Large‐Scale Distribution of Molecular Components in Chinese Grassland Soils: The Influence of Input and Decomposition Processes

Abstract

Chinese grasslands hold a third of the national soil organic carbon (OC) stocks but remain poorly investigated in terms of soil molecular components and their distribution patterns. Such information is important for understanding mechanisms governing grassland soil OC dynamics and its response to global changes. Here employing solvent‐extractable compounds as a group of widely used biomarkers, we present a large‐scale study on the distribution of different soil OC components (including plant‐ and microbial‐derived carbohydrates and aliphatic and cyclic lipids) in the surface soils of Chinese grasslands, spanning from temperate grasslands in the arid/semiarid regions to alpine grasslands on the Qinghai‐Tibetan Plateau. We show that alpine grassland soils are more enriched with carbohydrates and plant‐derived compounds relative to the temperate counterparts due to temperature‐inhibited decomposition. While plant belowground biomass plays a key role in explaining the spatial variation of compounds in the alpine grasslands, climatic variables do in the temperate region. In particular, aliphatic lipids accumulate with increasing mean annual temperature in the temperate grasslands due to a preferential decay of labile soil OC, whereas they decrease in the alpine grasslands owing to dilution by an enhanced plant input of nonlipid components. Collectively, these results demonstrate different mechanisms governing the distribution of solvent‐extractable compounds in grassland soils, with climate‐mediated decomposition processes dominating in the temperate grasslands and plant inputs being more important in the alpine region. In the context of climate change, alterations to soil OC input and decomposition processes may have varied impacts on soil carbon cycling in these two regions.

Compositional Characteristics of Fluvial Particulate Organic Matter Exported From the World's Largest Alpine Wetland

“…Lignin and P phenols were the dominant compounds analyzed in the catchment soils (83% ± 2%), followed by HMW lipids (9% ± 1%). This result is consistent with biomarker distributions in the survey of alpine meadows across a much wider span on the Qinghai‐Tibetan Plateau (Dai et al, ; Zhu et al, ). By comparison, HMW lipids were the most abundant (67% ± 5%) in the riverine POM, followed by LMW lipids (21% ± 5%), while lignin and P phenols only contributed to 9% ± 1% to all groups of compounds analyzed.…”

Contrasting Biogeographic Patterns of Bacterial and Archaeal Diversity in the Top- and Subsoils of Temperate Grasslands

“…Total carbon (TC) and total nitrogen (TN) concentrations of soil samples were measured by combustion using an elemental analyzer (Vario EL III; Elementar, Hanau, Germany). Soil OC was calculated as total carbon minus inorganic carbon, which was analyzed volumetrically by reaction with hydrochloric acid, as previously described (55). Total phosphorus (TP) was extracted using perchloric acid-sulfuric acid (HClO 4 -H 2 SO 4 ) digestion and measured by a colorimetric method with molybdenum blue (56).…”

Soil pH is the primary factor driving the distribution and function of microorganisms in farmland soils in northeastern China

“…Diversity, geographical distribution, and the metabolic activity of soil microorganisms are major factors shaping farmland ecosystems. Soil microbes are important decomposers and have multiple ecological and environmental functions (Nelson et al 2016;Delgado-Baquerizo et al 2017a;Bahram et al 2018;Dai et al 2018;Louca et al 2018). They directly participate in processes involved in plant nutrient acquisition and soil nutrient cycling, such as the decomposition and accumulation of organic matter in the soil and nitrogen transformation, including biological nitrogen fixation, which are closely related to microbial activity.…”