%0 Articles %T Impacts of thinning activities on boreal peatland forests %A Lepilin, Dmitrii %D 2023 %J Dissertationes Forestales %V 2023 %N 346 %R doi:10.14214/df.346 %U http://dissertationesforestales.fi/article/23013 %X

Boreal peatland forests are an important source of timber. Recently, timber harvesting has been extended to warmer months, resulting in machinery traffic over unfrozen soils, and leading to higher levels of soil disturbance, such as deeper ruts. Despite this, our knowledge of the impact of soil disturbance on peat physical properties and soil biochemistry is still limited. To address this gap, I conducted a study to examine the effects of soil disturbance caused by harvesting machinery during thinning operations on the soil physical, chemical, and biological properties and vegetation of drained boreal peatland forests. To assess the rate of recovery, I sampled six sites that formed a chronosequence covering 15 years since thinning. The results showed that soil disturbance caused an increase in the bulk density and field capacity of peat, along with a decrease in total porosity. In the vegetation, moss biomass and root production were reduced, but sedge cover increased. Furthermore, recently disturbed areas exhibited greater soil CO2 production potential, as well as higher soil CO2 and CH4 concentrations compared to control areas. However, CO2 and CH4 emissions, microbial communities, and cellulose decomposition rate were not impacted. Although the rate of recovery varied, all studied properties impacted by disturbance were fully recovered within 15 years. As the water retention characteristic (WRC) describes soil structure and its alterations, it a useful for disturbance assessment. Thus, I propose how WRC can be predicted using artificial neural networks. Overall, the study demonstrated that while drained boreal peatlands are sensitive to disturbance, they are also resilient to mechanical soil disturbance caused by thinnings.