Ivydene Gardens Soil: |
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Factors causing Subsidence of Buildings, especially Tree Roots in Clay Soils Subsidence is described as “ a movement involved in the site, normally downwards, so that damage occurs to the building standing upon it”. Some 150,000 homes in the UK Southeast have suffered from subsidence between 1980 and 1995. The main causes are: - |
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Source Number |
Subsidence effect |
Subsidence Cause |
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1 |
Erosion |
River or Sea |
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2 |
Mining |
Isolated or Wave. Along the North Downs escarpment of Southern England mining has been carried out to extract hearthstones, firestones, building stones and also pure silica sand. Chalk and flints have been mined by the application of pillar and stall methods in Kent. On reaching the mine boundary the pillars were then worked in retreat, allowing the roof to collapse. Often this collapse was not instigated and these uncharted shallow partially extracted workings now present engineering problems. |
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3 |
Tree Roots |
Clay soils and mechanical. Removal of trees from a clay soil just prior to construction could cause heave (caused by the rehydration and swelling of a clay soil from rainfall) of the soil after building construction. |
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4 |
Seasonal fluctuations |
Affected by climatic changes and vegetation. The Marine clay sediments of the Southeast have a high shrinkage potential, so swell when it rains and shrink during long hot dry summers. The Southeast also suffers the highest summer soil-moisture deficit in the UK. |
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5 |
Escape of water |
Defective drainage. If there are any defects in a drain, then a root is liable to enter and proliferate and thereby cause a blockage, but an intact drain cannot be penetrated. Inspect any manholes within 3 metres of a tree/hedge. |
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6 |
Over-stressing |
a. Overloading b. Building alongside |
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7 |
Undermining |
Deep drainage trench where trench bottom is lower than building foundations. |
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8 |
Landslip |
Movement of the site. Removal of material from the toe of a slope, side long excavations for the construction of roads or placement of foundations can instigate failure. Loading of slopes at the crest by construction can impose additional forces resulting in slope failure, especially on clay subsoil. |
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9 |
Compaction of infill/ settlement |
Cut and fill sites. If well-graded sand and gravel is used to fill the cut or fill side of site before the construction of the building upon it, then this has a very low compressibility. If it is domestic rubbish at the other extreme, then this is very highly compressible. Filling below solid floors. This is unlikely with sandy granular subsoil, but settlement relating to a clay sub-soil can take place up to 5 years after the building is completed and in exceptional circumstances, this may even extend to 10 years. |
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10 |
Inadequate foundations |
“Doomed from the start”. Since 1950 building foundations have been placed at not less than 900mm below ground level. Since that time, very few cases of subsidence have been reported to houses with foundations of such a depth purely due to this foundation depth.
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The influence of trees on House Foundations in clay soils:- |
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Ranking |
Tree Species |
Maximum Tree Height in metres |
Maximum Distance of tree from building for 75% of subsidence cases |
Minimum horizontal separation distance in very highly and highly shrinkable CLAYS in metres |
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1 |
Oak |
23 |
13 |
23 |
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2 |
Poplar |
24 |
15 |
24 |
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3 |
Lime |
24 |
8 |
12 |
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4 |
Common Ash |
23 |
10 |
12 |
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5 |
Plane |
30 |
7.5 |
15 |
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6 |
Willow |
15 |
11 |
15 |
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7 |
Elm |
25 |
12 |
12 |
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8 |
Hawthorn |
10 |
7 |
5 |
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9 |
Maple/ Sycamore |
24 |
9 |
12 |
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10 |
Cherry/Plum |
8 |
6 |
8 |
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11 |
Beech |
20 |
9 |
10 |
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12 |
