Radial Growth Response of Scots Pine (Pinus sylvestris L.) after Increasing the Availability of Water Resources

In the years 1998-2022, about eight thousand hydrotechnical facilities were built or planned for construction at the State Forests National Forest Holding in Poland, which could slow down the outflow of water from small forest catchments and store over 50 hm(3) of water. Due to the innovative and unprecedented nature of investments retaining water resources on forest land, having a significant impact on the adaptation and mitigation of the negative effects of climate change, the literature on the subject lacks in studies describing their impact on the adjacent forest environment. The aim of the presented research is to determine the evolution of the tree-ring width of Scots pine (Pinus sylvestris L.) before and after the reconstruction of two water reservoirs and the construction of gates in drainage ditches as part of small retention projects in lowland areas. The research was carried out on the basis of core drillings collected in four forest districts and climate data provided by the Polish Institute of Meteorology and Water Management-National Research Institute. In the first stage of the work, no statistically significant influence of climatic conditions on the shaping of growths was demonstrated. In the next step, the variability of increments and their width in individual years before and after the investment was examined. Then, the distance of individual trees from reservoirs and drainage ditches was analyzed, as well as its importance in forming increments. The calculated statistical significance of differences in increments, average, minimum and maximum values, as well as standard deviation indicated the possible influence of retention reservoirs and valves on shaping the increments. The study did not confirm the importance of the distance of trees from the newly available water resources in the growth of the width of the increments.