Objective To explore the driving factors of the dynamic processes of aboveground biomass of mixed forests in Northeast China for accurately understanding the forest services and functions.

Methods Based on 110 fixed plots in Jingouling Forest Farm in Northeast China, forest dynamics processes from 1987 to 2017 were described. Piecewise structural equation models were used to assess the impact of forest structure, climate, topography and diversity on the dynamic processes (growth, recruitment and mortality) of biomass, and the effects of dynamic processes on stability were further explored.

Result The results showed that the growth of biomass was positively affected by stand basal area (β=0.562), altitude(β=0.853), and mean annual temperature (β=0.820), and negatively correlated with the Gini coefficient of diameter at breast height (β=−0.274). The increment of tree recruitment was positively associated with altitude (β=0.913), mean annual temperature (β=0.944), and negatively related to the coefficient of variation of diameter at breast height (β=−0.233). The biomass loss was only significantly positively correlated with the stand basal area (β=0.467). In addition, this study also found that mortality was the most important factor affecting the biomass stability.

Conclusion In general, altitude and MAT plays an important role in the biomass change. We should pay more attention to the situation of dead trees in the future for forest management.