(1) Background: Forest gaps play an important role in promoting forest regeneration and facilitating the forest growth cycle. Since the 1980s, forest gaps have been widely studied by forestry scientists. The purpose of this study was to review the global literature from 1980 to 2021, based on the scientific database Web of Science Core Collection, and to summarize the research hotspots and the trends of the forest gaps. (2) Method: A bibliometric analysis was performed using the visual analytic software CiteSpace to quantify the description of annual publications, collaboration analysis of authors, institutions and countries, co-citation analysis of cited journals, cited authors, and cited references. The keyword co-occurrence, burst, and time zone were also analyzed by the software. (3) Results: The results show that the volume of annual publications is increasing. Dr. Harald Bugmann is the author with the most published works. The most active institution is the American Forest Service. The United States, Canada, and China are the three most productive countries. “Ecology” is the most cited journal. The results indicate that the hotspot in the forest gap research has shifted, and the effects of forest environmental changes caused by forest gaps under climate change have received more attention from scientists. In the future, more attention may be paid to the role of forest gaps on near-natural forest management patterns, the effect of forest gaps on forest sustainable development, and the way to study forest gaps using lidar technology. (4) Conclusion: Our results can help to understand emerging trends in forest gap research to inform forest ecology and management.

The mechanisms underpinning the soil microbial community assembly are important, particularly in the fragile karst forest ecosystem. Despite such significance, relevant topics remain limited. We investigated a typical karst area, the Maolan National Nature Reserve in China. For this purpose, 30 forest dynamics plots were established on three restoration gradients in degraded karst forests, namely shrub, pioneer tree, and climax communities. Using vegetation surveys, we explored the diversity patterns, driving factors, and community assembly of the soil microbial communities during the restoration of degraded karst forest ecosystems. In addition, the soil physicochemical properties and macrogenomic sequencing data were examined. One-way analysis of variance and principal coordinates analysis showed no significant changes in soil microbial α-diversity during restoration, and the opposite pattern was observed for β-diversity. Variation partitioning analysis revealed that the combined effect of both soil microbial β-diversity and soil was significant (28% and 32% for bacteria and fungi, respectively). Pearson correlation analyses showed that plant species diversity and soil multifunctionality correlated significantly with soil microbial β-diversity. In contrast, the direct effect of plants was smaller (2% and 3% for bacteria and fungi, respectively). According to the dispersal–niche continuum index, stochastic processes were responsible for the assembly of the bacterial and fungal soil microbial communities. During restoration, the dominant influence of stochastic effects on the assembly of bacterial communities intensified. In contrast, the reverse tendency was observed in soil fungi. The investigation of the diversity pattern of soil microbial communities and their assembly can provide theoretical references for the restoration of degraded ecosystems.

The biodiversity–ecosystem function (BEF) relationship is the basis for studying the restoration of degraded ecosystems, and the simultaneous assessment of multi-trophic-level biodiversity and ecosystem multifunctionality relationship is more conducive to unravelling the restoration mechanism of degraded ecosystems, especially for degraded forest ecosystems with harsh habitats and infertile soils such as karst. In this study, we evaluated the biodiversity and soil multifunctionality (SMF) of degraded karst forests (scrub, SB; secondary growth forests, SG; old-growth forests, OG) in the Maolan National Nature Reserve, China, using 30 sample plots. Biodiversity and soil multifunctionality (SMF) at three trophic levels (plant–soil fauna–soil microorganisms), were assessed through vegetation surveys and soil sampling. One-way ANOVA showed that SMF increased with natural restoration, but multi-trophic level biodiversity showed different trends. Pearson’s correlation analysis showed a positive correlation between plant species diversity and SMF (p < 0.001), whereas soil fauna and soil microorganisms were negatively correlated with SMF. Structural equation modeling revealed a cascading effect of the multi-trophic level on the stimulation of the SMF during restoration. Only soil microorganisms exhibited a direct driving effect on SMF (p < 0.001), whereas plants indirectly influenced soil microorganisms through soil fauna, which subsequently affected the SMF. Although we observed the negative effects of increased plant diversity on soil fauna and soil microbial diversity in terms of quantitative relationships, the increase in soil fauna species and the evenness of soil microbial function still contributed to SMF restoration. This study revealed the cascading effects of multi-trophic diversity in promoting SMF restoration and emphasized that soil microbes are key to unraveling restoration mechanisms and processes, whereas soil fauna is an important intermediate link.

Grassland ecosystem health is related to global ecological problems, and large areas of grassland are threatened by degradation. Various measures, such as aerial seeding, have been applied to restore degraded grassland ecosystems. However, the effects of these measures remain unclear. In this study, based on the CVOR (condition, vitality, organization, and resilience) model, the entropy method was used to calculate the ecosystem health of aerial seeding restoration sites in the Mu Us sandy grassland, China. Then, the relationship between CVOR value, various indices in the model, and restoration time was measured using correlation analysis. The results show that (1) the vitality criterion layer has the highest weight in the CVOR model; (2) the cautionary hierarchy is the most (40.0%), and the healthy hierarchy is the opposite (10.0%) among all the restoration sites; and (3) 30-year aerial seeding can promote ecosystem health in sandy grasslands. This study demonstrates that aerial seeding is an effective method for restoring degraded grassland ecosystems and can guide future restoration measures and policies for degraded ecosystems.