Search

In order to investigate the characteristics of soil structural stability and the factors influencing it under typical land use types in the karst region of western Hubei, soil samples were collected from five land use types (natural mixed forest [NF], cypress forest [CF], stone dike terrace [ST], stone dike forest [SF], and abandoned land [AL]) in Xialaoxi to analyze the particle size distribution of aggregates, structural stability, and the distribution characteristics of carbon, nitrogen, and extracellular enzyme contents. The results showed that the aggregates of NF, CF, SF, and AL were dominated by >2‐mm aggregates, while ST showed mostly 2–0.25‐mm aggregates. The mean weight diameter (EMWD) and the geometric mean diameter (EGMD) of mechanical aggregates showed a trend of CF > NF > SF > AL > ST, whereas the erodibility factor K showed an opposite trend. The total organic carbon (TOC), labile organic carbon (LOC), and total nitrogen (TN) contents of aggregates of each particle size were significantly higher in NF and CF than in ST and AL under the five land types. The content of available nitrogen (AN) was highest in NF and ST. The content of carbon and nitrogen and extracellular hydrolases (β‐glucosidase [BG], cellulose disaccharide hydrolase [CBH], β‐N‐acetyl‐aminoglucosidase [NAG], and leucine aminopeptidase [LAP]) in soil aggregates were mainly concentrated in <0.25–0.053‐mm aggregates. The variation in carbon and nitrogen abundance of each particle size agglomerate mainly originated from the LAP content of that particle size agglomerate and showed significant correlation. The partial least squares path models (PLS‐PM) showed that the main influences on the stability of soil aggregates in small watersheds were land use types, soil physical properties, carbon and nitrogen abundance, and extracellular enzyme activity. In conclusion, the structural stability of soil aggregates in Xialaoxi watershed is the result of the interaction between human disturbance and soil nutrient self‐cycling. In general, NF and CF have better soil aggregate stability and are conducive to soil carbon and nitrogen accumulation, whereas for later development and management of SF, ST, and AL sample plots, scientific cultivation means should be adopted, and attention should be paid to long‐term carbon and nitrogen accumulation and conservation. [ABSTRACT FROM AUTHOR]

Summary: Rice grains were obtained from two Chinese provinces (Hubei and Guangxi) and then their rice bran was abraded into four equal fractions by weight from outside to inside. The component distributions in these four fractions were then investigated. The contents of total lipid‐soluble antioxidant showed no significant difference between rice bran from the Hubei province and the Guangxi province. But the content of total water‐soluble antioxidant was 1690.20 ± 86.40 mg kg−1 for rice bran from the Hubei province, significantly higher than those from the Guangxi province (1014.67 ± 71.09 mg kg−1). Obvious differences between four rice bran fractions or two provinces were proved by principal component analysis (PCA). Lipase activities decreased significantly from outer fractions to inner fractions, and lipids mainly distributed in three outer fractions. The essential element contents decreased significantly, but a main heavy metal element (Pb) in cereal increased significantly to 0.36 mg kg−1 from outer fractions to inner fractions, which was just slightly below the upper limit of Chinese Standard (0.40 mg kg−1). Although protein contents had no significant difference in four fractions, the amino acid compositions were quite different. In summary, different fractions of rice bran had different compositions, which could provide guidance for the classified processing of rice bran. [ABSTRACT FROM AUTHOR]

Archaeological, genetic, and linguistic evidence has supported the idea that northern China is the original center of modern Sino‐Tibetan‐speaking populations. However, the demographic history of subsequent southward migration and genetic admixture of Han Chinese with surrounding indigenous populations remain uncharacterized, and the language shifts and assimilations accompanied by movement of people, or just an adaptation of cultural ideas among populations in central China is still unclear, especially for Tibeto‐Burman‐speaking Tujia and central Han Chinese populations. To resolve this, we genotyped over 60K genome‐wide markers in 505 unrelated individuals from 63 indigenous populations. Our results showed both studied Han and Tujia were at the intermediate position in the modern East Asian North–South genetic cline and there was a correlation between the genetic composition and the latitude. We observed the strong genetic assimilation between Tujia people and central Han Chinese, which suggested massive population movements and genetic admixture under language borrowing. Tujia and central Han Chinese could be modeled as a two‐way admixture deriving primary ancestry from a northern ancestral population closely related to the ancient DevilsCave and present‐day Tibetans and a southern ancestral population closely related to the present‐day Tai‐Kadai and Austronesian‐speaking groups. The ancestral northern population we suspect to be related to the Neolithic millet farming groups in the Yellow River Basin or central China. We showed that the newly genotyped populations in Hubei Province had a higher proportion of DevilsCave or modern Tungusic/Mongolic‐related northern ancestries, while the Hunan populations harbored a higher proportion of Austronesian/Tai‐Kadai‐related southern ancestries. [ABSTRACT FROM AUTHOR]