Temporal variations of soil respiration at multiple timescales in a spruce-fir valley forest, northeastern China

Abstract

There is a paucity of data regarding the multiple timescale variations of heterotrophic respiration (R H) and autotrophic respiration (R A) as well as the primary controlling factors. The objective of this study is to find the temporal variations of total soil respiration (R S) and its components, revealing the driving factors at different timescales. A trenching method was used to distinguish R S, R H, and R A in a spruce-fir valley forest in northeastern China. We used the closed dynamic chamber method to measure the soil respiration rate. Analyses of R S, R H, and R A in relation to biotic and abiotic factors were conducted to realize the temporal variations at different timescales. Only R S and R H showed a distinct diurnal variation and soil temperature (T S) can explain 68 and 59 % of the daily variation, respectively. R S, R H, and R A showed a pronounced, single peak curve seasonally, and T S can explain 11–95 % of the seasonal variation. Soil moisture (W S) maintained at a relatively high level and was not related to R S, R H, or R A on a seasonal scale, and there was no significant relationship between the seasonal R S, R A, and root biomass. However, for 5 years, only the mean R A of the growing season was significantly related to the mean W S, which can explain 39 % of the inter-annual variation of R A. The annual variations of litterfall and the relative growth rate of stems were not related to R S, R H, or R A. The contribution of R H to R S was larger, and the temperature sensitivity was 2.01–3.71 for R S, 1.90–3.08 for R H, and 2.20–5.65 for R A. R S, R H, and R A show different temporal variations at multiple timescales. When W S is not restricted, T S is the primary driving factor of daily and seasonal variation of R S and R H. In this site, R H accounts for a large proportion of R S and plays a crucial role in determining the magnitude and temporal variation of R S.