This assignment will cover picking the best tree or shrub to plant in a particular area covering the fundamental factors and procedures that are critical to tree and plant establishment in differing environments. Simply âTHE RIGHT TREE FOR THE RIGHT PLACEâ.
Trees that are planted in urban environments car parks, recreation areas, streets provide important benefits to urban populations.
Absorbtion of pollutants. Reduction of traffic noise. Windbreaks and shelter.
Reduction of radiation and solar heat gain through shading and evapotranspiration.
The planting and choice of trees and shrubs needs to be considered for different sites as certain plants may not survive in sites that are poorly drained or wet, weedy sites, exposed, or sandy soils.
One way to alleviate these problems could be to change the soil in the area you are planting, but if this is over a large area it may not be practical or monetarily achievable. Poorly drained or wet sites could be rectified by draining the sites or putting in drainage to remove the excess water from the area. Wet or poorly drained sites are usually associated with clay soils and clay soils can be broken down by the use of gypsum which is the active ingredient of clay improver’s. Manure can also be added to improve the working properties of clay.
The top five trees to plant in wet soils are
Amelanchier lamarckii ( Juneberry) Betula pendula (silver birch)
Crataegus laevigata (midland hawthorn) Sambucus nigra ( common elder)
Sorbus aucuparia (Rowan)
Exposed sites can be found in various places hillsides, mountains and coastal regions, to name but a few. The main problem that has to be looked at with these areas is high winds so the use of trees in wind breaks or shelter belts need to be considered. A windbreak can reduce wind on the leeward side by up to ten times the height of the windbreak and once this barrier has been established it may be possible to grow quite a wide range of shrubs and trees.
The top five trees to plant in exposed sites are
Elaeagnus x ebbingei Crataegus monogyna ( Hawthorn )
Alnus cordata (italian Alder) Hippophae rhamnoides (sea buckthorn)
Tilia cordata ( small leafed Lime )
Sandy soils can pose a variety of problems they may be easy to cultivate and work but dry out quickly and are low in nutrients. If planting in these environments some form of watering system or irrigation may be required or the use of mulch to help prevent water loss. The use of well rotted moisture retentive farm manure will need to be considered before any planting goes ahead.
The top five trees and shrubs to use in sandy soils are
Acer campastre ( field maple ) Lavandula ( french lavender )
Buddleja Verbena bonariensis ( Argentinian vervain )
Choisya ternata (Mexican orange blossom)
Weedy areas can be awkward for planting trees or shrubs as they may take over the area before the trees or shrubs become established. It may be prudent to spray the area with weed killers but this may make the area that you wish to plant unusable for a time as it could kill or damage the shrubs or trees that you want to use. Weeds can take away water before it reaches the roots of young plants or trees.
Any trees that are suitable for the soil type that is in the area can be used.
Overhead services can influence the selection of trees and shrubs for locations near these areas. The easiest to see is the height a tree will grow to and may affect or come into contact with overhead lines which are usually electric lines. This can pose a problem in the future as heavy pruning may need to be undertaken and this could damage the tree and make it susceptible to pests and diseases. Local authorities are also looking at children and adults possibly climbing these trees and coming into contact with the wires. A consideration would be if you want to plant near an overhead line to use a tree which will stop growing before it reaches the height of the overhead line.
Underground services can pose a larger problem as they invariably have to be dug up to allow maintenance and the root systems of trees can spread further than the spread of the branches above ground. If underground services are dug up it can cause damage to the tree roots which are basically the system to keep the tree upright and in extreme circumstances may cause the tree to become unstable. Problems are also encountered in planting, plans for underground services need to be inspected so that cables and pipes are not damaged when planting and some distance should be observed so that as the tree grows its roots do not damage the services.
Roadways and highways can influence tree and shrub selection as fast growing trees will need to be pruned back from the roadway and this will cause disruption to road users due to pruning operations. The use of trees and shrubs that are suitable as a noise barrier but don’t grow quickly horizontally could be considered or planting further back from the carriage way to allow the tree to grow and mature without need for pruning.
The way building foundations influence tree and shrub selection is probably one of the most emotive issues with home owners. Tree roots can spread up to three times the height of the tree and in dry conditions may cause damage as the clay round the roots can dry out and shrink. This can result in subsidence and structural cracking possibly around windows and doors. The main problem with this is usually only in shrinkable clay soils and only in buildings of four storeys or more built before the 1950s. Planting smaller trees or low growing trees is an option but if you have a tree on your property it could be advisable to have it professionally inspected. The compacting of soil around trees and shrubs can cause damage to the root system and the tree.
Four factors that influence tree and shrub selection are
SIZE.
Knowledge of the height and spread of trees and shrubs before planting can assist in positioning and also overcrowding and interference with overhead lines obstruction of roadways and pedestrian traffic. The trees and shrubs should have a longer lifespan and may require less pruning and maintenance.
ROOT SYSTEM.
Knowledge of the root system its spread and growing factors how intrusive it is speed of growth and any underground services it might affect.
PESTS and DISEASES.
It is pointless planting trees or shrubs that will be killed by pests or diseases that are common in nearby trees or shrubs. There are trees that have been developed that are resistant to pests that effected non resistant trees in the past.
SOIL CONDITIONS
Trees and shrubs should be suitable for the area you require them to grow in and they should be hardy enough to grow in the environment you plant them in.
Always buy well developed strong plants and the right tree for the right place.
...(download the rest of the essay above)