Autumn brings beautiful colour changes to many of our trees. Their leaves turn from green to yellow, orange, red or purple, depending on the species. Why does this happen? Like us, plants use glucose for growth and energy and they achieve this by using the power of light. This process is called photosynthesis and the chemical, chlorophyll, which gives leaves their green colour, helps this happen. As it works it is broken down and more is manufactured by the tree. Winter approaches, the temperature drops and the tree starts to shut down to rest and, as chlorophyll is no longer produced, the green colour disappears. The yellow and orange, which up until now, have been covered by the green, start to appear. The glucose that has been manufactured during the summer is turned into starch and stored in the roots to feed the tree during the winter and to make new buds in the spring. But in some species, like the maple, a little of the glucose gets trapped in the leaf, and sunlight, together with cooler conditions, act on this to turn the leaf red or purple and provide us with the displays of autumn. Eventually, the leaf will break off at the junction between the stalk and the branch, where the tree has formed a cork-like seal, and be discarded. Those that shed their leaves in this manner are called deciduous but others, the evergreens such as holly and pines, have tougher foliage that can withstand cold conditions and they continue to produce chlorophyll, enabling them to carry on with photosynthesis. Many insects in our gardens need places to hide for the winter, so it is best to delay tidying the fallen leaves until spring is round the corner. Much of the debris will rot down, anyway, and return nutrients to the soil.
Red deer stags are roaring around the countryside as they gather the hinds together during the rut. They often appear out of the woods, with their antlers draped in grass and foliage, where they have been slashing the undergrowth in a demonstration of power to impress the ladies.
Norfolk’s coastline, with its salt marshes and mudflats, provides a winter home for migrating wading birds, but there has been a decline in many species that arrive in Britain at this time of year. Ringed plovers, dunlin, redshanks, oystercatchers and curlew are among those that have seen populations drop in the last decade. There could be several reasons for this; climate change has warmed their Arctic breeding grounds, so it is possible that fewer young are being reared, and milder winters have meant that some species are shifting north-eastwards. Close monitoring is on-going to establish what is happening. However, it’s not all bad news. Some birds, the avocet and the black-tailed godwit, have seen their numbers increase.
A rare Montagu’s harrier has gone missing in Norfolk. Mo was carrying a small satellite tracker which stopped sending signals on August 8th; she has not been heard of since. There are only seven breeding pairs in Britain so her loss is keenly felt. I’m beginning to wonder whether Norfolk is a kind of Bermuda triangle for birds as a lost racing pigeon has set up home with us, roosting every night on the stable roof and showing no sign of moving on.
October is the month when many fungi push their way through the ground, but the bit we see is only a tiny bit of their life story. This is the reproductive part which releases the spores that will become new fungi; it is called the fruiting body. The main part of the organism is an underground tangle of threads that can sometimes stretch for miles and may be thousands of years old. These threads produce enzymes that break down organic matter to feed the fungus. Other types, such as Bracket fungi, feed on the heartwood of trees. The spores gain entrance via a wound and cause extensive rot. This process can take years and the first we know about it is when the shelf-like fruiting bodies appear on the trunks. They are very tough and some were used by barbers as strops to sharpen their razors. By the time we see them it may be too late to save the tree. However, brackets tend to attack old and weak trees that have sustained some sort of damage; healthy trees respond to wounds by producing a chemical that helps fight off the Bracket fungus spores. Dutch elm disease and Ash die-back are two other types of fungi that have caused devastation in our woodlands. Most are not bad, though. Some form partnerships with plants, via the roots, and help them to absorb water and minerals. In return the plant supplies the fungus with sugars and amino acids, which are essential for its existence.
Some moulds, which are types of fungi, have been very useful to humans. Probably the most well-known of these is the one that grew in a laboratory bacterial culture dish and led to the development of the antibiotic penicillin; another mould is vital to the production of blue cheese. There are also baddies in this group. An Aspergillum, which causes a disease known as ‘farmer’s lung’, is acquired by breathing in the dust from mouldy crops.
Lichens are interesting because they are, in fact, two different organisms that combine to form the beautiful structures that we see on wood, rocks and buildings. Part fungi, about 90%, and part algae, they live in complete partnership, supplying each other with vital nutrients. Lichens absorb water and minerals from rain and from the atmosphere, and therefore are very sensitive to pollution. Not many exist around busy towns and industrial areas; their presence is a sign of clean air.
Many of our woodland fungi are edible but you do need expert advice as to which ones; some can make you very ill or worse. Until I know more, the only one I feel entirely confident about is the Giant Puff-ball, simply because there is nothing else it can be – and it’s delicious!
Yeasts that make our bread rise, mould in the jam, rust on our garden plants, dry rot in the attic and powdery mildew, are all part of the amazing fungi family; they’re everywhere and we need them. So don’t kick them over when you come across them on your October walks; they are the great decomposers and without them we would be up to our necks in decaying matter!
Things to do this month include:-
• Getting to know trees – Gaywood Valley, Reffley.
• Strutting stags – Holkham Estate.
• Wildfowl & waders – Cley marshes.
• Fungus forays – Ken Hill woods & Foxley woods.
• Details at www.norfolkwildlifetrust.org.uk or call 01603 625540
• Hawk walks with Simon Rouse – 07928 412344 or firstname.lastname@example.org
© Sheila Sims 2014