Junping Lv

Phytoplankton communities are of vital importance to the functioning of freshwater ecosystems, but the role of the metabolic capacity of the community in regulating community dynamics under natural conditions has yet to be sufficiently considered. This study investigated 26 lakes situated along the eastern section of the Hu Line, combining field surveys with metagenome‐assembled analyses to ascertain the factors responsible for the divergence in Chlorophyta and Bacillariophyta communities. The results demonstrated that the diversity of Chlorophyta was markedly higher than that of Bacillariophyta whereas the abundance was significantly lower. These discrepancies in community attributes were predominantly attributable to variations in the response of the two algal groups to nutrients. The abundance and diversity of diatom metabolic genes were significantly higher than those of green algae. The greater diversity and extent of metabolic genes in Bacillariophyta confer enhanced metabolic capacity and, consequently, greater adaptive capacity. Such differences in metabolic gene composition may be attributed to the disparate evolutionary pathways that these organisms have followed.

The genus Epipyxis, belonging to the family Dinobryaceae, has been documented to have only sporadic occurrences in freshwater habitats. However, the species diversity of this genus remains largely unexplored due to the scarcity of available molecular sequences. This limitation has significantly hindered a comprehensive understanding of both the species diversity and evolutionary relationships of the genus Epipyxis. In this study, a new species Epipyxis fenheensissp. nov. was described from Shanxi Province, China, based on detailed morphological observations and phylogenetic analyses. This species was characterized by a tube-like lorica, a spindle protoplast, two heterokont flagella, and oval or elliptic scales. In addition, phylogenetic analysis based on multi-genes (SSU, LSU, and rbcL) indicated that strain SX231009 was closely related to E. pulchra. Given its distinct morphological characteristics and independent phylogenetic position, we propose the designation of this strain as a new species, E. fenheensissp. nov. The results of this study significantly expand the known diversity of the genus Epipyxis and provide valuable insights into the regional biodiversity and evolutionary history of freshwater chrysophytes.

Land‐use change has significant influences on soil respiration (Rs) in terrestrial ecosystems. Soil microbes play critical roles in soil carbon cycling. Nevertheless, the specific mechanism of how changes in soil microbial properties are linked to the variation of Rs rate during land‐use change still remains poorly understood, especially in the Loess Plateau, China. Here, the characteristics of Rs rate and soil microbial community following the land‐use change from farmland to plantation/grassland were analyzed via an automated soil CO₂ flux system and high‐throughput 16S rDNA gene sequencing. The afforestation altered soil microbial diversity and community composition, which was mainly explained by soil pH, temperature, organic matter, nitrate, alkali‐hydrolyzed nitrogen, and available phosphorus. The biomarkers of Bacteroidetes, Firmicutes, and Thaumarchaeota were found in farmland soil at the phylum level. The afforestation also significantly decreased Rs rate, which was closely related to Shannon's index, Simpson's index, and some microbial taxa, such as Bacteroidetes, Firmicutes, Nitrospirae, and Acidobacteria. Bacteroidetes, and Firmicutes were particularly expected to be important drivers of high Rs rate in farmland soil. Moreover, the microbial interaction was probably also an important factor affecting Rs rate. Our results indicate that the response of Rs to land‐use change depends on soil microbial community being regulated by soil physicochemical properties in the Loess Plateau, China.