ancient and coppiced woodland

Authors Avatar

Biology coursework:

Species diversity and species abundance in ancient and coppiced woodlands: Skill I, A and E

Analysis:

Species diversity is a measure of different species of vegetation found in one area. The amount of different species depends on various factors. One of the factors affecting species abundance is the carrying capacity of the environment. The carrying capacity is defined as the maximum size of a population that can be supported sustainably in a habitat. The carrying capacity is controlled by several different factors including abiotic combined with biotic factors. Abiotic factors include light intensity, temperature, pH, moisture content of soil, etc. Biotic factors include predation, competition and density. Competition includes intra- and interspecific competition within an ecosystem. Intraspecific competition is competition within a species and interspecific competition is defined as competition between different species. (2, 3, 4)

The average light intensity is 1411 lux in coppiced woodland and 674 lux in ancient woodland. This shows that the light intensity was much higher in coppiced woodland. A higher light intensity results in a higher rate of photosynthesis. The coppiced woodland was much lighter and with a greater variety of species. In ancient woodland we found more trees which covered the wood ground with shadow so that the ground species could not get as much light as in coppiced woodland where it was lighter. Photosynthesis is the fixation of carbon dioxide and its subsequent reduction to carbohydrate, using hydrogen from water. Plants require light energy to carry out photosynthesis and to produce their own food. In photosynthesis the light energy absorbed by the photosynthetic pigments (chlorophylls and carotenoids) is converted to chemical energy. Photosynthesis consists of two stages. The first needs light energy and consists of the light-dependent reaction. In this stage the energy from the sunlight is transferred into the production of ATP and the coenzyme NADP is reduced to NADPH. These two products are subsequently used in the light-independent reactions to reduce carbon dioxide to carbohydrate. The absorption of light is carried out by the photosynthetic pigment molecules in two different photosystems-photosystem 1 and photosystem 2. PS1 particles are mainly present on the intergranal lamellae, whereas PS2 particles are mainly found on the granal membranes. Each unit contains several hundred chlorophyll and carotenoid molecules. Carotenoids are accessory pigments which catch the photons of light and transfer their energy to the central molecule. PS1 contains the primary pigment P700, with an absorption peak at a wavelength of 700nm and PS2 contains P680 with a peak at 680nm. A primary pigment acts as a reaction centre for the photosystems.  The second stage of photosynthesis consists of the light-independent reactions. It takes place in the stroma of the chloroplast and uses the products of the light-dependent reactions, NADPH and ATP, to fix carbon dioxide to carbohydrate. NADPH supplies the reducing power and ATP is the energy source. Species in coppiced woodland produce more carbohydrates as they receive more light energy than species in the ancient woodland and as a result they can respire more as glucose is used for respiration. Glucose is broken down in the four stages: glycolysis, the link reaction, the Krebs cycle and oxidative phosphorylation. In anaerobic conditions glucose is completely oxidised and carbon dioxide, water and energy are the products. In coppiced woodlands the light energy increases the air and soil temperature which increases the rate of respiration in the species in the coppiced woodland. This results in more water being in the soil in the coppiced soil samples as water is one of the by products of respiration. The average % of water is in the coppiced woodland higher due to increased rates of respiration. (2, 3, 6)

 The average soil temperature in coppiced woodland is 15.1°C and in ancient woodland the average soil temperature is 13.7°C. It is clearly visible that the temperature in coppiced woodland is higher than in ancient woodland. As the light intensity in coppiced woodland is 1411lux, the light heats the air and the ground which results in higher air and soil temperatures in the coppiced woodland. On the other hand in ancient woodland the light intensity is 674lux which results in lower air and soil temperatures.  Enzyme-catalysed reactions vary with temperature. At low temperatures, the reaction takes place only very slowly as the molecules are moving very slowly. Further the substrate molecules won’t often collide with the active site resulting in not many enzyme-substrate complexes being formed. When temperatures rise, the enzyme and substrate molecules move faster, colliding more frequently, so that the substrate molecule can enter the active site of the enzyme, forming enzyme-substrate complexes. As the temperature increases, the speed of movement of the substrate and enzyme molecules also continues to increase. When reaching too high temperatures the structure of the enzyme vibrates so energetically that the bonds holding the enzyme molecule in shape break, especially hydrogen bonds. As a result the active site changes resulting in no more enzyme-substrate-complexes being formed as the substrate can no longer fit into the active site of the enzyme. The enzyme becomes denatured. Each enzyme has its optimum temperature where it catalyses the reaction at its maximum ability, the optimum temperature is different for every enzyme. Plant enzymes often have a lower optimum temperature, depending on their habitat. The average soil temperature of 15.1°C in coppiced woodlands is higher than in the ancient woodland where the mean soil temperature is 13.7°C this assumes that the rate of enzyme activity is higher in coppiced woodland. The enzyme and substrate molecules collide more often forming more enzyme-substrate molecules. (1, 4)

Join now!

 The mean relative humidity is 46.7% in coppiced woodland whereas in ancient woodland the relative humidity is 60.25%, which is greater than in coppiced woodland. The average air temperature is 27.4°C in coppiced woodland, whereas it is 20.1°C in ancient woodland. The mean relative humidity and the air temperature both affect the rate of transpiration. Transpiration is the loss of water vapour, by diffusion down a water potential gradient, from a plant to its environment. The cells in the mesophyll layers are not tightly packed and have many spaces around them filled with air. The walls of the mesophyll ...

This is a preview of the whole essay