Nitrogen addition has been shown to affect plant litter decomposition in terrestrial ecosystems. The way that nitrogen deposition impacts the relationship between plant litter decomposition and altered soil nitrogen availability is unclear, however. This study examined 18 co‐occurring litter types in a subtropical forest in China in terms of their decomposition (1 yr of exposure in the field) with nitrogen addition treatment (0, 0.4, 1.6, and 4.0 mol·N·m⁻²·yr⁻¹) and soil fauna exclusion (litter bags with 0.1 and 2 cm mesh size). Results showed that the plant litter decomposition rate is significantly reduced because of nitrogen addition; the strength of the nitrogen addition effect is closely related to the nitrogen addition levels. Plant litters with diverse quality responded to nitrogen addition differently. When soil fauna was present, the nitrogen addition effect on medium‐quality or high‐quality plant litter decomposition rate was −26% ± 5% and −29% ± 4%, respectively; these values are significantly higher than that of low‐quality plant litter decomposition. The pattern is similar when soil fauna is absent. In general, the plant litter decomposition rate is decreased by soil fauna exclusion; an average inhibition of −17% ± 1.5% was exhibited across nitrogen addition treatment and litter quality groups. However, this effect is weakly related to nitrogen addition treatment and plant litter quality. We conclude that the variations in plant litter quality, nitrogen deposition, and soil fauna are important factors of decomposition and nutrient cycling in a subtropical forest ecosystem.

Forest resources and the flow of ecosystem services they provide play a key role in supporting national and regional economies, improving people’s lives, protecting biodiversity, and mitigating the impacts of climate change. Based on the ISI (Institute of Scientific Information) Web of Science (WoS) database, we used a bibliometric approach to analyze the research status, evolution process, and hotspots of forest ecosystem services (FES) from a compilation of 8797 documents published between 1997 and 2019. The results indicated that: (1) research on forest ecosystem services has developed rapidly over the past 23 years. Institutions in the United States and other developed countries have significantly contributed to undertake research on the topic of ecosystem services. (2) The 11 hotpot key focus areas of completed research were payments for ecosystem services, biodiversity conservation, forest governance, ecosystem approaches, climate change, nitrogen, ecosystem management, pollination, cities, ecological restoration, and policy. (3) The trade-off relationships among ecosystem services, ecosystem resilience and stability have become the research frontier in this field. (4) Future research on FES will likely focus on the formation and evolution mechanism of ecosystem services; the interaction, feedback and intrinsic connections of ecosystem services at different scales; analysis of the trade-offs and synergies; unified evaluation standards, evaluation systems, model construction and scenario analyses; in-depth studies of the internal correlation mechanism between forest ecosystem services and human wellbeing; and realization of cross-disciplinary and multi-method integration in sustainable forest management and decision-making.