gets lost – a definite can’t see the trees for wood – if you know what I mean.

In most of our woodlands around Wigan at the moment the hazel are dripping with pale yellow catkins which are the male flowers.

They open in February, when hazel and the other deciduous trees are all leafless, so they are one of the first really obvious signs that spring in the woodland is just around the corner.

The female flowers are tiny red tufts, growing out of what look like swollen buds, and are visible on the same branches as the male catkins.

Pollination is by wind and hazel is self-incompatible - successful pollination only occurs between different trees, as a single tree cannot pollinate itself.

Then the fertilised female flowers develop into nuts which are up to 2cm in size and are in clusters of one to four.

Each nut looks like it’s been individually wrapped into a small paper package where in reality it’s actually a cup-shaped sheath of papery bracts or modified leaves.

The nuts ripen to a brown colour in September and October, with the nut itself enclosed by a tough, woody shell. Empty nuts are an occasional occurrence. I’ve never managed to find any edible hazel nuts locally but I live in hope!

Hazel is a member of the birch family of trees, Betulaceae, and can grow to a height of up to10 metres, although here in the North West it is usually around six to seven metres tall.

Really typical of hazel is the number of shoots or trunks branching out at, or just above, ground level, and this has led to some people thinking of it as more of a shrub or bush rather than a tree, because it doesn’t meet the strict definition for a tree, of having a single stem that is un-branched near the ground.

This ability to produce multiple stems gives hazel a dense spreading appearance and has led to its extensive use for coppicing.

In terms of ‘tree years’ hazel is a pretty short lived tree reaching between 50-70 years of age, but if it is coppiced it can go on living for hundreds of years.

Because of its densely-branched growth hazel has an important role in the understorey in that it plays a significant role in increasing the vertical structure within woodland, which is very important for bird diversity. Hazel leaves are a favourite with roe deer and this may be one of the reasons that all of our larger woodlands such as Haigh and Borsdane now have them either as regular visitors or residents.

The nuts, which are rich in fats and protein, are eaten by the wood mouse and are a favourite of the red squirrel.

It’s easy to see who are at it though - squirrels split the shell of the nut in two halves to get the kernel inside, whereas wood mice will gnaw a hole through the shell.