Sampling techniques and disturbance of algal vegetation in permanent quadrats

Summary In studying permanent quadrats established in an algal vegetation by means of sampling in the quadrat itself, the vegetation is exposed to the risk of disturbance by the sampling. By taking small samples (microsampling or reduced size sampling) this risk is reduced considerably. The quantitative minimal area of vegetation units ofVaucheria, filamentous green algae and Oscillatoriaceae is less than 20 mm². InVaucheria components, however, often the viability for cultivation purposes is the limiting factor for the size of a sample suitable for a complete analysis of the permanent quadrat. The minimum size of a viableVaucheria sample is 1 cm². The disturbance of the algal layer by other external factors is often more intense than that caused by sampling. Nomenclature follows Polderman (1975b). Contribution to the Symposium of the Working Group for Succession Research on Permanent Plots, held at Yerseke, The Netherlands, October 1975. The author thanks Dr. Ir. W. G. Beeftink for helpful criticism and Mrs. R.A. Polderman-Hall for correcting the English text. The investigation of the algal communities of saltmarshes in the Wadden area is a project of the Netherlands Organisation for the Advancement of Pure Research.