Plug method allows measurement of apical and lateral growth of fen brown mosses

Abstract

ABSTRACT Introduction: A reliable method for measuring brown moss production helps us to understand the functioning of fen peatlands and to quantify their peat formation rate. However, traditional methods based on height increment are not suitable for measuring the growth rate of brown mosses with numerous lateral branches. Methods: The growth rate of common brown moss species in temperate and boreal fens was measured using two methods: (i) the marking method – a moss shoot was marked with oil paint and its growth increment measured from the mark (in the laboratory and in the field); and (ii) the plug method – a fragment of a moss colony was ‘plugged' (i.e. cored), weighed and replanted in a small basket for a year, then weighed again; a similar and bottomless basket was fixed in the moss colony as a control. Key results and discussion: Despite promising laboratory results, the marking method gave low shoot survival in the field, probably due to the restriction of external water transport along the shoots. No differences in shoot elongation were found between the plug method and the control. The plug method comprises the measurement of both apical and lateral growth, and the authors of the present study therefore recommend it for measuring the growth of brown mosses with numerous lateral branches. Considering only the elongation of the top shoots leads to an underestimation of growth by 50% and consequently to an underestimation of the peat-forming potential of brown mosses.