Green sentinels in a changing climate: Moss biomonitoring reveals air pollution dynamics in New Zealand

We present the first island-wide biomonitoring survey of the South Island of New Zealand using epiphytic Orthotrichaceae. Mosses from 47 sites were analyzed for 16 elements, and enrichment factor (EF), contamination factor (CF), pollution load index (PLI) and potential ecological risk index (RI) were computed. Most locations exhibited background or only slightly elevated values, with PLI < 1 in approximately 70 % of samples, indicating generally low contamination. Localized hot spots of Cd, Hg, Zn, and Cu were detected, with EF ≥ 40, consistent with substantial anthropogenic influence. RI values ranged from 32.7 to 575.2 (mean 112). Over 80 % of sites fell into the low ecological-risk category (RI < 150), while several reached considerable risk (RI > 300). Overall, the atmosphere of the southern part of New Zealand remains relatively clean, and moss-based biomonitoring provides an effective complement to conventional instrumental measurements and a practical early-warning tool for environmental management.