ISOTHECIUM MYOSUROIDES AND THUIDIUM TAMARISCINUM MOSSES AS BIOINDICATORS OF NITROGEN AND HEAVY METAL DEPOSITION IN ATLANTIC OAK WOODLANDS

Abstract

Moss tissue chemistry is widely used as a bioindicator of atmospheric deposition. The objective of this study was to compare the tissue chemistry of two moss species in Irish Atlantic oak woodlands, Isothecium myosuroides [Im] and Thuidium tamariscinum [Tt], and to determine their relationship to indices of atmospheric deposition. Moss species were collected from twenty-two woodland sites during April 2013 and analysed for nitrogen, sulphur, and eleven heavy metals. Nitrogen content was significantly correlated between species (r_s = 0.84), but their mean values (Im = 1.23%, Tt = 1.34%) were significantly different. A simple linear regression suggested that nitrogen content was significantly related to atmospheric ammonia (R² = 0.67 [Im], R² = 0.65 [Tt]) and total nitrogen deposition (R² = 0.57 [Im], R² = 0.54 [Tt]). Many heavy metals had significant interspecies correlations (Al, V, Ni, Cu, Zn, As, Sb, Pb; r_s = 0.46−0.77). A few metals (As, Sb and Pb) were positively correlated with easting and northing for both species, which may suggest transboundary or national industrial emissions sources. The results suggest that both species could be used as bioindicators of deposition for nitrogen and some heavy metals, although further study of the relationship between tissue concentrations and atmospheric deposition is warranted. Furthermore, interspecies calibration is required to use both species in conjunction.