Nutrient limitation of alpine plants: Implications from leaf N : P stoichiometry and leaf delta N-15
Nutrient limitation of alpine plants: Implications from leaf N : P stoichiometry and leaf delta N-15
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DOI：
10.1002/jpln.201200061
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发表时间：
2014-06
影响因子：
2.5
通讯作者：
Xingliang Xu;W. Wanek;Cai-ping Zhou;Andreas Richter;Minghua Song;G. Cao;H. Ouyang;Y. Kuzyakov
中科院分区：
文献类型：
--
作者：
Xingliang Xu;W. Wanek;Cai-ping Zhou;Andreas Richter;Minghua Song;G. Cao;H. Ouyang;Y. Kuzyakov
氮沉降可以通过改变草地生物量、植物种类组成和丰富度来影响草地生态系统。因此，更好地了解优势植物物种对氮输入的反应是准确预测未来变化和植物群落内相互作用的先决条件。从物种个体和植物功能群两个层次上评价了青藏高原7种优势植物对氮素输入的响应。这是通过评估叶N：P化学计量，叶Δ N-15和植物功能组的生物量生产来实现的。7种优势植物--3种豆科植物、2种杂类植物、1种禾本科植物和1种莎草--在施用3种形态的氮（NO3-、NH 4+或NH 4 NO3）后2年，在4种施用量（0、7.5、30和150 kg N ha（-1）y（-1））下分析了N、P和Δ N-15。生物量生产和叶N：P比的基础上，我们得出的结论是，草的限制由有效N或共同限制由有效P.不像草，叶N：P和生物量生产是不合适的指标，氮限制的豆科植物和杂类草在高寒草甸。高氮条件下豆科植物的不良表现主要是由于与禾本科植物的强烈竞争。施氮不增加地上生物量。然而，物种组成转移到更高产的草。叶片N：P与叶片δ N-15呈显著负相关，表明麻花秦艽和雪莲两种杂类植物从缺N向缺P转变。例如，在一个实施例中，N过量）由于N施肥。这些结果意味着，高山草甸将更多的主导下，增加大气氮沉降的草。
Nitrogen (N) deposition can affect grassland ecosystems by altering biomass production, plant species composition and abundance. Therefore, a better understanding of the response of dominant plant species to N input is a prerequisite for accurate prediction of future changes and interactions within plant communities. We evaluated the response of seven dominant plant species on the Tibetan Plateau to N input at two levels: individual species and plant functional group. This was achieved by assessing leaf N : P stoichiometry, leaf delta N-15 and biomass production for the plant functional groups. Seven dominant plant species-three legumes, two forbs, one grass, one sedge-were analyzed for N, P, and delta N-15 2 years after fertilization with one of the three N forms: NO3-, NH4+, or NH4NO3 at four application rates (0, 7.5, 30, and 150 kg N ha(-1) y(-1)). On the basis of biomass production and leaf N : P ratios, we concluded that grasses were limited by available N or co-limited by available P. Unlike for grasses, leaf N : P and biomass production were not suitable indicators of N limitation for legumes and forbs in alpine meadows. The poor performance of legumes under high N fertilization was mainly due to strong competition with grasses. The total above-ground biomass was not increased by N fertilization. However, species composition shifted to more productive grasses. A significant negative correlation between leaf N : P and leaf delta N-15 indicated that the two forbs Gentiana straminea and Saussurea superba switched from N deficiency to P limitation (e. g., N excess) due to N fertilization. These findings imply that alpine meadows will be more dominated by grasses under increased atmospheric N deposition.