CNP stoichiometry and productivity limitations in high-altitude wetland ecosystems of the Eastern Pamir

Abstract

We studied two wetland plant community types that occur on flat lake terraces in the Eastern Pamir mountains (Tajikistan, Central Asia). We selected 13 homogeneous patches of salt marsh vegetation dominated by Blysmus rufus (Huds.) Link, and 20 homogeneous patches of saline small sedge meadow. From each patch we took soil and biomass samples which were analysed in the laboratory. We used δ13C and δ15N values for plant biomass to determine the type of nutrient limitation and to characterise dominant species, and we assessed the impact of detrital input on the CNP stoichiometry of biomass. Biomass δ13C was typical for plants growing under low partial pressure of CO2; while δ15N was very high, especially in the leaves of Carex orbicularis Boott. N limitation was indicated for the majority of sampled sites, yet we found no significant correlation between δ13C or δ15N and N/P quotient. There were pronounced differences in δ15N between species, the lowest values being recorded for Carex microglochin Wahlenb. No significant influence of detrital inputs on the chemical composition of plant biomass was detected.

Keywords

• Central Asia
• N/P quotient
• nutrient limitation
• stable isotopes
• Tajikistan