Unraveling the interaction effects of soil temperature and moisture on soil nematode community: A laboratory study

Soil nematode communities and their functions are simultaneously influenced by abiotic factors such as temperature and soil moisture. However, the complex interaction effects of these factors have not been clearly demonstrated, limiting our understanding of soil biodiversity and functions under different climate scenarios. Here, we conducted a short-term microcosm experiment, implementing three temperature treatments (20 degrees C, 25 degrees C, and 30 degrees C) combined with two soil moisture treatments (50% and 80% water-holding capacity). We comprehensively assessed the changes in abundance, diversity, composition, and functions (carbon footprints) of soil nematode communities under these different treatments. Our findings revealed that temperature and moisture did not have significant effects on the richness or Shannon diversity of nematodes, while they did have significant impacts on other properties. We found that the interaction effect between temperature and moisture had a greater influence on total abundance compared to their independent effects. Moisture emerged as the primary driver of nematode community composition, followed by the interaction term, while temperature exhibited the least influence. Contrary to expectations, increasing temperature did not cause a shift in the community towards small-bodied genera when considering intraspecific variability in body mass. However, elevating moisture level led to an increase in community-weighted mean body mass, irrespective of intraspecific variability. Consequently, the body-mass-related footprints varied among treatments when considering intraspecific variability, with the dominant influence arising from the interaction effect. Overall, our study highlights the dominant interaction effect of temperature and soil moisture on multiple ecological properties of nematode communities. Additionally, we underscore the importance of incorporating intraspecific trait variability when assessing the responses and functions of nematodes under distinct environmental conditions.