Depth-dependent drivers of soil aggregate carbon across Tibetan alpine grasslands

Junxiao Pan; Jiawei Shi; Dashuan Tian; Ruiyang Zhang; Yang Li; Yunlong He; Lei Song; Song Wang; Yicheng He; Jiaming Yang; Chunxue Wei; Shuli Niu; Jinsong Wang

doi:10.1016/j.scitotenv.2023.161428

Depth-dependent drivers of soil aggregate carbon across Tibetan alpine grasslands

Sci Total Environ. 2023 Apr 1:867:161428. doi: 10.1016/j.scitotenv.2023.161428. Epub 2023 Jan 6.

Authors

Junxiao Pan¹, Jiawei Shi¹, Dashuan Tian¹, Ruiyang Zhang¹, Yang Li¹, Yunlong He¹, Lei Song², Song Wang², Yicheng He¹, Jiaming Yang¹, Chunxue Wei¹, Shuli Niu², Jinsong Wang³

Affiliations

¹ Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, PR China.
² Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, PR China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, PR China.
³ Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, PR China. Electronic address: wangjinsong@igsnrr.ac.cn.

PMID: 36623644
DOI: 10.1016/j.scitotenv.2023.161428

Abstract

Elucidating the effects underlying soil organic carbon (SOC) variation is imperative for ascertaining the potential drivers of mitigating climate change. However, the drivers of variations in various SOC fractions (e.g., macroaggregate C, microaggregate C, and silt and clay C) at different soil depths remain poorly understood. Here, we investigated the effects and relative contributions of climatic, plant, edaphic, and microbial factors on soil aggregate C between the topsoil (0-10 cm) and subsoil (20-30 cm) across alpine grasslands on the Tibetan Plateau. Results showed that the C content of macroaggregates, microaggregates, and silt and clay fractions in the topsoil was 128.6 %, 49.6 %, and 242.4 % higher than that in the subsoil, respectively. Overall, plant properties were the most determinants controlling soil macroaggregate, microaggregate, and silt + clay associated C for both two soil depths, accounting for 32.2 %, 37.4 %, and 38.8 % of the variation, respectively, followed by edaphic, microbial, and climatic factors. The aggregate C of both soil depths was significantly related with the climatic, plant, edaphic, and microbial factors, but the relative importance of these determinants was soil-depth dependent. Specifically, the effects of plant root biomass and microbial (e.g., microbial biomass carbon and fungal diversity index) factors on each aggregate C weakened with soil depth, but the importance of edaphic factors (e.g., clay content, pH, and bulk density) strengthened with soil depth, except for the weakened effect of bulk density on the microaggregate C. And the effects of climatic factor (e.g., mean annual precipitation) on macroaggregate and microaggregate C increased with soil depth. Our results highlight differential drivers and their impacts on soil aggregate C between the topsoil and subsoil, which benefits biogeochemical models for more accurately forecasting soil C dynamics and its feedbacks to environmental changes.

Keywords: Aggregate carbon; Edaphic factors; Grassland ecosystems; Microbial biomass carbon; Plant C input; Subsoil.

MeSH terms

Carbon / analysis
Clay
Grassland*
Plants
Soil* / chemistry
Tibet

Substances

Soil
Carbon
Clay