The expansion of poisonous weed Ligularia virgaurea leads to functional heterogeneity of nematode community

Abstract

Soil nematodes are an important component of underground communities and are highly sensitive to external disturbances and changes. Nitrogen deposition and dominant poisonous weeds are important factors contributing to global climate change. However, much less is known about the interaction between nitrogen deposition and poisonous weed on the taxonomic and functional diversity of nematode community on the Tibetan Plateau. We established a full factorial experiment between nitrogen addition treatment (nitrogen addition and ambient) with poisonous weed treatment (with Ligularia virgaurea and without Ligularia virgaurea) on the Tibetan Plateau. We quantified plant diversity, plant biomass, and edaphic properties to assess the effects of nitrogen addition and poisonous weed Ligularia virgaurea and their interactions on both taxonomic and functional alpha/beta diversity of soil nematode communities. Ligularia virgaurea indirectly decreased nematode taxonomic and functional beta diversity through plant biomass (standardized path coefficients: −0.2146) and directly increased nematode taxonomic and functional beta diversity (standardized path coefficients:0.1891 and 0.3470, respectively). Nitrogen addition directly (standardized path coefficients: −0.2069) and indirectly (through pH and plant biomass, standardized path coefficients: −0.3468 and 0.2144, respectively) affected nematode taxonomic and functional beta diversity. The interaction between Ligularia virgaurea and nitrogen addition indirectly decreased taxonomic and functional beta diversity through plant beta diversity (standardized path coefficients: 0.3665). Our results indicate a pattern of functional heterogeneity of nematode community following the expansion of poisonous weed Ligularia virgaurea, which highlights the important roles of poisonous weed in maintaining biodiversity and ecosystem functions and provides an alternative to realize the comprehensive utilization of poisonous weeds on the Qinghai-Tibet Plateau.