Forest biomass is an essential indicator for monitoring the Earth’s ecosystems and climate. It is a critical input to greenhouse gas accounting, estimation of carbon losses and forest degradation, assessment of renewable energy potential, and for developing climate change mitigation policies such as REDD+, among others. Wall-to-wall mapping of aboveground biomass (AGB) is now possible with satellite remote sensing (RS). However, RS methods require extant, up-to-date, reliable, representative and comparable in situ data for calibration and validation. Here, we present the Forest Observation System (FOS) initiative, an international cooperation to establish and maintain a global in situ forest biomass database. AGB and canopy height estimates with their associated uncertainties are derived at a 0.25 ha scale from field measurements made in permanent research plots across the world’s forests. All plot estimates are geolocated and have a size that allows for direct comparison with many RS measurements. The FOS offers the potential to improve the accuracy of RS-based biomass products while developing new synergies between the RS and ground-based ecosystem research communities.

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Abstract— Changes in podzolic soils (Albic Retisols) and vegetation after felling blueberry spruce forest in the middle taiga of the Komi Republic are discussed. Changes in the morphological and physicochemical properties of soils after three and ten passes of the forwarder, as well as after ten passes with subsequent leveling of the ruts are characterized. It is shown that the number of forwarder passes is the decisive factor in soil changes. At the site with three passes, the formation of ruts with a depth of 11 ± 3 cm is observed, while at the site with ten passes, the depth of the ruts can reach 66 cm with an average value of 27 ± 4 cm. Leveling of forwarding trails to remove the ruts leads to the greatest transformation of the natural composition of the upper soil horizons over a larger area. A significant increase in the bulk density of the upper mineral horizon of the soil of the trail takes place after three passes. After ten passes, the bulk density of the upper mineral horizon decreases because of its mixing and loosening by wheeled vehicles. At the same time, an increase in the bulk density of the underlying middle-profile mineral horizon retaining its natural composition is observed. The upper horizons of the soil of the trail leveled with the use of an excavator are characterized by a significant increase in the bulk density compared to the initial soil. It was found that the regrowth of the main tree species in the first year after felling is extremely uneven. In the case of a strong clutter on the trails, there is no regrowth, which requires additional measures to improve tree growing these technological elements of felling area. On the leveled areas of the trails, the absence of regrowth in the first year after felling was observed. However, it can be assumed that in the future these areas will be fairly quickly populated with regrowth of tree species.