- ripe fruits are in abundance and the leaves on some trees are now starting to change colour.
This has been a good year for fruiting, and berries such as bramble have been seen earlier than usual as they flowered earlier in the warm spring. The abundance of rain helps with a juicy ‘bumper crop’. If you haven’t been out blackberry picking yet, don’t delay, as they tend to lose their flavour after the first hard frost. Try some recipes on our Nature Detectives website
Many people have noted that horse chestnut trees appear to be browning particularly early. In some years, this can be due to drought, but this year it is most likely to be a result of two specific problems. Some trees are infested with the leaf miner moth larva that burrows into the leaves and causes them to brown and dry. Other horse chestnuts are suffering from a bleeding canker disease. Symptoms visible on affected trees include bleeding areas on their stems and sometimes on major branches – unfortunately it is not treatable and can eventually prove fatal.
Why do leaves change colour in autumn? At this time of year, the cooler days and lower levels of sunlight cause the chlorophyll in leaves to break down. Chlorophyll is the chemical that is required for the leaves to turn sunlight into energy and is what makes plants appear green. But it is only produced when it is warm and sunny. As the chlorophyll breaks down the green colour fades revealing the yellow colour of Carotene, another pigment in leaves which was there all the time but masked by the chlorophyll. Carotene makes the leaves appear orange and yellow and as its name suggests is also found in carrots!
As autumn progresses the red colour of another chemical might also be seen - Anthocyanin. This pigment only forms when the sugars become concentrated in the leaves as they break down, so ideal conditions for this are dry late summers.
All of this together suggests that the best autumn colours can be seen in sunny dry autumns following drier summers. We certainly didn’t manage the dry summer but perhaps better weather is to follow?
Some of the Woodland Trust's more colourful 'autumn woods' are listed here. Please note that the woods may be muddy, so wear appropriate shoes or boots!
If you want to be involved in recording the first signs of autumn then please visit the Nature Detectives (for under 18s) or the Nature's Calendar websites.
September 2008
