Table 1.
Estimated mean ± 95% confidence interval (CI) for fluxes of the surface energy budget (SEB) and vegetation type effect significance across summer (JJA) and the annual timescale (Y)
| Season | Surface energy flux | Mean estimate ± 95% CI for surface energy flux magnitudes in W m−2 for each vegetation type (Mean estimate ± 95% CI for normalized magnitudes in % of maximum potential incoming shortwave radiation) | Effect significance | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Boreal peat bog | Wetland complex | Graminoid | Erect-shrub | Prostrate-shrub | Barren complex | Glacier | Vegetation type | ||
| JJA | Rnet | 135 ± 37 (17 ± 5%) | 103 ± 35 (14 ± 4%) | 100 ± 34 (13 ± 4%) | 102 ± 41 (13 ± 5%) | 91 ± 44 (13 ± 6%) | - | 51 ± 49 (6 ± 6%) | F5,23 = 2.1 n.s. |
| H | 7 ± 40 (1 ± 6%) | 34 ± 36 (5 ± 5%) | 26 ± 36 (3 ± 5%) | 38 ± 37 (5 ± 5%) | 39 ± 36 (6 ± 5%) | −18 ± 32 (−2 ± 5%) | −24 ± 18 (−3 ± 3%) | F6,20 = 3.6* | |
| LE | 75 ± 26 (9 ± 3%) | 32 ± 22 (5 ± 2%) | 47 ± 23 (5 ± 2%) | 25 ± 26 (4 ± 3%) | 24 ± 23 (4 ± 2%) | 0 ± 20 (0 ± 2%) | 8 ± 15 (1 ± 2%) | F6,10 = 5.2* | |
| G | 5 ± 6 (1 ± 1%) | 11 ± 7 (2 ± 1%) | 11 ± 6 (1 ± 1%) | 16 ± 7 (2 ± 1%) | 11 ± 8 (1 ± 1%) | - | 5 ± 7 (1 ± 1%) | F5,5 = 2.4 n.s. | |
| SWnet | 190 ± 36 (23 ± 5%) | 156 ± 34 (21 ± 4%) | 154 ± 32 (20 ± 4%) | 137 ± 45 (18 ± 6%) | 154 ± 41 (21 ± 5%) | - | 87 ± 49 (10 ± 7%) | F5,22 = 3.3* | |
| LWnet | −51 ± 19 (−6 ± 3%) | −39 ± 19 (−5 ± 3%) | −49 ± 18 (−6 ± 3%) | −29 ± 21 (−4 ± 3%) | −38 ± 24 (−6 ± 3%) | −71 ± 17 (−9 ± 2%) | −36 ± 16 (−4 ± 2%) | F6,15 = 5.5** | |
| Y | Rnet | 31 ± 17 (3 ± 2%) | 24 ± 19 (1 ± 3%) | 30 ± 19 (5 ± 2%) | - | 11 ± 21 (0 ± 3%) | - | 4 ± 20 (0 ± 2%) | F4,13 = 3.8* |
| H | - | −1 ± 31 | - | - | −8 ± 31 | −13 ± 22 | −25 ± 13 | - | |
| LE | - | - | - | - | - | - | - | - | |
| G | 1 ± 2 (0 ± 0%) | 0 ± 2 (0 ± 0%) | 1 ± 2 (0 ± 0%) | 1 ± 3 | 1 ± 2 (0 ± 0%) | - | −1 ± 2 (0 ± 0%) | F5,−3 = 0.0 n.s. | |
| SWnet | 63 ± 23 (9 ± 5%) | 60 ± 23 (8 ± 7%) | 55 ± 21 (9 ± 7%) | - | 54 ± 23 (7 ± 7%) | - | 34 ± 27 (4 ± 5%) | F4,10 = 1.3 n.s. | |
| LWnet | −35 ± 14 (−6 ± 3%) | −29 ± 14 (−6 ± 3%) | −27 ± 14 (−5 ± 3%) | −25 ± 17 | −32 ± 17 | −40 ± 12 (−7 ± 2%) | −31 ± 10 (−5 ± 2%) | F6,13 = 1.2 n.s. | |
Mean estimates ± 95% CI (Wm−2) are derived from a mixed-model analysis with seasonally aggregated SEB-data (nr. of sites: 64, nr. of site years: 652, period: 1994–2021). Surface energy fluxes: Rnet net radiation, H sensible heat flux, LE latent heat flux, G ground heat flux, SWnet net shortwave radiation, LWnet net longwave radiation. Effect significance is derived from ANOVA (F-value, P-value: ***P < 0.001, **P < 0.01, *P < 0.05, n.s. not significant). Estimates for normalized surface energy fluxes (i.e., percentage of maximum potential incoming shortwave radiation) are indicated in parentheses. Note: flux direction convention is positive away from the surface for heat fluxes (i.e. H, LE and G). Effect significance is not shown where 3 or more vegetation types are missing. See Supplementary Table 4 for significant pairwise differences among vegetation types and Supplementary Table 5 for a more detailed analysis of normalized surface energy fluxes across the summer months.