The average garden is about 2000 sq. ft, but the difference between one garden and another may be enormous. Tiny courtyard gardens abound in the cities, and there are houses in suburbia and the countryside with gardens measured in acres, but they all have one feature in common. The owner almost always considers it either impractical, unappealing, or impossible, to cover the whole area with a mixture of flowers, trees, shrubs and/or vegetables with exposed earth between the plants.

For most of us a garden is just not a garden without a lawn. On the large areas surrounding grand country houses nearly all the land may be down to grass lawns, but the position is rather different in the average garden. There is a universal need for some permanent form of ground cover in which beds, borders, rockery, greenhouse, pond etc. can be set. In most gardens the main type is the grass lawn; an area covered with closely-knit turf grasses. This grassy surface is regularly mown to keep it smooth and capable of standing up to a reasonable amount of foot traffic. Some types of lawn can tolerate the heavy wear of regular treading and children's games, but others cannot—some look like green velvet, whereas others are coarse, uneven and spotted, or dominated, with low-growing broad-leaved plants and moss. They are all grass lawns, and can only be maintained by cutting.

The conventional view is that the passage from a velvet emerald carpet to one dominated by daisies and dandelions, with bare patches, is due to neglect. The shift is certainly due to a low level of management. Another way to look at the different types of lawn is that a low managerial input leads to an increase in its biodiversity, and is a more sustainable operation. In this respect there are three grades of lawns.

Lawns of low biodiversity


There is no mistaking the luxury lawn, with its velvety close pile and 'bowling green' appearance. This velvet look, so beloved by visitors to Britain, is brought about by two factors.

First, the turf is composed of fine-leafed compact grasses—the Bents and Fescues; there are no broad-leaved lawn grasses and no Perennial Ryegrass.

Second, the grass is strictly managed, kept closely and regularly mown at carpet pile height. In this way the coarser broad-leaved grasses are prevented from taking hold and swamping the fine-leafed varieties. In time of drought it is kept well-watered. Here is the classical ornamental lawn, ideal for the area close to the house where it can be seen by all, but walked on by very few. If you want your lawn to be a thing of beauty, with its main function to arouse the envy of the neighbours, then this is the turf for you.

The disadvantages of low biodiversity are:
  • the lawn will not stand up to very hard wear, such as the feet of children at play, or the feet of its owner constantly using it as a pathway to the garage or vegetable plot;
  • it will not stand up to neglect;
  • seed and turf are more expensive than high diversity equivalents. The difference between the two grades is greater with turf than with seed.
  • establishment of low diversity lawn made from seed is a long process, because the grasses used are slow growing;
  • careful site preparation before seeding or turfing is all-important. Small bumps and hollows, which could well be invisible in a utility lawn, are an eyesore in the closely shorn luxury lawn.


Lawns of medium biodiversity


A lawn in which Perennial Ryegrass and broad-leaved turf grasses are dominant cannot compare in beauty with a well-kept luxury lawn composed entirely of Bents and
Fescues. However, if you want a utility lawn to share with animals, insects, and wild birds, as well as household pets, the specification of its botanical diversity has to be
high.

Such a lawn will stand up to tricycles, games, washday and all the other aspects of a lawn which is used as an outdoor living area. This is an important advantage, but not
the only one— the high diversity utility lawn is able to withstand moderate neglect and some bad management without serious deterioration.

Most of the native coarse grasses, and many dicots, which invade lawns, are hidden in this type of turf—in the luxury lawn they would stand out as weeds. Additional
advantages are the low cost of seed or turf and the ease with which the grass establishes itself in the new lawn.

Lawns of high biodiversity


The vast majority of the lawns in this country have a high biodiversity, usually due to neglect. On the other hand, over-close mowing at irregular intervals is a frequent cause of grasses to be replaced by dicots and moss. Omitting to feed, water or weed also promote and increased biodiversity. There will be a sparse covering of fine grasses, which have been replaced by moss, coarse grasses, broad-leaved low growing plants and bare earth.

Managing biodiversity


Conventional lawn management has the ultimate aim of a tidy and weed-free appearance. Therefore, there is much advice on management to bring a high species diversity lawn (a worn out lawn!) back to a monoculture. There is little information about how to manage a lawn for a particular level of biodiversity. This presents opportunities for making predictions about the likely outcomes of experimentation because there are some general rules for sustaining a high biodiversity lawn. These are:-

- mow infrequently, and do not remove the clippings;
- do not cut in dry weather and never water;
- do not use fertilisers or weed killers;
- do not rake or remove worm casts;
- do not aerate;
- do not top-dress;
- do not roll;
- do not remove autumn leaves, unless they smother all the grass.

Returning as much of the locally produced organic matter to the soil will encourage soil invertebrates, spread seeds of grasses and broad-leaved plants, and produce a thin spongy, fibrous layer of decaying matter on the surface. This will reduce the loss of soil moisture, and is a habitat for specialised invertebrates that live on the surface of the soil. The end point will be a patchy community of grasses, and broad-leaved plants that grow as rosettes, and moss. The patchiness will indicate soil differences which affect local drainage, and areas of local shade. The lawn will be used as a year-round feeding ground by blackbirds, thrushes and starlings attracted by the high level of soil invertebrates


Management objectives


Amenity grassland is of limited educational value when approached as a collection of species, without considering its management. Grass-SCAN approaches mowed grassland from the opposite direction; as a universally accessible model of ecological management. From this viewpoint, the first task is to determine the management objectives for the patch. The objectives may vary considerably e.g. from maintaining a uniform, velvety, ornamental grass monoculture, to maximising the lawn's species diversity, of say earthworms, or dicots. The next step is to set up a monitoring programme based on indicators by which the success of the management plan may be judged. These indicators, such as 'sward height', a list of the weed species, or the number of daisy flowers, will depend on the management objectives. From another angle, a management plan could be written to run an experiment where a mowed lawn is used to demonstrate an important ecological principle, such as competition between grasses and clover. In all cases the aim is to do year on year measurements to establish trends and variations of mowed grassland as a managed ecosystem.

Example


An UK low intensive front lawn action plan with ornamental weeds representing five ecoscopes in an area 15m x 5m.

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SALT (Smaller American Lawns Today)


A campaign against intensive management of domestic lawns