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Shrub encroachment in grasslands has a major impact on soil carbon storage (SOCS) and soil total nitrogen (STNS), which affects nutrient cycling and ecosystem processes. We explored the effects of shrub encroachment on SOCS and STNS in five grassland types in the Altai Mountains: mountain meadows, temperate meadow steppe, temperate steppe, temperate steppe desert, and temperate desert steppe. Shrub encroachment considerably improved SOCS and STNS, with the greatest increases occurring in locations with high encroachment. The interaction between grassland type and encroachment extent also significantly influenced soil properties, including bulk density, soil water content, and microbial carbon and nitrogen. Specifically, SOCS increased by 16%, 77%, and 129%, and STNS increased by 43%, 94%, and 127% under low, medium, and high shrub encroachment, respectively. The soil stoichiometry shifted, with C/N ratios decreasing and C/P and N/P ratios increasing with shrub encroachment. Structural equation modeling (SEM) revealed that shrub encroachment indirectly affected SOCS and STNS through changes in soil nutrients and climate. Our findings suggest that shrub encroachment promotes soil C sequestration and alters soil nutrient cycling, with implications for grassland management and ecological restoration in the face of global climate change. [ABSTRACT FROM AUTHOR]

Glomalin-related soil protein (GRSP) is an important component of soil organic carbon (SOC), which can promote long-term SOC sequestration. However, GRSP distribution characteristics and its contribution to the SOC pool among different grassland types remain poorly understood. Therefore, six grassland types (alpine meadow, mountain meadow, temperate meadow steppe, temperate steppe, temperate desert steppe, and temperate desert) were chosen to evaluate the contribution of GRSP to the SOC pool and the factors that influence GRSP accumulation in the Irtysh River Basin in China. The results revealed that GRSP (EE-GRSP, T-GRSP) accumulated more in the 0–10 cm soil layer than in the 10–20 cm soil layer (p < 0.05). GRSP content was higher in alpine grasslands (15.69 mg·g−1) than in desert grasslands (5.45 mg·g−1). However, their contribution to the SOC pool exhibited an opposite trend, whereas GRSP-C/SOC even accounted for 11.88% in the desert grasslands. The redundancy analysis (RDA) showed that SOC was the top important positive regulator for GRSP accumulation both in the two layers (explanatory rate > 80%). Besides the SOC factor, the two soil layers had different factors in regulating GRSP accumulation. Changes in GRSP content in the 0–10 cm soil layer were more strongly associated with mean annual temperature (MAT), sand content, soil water content (SWC), and silt content. In contrast, in the 10–20 cm soil layer, GRSP content was more influenced by SWC, electrical conductivity (EC), and pH (p < 0.05). Additionally, the main factor in the GRSP content variation was the interaction between climate and soil in the two soil layers (explanatory rate > 80%). Our findings underscore the critical role of GRSP in facilitating SOC sequestration within desert grasslands and elucidate the primary factors driving GRSP distribution across varying soil depths. [ABSTRACT FROM AUTHOR]

The topography of the Tianshan Mountains and the Pamir Plateau strongly shapes the seasonality of precipitation in Central Asia (CA): cold-season (October-April) precipitation dominates western CA and warm-season (May-September) precipitation dominates eastern CA. The precipitation/moisture patterns between western and eastern CA are completely opposite at seasonal, decadal and centennial scale. However, the pattern contrasts for millennial or longer time scales remain unknown. In this study, we investigated the precipitation variations in western CA, as recorded in a 6.5-m loess section in southern Kazakhstan, which has accumulated since ~14.4 ka. According to the robust relationship between the surface soil organic matter δ13C and the climatic parameters, the δ13C signature is here considered as a precipitation proxy. The record reveals an overall decreasing precipitation before ~6.0 ka followed by an increasing trend afterward, being consistent with the previously reported precipitation records in western CA. The late-deglaciation precipitation in western CA is in phase with that in eastern CA at millennial scales, which are both driven by the North Atlantic Oscillation (NAO) and the Siberian High. [ABSTRACT FROM AUTHOR]