关键词: meta分析, 土壤总氮, 施氮量, 生物量分配, 氮利用效率, 生态系统类型

Abstract: Aims Studies on the adaptation of biomass and nitrogen use efficiency (NUE) of whole plant and aboveground and belowground parts to atmospheric nitrogen (N) deposition were helpful to understand the changes of carbon (C) and N cycling in terrestrial ecosystems of China under the background of global N deposition. However, the effects of N addition on plant biomass and NUE and the main factors affecting these responses remained unclear. Our objective was to explore the effects of biomass and NUE to N addition in the whole and different components of plants. Methods We collected the results of artificial N addition in China from 95 publications. Meta-analysis was used to quantitatively assess the effects of N addition on biomass allocation and NUE of plants, their main influencing factors were also evaluated using this database. Important findings The results indicated that: (1) N addition significantly increased plant total, aboveground and belowground biomass while significantly decreased the NUE of different components(p < 0.01). Plant aboveground biomass (34%) increased more than that of belowground biomass (5.3%), and the decreased plant belowground NUE (29.9%) was higher than that of aboveground NUE (15.4%). (2) The effects of plant biomass and NUE to N addition were significantly different according to ecosystem types, N forms, N addition levels, duration and water conditions(p < 0.01), the responses of plant in grassland and desert ecosystems to N addition were significantly higher than that in other ecosystems. (3) Soil total N content was the most important factor affecting the responses of plant total, aboveground and belowground biomass. Meanwhile, the responses of plant and aboveground NUE were mainly modulated by N addition rate, and the form of N fertilizer mainly influenced the effects of belowground NUE. In conclusion, the effects of N addition on plant biomass and NUE were opposite, and they were mainly affected by soil total N content and N addition rate, respectively. These findings may provide a reference for further research and practice on the distribution and utilization of C and N in plants under the background of N deposition.

Key words: meta-analysis, soil total nitrogen, nitrogen addition rate, biomass allocation, nitrogen use efficiency, ecosystem type