Which Selective Logging Intensity is Most Suitable for the Maintenance of Soil Properties and the Promotion of Natural Regeneration in Highly Continental Scots Pine Forests?–Results 19 Years after Harvest Operations in Mongolia

Abstract

Scots pine (Pinus sylvestris L.) forests are one of the main vegetation types in the Asian forest-steppe zone. However, over-harvesting currently threatens the natural regeneration and sustainability of these forests. In this study, we examine the long-term effects of different logging intensities on soil properties and natural regeneration in a natural Scots pine forest in the West Khentii Mountains (Mongolia), 19 years after selective logging. Our experimental design included five treatments: clear cut (CC), treatments with high (HI), medium (MI), low (LI) intensities, and a reference parcel with no logging impact at all (RE). We described and quantified the harvest events and applied ANOVA and LMM modeling to analyze and explain the long-term impacts of the logging intensities on soil properties and natural regeneration. We found that logging has a significant negative influence on the physical and chemical properties of the soil because it increases soil compaction and reduces soil nutrients. The most critical impacts of logging were on soil bulk density, total porosity, organic matter, and total nitrogen and phosphorus. The LMM modeling showed that organic matter (OgM), total nitrogen (TN), available K (AK) and pH values are especially impacted by logging. Our study revealed that the values for all of these variables show a linear decrease with increasing selective logging intensity and have a level of significance of p < 0.05. Another finding of this study is that selective logging with low and medium intensities can promote natural regeneration of Scots pine to numbers above those of the reference site (RE). High intensity logging and clear-cuts, however, limit the regeneration of Scots pine, reduce overall seedling numbers (p < 0.05), and create conditions that are suitable only for the regeneration of deciduous tree species. This underlines the risk of Scots pine forest degradation, either by replacement by broad-leaf trees or by conversion into non-forest ecosystems.

Forest Management In Mongolia – A Review Of Challenges And Lessons Learned With Special Reference To Degradation And Deforestation

“…However, major disturbances that result in large-scale degradation can trigger continuous carbon emissions from these forests. Measures that reduce emissions from deforestation and degradation therefore go hand in hand with other objectives for stabilizing (Gerelbaatar et al 2019a). By reducing canopy cover, intensive logging and fire can trigger the melting of insular permafrost and the release of soil carbon (Juřička et al 2018).…”

“…Beside intensive logging, fires are considered to be the main cause for the recent compositional shift from one tree species to another. In Mongolia and neighboring regions, this shift is often from coniferous to deciduous forests (Tikhonova et al 2018;Gerelbaatar et al 2019a). Birch often dominates after disturbances due to its sprouting ability (Otoda et al 2013).…”

“…The development and implementation of sustainable forest management strategies is a key environmental policy issue in Mongolia (Gerelbaatar et al 2019a). The forests of northern Mongolia not only provide resources such as timber and firewood, but also ecosystem services that are relevant to the well-being of the whole country, such as water purification and retention, erosion control, and biodiversity (Krasnoshhekov 2001;Tsogt et al 2018; Government of Mongolia 2018).…”

“…In contrast, degradation is characterized by a qualitative loss that affects forest ecosystem functions and is often triggered by specific disturbances. Such disturbances may include a decrease in stocking volume (Government of Mongolia 2018) or a shift toward broad-leaf pioneer tree species after intensive logging (Gerelbaatar et al 2019a). Continuing degradation can eventually lead to complete deforestation (Government of Mongolia 2018; Gerelbaatar et al 2019a) and even desertification (Khaulenbek and Kang 2017).…”

“…Such disturbances may include a decrease in stocking volume (Government of Mongolia 2018) or a shift toward broad-leaf pioneer tree species after intensive logging (Gerelbaatar et al 2019a). Continuing degradation can eventually lead to complete deforestation (Government of Mongolia 2018; Gerelbaatar et al 2019a) and even desertification (Khaulenbek and Kang 2017). Direct drivers of deforestation and forest degradation are disturbances such as fire, pests, unsustainable harvest practices, overexploitation of forest resources, mining activities, and overgrazing (Kondrashov et al, 2008;Ykhanbai 2010;Dulamsuren et al 2011;Khishigjargal et al, 2014;MET 2016; Government of Mongolia 2018; Khongor et al 2018).…”