(Header photo credit to Tony Crofts)

“As long as Autumn lasts, I shall not have hands, canvas and colours enough to paint the beautiful things I see.”  This quote is summed up in the glorious scenes around the Forest at the moment – just like our header picture taken by Ranger Tony Crofts in the Millennium Country Park. This picture made me wonder what exactly happens to our trees in autumn – read on to find out more….

A short biology lesson

Many leaves are green because they contain chlorophyll – the green pigment that enables them to absorb light. The energy from the absorbed light is used, in a process called photosynthesis, to convert carbon dioxide (absorbed from the air) and water into glucose – a type of sugar. The tree uses glucose, along with other nutrients absorbed from the soil, to grow new leaves.

Leaves also contain two other pigments – carotenes (yellow) and anthocyanins (pink/red). In autumn, lower temperatures destroy the chlorophyll in the leaf and the yellow pigment appears. This too then also fades to reveal the anthocyanins, giving us the rich reds of autumn. If the temperature stays above freezing for longer, more anthocyanins are produced and the leaves will look redder. So the colours we see in our woodlands change every year, depending on the temperature.

Autumn Field Maple (photo credit Nicola Ceconi)

So why do the leaves fall off trees? Trees drop their leaves in autumn as a survival strategy. If they didn’t, the water in the leaves would freeze and the leaves would ultimately fall apart. If this happened, when spring came the tree would have no leaves able to photosysnthesise and they’d starve. Also without leaves a tree has a better chance of withstanding the windier autumn/winter weather, as gusts can pass through the branches without any resistance from leaves.

So basically trees that drop their leaves – deciduous trees, survive the winter by effectively hibernating, becoming dormant and conserving their energy for the next growing season. Evergreen trees that don’t drop their leaves in autumn, like the firs we have at Shocott Spring, have a resin on their leaves that protect them from freezing, so there’s no need to shed them.

Our autumn trees

When we’re planting trees in the Forest we plant a mixture of native broadleaves, including oak, hornbeam, wild cherry, silver birch, field maple, hazel and rowan. We also plant a variety of shrubs, but I’ll tell you more about those in the next newsletter. Here’s a handy little guide to what our trees look like now they’re getting ready for their winter nap…

Oaks are one that many of us can identify, and are like the wise old men of the Forest as they can live up to about 900 years – our oaks are still babies, of course! Oaks are one of the last trees to shed their leaves, which turn golden yellow and russet before they drop. Acorns from oaks are a vital source of food for many woodland mammals in autumn, helping them to put on fat reserves to get them through the winter.

 

Autumn Oak tree and acorn

If oaks are the wise old men, then Hornbeam are the tough guys - the name hornbeam means hard wood in old English, and it does have the hardest wood of any tree in Europe. The leaves turn golden yellow and orange in autumn and the seeds are a food staple for many finches and tits.

Autumnal Hornbeam leaf

Wild cherry are stunning in autumn with their spiky, oval leaves turning a mix of yellows, oranges and reds. They’re planted throughout the Forest, but we have a concentration of them in Shocott Spring.

Wild Cherry in autumn

Silver Birch are majestic with silvery, white bark and triangular shaped leaves. They’re often used to help improve soil quality as they have wide-reaching roots to absorb more nutrients from the soil, which are then recycled into the soil when the leaves are shed.

Silver Birch leaves

Field Maple is a fast growing tree, that lives for about 150 years. The leaves have five lobes that turn yellow-red in autumn.

  

Field Maple in summer and autumn, and the five-lobed leaf

Hazel trees have very bendy branches which means it can be woven to make things like baskets, they also make great gardening accessories as stakes. Hazelnuts are a vital food source in the autumn for many species of birds and small mammals.

 

Hazel leaf and hazelnuts on the tree

Rowan have elongated, feather-like leaves and produce bright red berries which are favoured by many autumn migrant birds, as well as making lovely jam.

Autumn Rowan leaves and berries

News from our sites

One task that goes on through autumn and winter is scrub clearance. Some of our most valuable habitats are those that occur when areas are allowed to naturally develop from bare ground to grassland to scrub and then to woodland (a natural process referred to as ‘succession’). Each stage provides important habitat for wildlife, and this value is increased, when a combination of different stages exist together in an area – structural diversity.  The Callow Mounds (adjacent to Stewartby Lake) are managed to maintain a mixed mosaic of bare ground, grassland and scrub that enables a range of wildflowers, insects, reptiles, and many species of bird to flourish. The area is dominated by hawthorn which is managed through rotational scrub clearance. Each year, a different area is selected, and the hawthorn is coppiced (cut down and then allowed to regrow) initially creating a new open area. By clearing new areas each winter, and then leaving the scrub to regrow, you create an evolving mix of different aged scrub along with open grassland and bare ground. Scrub and associated successional habitats can often be overlooked – they don’t sound very exciting, but together provide highly diverse and valuable wildlife habitats.

Hawthorn with berries

We’ve begun a programme of replacing old benches across our woodlands. Our talented volunteers are making the benches for us and the rangers have started replacing them, with new ones already installed at Rectory Wood and in Gateway Woods.

A structural engineer has been at the Millennium Country Park to assess our wooden structures, including the boardwalk across to Stewartby Lake. Currently both the boardwalk and the wooden ‘bandstand’ (in the picnic area outside the Forest Centre) are closed, while we await the report.

Finally, huge thanks to MH Agricultural Ltd who have replaced the gate near the wind turbine which was recently vandalised. They contacted us when they heard about the vandalism and very kindly offered us a new, heavy duty galvanised steel gate and to come and install it for us. They said, “We believe the Forest is a great asset to the local area to be enjoyed by everyone. We were saddened to see the vandalism the Forest suffered during an already difficult time. We wanted to make this donation to help keep the Forest safe and secure for everyone to continue to enjoy.” Thank you MH Agricultural!

New gate donated by MH Agricultural Ltd