The influence of a five-year nitrogen fertilization treatment on hydraulic architecture of Pinus sylvestris var. mongolica in a water-limited plantation of NE China
The influence of a five-year nitrogen fertilization treatment on hydraulic architecture of Pinus sylvestris var. mongolica in a water-limited plantation of NE China
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五年施氮肥处理对樟子松水力结构的影响
DOI：
10.1016/j.foreco.2017.11.059
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发表时间：
2018-06-01
影响因子：
3.7
通讯作者：
Hao, Guang-You
中科院分区：
文献类型：
--
作者：
Fang, Li-Dong;Zhao, Qiong;Hao, Guang-You
预计氮沉降的增加将通过其对树木性能的直接和间接影响对森林生态系统产生强烈影响。氮沉降可以极大地影响树木的性能的一种方式是通过改变植物的水力结构和水的关系，特别是在水有限的栖息地，然而，响应的幅度和方向被证明是物种和栖息地的具体和潜在的机制需要进一步的调查。在本研究中，我们着眼于潜在的影响，氮沉降对茎木质部水力学和叶水平水分的樟子松的变化。蒙古松（Mongolica）在东北典型人工林中进行了5年的氮肥试验。我们的研究结果表明，氮添加显着促进树木生长和改变树的水力结构在上层冠层。水力结构的反应，氮除了主要是由于叶和茎之间的异速生长关系的变化，而不是通过其对木质部的传导效率的影响，在茎导水率和减少叶面积边材面积比在N-施肥树的非显着差异。施N肥的蒙古松树表现出的特征模拟植物从更多的水分有限的栖息地，如较低的叶渗透势在充分膨压和膨压损失，这表明一个不太有利的水分状况有关的高氮可用性在水有限的栖息地。此外，减少叶片寿命的趋势可能使施氮树木更容易受到碳失衡的影响。我们的研究结果表明，尽管树木的生长在本实验中得到加强，氮沉降可能会产生负面影响樟子松人工林通过其对植物水分关系的负面影响，这可能会恶化在更多的水限制条件。在北方大面积的水分有限的人工林中，采取疏伐等减少水分利用的管理措施，可以减轻氮沉降对樟子松存活的负面影响。
The increase in nitrogen (N) deposition is expected to have strong influences on forest ecosystems through its direct and indirect effects on tree performance. One way that N deposition can greatly affect tree performance is by altering plant hydraulic architecture and water relations especially in water-limited habitats; however, the magnitude and direction of response are shown to be species and habitat specific and the underlying mechanism requires further investigations. In the present study, we looked at the potential impact of N deposition on stem xylem hydraulics and leaf level water relations of Pinus sylvestris var. mongolica (Mongolian pine), using a five-year N fertilization experiment at a typical plantation site in NE China. Our results showed that N addition significantly enhanced tree growth and altered tree hydraulic architecture in the upper canopy. Hydraulic architecture responses to N addition were mainly attributable to changes in allometric relationship between leaf and stem rather than through its impact on xylem conductive efficiency as indicated by the non-significant differences in stem hydraulic conductivity and decreased leaf area to sapwood area ratio in N-fertilized trees. The N-fertilized Mongolian pine trees exhibited characteristics simulating plants from more water-limited habitats, such as lower leaf osmotic potentials at full turgor and turgor loss, which indicates a less favorable water status related to higher nitrogen availability in a water limited habitat. Moreover, a tendency of reduced leaf lifespan may make the N-fertilized trees more susceptible to carbon imbalance. Our results suggest that, despite tree growth was enhanced in the present experiment, N deposition may negatively affect Mongolian pine plantations through its negative impacts on plant water relations, which may likely deteriorate in more water-limited conditions. Management measures aimed at reducing water use, such as tree thinning, may mitigate the negative influence of N deposition on survival of Mongolian pine trees in water-limited plantations of the vast areas of Northern China.