Within the great phylum of vertebrate animals, mammals are distinguished by their young being nourished for some time after birth on milk from the mothers mammary glands. The possession of mammary glands gives rise to the name mammal.
Other characteristics are; Hair covering the body, jawbone consisting of only one bone on each side, other animals have more, middle ear bones are three in number where other animals have less, Occipital condyles, the joint between the head and vertebra consists of two rounded knobs as opposed to one in other animals except amphibians, a diaphragm separating the heart and lungs from the abdominal cavity, the largest part of the brain known as the fore brain being greatly enlarged and with this enlargement comes the development of intelligence. There is also an increased complexity in the cross connections or commissures between the left and right halves with the diagnostic feature being the presence of the corpora quadrigemina, in the mid brain, connected with the functions of sight and hearing, finally the main artery in mammals leaving the heart curves round on the left side to form the aortic arch, in birds it curves to the right and in other vertebrates one or more curves are present on both sides.
The class Mammalia is divided into 3 subclasses, one of which is extinct the other two are Prototheria (containing egg laying mammals or monotremata) and Theria.
The subclass Theria is then split again into two infraclass‘s consisting of Marsupialia (marsupials) and Placentalia (mammals that gestate with a placenta) which contains the vast majority of living mammals divided into 16 orders, of which only 8 are present in Britain and Ireland. The eight orders are; Insectivora, Chiroptera, Carnivora, Lagomorpha, Rodentia, Ungulata, Cetacea(whales) and primates represented by man.
Species composition of hedgerows and verges have an infinite variety where not only are no 2 the same, but they are different every 100 yards or sometimes every few yards. The situations they are found in vary almost as much. From a hedge between two fields of differing crops to riverside and canal hedges, from small road hedges and verges through to wide motorway bankings, railway embankments and narrow rock cuttings. With soil types of all kinds.
Added on to this, the management regimes can alter composition dramatically. i.e. regularly mown of grazed verges tend to favour finer leaved, shorter plants such as fescues ( Festuca spp) and common bent (Agrestis capillaris) as well as rosette species e.g. dandelion (Taraxacum officinale spp.), greater plantain (Plantago major) and creeping buttercup (Ranunculus repens). Whereas the absence of this mowing or only mowing in autumn or winter, encourages coarser grasses and taller plants such as cocksfoot (Dactilis glomerata), Yorkshire fog (Holcus lanatus), meadow buttercup (Ranunculus acris) and large umbellifers such as cow parsley (Anthriscus sylvestris) and hogweed (Heracleum sphondylium).
Besides these differences a few themes run throughout. Although not all hedges are on banks or have ditches and not all verges have hedges. Where ditches are present sometime they have running water, sometimes standing water used as a soak away or may even be dry ditches where the water only appears in heavy rain or runs underground.
Verges can often, depending on their size, be divided into 3 zones which can usually be very easily distinguished.
Found at the road edge and is usually no more than 6 inches (15cm) wide though occasionally can be larger, and is greatly influenced by pollution (usually saline, now that lead is not such a problem), compaction by pedestrians or vehicles and disturbance. As can be expected it has a characteristic flora and often include halophytes (salt tolerant plants).
The soil at some places has the equivalent saline level of a salt marsh, which has far to high a level of salt for most common grasses which will die out leaving bare patches, which are then in tern colonised by halophytic plants.
Also sodium is known to play an important part in flocculation of clay (the action of the small clay particles clumping together). Therefore improving the soil texture and crumb structure as well as aeration and drainage. However an excess of sodium causes the flocculation process to break down and once again the clay particles form a dense compacted and impermeable layer.
Typical species include; Greater plantain(Plantago major) , ribwort planatin (P. lanceolata) , pineapple mayweed (Chamomilla suaveolens), scented mayweed (Matricaria perforata), red bartsia (Odentites verna), creeping cinquefoil (Potentilla reptens), corn spurry (Spergula arvensis), daisy (Bellis perennis), annual meadow grass (Poa annua), perennial ryegrass (Lolium perenne).
Most verges are now mown off at certain times of the year. Some are only mown in autumn which does not impact to dramatically, however the majority of ‘A’ and ‘B’ roads are now mown twice. Once in June or July and then again in the autumn. Except for motorways and some ‘A’ roads, this usually consists of a 1 metre strip along the roadside edge of the verge which is increased, for safety reasons, in width at corners and junctions for visability. These extra cuts can go back all the way to the hedge and are known as sight lines.
