Download Decomposition Rates and Factors Influencing Nutrient Regeneration in Ecosystems and more Slides Ecology and Environment in PDF only on Docsity! Lecture 20: Nutrient Regeneration in Terrestrial and Aquatic Ecosystems Docsity.com 20.3 Rates of Decomposition and influencing factors • Rate at which nutrients are made available to primary producers is determined largely by rate of decomposition. • influenced by: – temperature, – moisture, – chemical compositions of leaves – Decomposers Docsity.com Temperature influence on decomposition Diurnal changes in air temperature and decomposition in a temperature deciduous forest (Whitkamp and Frank 1969) Docsity.com 20.4 Nutrient regeneration can follow many paths Monomers: monomeric subunit of large organic polymers such as amino acids, nucleic acids. Depolymerization is accomplished by microorganisms secreting enzymes and other reactive substances. Docsity.com Mineralization, immobilization and net mineralization rate • Mineralization: a process that microbial decomposers –bacterial and fungi- transform nitrogen and other elements contained in organic matter compounds into inorganic (or mineral) forms. – Organic N ammonia (waste product of microbial metabolism) • Immobilization: uptake and assimilation of mineral nitrogen by microbial decomposer. – N used by microbes to grow • Net mineralization rate: different between the rate of mineralization and immobilization Docsity.com 20.5 Mycorrhizal associations of fungi and plant roots promote nutrient uptake Symbiotic association of fungus and root is called a Mycorrhiza: Arbuscular Mycorrhizae ( AM) penetrate cell walls in root tissue and form vesicles or branched structures in intimate contact with root cell membranes. Ectomychorrhizae ( EcM): form a dense sheath around the outsides of small roots and penetrate the spaces between the cells of the root cortical layer Function: promote plant growth, increase a plant’s uptake of minerals by penetrating a greater volume of soil than the roots. Docsity.com Plant roots and mycorrhizal fungi Fungi assist the plant with the uptake of nutrient from the soil (extended water and nutrients absorption) Plant provides the fungi with carbon, a source of energy. Endomycorrhizae (a) Ectomycorrhizae (b) Docsity.com 20.6 Key ecosystem processes influence the rate of nutrient cycling • Primary productivity determines rate of nutrient transform from inorganic form to organic form (nutrient uptake) • Decomposition determines the rate of transformation of organic to inorganic form (N mineralization) • Rates of these two determine the internal cycling Docsity.com
