Objective This paper constructs a larch biomass model that includes site class and climate factors, and analyzes the combined effects of environment and climate on biomass model within the same forest stand, so as to provide a theoretical basis for forest management and decision-making.

Method Based on the data from fixed sample plots of larch plantations in Jilin Province of northeastern China in 2004, 2009, and 2014, and average climate factors from 1950−2000 obtained through World Clim, the Richards model was selected as the base model. Topographic factors significantly correlated with biomass were classified and integrated into the site class, which was used as a dummy variable to establish a larch stand biomass model including both site quality and climate factors. The impacts of climate and site quality on stand biomass were also analyzed.

Result (1) The model incorporating site quality and climatic factors achieved a fitting accuracy of 0.961, with differences in evaluation metrics obtained from the training set being less than 5%, demonstrating good generalization ability. (2) Stand factors independently explained 93.7% of the variance in stand biomass, while site class accounted for 2.4%, and climate factors only 0.3%. (3) Temperature and precipitation jointly affected stand biomass. Higher temperatures in the driest season can reduce the maximum biomass of stand, while increased precipitation in the coldest season can accelerate the growth rate of stand biomass.

Conclusion Site quality has a greater impact on estimation of larch stand biomass than climate does. The established Larix gmelinii growth and yield prediction model, which incorporates both site class and climate factors, reveals the effects of these factors on larch biomass growth. This can provide scientific guidance for suitable forest stand management and precise carbon sequestration in forestry.