The action of this cut on the verge is described above and often overlaps in inner and outer zones.
The inner zone is not under as much pollution pressure as the outer zone, nor tends to be walked or driven over so its flora can grow unhindered. Its width varies considerably and is in some places absent altogether, due to mowing, where the whole verge is 1 metre or less in width. Where it is in place, it can vary from 1 or 2 metres to 20 to 30 metres in some cases, but generally speaking, the further from the road then the more stable the environment will be and the greater the variety of the slower growing flora.
With the exception of when it is very wide, the inner zones humidity, light and soil conditions tend to be dominated by the hedge. This zone has a generally undisturbed environment for the plants growing there (management aside). The plants that colonise these areas will also attempt to spread into the outer zone but rarely survive for long.
Dominant and common plants in this zones are; hogweed (Heracleum sphondylium), cow parsley (Anthriscus sylvestris), mugwort (Artimisia vulgaris), common knapweed (Centaurea nigra), thistle (Cirsium spp.), silverweed (Potentilla anserina), wild carrot (Daucus carota), hawkweeds (Hieracium spp.), common toad flax (Linaria vulgaris), birds foot trefoil (Lotus corniculatus), field forget-me-not (Myosotis arvensis), goatsbeard (Tragopogon pratensis), campions (Silene spp), white dead nettle (Lamium album), yarrow (Achillea millefolium), clover (Trifolum spp.), timothy (Phleum pratensis) and smooth meadow grass (Poa pratensis).
Ditches are absent as often as they are present, dependant on the soil type and drainage structure of the ground. When they do occur then it tends to be nearly always on one side. Ditches may vary in size from a shallow gully that is dry most of the year, through permanent water filled ditches that may be flowing or may be standing water, to large dykes commonly found in the eastern part of England which can measure tens of metres across and behave more like small rivers and have enough current to keep themselves relatively silt free.
With permanent standing water
The standing water ditch resembles an elongated pond, with a layer of mud at the bottom which may become short of oxygen and smell quite foul.
The following plants are commonly found growing on dryer parts of the ditch bottom although they are quite used to the wet and muddy conditions. These include fools water cress (Apium nodiflorum), marsh marigold (Caltha palustris), meadowsweet (Filipendula ulmaria), brooklime (Veronica beccabunga), water forget-me-not (Mysotis scorpioides), water figwort (Scrophularia auriculata), watercress (Nasturtium officinale), water crowsfoot (Ranunculus aquatilis), starwort (Callitriche stagnalis) as well as duckweeds (Lemna spp.) which is the only one not to have roots in the soil but to be free floating.
The tendency for mud to accumulate in ponds, lakes and still water ditches, as plants die year after year and sink to the bottom, to rot and be broken down by the water borne invertebrates and bacteria, creates a situation where the water gets progressively shallower. The edges then dry out and cause the mud rooting plants to be replaced by more vigorously growing plants that share the dry ditch environment. This action is called Hydro sere, and if left unchecked will dry up the ditch completely. Where ditches are regularly cleaned out, however, this process is stopped.
Ditches which become dry in the summer but wet in autumn, spring and winter provide a very unstable environment for colonisation according to the vagaries of the weather and can go from dry hard ground to flowing flood sometimes in a matter of minutes in heavy rain and then back to dry ground again.
Very few plants, with the exception of horsetails, can survive these conditions and so end up rooting themselves on the firmer, dryer sides of the ditch but there are a few that manage to get a hold in the mud. Commonly found in these conditions are common comfrey (Symphytum officinale), which could even have a commercial interest due to its high protein content and is a food source of the scarlet tiger moth (Callimorpha dominula) which is one of the most striking of diurnal moths. Also found here are marsh woundwort (Stachys palustris), lesser burdock (Actius minor), hemp agrimony (Eupatorium cannabinum), winter cress (Barbarea vulgaris), marsh thistle (Cirsium palustre), common horsetail (Equisetum arvense), great willow herb (Epilobium hirstutum), marsh bedstraw (Galium palustre), hogweed (Heracleum sphondylium), and common valerian (Valeriana officinalis).
