Bragazza Luca, Tahvanainen Teemu, Kutnar Lado, Rydin Håkan, Limpens Juul, Hájek Michal, Grosvernier Philippe, Hájek Tomáš, Hajkova Petra, Hansen Ina, Iacumin Paola, Gerdol Renato
Department of Natural and Cultural Resources, University of Ferrara, Corso Porta Mare 2, I-44100 Ferrara, Italy.
Department of Biology, University of Joensuu, PO Box 111, FIN-80101 Joensuu, Finland.
New Phytol. 2004 Sep;163(3):609-616. doi: 10.1111/j.1469-8137.2004.01154.x.
• We studied the effects of increasing levels of atmospheric nitrogen (N) deposition on nutrient limitation of ombrotrophic Sphagnum plants. • Fifteen mires in 11 European countries were selected across a natural gradient of bulk atmospheric N deposition from 0.1 to 2 g/m year . Nutritional constraints were assessed based on nutrient ratios of N, phosphorus (P), and potassium (K) in Sphagnum plants collected in hummocks (i.e. relatively drier microhabitats) and in lawns (i.e. relatively wetter microhabitats). • Nutrient ratios in Sphagnum plants increased steeply at low atmospheric N input, but above a threshold of N deposition of c. 1 g/m year the N : P and N : K ratios tended to saturation. Increasing atmospheric N deposition was also accompanied by a reduced retention of Ca and Mg in Sphagnum plants and a decreased stem volumetric density in hummock Sphagnum plants. • We suggest a critical load of N deposition in Europe of 1 g/m year above which Sphagnum plants change from being N-limited to be K + P colimited, at N : P > 30 and N : K > 3.
• 我们研究了大气氮（N）沉降水平增加对雨养泥炭藓植物养分限制的影响。
• 在11个欧洲国家选取了15个泥炭地，这些泥炭地跨越了从0.1至2克/平方米·年的大气总氮沉降自然梯度。根据在丘状高地（即相对干燥的微生境）和草甸（即相对湿润的微生境）采集的泥炭藓植物中氮、磷（P）和钾（K）的养分比例来评估营养限制。
• 在低大气氮输入时，泥炭藓植物中的养分比例急剧增加，但在约1克/平方米·年的氮沉降阈值以上，氮：磷和氮：钾比例趋于饱和。大气氮沉降增加还伴随着泥炭藓植物中钙和镁的保留减少以及丘状高地泥炭藓植物茎体积密度降低。
• 我们提出欧洲氮沉降的临界负荷为1克/平方米·年，高于此值，泥炭藓植物从受氮限制转变为受钾+磷共同限制，此时氮：磷>30且氮：钾>3。
