Results of pilot study comparing greenhouse gas fluxes from forwarding ruts and control area in moist mineral soil after clear-felling

Forest operations involving heavy machinery often result in soil compaction and rut formation, significantly affecting soil physical properties, greenhouse gas (GHG) emissions, and forest productivity. This pilot study evaluates the impact of rut formation on the emissions of methane (CH₄-C), nitrous oxide (N₂O-N), and carbon dioxide (CO₂-C) from forest soils in managed ecosystems. Gas flux measurements were conducted at two types of sites: undisturbed control plots and ruts affected areas created by forestry machinery. Measurements were done during summer and autumn 2024 in two spruce felling sites in the central part of Latvia, 16 measurement points in total (8 points in ruts and 8 points in control area). Gas samples were collected from opaque 60 L chambers and analysed using gas chromatography. CO₂ flux was determined in the field using EGM5 analyser. Statistical analyses compared gas emission rates between these sites to assess the influence of soil disturbance on GHG dynamics. The results showed that CH₄-C emissions were substantially higher in ruts affected areas due to anaerobic conditions induced by soil compaction and water retention. Conversely, N₂O-N emissions were higher in control plots, likely due to better aeration promoting nitrification and denitrification processes. CO₂-C emissions showed minor differences, suggesting limited microbial respiration in compacted soils. These findings highlight the significant environmental impact of rut formation, emphasizing the need for sustainable forest management practices that mitigate soil disturbances, reduce GHG emissions, and enhance ecosystem resilience. This study also highlights the necessity of comprehensive study to evaluate long term effect of rut formation in moist mineral soils and to elaborate activity data for a stand- and national-wise assessment of GHG outflow due to ruts formation.