Evaluating the potential of Pinus strobus, Pinus nigra, and Pinus rigida as alternatives to Pinus sylvestris in central Europe's changing climate

Abstract

The observed weakening and dying of Pinus sylvestris in central Europe has prompted a search for species that can replace it. For this purpose, historical late 19th-century survey plots in southern Poland containing Pinus sylvestris and three non-native species, i.e., Pinus strobus, Pinus rigida, and Pinus nigra, were analyzed. The width of annual tree-ring growth was used to measure the effect of climatic variability on tree growth. The climate–growth relationship was analyzed using multivariate methods, linear correlation, and machine learning, which enabled the identification of nonlinearities that would otherwise remain hidden. Temporal variability of these relationships was considered. The pines’ growth was significantly affected by winter temperatures, but March temperature was the dominant growth factor for P. sylvestris, P. rigida and P. nigra. Average March temperatures of 0°C and 5°C were found to be the threshold values, below and above which the effect of temperature on tree-ring growth remained constant. For July precipitation, which is the dominant climatic growth factor for P. strobus, these thresholds were 70 and 120 mm. P. strobus had the largest growth during the analyzed period. High April temperatures for P. rigida, cool May conditions favorable for P. nigra, and low December temperatures beneficial for P. strobus, could serve as distinguishing characteristics for these species under analyzed conditions. Water deficiency in early spring and in the summer negatively affected the growth of all the studied pine species. None of the analyzed non-native species appears suitable for large-scale replacement of P. sylvestris.