Write an Essay of Approximately 1000 Words
Write an essay of approximately 1000 words, plus appropriate illustrations and references that explores the relationships between lithology, topography, soils and vegetation. Vegetation is the sum of plant life covering the ground in an area. Vegetation is a more generalised term than flora. Lithology, topography and soils all have a relationship and impact on vegetation. Lithology is the macroscopic physical characteristics of a rock, (Thomas and Goudie, 2004). Such as the porosity, grain size and chemical composition.
The lithology that lies beneath the soil has an impact on the soil in an area, both the type and amount of coverage. It also has an impact upon the saturation point of the soil and rate at which any water filtrates through the soil and the bedrock. The hardness of the lithology has an impact on the type of soil and the amount of regolith. For example if the rock type is a particularly hard rock type, such as granite and the regolith is removed, as the rock is so resistant, the material cannot be as readily replenished, visa versa for a softer rock type such as a lime stone, which is weathered much more readily.
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The permeability of the underlying lithology has an impact on the vegetation and the soil. In certain areas, especially across the UK, in areas around Scotland, impermeable rock can result in the water logging of the ground. These moist growing conditions encourage the growth of certain communities of vegetation which are resistant to frequent flooding of the land, such as Salix and Cornos. The lithology beneath the soils has an impact on the main component of the soil itself.
The weathered material can have an impact on the Salinity, Alkalinity and Acidity of the soil. The type of weathered material which composes the majority of the soil (not including any biota or mixing agents) has a profound relationship with the composition with the soil. If the soil is particularly saline then only certain types of vegetation can survive the harsh environment. These types of plants are commonly known as halophytic plants, vegetation which grows in these particular conditions are communities such as Salicornia and Spartina.
It is a similar case for alkaline soils and acidic soils. Plants such as Baby’s Breath and Yarrow like to grow in alkaline (or chalky) environments, and plants such as Heather, Holly and many woodland plants are more suited to acidic soils. If the soil is high in minerals and nutrients it is perfect fertile ground for many different plant communities. Densely vegetated areas such as woodlands tend to have a large percentage of biota, which again encourages an even further growth of plats, and a wider variety of species.
There is also a great relationship between topography and vegetation. As topography changes, it not only changes the altitudinal height and the shape of the land, it usually indicates a change in geology, and/or a change in soil. As height increases the air temperature usually falls, due to the adiabatic lapse rate. This would naturally have a relationship with the type of vegetation which occurs. Vegetation varies with altitude in response to local atmospheric and environmental changes.
The higher you climb up a mountain for example, not only does the temperature decrease, but there are other weather changes, such as wind speed gains strength and precipitation levels increase (this is usually as a result of relief rainfall etc). General changes that occur in vegetation with height increase a reduction in plant size, lesser species of plants / plant communities, and also a slower rate of growth occurs over all. Vegetation and slopes do have a relationship, however it tend to be the slope being dependent on the vegetation as opposed to the vegetation being dependant on the slope.
The density of vegetation coverage on a slope has a major impact on the slopes stability. A dense network of roots; provide a binding surface, keeping the top layer of soil intact. The local lithology, soil type and density, and the topography all have a relationship with vegetation, the species, variety, growth rates and density. There are other more obvious factors which have certain controls on vegetation, such as temperature, rainfall and sun exposure. Overall everything that has been mentioned and more has a relationship with vegetation, either directly or indirectly.
Each factor is interlinked in a very sensitive and dynamic system. Word Count 781 References Websites Unknown. (2009). vegetation and soil. Available: http://www. yourclimateyourlife. org. uk/a_soil_types. html. Last accessed 12 Aug 2010. Unknown. (2010). Top Ten Herbaceous Perennials For Chalky / Alkaline Soils. Available: http://www. findmeplants. co. uk/plants-alkaline-soils. aspx. Last accessed 12 Aug 2010. Books David S. G. Thomas and Andrew Goudie (2004). The Dictionary of Physical Geography. 3rd ed. Oxford: Blackwell Publishing.