With permanent running water
The flora of running ditches are basically river living plants whose evolution has created then to be rooted in the substratum, or on the surface of stones with floating and/or submerged leaves, such as river water crowsfoot, starwort, Canadian pond weed and willow moss (Fontinalis antipyretica). At the water edges, mud areas are found that give rise to mud rooting plants as above.
Hedges are sometimes planted on banks of earth, especially at roadsides. These banks can range in size from several metres, where a road passes through a cutting to less than a foot in flat areas. Where a ditch is present, then the effects of the bank are increased on the ditch side.
Like verges the larger banks can be divided into 2 zones. The distribution between these two zones varies greatly in size, whether north or south facing, and with the flora of the verge inner zone or ditch.
The Lower zone
The lower zone tends to be dominated by the humidity of the soil (which tends to be relatively high if adjacent to a ditch, or low if adjacent to a road that is well drained.), and the organic matter from previous years plants. Possibly the greatest influence however comes from the shading effect of the hedge plants above, especially on a North facing bank.
If the soil conditions of the lower zone are quite damp then this will favour mosses and ferns as colonising plants with lords and ladies ( Arum maculatum) , harts tongue fern (Asplenium scolopendrium) , black spleenwort (A. adiantum nigrum), male fern (Dryopteris filix-mas), polypody (Polypodium vulgare), cut leaved cranesbill (Geranium dissectum), herb robert (G. robertianum), marsh bedstraw (Galium palustre), red campion (Silene dioica), rough chervil (Chaerophyllum tementum), lesser celandine (Ranunculus ficaria), creeping buttercup (Ranunculus repens), hedge woundwort (Stachys sylvatica), sweet violet (Viola odora), meadow fescue )Fuestuca pratensis), common st John’s wort (Hypericum perforatum), primrose (Primula vulgaris), bluebell (Endimion non-scriptus) , dandelion (Taraxacum spp.) and herb bennet (Guem urbanum).
The Upper zone
On the whole the upper part of the bank is drier than the lower zone, courtesy of the root systems from the hedge above, which can have a selective effect on the flora growing there. The plants found here are pretty much the same as those found in the inner zones of verges with the exception of the greater stitchwort (Stellar holostea) which tends to be restricted to hedge banks as its habitat.
The shrub and tree zone
As it sounds this section comprises of mainly woody stemmed bushes along with mature trees and saplings which are sometimes incorporated into the hedge.
However also sharing the environment are the climbing and rambling plants such as herbaceous white byrony (Bryonia dioica), hedge bindweed (Calystegia sepium), hop (Humulus lupulus), black byrony (Tamis communis), woody old mans beard (Clematis vitalba), ivy (Hedera helix), honeysuckle (Lonicera periclymenum), bittersweet (Solanum dulcamara) and brambles (Rubus spp.).
These plants root in the soil and then clamber or climb up through the hedge by means of either tendrils, like white byrony, which can be commonly seen on vetches and other pea family plants, or by twisting around the shrub stem as in bindweed.
Many species produce fruit which acts as an important source of food for birds and mice during the autumn and winter, complementing the berries found on the hedge plants themselves.
Common woody species found here are;
hawthorn (Crataegus monogyna) and or midland thorn, hazel, elder, dogwood, blackthorn, privet, holly, spindle, wayfaring tree, guilder rose, dog rose, field rose and as trees; field maple, ash, oak, elm, sycamore, crab apple, wild cherry, damson, beech, whitebeam, willow, mountain ash, birch, and chestnut.
Certain “indicator” plants can provide clues to the origin of a hedge, e.g. Bluebell (Hyacinthoides nonscriptus) , dogs mercury (Mecurialis perennis) and primrose (Primula vulgaris) are all species occurring in or at the edge of woodland. There existence in hedges strongly suggests a woodland origin that possibly dates back to the assarts of the 12th – 14th century.
On the other hand we need to not overlook the possibility of secondary colonisation at a later date, especially in the case of bluebells that are sometimes escapees from gardens and waste piles.
Hawthorn as an indicator species
Evidence has shown that, providing clay is present as a soil type, the older a hedge is then the greater the presence and proportion of Midland thorn (Crataegus leavigata). During the last enclosure period of the 19th century there evidentially was a tendency to use hawthorn (Crataegus monogyna) varieties. The reason for this change in hedge species planting may well have been due to the direct correlation between the increasing dissection of the leaves and the number of thorns on a plant, thereby providing a greater stock proofing barrier ability to the hedge.
