ObjectiveIn this study, the natural secondary coniferous and broadleaved mixed forests of Jiaohe in Jilin Province, northeastern China were used as research objects to study the effects of tending and cutting on the growth of stand, in order to provide a theoretical basis for the sustainable management of Jiaohe mixed forest of coniferous and broadleaved forests in Jilin Province.

MethodThe study used volume and biomass as the indicators of productivity respectively, through the correlation analysis, the variables related to productivity were selected from the three species diversity and the five forest structure indexes, and then the structural equation model was used to analyze the harvesting for stand structure, species diversity, productivity impacts, and causal relationships between forest structure, species diversity, and productivity.

ResultIn the structural equation model of accumulation productivity, harvesting has a negative impact on stand density and stand structure, with path coefficients of − 0.661 and − 0.216, respectively; harvesting indirectly affected productivity through stand density and stand structure, and indirectly affected species richness through stand density. The stand density had a positive impact on species richness, stand structure and productivity, and the path coefficients were 0.330, 0.599 and 0.473, respectively. The stand structure had a positive impact on productivity with a path coefficient of 0.310. Species richness had a positive impact on the stand structure, with a path coefficient of 0.414. Species richness affected stand structure and indirectly affected productivity. In the structural equation model of biomass productivity, except for the stand structure had no effect on productivity, the mode of action between other variables was the same as the model of accumulation productivity.

ConclusionThe study suggests that tending can directly or indirectly change the stand structure, species diversity and productivity, while the stand structure has a greater impact on productivity than species diversity. Therefore, in forest management, under the premise of protecting species diversity, attention should be paid to the optimization and adjustment of the stand structure.