Biomass partitioning and allometric relations of the Reaumuria soongorica shrub in Alxa steppe desert in NW China

Abstract

Allometry and partitioning of above- and below-ground biomass are needed to evaluate the sustainability of arid ecosystems. Biomass accumulation, allocation patterns, and allometric relationships for above- and below-ground components of the desert shrub Reaumuria soongorica were studied across five age classes (0–10, 11–20, 21–30, 31–40, and > 40 years) in Alxa desert steppe, northwestern (NW) China, where the biomass of each shrub component (i.e., leaves, branches, and coarse and fine roots) was harvested by destructive sampling and the allocation patterns between leaves (ML), roots (MR), branches (MB) were studied by regression analysis of log10-transformed data, and tested for data classified by age class and pooled data. By using basal diameter, age, height, and canopy area, we can predict the allometry properties of the R. soongorica shrub in terms of age class and/or entire age-sequence. The experimental results indicate that biomass accumulation has an obvious gradient across the five age classes, branch, and coarse root biomass were the main biomass pool as mature shrub. R. soongorica shrub partitioned a greater proportion of total biomass to roots with age in order to adapt to the extreme arid conditions. Shrub allometry was affected by variation of biomass partitioning, where the allometric relationships were strongly related to basal shrub diameter for almost all shrub components. Allometric biomass relationships were improved with the introduction of a second variable crown area.