Nitrogen deposition and multi-dimensional plant diversity at the landscape scale

Estimating effects of nitrogen (N) deposition is essential for understanding human impacts on biodiversity. However, studies relating atmospheric N deposition to plant diversity are usually restricted to small plots of high conservation value. Here, we used data on 381 randomly selected 1 km2 plots covering most habitat types of Central Europe and an elevational range of 2900 m. We found that high atmospheric N deposition was associated with low values of six measures of plant diversity. The weakest negative relation to N deposition was found in the traditionally measured total species richness. The strongest relation to N deposition was in phylogenetic diversity, with an estimated loss of 19% due to atmospheric N deposition as compared with a homogeneously distributed historic N deposition without human influence, or of 11% as compared with a spatially varying N deposition for the year 1880, during industrialization in Europe. Because phylogenetic plant diversity is often related to ecosystem functioning, we suggest that atmospheric N deposition threatens functioning of ecosystems at the landscape scale.

估算氮沉降（nitrogen deposition）的影响，对于阐明人类活动对生物多样性的影响至关重要。然而，当前将大气氮沉降与植物多样性相关联的研究，通常仅局限于具有较高保护价值的小型样地。本研究采用381个随机选取的1平方千米样地的调查数据，这些样地覆盖了中欧绝大多数生境类型，且海拔跨度达2900米。研究结果显示，高大气氮沉降与植物多样性六项评估指标的较低水平显著相关。其中，传统方法测得的总物种丰富度与氮沉降的负相关关系最弱，而相关性最强的指标为系统发育多样性（phylogenetic diversity）：与无人类影响的均匀分布历史氮沉降情景相比，大气氮沉降导致系统发育多样性预计损失19%；而与1880年欧洲工业化时期的空间异质性氮沉降情景相比，该损失则为11%。鉴于植物系统发育多样性通常与生态系统功能密切相关，本研究认为大气氮沉降会威胁景观尺度下的生态系统功能。