Seasonal and Interannual Microbial Community Dynamics in Dacrydium pierrei and Vatica mangachapoi Tropical Rainforest

Abstract

Elucidating plant-microbiome temporal dynamics is essential to forecast plant vulnerability under climate change, particularly for endangered tropical trees. Therefore, we investigated the assembly mechanisms of phylloplane and rhizoplane microbial communities in two endangered tropical rainforest tree species in Hainan—Dacrydium pierrei and Vatica mangachapoi—across seasonal and interannual scales. We sampled the phylloplane and rhizoplane microbiomes of these two tree species across seasons and years and combined high-throughput sequencing with physical and chemical measurements to analyze their community assembly mechanisms. The main findings are as follows: (1) Both phylloplane and rhizoplane bacterial communities exhibited significantly stronger interannual variation, whereas phylloplane fungal communities showed significant seasonal variation but no significant interannual variation. Most dominant taxa exhibiting significant changes were mainly driven by nutrient factors. (2) Bacterial communities and phylloplane fungal communities exhibited significant interannual variation in α-diversity, whereas rhizoplane fungal communities showed significant seasonal variation, with temperature serving as an important driver of these diversity changes. β-diversity analyses confirmed that interannual variation was the dominant force restructuring phylloplane and rhizoplane bacterial communities, and community structure changes were mainly influenced by pH, temperature, and water content (WC). (3) Network analysis showed that both phylloplane and rhizoplane microbial community complexity exhibited stronger interannual than seasonal variation. Phylloplane bacterial complexity was influenced by temperature and leaf water content (WC) and fungal complexity by leaf pH, soil pH, and soil total potassium (TK), while rhizoplane fungal complexity was jointly affected by leaf pH, leaf total nitrogen (TN), leaf total potassium (TK), soil water content (WC), and soil available potassium (AK). Overall, our results clarify how environmental factors differentially govern microbiome assembly at distinct temporal scales, laying the mechanistic groundwork for predicting rare tree species’ responses to current climate trends and informs the design of microbiome-assisted protection strategies.