Mixed broadleaf-Korean pine (Pinus koraiensis) forests are a major ecosystem of the Xiaoxing'an Mountains of northeast China. It is critical to better understand the disturbance regimes and growth dynamics of the main conifer species in these forests, especially in the context of global climate change. The objective of this study was to investigate timing of tree recruitment and forest gap formation using growth releases recorded in tree-ring series of two conifer species, Korean pine and Koyama spruce (Picea koraiensis), and their responses to annual variation in temperature and precipitation. We sampled trees from three randomly selected stands in the experimental area of Shengshan National Nature Reserve, Heilongjiang Province. All Korean pine and Koyama spruce trees with diameter at breast height ≥ 10 cm in each plot were mapped and increment cores collected from each. All cores were dendrochronologically crossdated with a locally developed chronology and ring widths measured to the nearest 0.001 mm. After measuring, growth release events on each series were determined using the boundary line release criteria and the relationship between percent growth change and prior growth. The results showed that the prior growth was an important decision factor to define growth release events. Both the tree-ring widths and percent growth change curve of each series indicated that Koyama spruce had stronger consistent between-tree growth responses, while Korean pine had less consistent growth responses probably because of greater differences in micro-environments. Almost all Korean pine series had more than one growth release event, with 2.75 average growth releases per tree. 87.5% of the Korean pine series had at least one major release. Koyama spruce had a lower average growth release rate per tree due to the shorter length of their tree-ring series. The average release number of each Koyama spruce series was 0.92, and 41.7% of the growth series had more than one major release. Eight trees in plot 1 contained 15 growth release events (eight major and seven moderate releases). Four major and five moderate releases occurred during the period 1970 1990, which had the greatest frequency of release events. Twenty trees in plot 2 contained 29 growth releases, most of which were major (25 major releases and four moderate). Twelve trees in plot 3 had 22 growth release events with 13 major releases and nine moderate releases. There were four samples in each plot without growth release events. Seventeen major releases and three moderate releases in plot 2, and 10 major releases and two moderate releases in plot 3 occurred during the period 1970 1990, while six in nine moderate releases in plot 3 occurred during 1930 1960, which was another high growth release period. For growth releases lasting less than 5 years, 71.4% of these releases also appeared in the periods 1930 1960 and 1970 1990. Spatial distribution patterns of Korean pine and Koyama spruce trees indicated that forest gap opening due to a variety of mortality factors is likely the main reason for tree growth releases. A comparison analysis between the percent tree growth and climate changes showed that temperature and precipitation could be another important factor causing growth releases, especially for growth releases that occurred synchronously between plots. Precipitation was more important than temperature to cause growth releases in this area. Results from this study provide preliminary data and scientific support for the management of mixed broadleaved-Korean pine forests in this area, which is the northern limit of Korean pine distribution in Heihe.