Comparison of soil temperature and soil moisture among diverse warming treatments.

(a) is soil temperature (Ts) and (b) is soil moisture (SM) among diverse warming treatments in 2015 and 2016. C: control; DW: daytime warming; NW: nighttime warming; DW+NW: daytime plus nighttime warming.</p

Relationships between <i>R</i>_s and <i>T</i>_s.

Rs: soil respiration. Ts: soil temperature.(a) control, (b) daytime warming, (c) nighttime warming and (d) daytime plus nighttime warming.</p

Impact of diurnal unsymmetrical warming on soil respiration in an agroecological system of the Lhasa region

PurposeThe impact of diurnal unsymmetrical rise in temperature on soil respiration (Rs) is not fully understood; thus, we explored such a warming influence on Rs in an agroecological system of the Lhasa.Materials and methodsA field warming experiment (C: control; DW: daytime warming; NW: nighttime warming; DW+NW: daytime plus nighttime warming) was carried out in a naked barley ecological system.Results and discussionThe DW, NW and DW+NW treatments dramatically increased soil temperature and decreased soil moisture but did not markedly modify Rs. The effects of DW and NW on soil respiration sensitivity (Q10) during the daytime and nighttime were different; they had no effects on daytime Q10 of Rs, but a significant inhibitory effect on nighttime Q10 of Rs.ConclusionsA diurnal unsymmetrical rise in temperature brought about different results for the Q10 of Rs but did not cause changes in Rs under different experimental treatments in agroecological systems of the Lhasa.</div

Relationships between <i>Q</i>₁₀ and <i>T</i>_s and relationships between <i>Q</i>₁₀ and SM.

(a): Relationships between the temperature sensibility (Q10) of soil respiration and soil temperature (Ts) (b): Relationships between the temperature sensibility (Q10) of soil respiration and soil moisture (SM).</p

Multiple stepwise regressions between soil respiration (<i>R</i>_s) and soil temperature (<i>T</i>_s) and moisture (SM).

Multiple stepwise regressions between soil respiration (Rs) and soil temperature (Ts) and moisture (SM).</p

Repeated-measures ANOVA was used to estimate the main and interaction impacts of warming (W) and observation date (D) on soil respiration (<i>R</i>_s) during the growing seasons in 2015 and 2016.

Repeated-measures ANOVA was used to estimate the main and interaction impacts of warming (W) and observation date (D) on soil respiration (Rs) during the growing seasons in 2015 and 2016.</p

Comparison of <i>R</i>_s among diverse warming treatments in different months.

Rs: soil respiration (a) May 25–26, 2015, (b) June 16–17, 2015, (c) June 30–July 1, 2015, (d) July 16–17, 2015 (e) July 30–31, 2015, (f) August 14–15, 2015, (g) May 6–7, 2016, (h) June 12–13, 2016, (i) July 16–17, 2016, (j) July 27–28, 2016 and (k) August 10–11, 2016. C: control; DW: daytime warming; NW: nighttime warming; DW+NW: daytime plus nighttime warming.</p

Comparison of AGB and BGB among diverse warming treatments in 2016.

AGB: aboveground biomass; BGB: belowground biomass. C: control; DW: daytime warming; NW: nighttime warming; DW+NW: daytime plus nighttime warming.</p

Comparison of four treatments in the <i>R</i>_<i>s</i> <i>and Q</i>₁₀ of three time periods.

Rs: soil respiration .Q10: temperature sensibility of soil respiration. The four treatments were C: control; DW: daytime warming; NW: nighttime warming; and DW+NW: daytime plus nighttime warming. The three time periods were 8:00–8:00, 8:00–20:00, and 20:00–8:00.</p

Comparison of the mean <i>R</i>_s for the two growing seasons under the four treatments.

Rs: soil respiration. C: control; DW: daytime warming; NW: nighttime warming; DW+NW: daytime plus nighttime warming.</p