TECHNICAL ARTICLEContributions of Carbonates to Carbon Dioxide Release From a Calcareous Soil in Response to Experimental WarmingZhang, Chunhua1,2; Sun, Yongyu1,2; Tang, Guoyong1,2,3; Liu, Fanyan1,2 Author Information 1Research Institute of Resource Insects, Chinese Academy of Forestry, Kunming, Yunnan Province, China. 2Yuanmou Desertification Ecosystem Research Station, State Forestry Administration of China, Kunming, Yunnan Province, China. 3Jianshui Research Station, School of Soil and Water Conservation, Beijing Forestry University, Beijing, China. Address for correspondence: Dr. Guoyong Tang, Research Institute of Resource Insects, Chinese Academy of Forestry, Kunming, Yunnan Province 650233, China. E-mail: [email protected] Financial Disclosures/Conflicts of Interest: Central Non-profit Research Institution of CAF (grant CAFYBB2018ZD002) and Fundamental Research Funds for the National Natural Science Foundation of China (grant 31670613). Received February 21, 2019. Accepted for publication October 8, 2019. Online date: November 4, 2019 Soil Science: April 2019 - Volume 184 - Issue 2 - p 52-59 doi: 10.1097/SS.0000000000000251 Buy Metrics Abstract Seasonal asymmetric warming is a distinguishing feature of climate change, which is not often considered when evaluating the effects of global change on terrestrial ecosystems. Responses of soil CO2 efflux from organic and inorganic sources to asymmetric and symmetric warming are not well understood. A 5-year warming experiment was performed to evaluate the effects of symmetric and asymmetric warming on soil organic carbon (SOC)–derived and carbonate-derived effluxes from a calcareous soil in the karst region of southwestern China. On average, the carbonate-derived efflux represented 31% of the total CO2 efflux in the six treatments. Warming of 2.0°C substantially stimulated soil CO2 efflux from both sources, except for the carbonate-derived efflux in summer-autumn. Soil CO2 efflux and SOC-derived efflux were appreciably reduced when ratios of warming in winter-spring to summer-autumn ratio of asymmetric warming (RAW) increased, while no changes (full year or in summer-autumn) were found for the carbonate-derived efflux. However, soil CO2 efflux from both sources were considerably enhanced in winter-spring with increasing RAW values. Temperature sensitivity temperature coefficient (Q10) of CO2 efflux from both sources decreased with increasing RAW values. The average Q10 of SOC-derived efflux was 1.3 times greater that of the carbonate-derived efflux. Symmetric warming potentially overestimates CO2 efflux from calcareous soils, compared with the projected asymmetric warming scenario, likely because of overestimation of SOC-derived effluxes in summer-autumn. Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.