摘要：Low temperature is considered the main limiting factor for plant growth and nutrient supply at high elevations. It has been repeatedly reported that an increase in foliar nutrient contents occurs with elevation which is interpreted as the plants’ inability to use the absorbed resources for growth. However, although large data sets from various mountainous regions are available, data from elevations exceeding 5000 m elevation are rare, leaving uncertainties on the relevance of these patterns under extreme alpine conditions. To fill this gap, we examined foliar macronutrients (N, P, K, Ca, Mg) content in Poa attenuata and Waldheimia tridactylites along an elevation gradient of 1600 m in Ladakh, northwestern Himalaya. Species showed rather similar response: N, Ca, and Mg concentration decreased with elevation. However, P concentration decreased with elevation in Poa but slightly increased in Waldheimia ; K concentration was related to elevation in Poa only (positively). The surprising decreases of N, and/or N/P and N/K ratios towards higher elevation suggest that nitrogen uptake decreased with elevation and it may limit plant growth. Our results suggest that plants growing at very high elevations tend to be limited by a combination of lower nutrient uptake, possibly because of poorly developed soils, and scarcity of water.
