Changes in soil physical properties and understory vegetation in abandoned skidding trails

Skidding trails are primary pathways for transporting harvested timber from stumps to landings near forest roads. While they function as temporary routes for logging, their construction can alter ecological dynamics, potentially affecting plant regeneration, diversity, and species composition. This study investigated the physical properties of soil specifically bulk density, soil moisture, saturation, and field capacity as well as the biodiversity of understory vegetation within abandoned skidding trails in the Hazarjarib forest of Iran. Four skidding trails of varying ages (15, 25, 35, and 45 years past-skidding) were selected for the analysis. At each logging route, three plots were established; for each plot, an off-route control plot was placed nearby. To assess the richness and diversity of understory vegetation, we employed various metrics including evenness, Margalef richness index, and the Simpson, Shannon, and Sorenson diversity indices. Results showed that there is significant difference in all investigated soil parameters between the skidding trails and the untrafficked areas (control) except skidding trail with 45 years. The 15-years skidding trail exhibited the highest bulk density (1.80 g cm^–3), while the 45-year skidding trail showed the lowest (1.46 g cm^–3). This suggests that after 45 years since the last skidding, the bulk density has decreased and is now comparable to that of the untrafficked control area. Also, we observe a higher diversity of species and genera in the control areas compared to the skidding trials.