Abstract:
The generalized additive model (GAM) was used to investigate the effects of climate on individual
tree radial growth and tree species' responses to climate. The data was collected from long-term
permanent plots of larch-spruce-fir forests repeatedly measured for 25 years in Wangqing Forestry Bureau,
Jilin Province of northeastern China. Our results showed that accumulated temperature in growing season,
mean minimum temperature during growing season, annual total precipitation, mean temperature
difference between the coldest and warmest months and the ratio of annual temperature and annual total
precipitation significantly explained the variation in radial growth, but varied in the response variables
and magnitude of different tree species (larch, spruce, fir, Korean pine and two hardwood groups). The
full model, reduced model 1 (stand variables) and 2 (climate variables) could explain 50.8%, 45.7%
and 29.5% of the variation in radial growth, respectively. It is concluded that climate has limited
capacity in explaining the variation in radial growth, while the size, competition among individuals and
stand density are the main drivers to radial growth on the local scale.