Think of autumn and it’s likely that one of the first images to enter your mind will be that of the changing colours in our trees. Golden yellows, deep reds, burnished bronzes, rich oranges and resisting greens all grace our skylines and make the most mundane journeys a visual treat. Autumn is a time when we become acutely aware of the trees that surround us – and not only because of the myriad of colour but also because of the bounty they yield. Shiny conkers in spikey jackets, Sycamore ‘helicopter’ seeds, and perfectly formed acorns crunching underfoot all help to put trees in the spotlight during the autumn months. But what happens to trees throughout the year as the seasons change and how does our wildlife benefit from them? Read on to discover more…
Spring
The rebirth of wildlife in spring is a spectacle in itself, and trees play a big part in this season. Flowers begin to bloom from trees such as fruit-bearing trees, their pretty blossom synonymous with springtime. Flowers are important for the survival of insects, which feed on the nectar and pollen from the base of the stamen. Blackthorns and willow trees are some of the earliest flowering trees to show the first signs of spring.
Summer
Summer is the time for a tree’s canopy to reach full leaf. Oak trees which stand alone will spread their canopy wide and support a number of wild species in the nesting season including birds and bats. As the temperature rises, fruit bearing trees will drop apples, pears and peaches onto the floor, ripe for the taking.
Autumn
As we’ve already alluded to, this is a beautiful time of year in the seasonal tree lifecycle: the leaves of many tree species will change colour in autumn. The colours of leaves are made up of pigments: chlorophyll (green), carotenes (yellow) and anthocyanins (reds and pinks). The temperature and sunlight effect these pigments and in autumn, as the sun begins to creep in earlier and the days become colder, chlorophyll is destroyed leaving the yellow and reddish leaves on the tree’s edge.
Trees support a wide range of wildlife in autumn. Leaf litter from broadleaved trees provides warm and wet habitat for fungi to grow on the ground and recycle the nutrients in the area. Leaf litter is also important for the survival of some insects and hibernating mammals such as hedgehogs.
Winter
In winter, broadleaved trees have dropped their leaves and look bare, sometimes casting dramatic silhouettes in the darkness. Trees are a vital life source for wildlife in winter as they offer shelter for hibernating bats, food such as berries for birds and a place of refuge for small mammals hiding from their predators.
For trees to survive the cold season, they dehydrate their limbs by dropping leaves and slow the flow of water in their branches, combining it with increased sugar concentration in their cells to reduce the freezing point in the water. If the water within a tree’s branches were to freeze this could be fatal for the tree.
Many of Herts and Middlesex Wildlife Trust’s nature reserves feature areas of ancient and varied woodland. In particular, Astonbury Wood, Hawkins Wood, Fir and Pond Woods, Hobbyhorse Wood, Balls Wood, Oughtonhead, Gobions Wood, Long Deans, Old Park Wood, Danemead and Fox Covert are well worth exploring in all their autumnal glory – find out more at hertswildlifetrust.org.uk/nature-reserves
