Climate and site class impact on biomass estimation in Larix gmelinii forest stands

Objective The impact of environment and climate on forest stand biomass cannot be overlooked. However, previous models of forest stand growth generally assumed a constant climate or only considered the influence of a single environmental factor on biomass estimation, which is not conducive to analyzing the overall impact of the environment on forest stand biomass growth. Constructing a larch biomass model that includes site class and climate factors, and analyzing the combined effects of environment and climate on the biomass model within the same forest stand, provides a theoretical basis for forest management and decision-making.

Method Based on the data from fixed sample plots in Jilin Province’s larch plantations from 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 used as a dummy variable to establish a larch stand biomass model that includes both site quality and climate factors. The impacts of climate and site quality on stand biomass were also analyzed.

Result A new larch biomass model incorporating site class and climate improved the model fitting accuracy from 0.937 to 0.961. (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 affect stand biomass. Higher temperatures in the driest season can reduce the maximum biomass of the stand, while increased precipitation in the coldest season can accelerate the growth rate of stand biomass.

Conclusion Site quality has a greater impact on the estimation of larch stand biomass than climate does. The established larch 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.