Effects of N deposition on plant species richness and community structure in a temperate grassland

摘要

Humans are adding nitrogen (N) worldwide.It remains unclear, however, whether plant diversity and community structure will be equally impacted by inputs of reactive N coming from either small and frequent N deposition events or large and infrequent N fertilization events.By independently manipulating the rate and frequency of N(NH4NO3) input, with nine-rate (from 0 to 50 g N m-2 yr-1) crossed with two frequencies (twice or monthly yr-1) in a temperate steppe of northern China across 2008-2013, this study tried to tease apart these potentially contrasting effects.Our results showed that, 1), plant species richness decreased more quickly at high rates and at low frequency of N addition.2), community structure also changed more quickly at low frequency of N addition.Our results suggest that previous fertilization studies have likely over-estimated the effects of N deposition on plant species loss and community structure change.