Temporal ecological processes have different seasonal influences on multiple dimensions of riverine insect diversity in China

Abstract An understanding of the relative importance of ecological processes affecting biological communities can assist in interpretations of biodiversity patterns. However, the mechanism behind temporal beta diversity, which refers to the dissimilarity between community structures at different times, remains unclear for aquatic insect communities. Therefore, we collected monthly samples of aquatic insects at five sites in streams from July 2011 to June 2012 in Central China. The five sample sites were located in river sections with perennially flowing water, which were subject to little human disturbance. We examined taxonomic‐ and trait‐based temporal beta diversity patterns of riverine insects across seasons in sites. Taxonomic‐ and trait‐based temporal beta diversity demonstrated a decline with species richness but an increase with the time between sampling dates. Taxonomic‐based temporal beta diversity was significantly higher than trait‐based temporal beta diversity. Turnover (i.e. species replacement) was the main driver of taxonomic‐based temporal beta diversity whereas nestedness (i.e. species gain or loss) contributed more to trait‐based temporal beta‐diversity values. In addition, the correlation between taxonomic‐ and trait‐based temporal beta diversity was weak. Deterministic processes (i.e. operating through physico‐chemical factors and climate) and stochastic processes (i.e. operating through temporal variables) are distinct, but they can act together in influencing the temporal beta diversity of riverine insects. Taxonomic‐based temporal beta diversity was more sensitive to environmental changes than trait‐based temporal beta diversity, and taxonomic shift do not necessarily result in trait changes. The main driver of taxonomic‐based temporal beta diversity changed with the location and components analysed. In contrast, stochastic processes were the most dominant influence on trait‐based temporal beta diversity. Results suggest that taxonomic‐ and trait‐based conservation measures should consider both turnover and nestedness patterns in the protection of riverine insects in China and elsewhere. Additionally, the development of integrated monitoring and management protocols that apply across seasons and life stages should be considered.