Seasonal variations in temperature sensitivity of soil respiration in a larch forest in the Northern Daxing’an Mountains in Northeast China

Lin Yang,Qiuliang Zhang,Valentin V Spektor,Huijun Jin,Zhongtao Ma,Sergey S Marchenko,Xiaoli Chang

doi:10.1007/s11676-021-01346-4

Abstract

Temperature sensitivity of respiration of forest soils is important for its responses to climate warming and for the accurate assessment of soil carbon budget. The sensitivity of temperature (Ti) to soil respiration rate (Rs), and Q10 defined by e10(lnRs−lna)/Ti has been used extensively for indicating the sensitivity of soil respiration. The soil respiration under a larch (Larix gmelinii) forest in the northern Daxing’an Mountains, Northeast China was observed in situ from April to September, 2019 using the dynamic chamber method. Air temperatures (Tair), soil surface temperatures (T0cm), soil temperatures at depths of 5 and 10 cm (T5cm and T10cm, respectively), and soil-surface water vapor concentrations were monitored at the same time. The results show a significant monthly variability in soil respiration rate in the growing season (April–September). The Q10 at the surface and at depths of 5 and 10 cm was estimated at 5.6, 6.3, and 7.2, respectively. The Q10@10 cm over the period of surface soil thawing (Q10@10 cm, thaw = 36.89) were significantly higher than that of the growing season (Q10@10 cm, growth = 3.82). Furthermore, the Rs in the early stage of near-surface soil thawing and in the middle of the growing season is more sensitive to changes in soil temperatures. Soil temperature is thus the dominant factor for season variations in soil respiration, but rainfall is the main controller for short-term fluctuations in respiration. Thus, the higher sensitivity of soil respiration to temperature (Q10) is found in the middle part of the growing season. The monthly and seasonal Q10 values better reflect the responsiveness of soil respiration to changes in hydrometeorology and ground freeze-thaw processes. This study may help assess the stability of the soil carbon pool and strength of carbon fluxes in the larch forested permafrost regions in the northern Daxing’an Mountains.

Highlights

Temperature and moisture content are key to seasonal variations in soil respiration (Paustian et al 2016)
Q10 differs with time scales and soil depth, values for the surface thawing period are significantly higher than those for the growing season or thawed period of surface soil
Soil respiration rates in the early stage of near-surface soil thawing and in the middle of the main growing period are more sensitive to temperature changes

Summary

Introduction

Temperature and moisture content are key to seasonal variations in soil respiration (Paustian et al 2016). A Q10 has been defined as the degree of temperature sensitivity of soil respiration. Current estimates of carbon emissions from terrestrial ecosystems and the direct impacts of climate change are directly influenced and/or predicted by Q10 values (Schlesinger and Andrews 2000). Q10 largely determines the feedback relationship between climate change and carbon cycling (Pokharel et al 2018). Under a warming climate, it is important to understand Q10 changes and their influencing factors in order to more accurately simulate and predict the key parameters of carbon cycles and processes and to clarify the relationship between soil respiration and its temperature sensitivity

Methods

Results

Discussion

Conclusion