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. 2016 Sep 27;7(5):e00976-16. doi: 10.1128/mBio.00976-16

TABLE 1 .

Observed percent changes of soil and plant properties in response to warming or clipping alone, or their combination, the predicted additive effect of warming and clipping, and the types of the interaction

Category Parameter Parameter value or P value
 Type of interactive effecte
Yr Wa Cb OEc PEd OE-PE
Soil properties Temperature 2007 8.13*** 0.84 14.46*** 8.97 5.49*** Synergistic
Moisture 2007 −4.62** −0.98 −4.42** −5.60 1.18 Additive
Bulk density 2005 2.17 9.04** 4.31 11.21 −6.90 Additive
Total organic C 2008 4.05 −1.21 7.48 2.84 4.64 Additive
Labile C Pool 1 2008 −0.69 −7.44 −1.86 −8.13 6.27 Additive
Labile C pool 2 2008 12.90 −2.21 13.32 10.69 2.63 Additive
Recalcitrant C pool 2008 1.11 1.77 7.97 2.88 5.09 Additive
C derived from C4 plant 2008 18.81** 4.36 22.26*** 23.17 −0.91 Additive
Total N 2008 0.79 −3.23 5.01 −2.44 7.45 Additive
NH4+ 2007 −6.56 −19.84*** 1.40 −26.40 27.80*** Synergistic
NO3− 2007 −23.76 −30.98 −34.57 −54.74 20.17 Additive
C/N ratio 2008 2.80 1.47 0.34 4.27 −3.93 Additive
13C 2008 6.61** 2.14 8.24*** 8.74 0.50 Additive
15N 2008 16.37 −3.43 46.07** 12.94 33.13*** Synergistic
Phenol oxidase 2008 3.49 16.28** 39.71 19.77 19.94 Additive
Soil respiration Total 2007 29.06** 19.84* 52.57** 48.90 3.67 Additive
PLFAs Total PLFA 2008 34.91** 17.07 55.47** 51.98 3.49 Additive
Fungi/bacteria 2008 −6.92 −13.84 −0.82 −20.76 19.94 Additive
Plant properties C3 peak biomass 2007 34.13 35.15 50.55 69.28 −18.73 Additive
C4 peak biomass 2007 25.05** 1.37 46.53* 26.42 20.11 Additive
BNPP 2007 22.44 10.42 109.54*** 32.86 76.68*** Synergistic
Litter 2006 27.83 −80.80*** −75.27*** −52.97 −22.30 Additive
a

W, warming effect alone, calculated as 100% × (UW − UU)/UU, where UW and UU represent the averaged values in unclipped-warmed and unclipped-unwarmed plots, respectively.

b

C, clipping effect alone, calculated as 100% × (CU − UU)/UU, where CU represents the averaged values in clipped-unwarmed plots. The significance data are in bold font and labeled with *** where P = ≤0.01, ** where P = ≤0.05, and * where P = ≤0.10. The two-tailed paired t test was used for most variables, while the two-tailed permutation paired t test was used for C/N ratio and C4 peak biomass calculations.

c

OE, observed effect, calculated as 100% × (CW − UU)/UU, where CW represents the averaged values in clipped-warmed plots.

d

PE, predicted additive effect, calculated as [100% × (UW − UU)/UU +100% × (CU − UU)/UU].

e

Interactive effect is additive when PE does not differ significantly from OE, synergistic when PE is significantly smaller than OE, or antagonistic when PE is significantly larger than OE.