HOLÍK, L., DUNDEK, P., FORMÁNEK, P., REJŠEK, K., VRANOVÁ, V.: Proportion of root-derived acid phosphomonoesterase in total soil acid phosphomonoesterase in diff erent forests. Acta univ. agric. et silvic. Mendel. Brun., 2011, LIX, No. 3, pp. 55-58 Enzyme acid phosphomonoesterase (APM) plays an important role in phosphorus mineralization in diff erent type of terrestrial ecosystems. This enzyme is of great agronomic signifi cance because it hydrolyses organic phosphorus to diff erent forms of inorganic phosphorus which are assimilable by plants. APM may also indicate changes in the quantity and quality of phosphorylated substrates in soil and is a good indicator of its biological state as well as presence of pollutants. APM may be produced by plant roots and soil microorganisms and both of these sources may play diff erent role in phosphorus mineralization in diff erent ecosystems. The aim of this work was determine acid phosphomonoesterase (APM) activity location in soil of diff erent forest ecosystems. The APM activity location determination was performed on the basis of root-derived and soil-derived APM and expression of proportion of those root-derived in total soil APM up to 13 cm depth. The results of this preliminary study showed that root-derived APM formed 21-34 % of total soil APM in pine and oak forest.acid phosphomonoesterase, soil, forests, roots Extracellular phosphomonoesterases (orthophosphoric monoester phosphohydrolases) catalyze hydrolysis of a variety of organic phosphomonoesters and are therefore important in soil organic P mineralization and plant nutrition. Acid phosphomonoesterase (APM) in soil is located in diff erent compartments. These include soil and its diff erent fractions, plant roots and mycorrhizal fungi (Burns et al