Winter soil respiration during soil-freezing process in a boreal forest in Northeast China

• Published in: Journal of Plant Ecology
• Main Authors: Du, Enzai, Zhou, Zhang, Li, Peng, Jiang, Lai, Hu, Xueyang, Fang, Jingyun
• Other Authors: Fang, JY (reprint author), Peking Univ, Dept Ecol, Coll Urban & Environm Sci, Beijing 100871, Peoples R China., Peking Univ, Dept Ecol, Coll Urban & Environm Sci, Beijing 100871, Peoples R China.
• Format: Journal/Newspaper
• Language: English
• Published: journal of plant ecology 2013
• Subjects: soil respiration; freezethaw critical point; snow depth; boreal forest; winter; TAIGA SOILS; CO2 EFFLUX; ECOLOGICAL PROCESSES; MICROBIAL ACTIVITY; TEMPERATE FORESTS; EUROPEAN FORESTS; CARBON BALANCE; NITROUS-OXIDE; THAW CYCLES; taiga
• Online Access: https://hdl.handle.net/20.500.11897/322241; https://doi.org/10.1093/jpe/rtt012

Boreal forest is the largest and contains the most soil carbon among global terrestrial biomes. Soil respiration during the prolonged winter period may play an important role in the carbon cycles in boreal forests. This study aims to explore the characteristics of winter soil respiration in the boreal forest and to show how it is regulated by environmental factors, such as soil temperature, soil moisture and snowpack. Soil respiration in an old-growth larch forest (Larix gmelinii Ruppr.) in Northeast China was intensively measured during the winter soil-freezing process in 2011 using an automated soil CO2 flux system. The effects of soil temperature, soil moisture and thin snowpack on soil respiration and its temperature sensitivity were investigated. Total soil respiration and heterotrophic respiration both showed a declining trend during the observation period, and no significant difference was found between soil respiration and heterotrophic respiration until the snowpack exceeded 20cm. Soil respiration was exponentially correlated with soil temperature and its temperature sensitivity (Q(10) value) for the entire measurement duration was 10.5. Snow depth and soil moisture both showed positive effects on the temperature sensitivity of soil respiration. Based on the change in the Q(10) value, we proposed a freezethaw critical point hypothesis, which states that the Q(10) value above freezethaw critical point is much higher than that below it (16.0 vs. 3.5), and this was probably regulated by the abrupt change in soil water availability during the soil-freezing process. Our findings suggest interactive effects of multiple environmental factors on winter soil respiration and recommend adopting the freezethaw critical point to model soil respiration in a changing winter climate. Plant Sciences Ecology SCI(E) 5 ARTICLE 5 349-357 6