Nitrogen Deposition and Deyeuxia angustifolia Encroachment in Alpine Tundra

Abstract

Vegetation in the alpine tundra area of the Changbai Mountain has undergone great changes in recent decades. The aggressive herb species Deyeuxia angustifolia (Komarov) Y. L. Chang is currently encroaching upon the alpine landscape and threatening tundra biota. The alpine tundra of the Changbai Mountain has been experiencing a warmer climate and receiving a high load of atmospheric nitrogen deposition. To assess the respective roles of climate warming and atmospheric nitrogen deposition in promoting the upward encroachment of D. angustifolia, a multi-factorial experiment was conducted for 3 years to examine the response of D. angustifolia and a native alpine shrub, Rhododendron chrysanthum, to the conditions in which temperature and nitrogen were increased. Results showed that D. angustifolia grew in response to added nutrients but did not grow well when temperature increased. R. chrysanthum showed negligible responses to the simulated environmental changes. The difference in nitrogen uptake abilities between the two species contributed to expansion of D. angustifolia. Our research indicated that nutrient perturbation may be more influential than temperature perturbation in promoting D. angustifolia encroachment upon the nutrient- and species-poor alpine tundra ecosystem in the Changbai Mountain.