Precipitation shifting plant community assembly drivers multitrophic interactions in a semiarid ecosystem

Climate change has significantly impacted biodiversity distribution and community assembly globally, particularly in dryland ecosystems vulnerable to precipitation fluctuations. However, little is known about the response of plant and arthropod community assembly to precipitation changes and their multitrophic relations in b diversity. To verify this, we examined the community assembly process and b diversity distribution across three trophic community levels (i.e., plants, herbivorous and predatory arthropods) under precipitation changes (±20%, ±40%, ±60%) in a semiarid region. We found that plant community assembly shifted from deterministic to stochastic process with 380 mm (between 336-392 mm) serving as a threshold. However, both herbivorous and predatory arthropod community assembly remained unaffected by precipitation changes, being consistently dominated by stochastic process. Being below 380 mm, we observed a positive effect of precipitation on plant b diversity, which in turn induced cascading effects on b diversity of herbivorous toward predatory arthropod communities. Being above 380 mm, however, the positive relation in b diversity between herbivorous and predatory arthropods was decoupled, despite a consistent positive relation between plant and herbivorous arthropods. Similarly, Likewise, there was similar species turnover results of multitrophic interactions in were similar to b diversity under precipitation below and above 380 mm; however, there were no significant relationships in species nestedness between these three trophic communities under precipitation change. It was suggested that the observed ecological filtering in plants (triggered by high precipitation) and their associated cascading effects on arthropod communities could lead to greater species turnover and less predictable community compositions under wet conditions. These insights were critical for developing conservation strategies on the maintenance of biological diversity that could help arid grassland ecosystems adapt to ongoing and future global climate change.