Fig 1.
Map of the study area showing the Northeast Science Station and measurement locations.
The yellow circle denotes the flux and soil temperature timeseries measurement site, and gray points indicate locations of lichen and canopy cover measurements. Sites in the western half of the map, including the flux plots, are in the Y4 watershed while those along the road in the eastern half are in the Y3 watershed. Stands in the Y3 watershed are approximately 50 years old and of relatively high-density, while the stands in Y4 are older (~150 years) and have generally lower forests density. Background image is a WorldView2 true color composite from 21 August 2012 provided by the Polar Geospatial Center.
Fig 2.
Relationship between larch canopy cover and lichen percent cover.
Areal percent cover of lichen declined non-linearly with increasing larch canopy cover for 35 stands in the study area. Lichen cover was estimated visaually and larch canopy cover was measured with a hemispherical densitometer.
Fig 3.
Surface and subsurface characteristics of understory lichen mats.
Photograph showing lichen mat and resistivity survey near Cherskii, Siberia. Two representative resistivity profiles where colors indicate resistivity, black lines represent thaw depth measurements, and green boxes labeled lichen above each profile denote the location of lichen mats. Note the deep areas of low resistivity (blue) and thaw depth beneath lichen.
Fig 4.
Soil temperatures beneath lichen and shrub understory vegetation.
(A) Time series of daily mean Tsoil at 10 cm depth beneath lichen mats (n = 9) and shrub patches (n = 9) from July 2012 –June 2014. Dotted lines indicate one standard deviation. (B) The difference between daily mean lichen and shrub temperatures (lichen-shrub).
Table 1.
Seasonal soil temperatures at 10cm depth beneath lichen mats and shrub moss patches1.
Table 2.
Soil properties for lichen mats and shrub/moss patches in a low-density larch stand in Northeastern Siberia1.
Table 3.
Summary of key vegetation and physical parameters for CO2 and H2O flux plots measured between 17 July and 5 August 20131.
Table 4.
Variability in soil, air, and radiometric surface temperatures, photosynthetically active radiation, and evapotranspiration between vegetation types measured at flux-plots for two sampling periods with contrasting meteorlogical conditions during the 2013 field season1.
Fig 5.
Variation in ecosystem respiration with air and soil temperatures.
(A) RECO was not significantly related to Tsoil. (B) RECO was was positively related to air temperature when observations were polled across plant communities and sampling periods (intercept = 1.16, slope = 0.09, adj r2 = 0.19, p < 0.01).
Table 5.
Comparison of mean values of key carbon and water fluxes, and key meteorological drivers for each vegetation type averaged across the study period between 17 July and 5 August 20131.