Nitrogen and phosphorus addition differentially affect plant ecological stoichiometry in desert grassland

Abstract

Plant C:N:P stoichiometric relations drive powerful constraints on ecological interactions and processes. However, information about plant stoichiometric responses to N and P availability in desert grassland is limited. We conducted two field experiments with 7 levels of N (from 0.5 g to 24 g N ∙ m−2 yr−1) and P (from 0.05 g to 3.2 g P ∙ m−2 yr−1) additions in a desert grassland of Kunlun Mountain in the northwest of China to investigate the effects of these addition rates on the N and P stoichiometry of the dominant grass species Seriphidium korovinii. Nitrogen and P additions both affected plant stoichiometry. N addition suppressed P concentrations, whereas P addition had no effect on plant N concentrations. The N:P ratios of green aboveground biomass (AGB) were positively correlated with N addition ranging from 14.73 to 29.08, whereas those for P additions decreased ranging from 14.73 to 8.29. N concentrations were positively correlated with soil available N:P ratios, whereas, P concentrations were negatively correlated with soil availably N:P. Our results suggest that chemistry and stoichiometry of S. korovinii was directly affected by soil nutrient availability. Soil N availability affects S. korovinii stoichiometry to a greater extent that does soil P availability in this ecosystem. These findings suggest that N-deposition could affect the stoichiometry of this desert grassland ecosystem, and thereby potentially alter litter decomposition, plant community composition, nutrient cycling, and food-web dynamics of these desert ecosystems.

Effects of nutrient supply on leaf stoichiometry and relative growth rate of three stoloniferous alien plants

“…Phosphorus addition increased phosphorus concentration in leaves of alpine grassland [18]. Responses of phosphorus concentration in the three alien plants to phosphorus addition were complex, which is similar to the previous study [20]. Compared with those in previous studies, N: P ratio (<14) in leaf of the three alien plants was lower [27,60].…”

“…In central Brazil, the similar pattern was not observed in four plants (Caryocar Brasiliense, Qualea parviflora, Schefflera macrocarpa and Ouratea hexasperma) grown on a dystrophic soil [25]. Nitrogen concentration in the leaf of Arabidopsis thaliana and desert grasses was not significantly affected by phosphorus supply [20,21]. With increase of phosphorus supply, nitrogen concentration in the leaf of the oak Quercus acutissima and shrub Rhus typhina significantly decreased [21,24].…”

“…For example, with increase of nitrogen availability, phosphorus concentration in the leaf of desert grass Seriphidium korovinii and two alpine grasses significantly increased [17,18]. Meanwhile, an opposite pattern was observed in the phosphorus concentration of leaf [19][20][21][22]. With increase of nitrogen availability, nitrogen concentration in the leaf significantly increased [23,24].…”

“…With increase of phosphorus supply, phosphorus concentration in leaves of the alpine grassland significantly increased [18]. With increase of phosphorus supply, phosphorus concentration in the leaf of S. korovinii was various [20]. So, the effects of nitrogen and phosphorus supply on leaf stoichiometry of plants are still controversial.…”

Seasonal Variations in Carbon, Nitrogen, and Phosphorus Stoichiometry of a Robinia pseudoacacia Plantation on the Loess Hilly Region, China

“…It emphasizes the proportional relationships between chemical elements in ecological processes, especially those of carbon (C), nitrogen (N), and phosphorus (P) [2,3]. The elements of C, N, and P are strongly coupled in plants, and understanding their stoichiometric characteristics plays a crucial role in exploring plant growth, litter decomposition, and biogeochemical cycling [4][5][6].…”