Foliar C:N:P stoichiometric traits of herbaceous synusia and the spatial patterns and drivers in a temperate desert in Central Asia

Abstract

Herbaceous synusia is an important component of shrub community/ecosystem in the Junggar Desert and contributes a large proportion of net primary productivity in spring and early summer. Soil in the Junggar Desert is seriously deficient in nitrogen (N), but herbaceous plants possess high N concentration and N:P (phosphorous) ratio at the individual and interspecies levels; however, the community-level leaf stoichiometric characteristics of herbaceous synusia, spatial distribution patterns, and the driving factors at the regional scale remain unclear. In this study, 79 sampling plots were set up across the entire Junggar Desert. Foliar samples were collected by whole-plant harvesting method in each sampling plot, and the status of foliar carbon (C), N, and P concentrations, stoichiometric ratios, interrelationships, spatial patterns, and influencing factors were systematically analyzed. Results showed that the average contents of foliar C, N, and P in herbaceous synusia were 331.47, 25.85, and 1.54 mg g−1, respectively, and foliar C:N, C:P, and N:P were 13.76, 225.91, and 17.30, respectively. In contrast to most terrestrial ecosystems and global vegetation, herbaceous synusia was characterized by low C, C:N, and C:P and high N and N:P. Foliar C, N, and P were linearly and allometrically correlated with one another significantly. The foliar N–C, P–C, and N–P scaling exponents were 1.987, 1.770, and 1.122, respectively, thus the order of accumulation rates of foliar C, N, and P was N > P > C. Foliar C, N, C:N, and N:P presented significant differences among different soil habitats and shrub communities. Foliar stoichiometric traits showed obvious and different spatial heterogeneity at the regional scale. Multi-environmental factors jointly influenced foliar stoichiometric traits, and climate and geographical factors presented greater impact than soil. In conclusion, the foliar C:N:P stoichiometric traits might be the unique and inherent property of desert herbaceous species in this study area formed by long-term adaptation to the arid and barren environments in Central Asia, and this finding should be fully considered in regional ecological conservation and management.