Dryland soils in northern China sequester carbon during the early 2000s warming hiatus period

Abstract

Drylands, covering c. 45% of the Earth's terrestrial surface and supporting c. 38% of the global population, play a dominant role in the trend and interannual variability of global land carbon (C) sink. Given that a large proportion of organic C is stored in soils, our knowledge on soil C dynamics in drylands is crucial to evaluate terrestrial C‐climate feedback. However, credible understanding on this issue is still greatly limited by the lack of direct observations. Here, based on a regional resampling of historical sites collected during 2002–2004, we explored the soil organic C (SOC) changes in various layers over the past decade across the arid/semi‐arid grasslands on the Inner Mongolian Plateau. Our results revealed that the SOC density in this typical dryland increased significantly over the monitoring period, with a mean increase in 50.6 g C m−2 year−1 or 0.8% per year in the top 50 cm depth. Moreover, soil C dynamics exhibited contrasting spatial patterns between different layers: the rate of C accumulation in surface soils (0–10 cm) decreased, whereas that in deep soils (30–50 cm) exhibited an increasing trend along the aridity gradient. Collectively, these findings demonstrate that dryland soils function as an important C sink, with the drier region tending to sequester C in deeper soils due to the greater root biomass allocation. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.13088/suppinfo is available for this article.

A bibliometric analysis of carbon exchange in global drylands

“…The ten marked institutions almost were located in drylands in America, China, and Australia. Many studies have shown that drylands have a strong carbon sequestration potential (Tagesson et al, 2016;Kou et al, 2018;Abdi et al, 2019). America, China, and Australia cover tremedous typical semi-arid and arid areas at the global scale (Yang et al, 2019), and attach great importance to the trend and variability of the land carbon balance (Ahlstrom et al, 2015).…”

A comparison of patterns of microbial C : N : P stoichiometry between topsoil and subsoil along an aridity gradient

“…In this study, we aim to access the effect of soil depth on soil microbial C : N : P stoichiometry along the aridity gradient. We hypothesized that the microbial C : N and C : P ratios decrease and the microbial N : P ratio increases with temperature Li et al, 2015;Xu et al, 2013), and the microbial C : N and C : P ratios decrease and the microbial N : P ratio increases with decreasing aridity index (Wang et al, 2014;Li et al, 2017). In addition, the identification of soil depth for vertical study is different in some published literature (Li and Chen, 2004;Aponte et al, 2010;Tischer et al, 2014;Peng and Wang, 2016).…”

“…Furthermore, less exploration of soil microbial stoichiometry along an aridity gradient at the regional scale impedes our ability to disentangle the trend of the changes in microbial stoichiometry amid climate changes. Climate change, such as global warming, is increasing the degree of aridity in drylands owing to the decreased precipitation and increased evaporation (Wang et al, 2014;Li et al, 2017). Given this background, key ecosystem processes that are regulated by soil microbes, such as soil respiration and nutrient mineralization, may be dramatically impacted by the increased degree of aridity, especially in fragile areas of arid and semiarid ecosystems (Delgado-Baquerizo et al, 2013;Chen et al, 2014).…”

“…In Inner Mongolia grasslands, the aridity exhibits a gradient that increases from northeast to southwest (aridity index, calculated as precipitation divided by potential evapotranspiration, ranges from 0.16 to 0.54), thus providing an ideal platform to better estimate the patterns and drivers of microbial C : N : P stoichiometry along an aridity gradient (Chen et al, 2014;Li et al, 2017). In this study, we aim to access the effect of soil depth on soil microbial C : N : P stoichiometry along the aridity gradient.…”

A Comparison of Soil C, N, and P Stoichiometry Characteristics under Different Thinning Intensities in a Subtropical Moso bamboo (Phyllostachys edulis) Forest of China

“…The stocks of C, N, and P vary with soil depth, but their driving processes could be also different for thinning. Thinning causes fresh dissolved organic carbon from the topsoil to leach into the deep subsoil in subtropical regions, enhancing the effect of the deep soil C decomposition [13,14]. N deposition [15], litter decomposition [16], and rock weathering [17] contribute to soil N. N input with leaching intensifies the imbalance of N distribution in different soil layers.…”