Epsilon Archive for Student Projects

Abstract

A critical aspect to create a sustainable long-term forest plan involves understanding how drought will pose a significant challenge to the success of the regeneration in face of climate change. For a resilient forest promotion is key that forest managers consider the selection of tree species based on their capacity to withstand the climatic conditions and that are better suited for the given soil moisture type. This study delves into addressing the need to use site adaptation in the regeneration phase to increase seedling survival. The material used to perform the investigation was an inventory dataset on forest regeneration from Södra Skogsägarna, a Swedish forest owners association from Götaland, which had its data compiled since 2006. Focusing on the latest five years, we investigate if the mortality of Norway spruce seedlings was linked to soil moisture. The highest seedling mortality was seen in dry sites, as hypothesized, with 10% in contrast to 7%, 5%, and 7% in the mesic, moist, and wet sites, respectively. To understand if seedling mortality displayed an impact on a different gradient of soil moistures, we extracted the soil moisture data using the SLU Soil Moisture map, which is based on remote sensing and the National Forest Inventory (NFI), from a sampling of 18 clearcuts. By analysing the pixel reading, based on plot-level coordinates, we could thus infer if there was a relationship. The results show a significant statistical difference between soil moisture and mortality (P <0.001). Unfortunately, no correlation was found between soil moisture from the pixel reading and seedling mortality (r < 0.2), which can be a direct effect of doing only a small sampling. The important findings of this study are (a) N. spruce seedlings are shown not to be the optimal species for regeneration in dry sites, due to its high seedling mortality, and would likely be worsened by the climatic changes; (b) soil moisture disclosure a useful information on plot-level mortality; (c) planning efficiency could be likely enhanced by using data from digital remote sensing tools as the SLU Soil Moisture Map, particularly in the close future; (d) seedling mortality is influenced by soil moisture; (e) site adaptation is not necessarily being considered in the extent it could, but the study could not prove that regeneration success would be directly linked to site adaptation measures. We conclude that even though this study could not disclosure a solid proof that linked soil moisture to seedling mortality due to weak correlation results, the preposition to create a climate-resilient forest in Götaland remains. Thus, a plan tailored for soil factors and right tree-species selection for the given site, with the usage of different tools that had not been presented to the forest industry yet, can potentially enhance seedling survival in the future climate scenario.