Simulation of Radial Growth of Mongolian Pine (Pinus sylvestris var. mongolica) and Dahurian Larch (Larix gmelinii) Using the Vaganov–Shashkin Model in the Greater Khingan Range, Northeast China

Abstract

It is necessary to understand the radial growth responses of trees in the Greater Khingan Range to climatic factors to predict changes in forest ecosystems under climate change scenarios. We sampled Mongolian pine (Pinus sylvestris var. mongolica) and Dahurian larch (Larix gmelinii (Rupr.) Kuzen) at four locations at elevations of 900–1100 m in the Greater Khingan Range to establish a tree-ring chronology. The Vaganov–Shashkin (VS) model was used to describe the relationship between tree radial growth and the dominant limiting climatic factors with a focus on physiological processes. The results showed that the VS model accurately reflected the effects of various climatic factors on the growth of Mongolian pine and Dahurian larch. The simulated and measured tree-ring widths index (RWI, the same as below) were consistent. The physiological parameters affecting tree growth differed for the two tree species in the study area. Mongolian pine required higher temperatures and less soil moisture for growth than Dahurian larch. The growth rings of the two tree species are more consistent across the elevation gradient. Higher-elevation trees had an “intensive strategy” with shorter growing periods and high growth rates, whereas low-elevation tree species had a “broad strategy” with lower maximum growth rates for longer periods. The start and cessation date of tree growth strongly affected the RWI of Mongolian pine and high-elevation Dahurian larch, but no significant effect on the RWI of low-elevation Dahurian larch. Differences in the limiting climatic factors were observed between Mongolian pine and Dahurian larch. Mongolian pine shows some similarity between high and low elevations, subject to the common limitations of temperature and soil moisture during the growing season for both, with a greater proportion of the lower elevations being limited by soil moisture. Dahurian larch was influenced by the growing season temperatures and May–August soil moisture at higher elevations and by the growing season soil moisture at lower elevations. This study provides a scientific basis for the management and conservation of forest ecosystems in the Greater Khingan Range.