NITROGEN FIXATION BY MEMBERS OF THE STICTACEAE (LICHENES) OF NEW ZEALAND

Abstract

Forty‐four species of New Zealand lichens, including 22 species of Pseudocyphellaria and seven of Sticta, were assayed for nitrogenase activity by acetylene reduction. Nitiogen fixation was confirmed by 15N enrichment studies. Ten species, all with green algal phycobionts, showed no detectable nitrogenase activity; the remainder, including all species of Pseudocyphellaria and Sticta, assayed positively. Fixation rates were found to be species specific ranging from 0·2 to 52 nmol g‐1 min‐1. Nitrogen fixing lichens showed a species specific range of total nitrogen content and all had greater values than non‐fixing species. Further analysis of nitrogen fixation in Sticta and Pseudocyphellaria species by plotting a graph of acetylene reduction against nitrogen content showed a highly significant positive relationship; also species of like chemical strain grouped together, and in any one chemical strain lichens with solely blue‐green phycobionts possessed higher rates. The possibility exists that these lichens could provide a significant input of nitrogen into some native forests in New Zealand. Copyright © 1980, Wiley Blackwell. All rights reserved