Coupling N Cycling and N Productivity in Relation to Seasonal Stress in Quercus Pyrenaica Willd. Saplings
Coupling N Cycling and N Productivity in Relation to Seasonal Stress in Quercus Pyrenaica Willd. Saplings
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DOI：
10.1007/s11104-006-6249-1
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发表时间：
2006-04
期刊：
影响因子：
4.9
通讯作者：
Fernando Silla;A. Escudero
中科院分区：
文献类型：
--
作者：
Fernando Silla;A. Escudero
地中海栎幼树的氮经济在全植物水平上分析了物种。氮循环的数量和时间是由强烈的季节性在氮生产力，在晚春达到高峰。大部分叶片氮分配到一个主要的第一次冲洗的叶片在早春，和一个较小的第二次冲洗在初夏或秋季。在氮素生产高峰期后，生物量生产和氮素资源的分配主要转向木质部和粗根。与其他共生栎属物种相比，Pyrenaica表现出非保守的N利用模式。潜在的叶片N-再吸收效率是中等的，但N的熟练程度低，这有助于整个凋落叶N的高损失和短的平均停留时间的N（MRTN）。此外，夏季水分胁迫减少叶面积，产生的凋落叶氮浓度高，由于几乎可以忽略不计的再吸收效率，在某些情况下，整个地上部分的损失。植物资源对根系的大量投入是影响矮牵牛氮经济性和植株适合度的关键性状。pyrenaicasapplings，允许他们：（1）抵消氮素损失并保持正氮平衡;（2）获取深层土壤资源（水和养分）;（3）“安全”储存氮素，以耦合春季生长或夏季干旱后发芽期间的供需过程。
The N economy of saplings of the MediterraneanQuercus pyrenaicaWilld. species was analysed at whole-plant level. The amount and timing of N cycling were determined by strong seasonality in N productivity, which peaked in late spring. Most leaf N was allocated to a main first flush of leaves in early spring, and a minor second flush during early summer or autumn. After peak of N productivity, the allocation of biomass production and N resources was mainly switched to lignotuber and coarse roots.Q. pyrenaicadisplayed a non-conservative pattern of N use as compared with other co-occurringQuercusspecies. Potential leaf N-resorption efficiency was moderate, but N proficiency was low, which contributed to high losses of N throughout leaf litter and to short mean residence times of N (MRTN). Additionally, summer water stress reduced foliar area, producing leaf litter with a high N concentration due to almost negligible resorption efficiency, and in some cases, the loss of the whole above-ground fraction. A large investment of plant resources to the root system appeared as a key trait in the N economy and plant fitness of youngQ. pyrenaicasaplings, allowing them: (1) to counteract N losses and to maintain a positive N balance, (2) to access deep soil resources (water and nutrients), and (3) to ‘safe’-store N for coupling supply and demand processes during spring growth or sprouting after a strong summer drought.