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A composting experiment with sewage sludge and green waste was conducted to explore the effects of aeration directions (i.e., upward and downward) on static composting systems. The compost properties, including humification indexes and organic matter loss rate, and microbial diversity during the composting, were determined. Results showed that the downward aeration promoted the homogenization of temperature and moisture of the static composting system, thereby stimulating microbial metabolism and accelerating mineralization and humification. Microbial community profiles significantly changed among the composting phases. The humification dynamics were significantly correlated with the relative abundance of multiple microbial functional groups. However, no significant effects of aeration direction on the microbial community profiles were observed. The findings indicate that downward aeration is promising to improve the quality of static compost production, by stimulating microbial metabolism rather than altering microbial community profiles.

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.

Orchidaceae, the orchid family, is one of the species richest families and the most endangered plant groups. Most orchids are narrowly distributed in specific habitats because of their mycorrhizal specificity, pollinator specialization and limited seed germination rate; compared to plants from other families, orchids are extremely susceptible to habitat disturbance. However, little is known about how orchids are distributed and how they are protected at large scales. In this study, we developed a distribution database for all the 1449 orchid species in China. Using this database, we explored patterns of orchid richness in relation to climate, net primary productivity and habitat heterogeneity in China. We then evaluated the in situ conservation status of the orchids in China by overlapping the species distribution and the terrestrial national and provincial nature reserves (NNRs and PNRs) in C\hina. We found that 90% of orchid species in China were distributed in 258,800 km