Effects of simulated nitrogen deposition on the ecophysiological responses of Populus beijingensis and P. cathayana under intra- and interspecific competition

High N deposition has been recognized as a major factor influencing plant-plant interactions. We aim to discover whether could affect competitive relationships between poplars predict threats posed by the introduction of exotic hybrids native relative species. Intra- and interspecific competition was investigated for an introduced hybrid poplar (Populus beijingensis) paternal species P. cathayana under two regimes. Under control conditions, grown either intra- or showed consistently greater above-ground biomass, root-to-shoot ratio (R/S), photosynthetic capacity, higher activities N-assimilation enzymes in leaves, preference N-NO3? than corresponding beijingensis. Interspecific increased leaf area, specific area (SLA), R/S, nitrogen use efficiency (PNUE) cathayana, but decreased PNUE beijingensis compared values monoculture. Thus, can gain advantage over at low availability. In contrast, deposition, mixture more positive responses growth, plasticity biomass allocation root architecture, shift when with which resulted relatively SLA, accumulation Nitrogen intrinsic water-use conspecific heterospecific cahtayana. Our results suggest that reverse poplars, potential outcompete growing deposition.