Brambles as a possible indicator species
The use of predominant shrubs as an indicators species could well be expanded dramatically once more is understood about the nature of these variants. With 387 subspecies then, in theory, the older the site, the greater the opportunity for different species to colonise it. Identification, however, is difficult for the inexperienced as some features, such as stem colour will vary according to the amount of light or shade.
While bramble dating may help in the future, in our present state of knowledge, it still lies in the experimental stage and as such can not be more than subjective.
Trees as indicators of hedgerow age
Mature trees commonly found in hedgerows can provide a good judge of hedgerow age, by finding out the age of the trees themselves. This can be done easily with dead tree stumps, such as those provided by the pathogen Ophiostoma ulmi (dutch elm disease), especially in the southern areas, as well as hurricane damage, by counting the growth rings of the stumps.
If there are however, no stumps available then the age can be estimated by measuring the girth of the trunk at 1 metre from the ground. An increase in girth of about 1” per year is a relatively good average approximation for larger trees such as oak Quercus robur), ash (Fraxinus excelsior), beech (Fagus sylvatica), elm (Ulmus glabra) etc. This is providing that the tree is able to grow a full crown and is in the open, which is the usual case with hedgerow trees. Smaller trees such as apple (Malus sylvestris), cherry (Prunus avium), holly (Ilex aquifolium), hawthorn (Crataegus monogyna) , rowan (Sorbus acuparia) and white beam then the rate is nearer half an inch per year. Woodland or copse trees, where the competition is higher tend to increase at a rate of approximately half the full canopy rate.
This measuring method is known as the Forestry Commission rule of thumb and is the product of some 20,000 records showing that most of the larger tree species have a closely linked pattern of growth. Young trees tend to grow faster than the older ones but the 1 inch per year average tends to hold good.
Counting the rings of a tree stump will give a very accurate record of its age, or measuring the girth will give a close approximation. If this is greater than the hedge then the area may well have been woodland that was felled to make the fields. Perhaps more likely if several trees of the same age appear in the same hedge. If the trees appear to be younger than the hedge (worked out in the usual method) then they are probably later colonists or planted at a later age.
The ages of the trees compared to the hedge itself can provide complimentary confirmation as to the age of the hedge or may shout out loud if the age of the hedge and the age of the trees does not correspond at all. Thus pointing to a possible error.
Possible Age of Hedges by Colonisation of Tree and Shrub Species
Hawthorn is by far the commonest hedgerow shrub, and the two species, (Crataegus monogyna) and (C. laevigata), and occupy different locations and ages of hedge with C. laevigata hedges tending to be of a more ancient origin.
Elder (Sambucus nigra) is a small tree of about 10 metres in height if left alone, however when it is cut back, it grows at an outstanding rate and can kill off sections of other hedge plants due to shading. Coupled with its very fast growth rate and its favour of disturbed ground, spread by birds or small mammals eating the berries and then depositing the seeds with ready made fertilizer. Its relatively short life and fast growth rate tends to indicate that the hedge is relatively young or on impoverished soil. A caveat to this however, I have seen a very old hedge suddenly swamped with elder within 5 years after a rabbit fence was added along its length. So disturbance of the ground around a hedge can cause misleading interpretations.
Dog rose (Rosa canina), blackthorn (Prunus spinosa) and ash (Fraxinus excelsior) tend to occupy a middle position in colonisation and occurs in both species rich and species poor hedges.
Contrastingly hazel (Corylus avellana), field maple (Acer campestre) and dogwood (Cornus sanguinea) are more commonly found in a hedge with a high species diversity and as such have probably been used widely in the past for planting mixed hedgerows as they are today, in fact they are a staple addition in hedges that have been planted within the last 10 years.
Dating hedges from quantitive evidence
Other than the influence of man, the most powerful ecological factors influencing the rate of change in a hedge are colonisers by outside species and their competition with the already present. The greater the age of a hedgerow, then the more varied the flora, and consequently fauna should become.
This theory was tested by selecting 227 hedges in different parts of the country whose dates of origin could be determined from documentary evidence with some degree of certainty, then by estimating the number of species of shrubs occurring in lengths of 30 yards.
