TY - JOUR

T1 - Land-use change under different climatic conditions

T2 - Consequences for organic matter and microbial communities in Siberian steppe soils

AU - Bischoff, Norbert

AU - Mikutta, Robert

AU - Shibistova, Olga

AU - Puzanov, Alexander

AU - Reichert, Evgeny

AU - Silanteva, Marina

AU - Grebennikova, Anna

AU - Schaarschmidt, Frank

AU - Heinicke, Steffen

AU - Guggenberger, Georg

N1 - Funding information: Financial support was provided by the Federal Ministry of Education and Research (Germany) in the framework of the KULUNDA project ( 01LL0905 ). We thank the entire KULUNDA team for great collaborations and good team spirit. We are thankful to all farmers of the Kulunda steppe for collaboration during sampling. Daniel Herdtle and Lukas Gerhard are acknowledged for indispensable assistance in the field. Thanks for laboratory assistance to Silke Bokeloh, Elke Eichmann-Prusch, Roger-Michael Klatt, Pieter Wiese, Fabian Kalks and Dr. Leopold Sauheitl. We are thankful to two anonymous reviewers for valuable comments which significantly improved the manuscript.

PY - 2016/11/1

Y1 - 2016/11/1

N2 - The Kulunda steppe is part of the greatest conversion areas of the world where 420,000 km2 grassland have been converted into cropland between 1954 and 1963. However, little is known about the recent and future impacts of land-use change (LUC) on soil organic carbon (OC) dynamics in Siberian steppe soils under various climatic conditions. By investigating grassland vs. cropland soils along a climatic gradient from forest to typical to dry steppe types of the Kulunda steppe, our study aimed to (i) quantify the change of OC stocks (0–60 cm) after LUC from grassland to cropland as function of climate, (ii) elucidate the concurrent effects on aggregate stability and different functional soil organic matter (OM) fractions (particulate vs. mineral-bound OM), and (iii) assess climate- and LUC-induced changes in the microbial community composition and the contribution of fungi to aggregate stability based on phospholipid fatty acid (PLFA) profiles. Soil OC stocks decreased from the forest steppe (grassland: 218 ± 17 Mg ha−1) over the typical steppe (153 ± 10 Mg ha−1) to the dry steppe (134 ± 11 Mg ha−1). Across all climatic regimes, LUC caused similar OC losses of 31% (95% confidence interval: 17–43%) in 0–25 cm depth and a concurrent decline in aggregate stability, which was not related to the amount of fungal PLFA. Density fractionation revealed that the largest part of soil OM (>90% of total OC) was associated with minerals and <10% of C existed in particulate OM. While LUC induced smaller relative losses of mineral-associated OC than particulate OC, the absolute decline in total OC stocks was largely due to losses of OM bound to minerals. This result together with the high 14C ages of mineral-bound OM in croplands (500–2900 yrs B.P.) suggests that mineral-bound OM comprises, in addition to stable OC, also management-susceptible labile OC. The steppe type had a larger impact on microbial communities than LUC, with a larger relative abundance of gram-positive bacteria and less fungi under dry conditions. Our results imply that future drier climate conditions in the Siberian steppes will (i) result in smaller OC stocks on a biome scale but (ii) not alter the effect of LUC on soil OC, and (iii) change the microbial community composition more than the conversion from grassland to cropland.

AB - The Kulunda steppe is part of the greatest conversion areas of the world where 420,000 km2 grassland have been converted into cropland between 1954 and 1963. However, little is known about the recent and future impacts of land-use change (LUC) on soil organic carbon (OC) dynamics in Siberian steppe soils under various climatic conditions. By investigating grassland vs. cropland soils along a climatic gradient from forest to typical to dry steppe types of the Kulunda steppe, our study aimed to (i) quantify the change of OC stocks (0–60 cm) after LUC from grassland to cropland as function of climate, (ii) elucidate the concurrent effects on aggregate stability and different functional soil organic matter (OM) fractions (particulate vs. mineral-bound OM), and (iii) assess climate- and LUC-induced changes in the microbial community composition and the contribution of fungi to aggregate stability based on phospholipid fatty acid (PLFA) profiles. Soil OC stocks decreased from the forest steppe (grassland: 218 ± 17 Mg ha−1) over the typical steppe (153 ± 10 Mg ha−1) to the dry steppe (134 ± 11 Mg ha−1). Across all climatic regimes, LUC caused similar OC losses of 31% (95% confidence interval: 17–43%) in 0–25 cm depth and a concurrent decline in aggregate stability, which was not related to the amount of fungal PLFA. Density fractionation revealed that the largest part of soil OM (>90% of total OC) was associated with minerals and <10% of C existed in particulate OM. While LUC induced smaller relative losses of mineral-associated OC than particulate OC, the absolute decline in total OC stocks was largely due to losses of OM bound to minerals. This result together with the high 14C ages of mineral-bound OM in croplands (500–2900 yrs B.P.) suggests that mineral-bound OM comprises, in addition to stable OC, also management-susceptible labile OC. The steppe type had a larger impact on microbial communities than LUC, with a larger relative abundance of gram-positive bacteria and less fungi under dry conditions. Our results imply that future drier climate conditions in the Siberian steppes will (i) result in smaller OC stocks on a biome scale but (ii) not alter the effect of LUC on soil OC, and (iii) change the microbial community composition more than the conversion from grassland to cropland.

KW - Climate

KW - Land-use change

KW - PLFA

KW - Semi-arid region

KW - Soil microbial community

KW - Soil organic matter

KW - Steppe soil

UR - http://www.scopus.com/inward/record.url?scp=84993977955&partnerID=8YFLogxK

U2 - 10.1016/j.agee.2016.10.022

DO - 10.1016/j.agee.2016.10.022

M3 - Article

AN - SCOPUS:84993977955

VL - 235

SP - 253

EP - 264

JO - Agriculture, Ecosystems and Environment

JF - Agriculture, Ecosystems and Environment

SN - 0167-8809

ER -