Abstract:

Aims: Changes in precipitation and nitrogen deposition significantly affect ecological functions and processes. As the most important soil organisms in terrestrial ecosystems, nematodes participate in various ecological processes. However, it remains unclear how the functional and phylogenetic diversity of nematode communities respond to changes in precipitation patterns and how nitrogen deposition regulates these responses. This paper aims to explore the effects of long-term precipitation intensity changes on soil nematode diversity and how changes in precipitation patterns affect soil nematode functional and phylogenetic diversity with and without nitrogen addition.
Methods: In this study, an 8-year experimental simulation of precipitation patterns and nitrogen addition was conducted, including precipitation intensity 2 mm, 5 mm, 10 mm, 20 mm, 40 mm and nitrogen addition (10 g N·m^–2·yr^–1). The diversity of soil nematodes was determined through taxonomy.
Results: The results showed that larger precipitation intensity increased the functional α diversity and phylogenetic α diversity of soil nematodes,while decreasing the taxonomic β diversity and phylogenetic β diversity. Nitrogen addition decreased the taxonomic, functional and phylogenetic α diversity,while increasing taxonomic, functional and phylogenetic β diversity. An increase in functional and phylogenetic diversity was observed under moderated and high precipitation intensity treatments. Soil water content and soil microbial biomass carbon content were the main factors impacting the functional and phylogenetic diversity of soil nematodes.
Conclusions: Due to global climate change, an increase in rainfall intensity in the coming decades may favor an increase in soil nematode functional and phylogenetic diversity in arid and semi-arid ecosystems. However, in areas with heavy nitrogen deposition, this positive effect may be offset by the deterioration of the soil environment caused by nitrogen deposition.

Key words: Soil nematode, Precipitation regime change, Nitrogen deposition, Functional diversity, Phylogenetic diversity, Climate change