A correlation coefficient of +0.85 was obtained indicating a close positive relationship between the two variables. A figure of +1 would have meant a perfect linear correlation existed and 0 meant that there was no correlation, while a minus would indicate an inverse correlation.
An equation for estimating the age of a hedge from the number of shrub species in a 30 yard stretch = x+100y+30 where x = the age of the hedge in years y = the number of shrub species in a 30 yd length.
The procedure is an approximate, so in practice a sampling distance of 30 yards is accurate enough. Given variation in the sequence and rate of change in hedgerows, making it not surprising that estimates from the equation are subject to appreciable error. On statistical grounds it is estimated that 95% of confidence limits lie within the range of + or – 200 years.
This procedure is applicable in all areas where traditionally single species hedges were planted.
Practical problems in hedge dating
This method of dating assumes that the rate of accumulation of woody species of plants is correlated positively with hedgerow age. Two questions must be asked if we are to evaluated more closely.
What evidence is there that changes do take place in the composition of hedges ?
To what extent do estimated ages of different hedgerows agree with evidence from documentary records, both over wide areas and in more localised situations.
Evidence for Change
Very little is known of the nature of changes in sequence in hedgerows as opposed to woodland or heathland due mainly to the neglect of the subject and possibly is the difficulty in ascertaining the originally planted species present. Management methods also change constitution of species presence e.g. elder (Sambucus nigra) the biggest problem is usually removed when hedges are laid but exists in greater numbers when the hedge is managed than when not, suggesting that management encourages regeneration from plant remains or colonisation by propagules predominantly from fruits and seed dispersal.
Other useful indicators that can help indicate hedge age.
Field maple (Acer campestre), found in many hedges on alkaline and neutral soils. It is however rare to find it with only one or two other species or in young hedges. It tends to start appearing when four or more woody species are present, ie circa 400 years plus.
Spindle, Evonymus europaeus, behaves in a similar manner to the field maple but coming in at a later date of circa 600 years plus. Its preference for calcareous soils prevents it from being a general age representative shrub due to its restricted distribution.
Species with a wide soil tolerance include hazel (Corylus avellana) and holly (Ilex aquifolium) while the wayfaring tree, Vibarnum lantana, and dogwood (Cornus sanguinea), are conspicuous colonists of calcareous soils and often establish themselves relatively early in a hedgerow.
Error in Age Prediction
The original sample of hedges from which the predictive formula was derived consisted of 227 hedges and covered a sizable part of the country which different soil conditions and management regimes as well as age and origin. With this in mind it is perhaps surprising and encouraging that this method of aging has stood the test of time so well and across many areas. Subsequent studies have supported and co-oberated the idea of an approximate linear relationship between a hedge and the number of shrub species that it comprised of.
However, anomalies do sometimes occur as seen in the table below, which summarizes data obtained in 3 villages in Shropshire. The 50 samples were each 50 yards (27.4m) long.
Documentary and estimated ages of 3 kinds of hedge in Shropshire.
|Origin of Hedge||Average # Shrub Species/30 yd||Documentary Age||Estimated Age|
|ASSART||5.5||900 – 600||800 – 400|
|Piecemeal Enclosure||4.7||500 -300||700 – 300|
|Commons Enclosure||5.7||200 – 100||900 – 500|
All figures are to the newest 100 years.
While estimates for the ASSART hedges and those of the 15th – 17th century are predominantly in close agreement with the documentary evidence, the Commons Enclosure hedges differ considerably. This difference in years is explained by the agricultural records of the time, where the farmers and the land owners were planting any woody species found near to a hedge in order to save in the cost of buying the hedgerow plants.
This difference reinforces the need to cross check with local records and reliable documents because the correlations between species and age is evidentially fictional in this situation.
Another problem with the species/age equation are hedges that have been planted within the last 20 years and especially within the last 10, where it is now common place for the hedge to be planted with a diverse species type such as hawthorn (Crataegus monogyna) , hazel (Corylus avellana), field maple (Acer campestre), oak (Quercus robur), dog rose (Rosa canina) and/or field rose (Rosa arvensis), dogwood (Cornus sanguinea), spindle (Euonymus europaeus) , birch (Betula pendula) and holly (Ilex aquifolium). There then are occasionally a few other species thrown in depending on location and owners choice.
