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Microbial abundance and diversity in river ecosystems are being increasingly investigated, yet a synthesized understanding is still lacking. Here, studies of microbial abundance and diversity along global rivers are systematically reviewed based on 814 investigations performed across 8376 sites. We found that riverine microbial investigations are extremely heterogeneous regarding the spatiotemporal distribution of the sampling sites, the environmental media concerned, the microbial groups and indices targeted, the methods used, and the physicochemical properties examined. More than 72.23% of the studies were performed in the last 8 years, with most studies conducted in Europe, China, and the United States, while other regions were poorly investigated. Most studies have examined microbes in water, but very few studies have systematically investigated microbes in water, sediments, and riparian soils. Bacteria are the most studied microbial taxonomic groups; microbes with resistance genes and nitrogen cycling genes are the most studied microbial functional groups. High-throughput sequencing has greatly expanded our understanding of microbial diversity along rivers. Nevertheless, the ecological implications of microbial diversity are still poorly understood. Regarding physicochemical properties, researchers tend to examine environmental parameters that are critical for shaping microbial communities, such as pH, nitrogen, and phosphorus. Future research should pay more attention to rivers that have not been well studied, especially large rivers. Additionally, microbial studies along rivers should be conducted in a more systematic way, taking the underinvestigated environmental media, microbial groups, microbial indices, and physicochemical properties into consideration. Advanced microbiology techniques, such as multiple omics technologies, should be increasingly applied.

Medicinal plants are more vulnerable to threats than non-medicinal plants. In China, a large number of medicinal plants are threatened by human activities and climate change, which greatly affect the conservation of species diversity, genetic resources and sustainable development of the traditional Chinese medicine industry. In this study, we established the first database for the distributions of 535 threatened medicinal plant species in China at the county level. Using this database, we explored geographic patterns, identified biodiversity hotspots and determined the conservation gaps for these threatened medicinal plants. Threatened medicinal plants were widely distributed in 1709 counties across the whole country. The species richness was higher in southern than in northern China. Using the “top 5% richness algorithm” and the “complementary algorithm”, we identified 213 counties as biodiversity hotspots for threatened medicinal plants in China. However, based on further conservation gap analysis, we found that 30 hotspot counties were not covered by any type of nature reserve (complete conservation gaps), and 27 more hotspot counties were not covered by national or provincial nature reserves in mainland China. We suggest that new nature reserves should be established for the 30 complete conservation gaps, while range, level or management strategies for the current nature reserves should be improved for the remaining 27 conservation gaps to promote the conservation of threatened medicinal plants in China.

China is very rich in biodiversity, however, it is also characterized by a long history of civilization. As a result, China has a large number of threatened species. Recently the Chinese government evaluated the living status of plants, and published the China Biodiversity Red List: Higher Plants. However, little is known about how threatened plants are distributed and conserved in China. In this study, we developed a fine resolution distribution database for 3244 threatened plants, explored richness patterns and evaluated the in situ conservation status of the threatened plants by overlapping the species distribution with terrestrial national and provincial nature reserves (NNRs and PNRs) in China. We found the greatest richness of threatened plants in the southwestern region of mainland China (mainly Yunnan, southeastern Xizang and western Sichuan), northwestern Guangxi, northern Guangdong, Hainan Island and the mountainous region of Taiwan, while the lowest richness was found in Qinghai, Hebei, Shandong, Jiangsu and Chongqing Provinces. On average, NNRs covered 18.8%, and NNRs and PNRs together covered 27.5%, of threatened plant distribution areas. However, 827 threatened plants (including 627 species endemic to China) were not covered by NNRs and 397 threatened plants (including 293 endemic to China) were not covered by either NNRs or PNRs. We proposed that nature reserves specifically designed for threatened plants need to be established in South China, especially in the Yunnan, Guizhou, Guangxi, Xinjiang Hainan, and Zhejiang Provinces.