Nutrient limitation of alpine plants: Implications from leaf N : P stoichiometry and leaf δ¹⁵N

Abstract

Nitrogen (N) deposition can affect grassland ecosystems by altering biomass production, plant species composition and abundance. Therefore, a better understanding of the response of dominant plant species to N input is a prerequisite for accurate prediction of future changes and interactions within plant communities. We evaluated the response of seven dominant plant species on the Tibetan Plateau to N input at two levels: individual species and plant functional group. This was achieved by assessing leaf N : P stoichiometry, leaf d 15 N and biomass production for the plant functional groups. Seven dominant plant species-three legumes, two forbs, one grass, one sedge-were analyzed for N, P, and d 15 N 2 years after fertilization with one of the three N forms: NO À 3 , NH 4 , or NH 4 NO 3 at four application rates (0, 7.5, 30, and 150 kg N ha -1 y -1 ). On the basis of biomass production and leaf N : P ratios, we concluded that grasses were limited by available N or co-limited by available P. Unlike for grasses, leaf N : P and biomass production were not suitable indicators of N limitation for legumes and forbs in alpine meadows. The poor performance of legumes under high N fertilization was mainly due to strong competition with grasses. The total above-ground biomass was not increased by N fertilization. However, species composition shifted to more productive grasses. A significant negative correlation between leaf N : P and leaf d 15 N indicated that the two forbs Gentiana straminea and Saussurea superba switched from N deficiency to P limitation (e.g., N excess) due to N fertilization. These findings imply that alpine meadows will be more dominated by grasses under increased atmospheric N deposition.

Leaf N and P stoichiometry in relation to leaf shape and plant size for Quercus acutissima provenances across China

“…These relationships suggest that leaf N and P stoichiometry, as the endogenous nutrition, has shaped the morphological performances of leaves and stem, supporting the previous report that N and P frequently limit plant growth39. However, we also found that these associations among indices showed huge differences.…”

The forb, Ajania tenuifolia, uses soil nitrogen efficiently, allowing it to be dominant over sedges and Graminae in extremely degraded grasslands: Implications for grassland restoration and development on the Tibetan Plateau

“…It has been reported that plant species differ in N acquisition strategies in alpine meadows (Xu et al, ), which suggests that N input may have the potential to affect species composition and abundance in alpine meadows (Xu et al, ). Plant species composition has altered substantially in recent decades due to the intensive degradation of alpine grasslands and differences among species in the efficiency of N uptake in N‐limited ecosystems (Schleuss et al, ).…”

Leaf Nitrogen and Phosphorus Stoichiometry of Chinese fir Plantations across China: A Meta-Analysis

“…Leaf N and P stoichiometry have certain indicative effects on the growth rate, adaptation strategy, nutrient limitation, and community function of plants [1][2][3][4]. Leaf stoichiometry is likely affected by changes in the environment, including biotic and abiotic factors [5,6].…”