Birch |
14 |
7 |
7 |
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13 |
Whitebeam/ Rowan |
12 |
9.5 |
12 |
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14 |
Cypress |
25 |
3.5 |
12 |
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Minimum distance (metres) between structure and centre of trunk to avoid direct damage to a structure from future growth of the base of the trunk and tree roots: - |
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Mature Height of Tree |
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8m to 15m |
Over 15m |
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Buildings and heavily loaded structures |
0.5 |
1.2 |
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Lightly loaded structures such as single storey timber frame, garages, porch, etc |
0.7 |
1.5 |
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Water demand of different conifer and broadleafed tree species – with 5.6 being moderate water demand and 8 being the highest:- |
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Tree Category |
8 |
7 |
6 |
5 |
4 |
3 |
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Broad-leaved Broad-leaved trees not listed have a factor of 4 |
Eucalyptus Populus Quercus |
Crataegus Salix Sorbus (simple leaved) Ulmus |
Aesculus Fraxinus Platanus Tilia |
Acer Castanea Fagus Malus Prunus Pyrus Robinia Sorbus (compound leaved) |
Ailanthus Alnus Betula Carpinus Gleditsia Ilex Juglans Laburnum |
Catalpa Corylus Ficus Liquid-ambar Lirio-dendron Magnolia Morus Sambucus |
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Conifer Conifer trees not listed have a factor of 3 |
Cupressus |
Chamaecyparis x cupressocyparis |
Sequoia-dendron |
Cedrus Thuja |
Juniperus Taxus Tsuga |
Abies Araucaria Ginkgo Larix Picea Pinus |
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Before you buy another building, please take account of the following future possible causes of its subsidence, as well as any of the other causes of subsidence detailed above: -
If tree/hedge/climber/shrub pruning is contemplated to alleviate a possible problem, the objective is to reduce the leaf area of the plant; as the amount of water utilised by this plant and thus the extent of soil drying which can develop is closely related to this leaf area. Thus control of this leaf area provides a means of controlling soil drying. Crown reduction is generally the most effective method of pruning, but other techniques such as thinning or crown lifting may be used where appropriate. This treatment may have to be repeated on a regular basis, which is no problem for a climber, shrub or hedge, but could be too expensive for a tree.
Recommendations
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Site design and content copyright ©December 2006. Page structure amended September 2012. Menu tables amanded July 2015 by Chris Garnons-Williams. DISCLAIMER: Links to external sites are provided as a courtesy to visitors. Ivydene Horticultural Services are not responsible for the content and/or quality of external web sites linked from this site. |
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SOIL PAGE MENU In Soil Formation - WHAT IS SOIL STRUCTURE? How does Water act in the Soil? ACTION PLAN FOR YOU TO DO WITH YOUR SOIL. What to do about Subsidence caused by Clay?
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PLANTS PAGE PLANT USE Groundcover Height Poisonous Cultivated and UK Wildflower Plants with Photos
Following parts of Level 2a, |
PLANTS PAGE MENU
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PLANTS PAGE MENU
Photos - 12 Flower Colours per Month in its Bloom Colour Wheel Gallery
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To locate mail-order nursery for plants from the UK in this gallery try using search in RHS Find a Plant. To locate plants in the European Union (EU) try using Search Term in Gardens4You and Meilland Richardier in France. To locate mail-order nursery for plants from America in this gallery try using search in Plant Lust. To locate plant information in Australia try using Plant Finder in Gardening Australia. |
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The following details come from Cactus Art:- "A flower is the the complex sexual reproductive structure of Angiosperms, typically consisting of an axis bearing perianth parts, androecium (male) and gynoecium (female). Bisexual flower show four distinctive parts arranged in rings inside each other which are technically modified leaves: Sepal, petal, stamen & pistil. This flower is referred to as complete (with all four parts) and perfect (with "male" stamens and "female" pistil). The ovary ripens into a fruit and the ovules inside develop into seeds. Incomplete flowers are lacking one or more of the four main parts. Imperfect (unisexual) flowers contain a pistil or stamens, but not both. The colourful parts of a flower and its scent attract pollinators and guide them to the nectary, usually at the base of the flower tube.
