Shrub models in a spruce-fir forest of different densities in Jingouling Plantation, Jilin Province

Abstract

In order to study the shrub biomass in the forest in Jingouling Plantation and there wasn’t a comprehensive shrub models study in this area. Three different forest densities (0.6, 0.8, 1.0) of a natural spruce-fir Picea koraiensis-Picea jezoensis-Abies nephrolepis forest in Jingouling Plantation, Jilin Province were used for this research. Based on measured data for shrub biomass under the forest canopy, 13 mixed biomass models for 13 different species and biomass models of the different shrubs’ organs were respectively constructed by R software. Then the optimal model was selected using the largest R2 and F and the smallest ESEE and E. Also differences in shrub biomass for forests of different densities and for different species distribution with the same forest density were studied. Shrub quadrat 5 m × 5 m were setted in the center and four corner at each sample plot (20 m × 20 m), then measured the diameter D, crown width C1, C2, and height H. According to the results of the shrub species, 13 species, were selected from the sample plots. Results showed that the optimal biomass model (R2=0.626 2-0.997 9)for different organs in each species as well as for leaves and roots of Acer tegmentosum, and the trunk of Acer ukurunduense was a power function; whereas the optimal model of the other species was a quadratic equation or binary linear equation. The independent variable of the model for stem and branch biomass was AC(AC=πC1C2/4) with the other species being D2H and CH(crown width multiply height). The independent variables in the optimal model of leaf biomass for species Spiraea pubescens, Acanthopanax senticosus and A. tegmentosum used factors of AC and CH, but other species used variables D and D2H. The optimal model for root biomass was D2H. The accuracy of the models are relatively high, and they meets the requirements of biomass model estimation, which provides the basis for the measurement of shrub biomass in this region. The research is only suitable for this area and the shrubs’ ground diameter must in a certain range, for other areas to be further studied[Ch, 2 fig. 4 tab. 27 ref.]