Different winter soil respiration between two mid-temperate plantation forests

Abstract

Abstract Larch and Chinese pine plantation forests are important carbon (C) sinks in the temperate regions, especially in China. However, their soil respiration in winter is still poorly studied. Here we explored the different microbial characteristics and winter soil respiration in larch and Chinese pine plantation forests in northeastern China, which has similar climate and basic soil characteristics. Results showed that both mean and cumulative winter soil CO2 fluxes were significantly higher in Chinese pine forest (0.45 µmol m−2 s−1 and 46.39 g C m−2, respectively) than in larch forest (0.25 µmol m−2 s−1 and 25.92 g C m−2, respectively). Snow depth and inorganic nitrogen (N) could not explain the differences in winter soil respiration between the two sites. Instead, Chinese pine forest had higher soil microbial biomass, fungi abundance, F/B (ratio of fungi to bacteria), and extracellular enzymatic activities (EEAs) than larch forest, which could lead to higher winter soil respiration in Chinese pine forest than in larch forest. Our findings indicated that the thermal insulation effect of litter cover was important to winter soil respiration, especially when the snow cover depth was less than 30 cm. Soil microbes played a more important role in soil respiration than soil nutrient status and should be carefully considered for better estimation of the C budget in different forest ecosystems. Although soil respiration was higher in Chinese pine forest, soil organic C content was also higher, suggesting its better C sequestration capacity than larch forest.