ASSESSING THE INFLUENCE OF ENVIRONMENTAL POLLUTION ON PLANT DIVERSITY AND ECOSYSTEM STABILITY USING ECOLOGICAL MODELING

Abstract

Nitrogen enrichment is a critical type of environmental contamination that may influence post-fire vegetation recovery, plant diversity, community structure and ecosystem stability. This study evaluated how contrasting nitrogen treatments influenced plant diversity, native–nonnative vegetation structure, community composition, and temporal stability across three post-fire sampling years. Plot-level observations were repeatedly analyzed with diversity indices, mixed-effects models, temporal stability metrics, PERMANOVA, PERMDISP and non-metric multidimensional scaling. The analyses included nitrogen treatment, year, invasion status and relevant interactions. Significant nitrogen × year interactions were detected for total richness, native richness, Shannon diversity, Simpson diversity, and Pielou evenness. High nitrogen was associated with lower native vegetation cover and greater nonnative cover, while native and nonnative vegetation components exhibited significant temporal responses. Community composition differed significantly among nitrogen treatments (PERMANOVA, p = 0.006), with significant pairwise differences involving the high-nitrogen treatment. The evaluated temporal stability metrics were not significantly affected by nitrogen treatment, but invasion status did affect some of the stability outcomes. Overall, the post-fire plant diversity and community composition changed in a highly time dependent way as a result of the nitrogen enrichment, especially through shifts in the native–nonnative vegetation balance, while temporal stability was relatively unaffected.