Short-Term Effects of Pine Plantations on Vegetation and Soil in Northern Mongolia

This study looked at the impact of planting year differences on vegetation and soil parameters in Pinus sylvestris plantation forests in northern Mongolia. Tujiin nars region has three study sites: 18- to 20-year-old plantation forests planted in 2003, 2004, and 2005, as well as natural regeneration stand, natural forest, and steppe area. Three plots with distinct plantation stand types were constructed at each location to investigate changes in vegetation and soil attributes. Understory vegetation was comprised of 92 species of plants, including 4 shrubs, 1 semi-shrub, species, and 84 herb species (5 annuals and 87 perennials) belonging to 78 genera of 35 families. Species richness, total coverage, and biomass accumulation were significantly higher in the oldest plantation (2003). Soil pH ranged from 6.52 to 7.41, across plantations, with steppe and forest edge soils being alkaline and plantation soils slightly acidic. Soil temperature varied between 17.7 and 24.7 °C, where the lowest temperature was in the naturally regenerated stand and the highest was in the steppe plot. The average soil moisture varied from STP (5.1%) to MGS (12.0%) and decreased by 2.0% in the 2003 plantation forest. Available nitrogen, soil organic carbon, and carbon stock were higher in the top soil and decreased by depth of profile and differed in plantations by year of planting. Furthermore, the change in understory vegetation was significantly correlated with the soil moisture, fertility, and species composition was driven by over story density and crown parameters. Our findings revealed the importance of soil characteristics and understory vegetation in the effective restoration and management of Scots pine plantation in Mongolia and further management of planted Scots pine plantation in safeguarding resilient and productive forests in Mongolia.