TY - JOUR

T1 - Carbon fluxes within tree-crop-grass agroforestry system

T2 - 13C field labeling and tracing

AU - Zhou, Jie

AU - Shao, Guodong

AU - Kumar, Amit

AU - Shi, Lingling

AU - Kuzyakov, Yakov

AU - Pausch, Johanna

N1 - Funding Information: The isotopic analyses were performed at the Centre for Stable Isotope Research and Analysis (KOSI), Göttingen. Yakov Kuzyakov thanks the RUDN University Strategic Academic Leadership Program. Jie Zhou (201606850093) and Guodong Shao (201703270029) also thank the China Scholarship Council (CSC) for supporting their study in Germany. Funding Information: This study was financially supported by the German Research Foundation (DFG) within the project BMBF project SIGNAL, the National Natural Science Foundation of China (318611430002), and the Yunnan Fundamental Research Projects (202101AS070045). Publisher Copyright: © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.

PY - 2022/10/1

Y1 - 2022/10/1

N2 - Agroforestry systems are characterized by a high complexity between vegetation components and niche partitioning. In a crop-grass-tree agroforestry system, rape, willow, and grasses were in situ pulse labeled separately with 13CO2 for 6 h, and 13C was traced in shoots, roots, topsoil (0–15 cm) and subsoil (15–30 cm), microbial biomass carbon (C), and dissolved organic C, as well as respiration losses (CO2) up to 28 days after labeling to investigate the effects of vegetation components on C allocation belowground. 13C recovery in roots after 28 days was 7.0% of total assimilated C for grassland, which was 3.5- and 5.2-fold higher than that for rape and willow, respectively. The larger C allocation belowground in grassland was ascribed to its higher root/shoot ratio compared to willow and rape. Grassland facilitated higher accumulation of root-derived C in soil compared to rape (9.2% of recovered 13C) and compared to willow (1.6% of 13C). Willow retained more photosynthetic C aboveground and less was allocated to roots compared to rape. Although the C allocated to the top 15-cm soil was similar between willow and rape, willow facilitated C allocation in deeper soil compared to rape (0.6% vs. 0.2%). This could be explained by the lower microbial activity and subsequent weaker decomposition of rhizodeposits in 15–30-cm depth under willow. The net belowground C inputs in grassland, willow, and rape were 0.53, 0.06, and 0.10 g C m−2 month−1 of vegetation period, including rhizodeposition of 0.24, 0.05, and 0.04 g C m−2 month−1, respectively. Overall, integrating trees and grassland within cropland facilitates higher root-derived C input into soil, thus contributing to the soil C sequestration in agroforestry systems.

AB - Agroforestry systems are characterized by a high complexity between vegetation components and niche partitioning. In a crop-grass-tree agroforestry system, rape, willow, and grasses were in situ pulse labeled separately with 13CO2 for 6 h, and 13C was traced in shoots, roots, topsoil (0–15 cm) and subsoil (15–30 cm), microbial biomass carbon (C), and dissolved organic C, as well as respiration losses (CO2) up to 28 days after labeling to investigate the effects of vegetation components on C allocation belowground. 13C recovery in roots after 28 days was 7.0% of total assimilated C for grassland, which was 3.5- and 5.2-fold higher than that for rape and willow, respectively. The larger C allocation belowground in grassland was ascribed to its higher root/shoot ratio compared to willow and rape. Grassland facilitated higher accumulation of root-derived C in soil compared to rape (9.2% of recovered 13C) and compared to willow (1.6% of 13C). Willow retained more photosynthetic C aboveground and less was allocated to roots compared to rape. Although the C allocated to the top 15-cm soil was similar between willow and rape, willow facilitated C allocation in deeper soil compared to rape (0.6% vs. 0.2%). This could be explained by the lower microbial activity and subsequent weaker decomposition of rhizodeposits in 15–30-cm depth under willow. The net belowground C inputs in grassland, willow, and rape were 0.53, 0.06, and 0.10 g C m−2 month−1 of vegetation period, including rhizodeposition of 0.24, 0.05, and 0.04 g C m−2 month−1, respectively. Overall, integrating trees and grassland within cropland facilitates higher root-derived C input into soil, thus contributing to the soil C sequestration in agroforestry systems.

KW - Carbon allocation

KW - Rhizodeposition

KW - Pulse labeling

KW - Agroforestry

KW - Vegetation components

KW - Ecosystems Research

UR - http://www.scopus.com/inward/record.url?scp=85136152717&partnerID=8YFLogxK

U2 - 10.1007/s00374-022-01659-4

DO - 10.1007/s00374-022-01659-4

M3 - Journal articles

VL - 58

SP - 733

EP - 743

JO - Biology and Fertility of Soils

JF - Biology and Fertility of Soils

SN - 0178-2762

IS - 7

ER -