Androecium (male Parts or stamens) Gynoecium (female Parts or carpels or pistil) It is made up of the stigma, style, and ovary. Each pistil is constructed of one to many rolled leaflike structures. Stigma This is the part of the pistil which receives the pollen grains and on which they germinate. Style This is the long stalk that the stigma sits on top of. Ovary The part of the plant that contains the ovules. Ovule The part of the ovary that becomes the seeds. Petal The colorful, often bright part of the flower (corolla). Sepal The parts that look like little green leaves that cover the outside of a flower bud (calix). (Undifferentiated "Perianth segment" that are not clearly differentiated into sepals and petals, take the names of tepals.)"
The following details come from Nectary Genomics:- "NECTAR. Many flowering plants attract potential pollinators by offering a reward of floral nectar. The primary solutes found in most nectars are varying ratios of sucrose, glucose and fructose, which can range from as little a 8% (w/w) in some species to as high as 80% in others. This abundance of simple sugars has resulted in the general perception that nectar consists of little more than sugar-water; however, numerous studies indicate that it is actually a complex mixture of components. Additional compounds found in a variety of nectars include other sugars, all 20 standard amino acids, phenolics, alkaloids, flavonoids, terpenes, vitamins, organic acids, oils, free fatty acids, metal ions and proteins. NECTARIES. An organ known as the floral nectary is responsible for producing the complex mixture of compounds found in nectar. Nectaries can occur in different areas of flowers, and often take on diverse forms in different species, even to the point of being used for taxonomic purposes. Nectaries undergo remarkable morphological and metabolic changes during the course of floral development. For example, it is known that pre-secretory nectaries in a number of species accumulate large amounts of starch, which is followed by a rapid degradation of amyloplast granules just prior to anthesis and nectar secretion. These sugars presumably serve as a source of nectar carbohydrate. WHY STUDY NECTAR? Nearly one-third of all worldwide crops are dependent on animals to achieve efficient pollination. In addition, U.S. pollinator-dependent crops have been estimated to have an annual value of up to $15 billion. Many crop species are largely self-incompatible (not self-fertile) and almost entirely on animal pollinators to achieve full fecundity; poor pollinator visitation has been reported to reduce yields of certain species by up to 50%." |
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The following details about DOUBLE FLOWERS comes from Wikipedia:- "Double-flowered" describes varieties of flowers with extra petals, often containing flowers within flowers. The double-flowered trait is often noted alongside the scientific name with the abbreviation fl. pl. (flore pleno, a Latin ablative form meaning "with full flower"). The first abnormality to be documented in flowers, double flowers are popular varieties of many commercial flower types, including roses, camellias and carnations. In some double-flowered varieties all of the reproductive organs are converted to petals — as a result, they are sexually sterile and must be propagated through cuttings. Many double-flowered plants have little wildlife value as access to the nectaries is typically blocked by the mutation.
There is further photographic, diagramatic and text about Double Flowers from an education department - dept.ca.uky.edu - in the University of Kentucky in America.
"Meet the plant hunter obsessed with double-flowering blooms" - an article from The Telegraph. |
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THE 2 EUREKA EFFECT PAGES FOR UNDERSTANDING SOIL AND HOW PLANTS INTERACT WITH IT OUT OF 15,000:-
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Choose 1 of these different Plant selection Methods:-
1. Choose a plant from 1 of 53 flower colours in the Colour Wheel Gallery.
2. Choose a plant from 1 of 12 flower colours in each month of the year from 12 Bloom Colours per Month Index Gallery.
3. Choose a plant from 1 of 6 flower colours per month for each type of plant:- Aquatic
4. Choose a plant from its Flower Shape:- Shape, Form
5. Choose a plant from its foliage:- Bamboo
6. There are 6 Plant Selection Levels including Bee Pollinated Plants for Hay Fever Sufferers in
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7. when I do not have my own or ones from mail-order nursery photos , then from March 2016, if you want to start from the uppermost design levels through to your choice of cultivated and wildflower plants to change your Plant Selection Process then use the following galleries:-
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There are other pages on Plants which bloom in each month of the year in this website:-
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