Biomass estimation, nutrient accumulation, and stoichiometric characteristics of dominant tree species in the semi-arid region on the loess plateau of China

Abstract

The biomass estimation, nutrient stock, and stoichiometric characteristics are critical for understanding forest productivity and quality. To date, there is not enough comprehensive research on nutrient stock and stoichiometric characteristics of each tissue among different tree species in the semi-arid region on the Loess Plateau. So, six dominant tree species were selected to estimate the forest biomass by allometric equation and to analyze the effects of tissue and species on biomass allocation and nutrient stock by variance analysis in our study. Results showed that forest biomass, nutrient concentration, nutrient stock, and stoichiometric characteristics varied with tissue and species. Betula platyphylla and Pinus tabulaeformis had high total biomass while Populus davidiana had the least total biomass, and the biomass allocation of each tissue generally followed the order of stem > branch > root > foliage. The weighted mean concentrations of carbon (C), nitrogen (N), and phosphorus (P) changed from 432.67 g kg1 to 481.43 g kg1, from 6.15 to 8.30 g kg1, and from 0.43 to 0.74 g kg1, respectively. The relatively high nutrient stocks were observed in Pinus tabulaeformis and Betula platyphylla across organs and in stem across species. The C:N and C:P ratios were higher in stem and root than those in branch and foliage for each species, while the effects of tissue on N:P varied with species. Overall, the N:P ranged from 7.92 for stem (Larix principis-rupprechtii) to 22.18 for foliage (Populus davidiana). Therefore, Pinus tabulaeformis and Betula platyphylla can increase effectively nutrient fixation capacity in the semi-arid region on the Loess Plateau. Also, N or P limitation of tree growth in this region varied with species.