The term Hedge appears to stem from the Old English word HEGG which is believed to be derived from the Anglo-Saxon words ;
- HAEG – hurdle
- HECG – territorial boundary dead or planted
- HEGA – living border boundary
The term Hedgerow used to refer to 2 hedges running side by side separated by a track or pathway. These hedgerows served 2 traditional purposes , that of being a barrier to livestock and as a means of marking out territory or property boundaries. The term however tends to be used these days to describe a hedge of wild shrubs and occasional trees that create a border between fields or gardens.
From Saxon times (circa 500 AD) to Norman times (11th century), as much as 70% of Britain was woodland with a small population of people living and working in isolated clear areas.
By the 12th century it was becoming customary for land owners to clear areas of woodland for farming (assart) and lease them to their tenants as a source of income. The boundaries of these assarts will be composed of trees and shrubs the composition of which would be the same as the species already found at the woodland edge or in the woodland itself.
During this time some of the hedges were managed in relation to hunting activities as born out by an edict of King Richard I to his tenants informing them of a maximum hedge height of 4’ 6” so as not to impede the movement of his deer.
Effects of the enclosures
During the 13th century, the clearing of assarts and the establishment of purprestures (wrongful seizing of, or encroachment on, others or common land) and encroachments amongst others.
The first step of the enclosure movement:
Each village was allotted 6 areas of land by the local land owner;
- 1 domestic area, e.g. Housing
- 1 meadow area, including hay
- 1 grazing area
- 3 agricultural areas, one of winter corn, one of spring corn and one fallow
This system persisted for the following 200 years and hedges must have played a significant part in the demarcation of the said areas as well as livestock proofing to protect the agricultural areas.
By the 16th century the 2nd phase of the enclosures movement was under way. This was the expansion of the wool industry and the higher demands for meat to feed and increasing population. To achieve this, sheep began to replace the 3 field system and emphasis was placed on hedges that were stock proof.
The 3rd phase of the enclosures movement circa 1750 to the mid 19th century. This was the closing off of the old open field system and there associated arable and fallow crops (often referred to as “common ground“). By the end of the 19th century , the newly planted hedges (mainly hawthorn (Crataegus monogyna) ) had reached a mature stage.
In the 20th century, particularly the latter half, the emphasis changed again, this time in favour of cereal crops and with larger machinery to harvest them with, hedges were pulled out and field sizes were increased.
Age and diversity of hedges
There is only one way to tell the age of a hedge or verge for certain, and that is from documentary evidence. All to often, however, that evidence does not exists forcing the adoption of les definitive methods of guessing.
E.g. A hedge planted in the early 19th century consisting of a double row of hawthorn planted 2’ apart.
At first there will have been plenty of room for colonisation by other plants
Herbaceous annuals e.g. chickweed (Stellaria media), groundsel (senecio vulgaris), shepherds purse (Capsella burse-pastoris) and several grasses
Herbaceous perennials (capable of storing food over winter providing an early start in spring e.g., bluebell (Endimion non-scriptus) , primrose (Primula vulgaris), dogs mercuryMercurialis perennis, nettles, dandelion (Taraxacum officinale spp.) and thistles.
Woody perennials – shrubs and small trees e.g. elder (Sambucus nigra), holly (Ilex aquifolium), ash (Fraxinus excelsior) and sycamore (Acer pseudoplatanus).
Large forest trees e.g. oak (Quercus robur). Some of these like some hedges them selves will have been survivors of original woodland. While others will grown from seedlings. The majority, however, will have been planted at the same time as the hedge (predominantly in the 19th century) as demonstrated by there systematic and regular spacing.
Many of the early colonists will have succumbed in competition with later arrivals of quicker growing plants as light, water and nutrition become much in demand. Super imposed on this is the effect of mans management which will favour some species at the expense of others.
Thus in theory the older the hedge, the greater the diversity of species. It should therefore be possible to use diversity as an index of age. This method, however, is open to a considerable margin of error, i.e.;
No two hedges are the same and vary from one part of the country to another,
The presence of a wide variety of plants attracts a wide variety of insects and animals acting as herbivores and defoliators of parasites. Their density can exact a powerful effect on the rate of change,
The range of plant species that made up the original hedge planted which were often mixed or incorporated close at hand species,
Physical conditions e.g. Soil, climate, exposure, pollution and altitude,
Types of maintenance, the effects of such, the frequency of such, or the lack of maintenance.