This is the time of year farmers trim hedges, and there are about 46,000 km of hedgerows in Scotland to maintain - roughly equivalent to the circumference of the Earth.

Hedges need to be trimmed every two or three years to keep them dense and stock-proof as well as providing a good source of food and shelter for wildlife. Indeed, hedge trimming is delayed to the autumn and winter so as not to disturb nesting birds, and when done in rotation leaves stretches laden with berries to act as a food source for them.

Conservation and biodiversity is the name of the game nowadays. Rare plants and other wildlife are being appreciated and enjoyed by more and more people, while farmers are increasingly aware that many insects pollinate or protect their crops from pests.

Strange to say, but modern, intensive farming methods make the objectives of conservation easier to achieve as they release less-productive land for other uses. With the aid of some very generous grants from the EU and various other organisations , farmers have been planting hedges and trees, fencing off naturally regenerating woodlands to protect them from grazing, creating new ponds and fencing off water margins and wetlands, or reducing grazing pressure on moorland.

Many thousands of miles of British hedgerows were neglected and became very overgrown in the depression of the 1930s. Farmers simply didn't have enough money to employ men to trim the hedges, or lay them. That's where branches and stems in lank hedges are partially cut and laid horizontally to re-grow into a thicker hedge.

Overgrown to the point they had become a row of trees, those neglected hedgerows were neither stock-proof nor a source of shelter. Many also held the mistaken view of those times that hedges harboured weeds and pests.

An overgrown hedge can be more than four yards wide, so a modest 300 acres farm with seven or eight miles of hedges will lose the use of about 13 acres of land.

When arable farming started to really intensify in the sixties and seventies, miles of overgrown hedges were grubbed out, partly to crop those unused acres, but mainly to make fields bigger for modern machinery and cropping techniques.

Things changed about twenty years ago when a new range of grants were introduced that helped cover the huge costs of planting hedges and the protective fencing needed to prevent rabbits, hares and deer from nibbling the young plants. There were also payments for the annual cost of keeping weeds down till the hedge was established.

Once established, there are now modern tractor-driven hedging machines to take the hard work out of trimming.

There were no hedges on the hill farm I used to rent, except for a short length at the edge of a wood that had been long neglected and had grown into a row of thorn trees. Nevertheless, as a student I had the unpleasant experience of trimming hedges by hand, using a hedging knife with its 12-inch blade on a stout wooden shaft. The idea is to slash upwards trimming off the new growth, but in my inexperienced hands I discovered that pain was the order of the day. I learned the hard way that thorns could penetrate the protective leather gloves I wore, or that disturbing a hidden wasps' bike could be just as painful.

The recent reforms of the Common Agricultural Policy (CAP) introduced new GAEC (Good Agricultural and Environmental Conditions) rules on hedges that requires a two-metre wide, uncultivated strip alongside them in arable crops.

The idea is that those field margins are kept free of pesticides, herbicides and fertilisers so that invertebrates and other wildlife can thrive.

Compliance with GAEC is a pre-requisite to receiving support payments and they can be reduced if GAEC requirements are not met.

From a livestock farmers point of view well-maintained hedges offer several advantages in addition to shelter for cattle and sheep, particularly young lambs on a wet and windy day in March - they can also offer a very effective field barrier.

There's nothing worse than straying livestock and I believe that farmers should spend their time looking after their animals instead of wasting time looking for them.

Sheep are the Houdinis of the animal world and easily spot holes in a badly-maintained fence or hedge, often leaving a piece of wool behind on the thorns that signals to others where the escape route is.