The natural abundance of stable nitrogen (N) isotope (δ¹⁵N) in plants and soils can reflect N cycling processes in ecosystems. However, we still do not fully understand patterns of plant and soil δ¹⁵N at alpine treelines and shrublines in different climate zones. We measured δ¹⁵N and N concentration in leaves of trees and shrubs and also in soils along elevational gradients from lower altitudes to the upper limits of treelines and shrublines in subtropical, dry- and wet-temperate regions in China. The patterns of leaf δ¹⁵N in trees and shrubs in response to altitude changes were consistent, with lower values occurring at higher altitude in all three climate zones, but such patterns did not exist for leaf Δδ¹⁵N and soil δ¹⁵N. Average δ¹⁵N values of leaves (−1.2‰) and soils (5.6‰) in the subtropical region were significantly higher than those in the two temperate regions (−3.4‰ and 3.2‰, respectively). Significant higher δ¹⁵N values in subtro4pical forest compared with temperate forests prove that N cycles are more open in warm regions. The different responses of leaf and soil δ¹⁵N to altitude indicate complex mechanisms of soil biogeochemical process and N sources uptake with environmental variations.