School of Ocean Sciences, Bangor University, Anglesey LL59 5AB, UK; Centre for Ecology and Hydrology, Environment Centre Wales, Bangor LL57 2UW, UK.
Centre for Ecology and Hydrology, Environment Centre Wales, Bangor LL57 2UW, UK.
Sci Total Environ. 2016 Jan 15;542(Pt A):203-9. doi: 10.1016/j.scitotenv.2015.10.089. Epub 2015 Oct 28.
Atmospheric nitrogen (N) deposition alters plant biodiversity and ecosystem function in grasslands worldwide. This study examines the impact of 6 years of nutrient addition and grazing management on a sand dune grassland. Results indicate that co-limitation of N and phosphorus (P) moderates the impact of realistic rates of N addition (7.5, 15 kg N ha(1) year(-1)). Combined NP addition (15 kg N + 10 kg P ha(-1) year(-1)) was the only nutrient treatment to differ significantly from the control, with greater above-ground biomass (mainly moss), and enhanced N and P mineralisation rates. Grazing management altered plant functional group composition, reduced above-ground biomass and meso-faunal feeding rates, and decoupled N and P mineralisation. There were no synergistic effects of grazing and N treatment. Although NP co-limitation apparently prevents adverse impacts of N deposition above the critical load, excess N is likely to be stored in moss biomass and soil, with unknown future consequences.
This study shows that at realistic levels of N addition, NP co-limitation in a dune grassland appears to prevent adverse impacts of N on plant growth and nutrient cycling.
大气氮（N）沉积改变了世界各地草原的植物生物多样性和生态系统功能。本研究考察了 6 年的养分添加和放牧管理对沙丘草原的影响。结果表明，N 和磷（P）的共同限制缓和了实际 N 添加率（7.5、15 kg N ha（1）年（-1））的影响。只有 NP 联合添加（15 kg N + 10 kg P ha（-1）年（-1））与对照相比有显著差异，地上生物量（主要为苔藓）增加，氮和磷矿化速率增强。放牧管理改变了植物功能群组成，降低了地上生物量和中型土壤动物的摄食率，并使氮和磷矿化解耦。放牧和 N 处理之间没有协同作用。尽管 NP 共同限制显然可以防止临界负荷以上 N 沉积的不利影响，但过量的 N 可能会储存在苔藓生物量和土壤中，其未来的后果尚不清楚。
本研究表明，在实际 N 添加水平下，沙丘草原中的 NP 共同限制似乎可以防止 N 对植物生长和养分循环的不利影响。
