NOW that autumn is here, the trees have already started to change colour, though it's a slow process which will continue in some species until December.

When exactly the colours will peak is dependent on the weather over the next few weeks. Just how bright the colours will be also depends on the weather. There are various permutations which increase the intensity of colour -for instance, the combination of sunny days and frosty nights is a good one, which is why much of North America has such a magnificent autumn display each year.

For many years those American states which enjoy good autumn colours have operated telephone hotlines to inform people where to view the best displays. We now have something similar here, with the introduction of a Forestry Commission website which is updated daily to report on the changing colours as autumn moves southwards across the country.

Log on to www.forestry.gov.uk/autumn and you'll discover lists of woods scored from one to five, depending on colour intensity, while the website maps are colour-coded from green through to deep gold so you can see at a glance the current state of play in your local wood and enjoy what the Forestry Commission calls leaf-peeping paradise . Or you can phone 0845 367 3787 and ask to receive a free information pack. This tells you where your best local woods are and what to see and do when you get there.

But why do leaves change colour in the autumn? Well, the Forestry Commission explains that a deciduous tree uses its leaves as a sort of food factory. The roots extract nutrients and minerals from the soil and these are then transported through the tree's vascular system to the leaves. The nutrients mix with oxygen, which is taken in through pores in the leaves, and are converted into sugars and starches. This process requires energy, and that comes from the sun. Leaves contain a green pigment called chlorophyll which has the ability to trap sunlight. It's chlorophyll which makes leaves look green in spring and summer. When the shorter days and lower night-time temperatures tell the tree that winter is coming it shuts down its system. Because it's going to remain dormant throughout winter it doesn't need food. The remaining chlorophyll breaks down and the gold and red pigmentation of the sugars and starches starts to show through instead, giving us the glorious colours we enjoy each autumn.

And one of the best places to enjoy the show is Wyre Forest, as this walk demonstrates.

DIRECTIONS

Stand with your back to the visitor centre, looking in the direction of Bewdley, and you'll see a green post indicating three walks (yellow, green and red) and two cycle trails (green and blue). Walk in the direction indicated and shortly fork left through a black-painted, metal archway.

Keep straight on, ignoring branching paths, to reach a T-junction. Turn left, keep straight on at the next junction and then fork right at the next, joining a sandy bridleway, and soon right again.

n As you approach the edge of the forest turn left, still on the bridleway, and go slightly downhill through conifers, looking for an unsigned path on the right which runs ruler-straight through the conifers. Follow it to a gate and pass through into the oakwoods of the Wyre Forest National Nature Reserve.

Keep straight on to a T-junction at the edge of the forest and turn left. Turn right at the next junction, still by the edge of the forest. Ignore any branching paths and you'll soon descend into a valley full of rhododendrons around a marshy area by a stream. Turn left. The path is damp for a while but very soon improves. Fork left when you reach a dried-up pool, climb to the edge of the forest, turn left and shortly fork right, and soon right again. Keep straight on at a crosspaths to meet a track.

Turn right past a cherry orchard, leaving the forest. Keep straight on when the track meets a lane at a cattle grid. The lane is called Tanners Hill, recalling the tanning trade which used to be a big part of Bewdley's economy. It passes between orchards and meadows and then climbs to a T-junction where you turn left on Hop Pole Lane.

n At the next junction go left again, joining Dry Mill Lane. After 500m turn left on a track into the forest. This track was formerly the Bewdley to Cleobury railway. Keep straight on until you come to a signpost indicating the visitor centre to the left.

A few paces further on the path forks - go to the right. A little further on a sign indicates a conservation area - fork left here but please heed the instruction to keep dogs on leads in this area. When you come to a junction take the right fork as indicated by a yellow arrow.

Follow the yellow arrows until one near a bench indicates a right turn. Branch left instead, through beech trees, then turn right at the next junction, left at the next, straight on at another and finally left on a cycleway. Keep straight on to the visitor centre.

FACTFILE

Start: Wyre Forest Visitor Centre, on A456 near Bewdley; grid reference SO 50740.

Length: 6 miles/9.6km.

Maps: OS Explorer 218, OS Landranger 138.

Terrain: forest paths, undulating but not steep.

Stiles: 0.

Parking: Wyre Forest Visitor Centre.

Public transport: by bus or train to Kidderminster then 292 (daily) to Visitor Centre, or 2/2C every 15 minutes to Dry Mill Lane (not Sundays); Traveline 0870 608 2608.

Refreshments: Wyre Forest Visitor Centre or the Hop Pole Inn.

DISCLAIMER

This walk has been carefully checked and the directions are believed to be correct at the time of publication. No responsibility is accepted by either the author or publisher for errors or omissions, or for any loss or injury, however caused.