Paul Ola Igboji Phd

Effect of park grassland management on C-fluxes in temperate ecosystem Paul Ola Igboji Phd

Living cells need a constant supply of energy, which for heterotrophic microflora is derived from the transformation of organic matter such as cellulose, proteins, nucleotides and humifieds compounds. Energy supplying reactions in the cell are redox reactions based on the transfer of electrons from a donor to an acceptor. Through aerobic respiration that is the oxidation of organic matter by aerobic micro-organisms oxygen functions as the terminal acceptor of the electrons. The metabolic activities of soil micro-organisms can therefore be quantified by measuring the CO2 production or O2 consumption . Soil respiration is one of the oldest and still most frequently used parameters for quantifying microbial activities in soils. Basal respiration is defined as respiration without the addition of organic substance to soil. Substrate-induced respiration (SIR) is the soil respiration measured in the presence of an added substrate such as glucose. Respiration is not only restricted to micro-organisms but it is also carried out by other organisms inhabiting the soils. Like other metabolic activities it depends on the physiological state of the cells and is influenced by different factors in the soil. Respiration is influenced by soil moisture, temperature, the availability of nutrients, soil structure and tillage. Air drying significantly reduces soil respiration. Re-moistened soils however show very high initial activities; probably as a result of the high concentrations of easily degradable organic compounds such as amino and organic acids caused by chemical and physical processes at the moistening of dry soils. The re-moistening of air dry soils containing carbonate also causes the release of abiotic CO2. In this case it is recommended that the O2 consumption is measured. Soil respiration decreases with the depth of soil and correlates significantly with SOM (Corg), and most microbial parameters. Soil respiration changes according to soil treatment and cultivation methods and has been used as a measure of the effects of chemicals such as pesticides and heavy metals. Basal soil respiration can be followed for long periods of time. However, changes in the composition of aerobic microflora can occur during long term incubation. In the case of the SIR method, a change in population is expected when the incubation period is longer than 4 - 6 h. The incubation temperature used varies between 20 and 30oC and the water holding capacity between 50 and 70%. The pH value of the measurement is usually that of the soil in water. This book explores the effect of park grassland management on C-fluxes in temperate ecosystem.