Functional group contributions to carbon fluxes in arctic-alpine ecosystems

Figures & data

Table 1. Environmental conditions during CO₂ flux measurement in 2015. Mean ± SD, n = 6 plots in each community.

Parameter	Heath	Meadow	Shrub
Measurement period	12 - 13 August	15 - 17 July	19 - 22 July
Chamber temperatureNEE (°C)	20.3 ± 4.8	18.7 ± 3.3	17.5 ± 3.3
Temperature spanNEE*(°C)	8.1 ± 2.6	7.6 ± 2.1	7.8 ± 3.2
Chamber temperatureER (°C)	18.3 ± 4.4	16.6 ± 3.1	17.3 ± 3.5
Soil temperature NEE (°C)	8.3 ± 0.5	7.3 ± 1.8	8.0 ± 1.0
Soil temperature ER (°C)	8.4 ± 0.5	7.9 ± 1.5	8.0 ± 1.0
PAR NEE (μmol m^−2 s^−1)	1187 ± 537	493 ± 561	464 ± 227

*The difference between the highest and lowest chamber temperature among functional group measurements in each plot.

Table 2. Partitioning of growing season daytime ecosystem respiration (ER) and gross photosynthesis (GP) into aboveground and belowground respiration (R) and net ecosystem exchange (NEE) in three arctic-alpine communities, expressed as mean CO₂ flux (μmol m⁻² s⁻¹) and as mean proportion of ER (%ER) or GP (%GP), based on adjusted estimates (n = 6).

	CO2 Flux(μmol m^−2 s^−1)	%ER	%GP
Heath
Aboveground R	−1.78	36.8	28.6
Belowground R	−3.05	63.2	49.0
ER	−4.83		77.6
NEE	1.39		22.4
Meadow
Aboveground R	−0.56	12.5	5.8
Belowground R	−3.91	87.5	40.5
ER	−4.47		46.3
NEE	5.19		53.7
Shrub
Aboveground R	−3.65	59.9	29.3
Belowground R	−2.44	40.1	19.6
ER	−6.09		48.9
NEE	6.35		51.1

Figure 1. Total CO₂ fluxes in three arctic-alpine plant communities calculated from raw measurements and after adjustment for anomalous measurements and differences in temperature and light conditions during measurement. Mean ± standard deviation of six plots per community.

Figure 2. a–c: Adjusted soil and functional group contributions to ecosystem CO₂ fluxes in three arctic-alpine plant communities based on sequential harvest and closed-system measurements in light and dark after removal of each functional group. d: Functional group biomass, with deciduous and dwarf shrub leaf and woody stem biomass separated and herbaceous plants and cryptogams divided into subgroups. Means of six plots per community, including null values for plots where a functional group was absent.