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.

Forest gaps play a crucial role in community succession and assembly in forest ecosystems; therefore, they have recently been recognized and implemented as effective forest management practice all over the world. Forest gaps are commonly created as small disturbances in secondary forests to improve forest regeneration, nutrient cycling, ecosystem functioning, and biodiversity. The objective of this study was to investigate the responses of the physico-chemical and biological properties and microbial communities in soil to different sizes of forest gaps—including small gaps (60–80 m²), medium gaps (130–160 m²), and large gaps (270–300 m²)—and to examine the driving factors that influence soil microbial community structure and composition. The results show that Gram-positive bacteria, Gram-negative bacteria, fungi, arbuscular mycorrhizal fungi (AMF), and actinomycetes were mainly aggregated in the gaps, and the structural diversity of soil microbial communities was related to the gap size (p < 0.05). The soil microbial community diversity increased and then decreased with an increase in gap size. Moreover, the effects of the available phosphorus, soil pH, soil water content, available potassium, nitrate nitrogen and ammonium nitrogen on changes in microbial biomass were significant (p < 0.05). The gap area and gap position and their combined interactions also had significant effects on soil nutrients, which impacts the soil microbial community. Medium gaps (130–160 m²) always significantly improved the availability of soil nutrients, and good management practices in secondary forests can provide effective microenvironments for soil microbes.

Nitrogen (N), an indispensable mineral nutrient element for plant growth and development, is a major limiting source of productivity in many terrestrial ecosystems. Soil organic nitrogen (SON) is a crucial form of nitrogen (N) in the N cycle within terrestrial ecosystems, acting as either a “source” or a “sink” for environmental N release. In order to illustrate the research trends, evolution process and hotspots of SON, a bibliometric analysis was used to analyze 906 documents based on the ISI (Institute of Scientific Information) Web of Science (WoS) database. The results indicated that (1) the number of published papers on SON research showed a wavy growth from 2000 to 2022 and the research has entered a mature development period; China has been increasing its number of publications and has long been in the lead; (2) the most productive institutions and authors in this subject area are in the USA and China, with the Chinese Academy of Sciences being the key institution performing such research; (3) in the sample, Soil Biology and Biochemistry, Science of the Total Environment, and Biogeochemistry are the leading international journals that have played a key role in the evolution of the field and have laid a solid foundation for future research; (4) the characteristics and maintenance of SON in farmland and SON migration in small watersheds under forest conversion have become research hotspots. Through the in-depth analysis of SON research, this paper provides a better understanding of the development trends of SON over the past 20 years, which can also provide reference for future research.