Nitrogen Addition Increases Freeze Resistance in Black Mangrove (Avicennia germinans) Shrubs in a Temperate-Tropical Ecotone
Nitrogen Addition Increases Freeze Resistance in Black Mangrove (Avicennia germinans) Shrubs in a Temperate-Tropical Ecotone
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DOI：
10.1007/s10021-022-00796-z
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发表时间：
2022-12
期刊：
影响因子：
3.7
通讯作者：
I. Feller;Uta Berger;S. Chapman;E. M. Dangremond;N. Dix;J. Langley;C. Lovelock;T. Osborne;Audrey C Shor;L. Simpson
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文献类型：
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作者：
I. Feller;Uta Berger;S. Chapman;E. M. Dangremond;N. Dix;J. Langley;C. Lovelock;T. Osborne;Audrey C Shor;L. Simpson
低温胁迫是决定热带植物纬向极限的主要因素。随着气候变暖，热带物种向极地迁移，取代了本地物种，改变了生态系统的结构和功能。沿纬度梯度变化特别明显，湿地变化速度最快。在沿海湿地，盐沼在纬度高于30°的地区占主导地位，而红树林主要出现在热带地区，因为大多数物种不耐冰冻温度，但其他物种，如avicennia germinans（黑红树林），确实耐受冰冻温度。为了应对气候变暖和结冰减少，红树林目前正在向盐沼扩张。然而，从盐沼到红树林的转变速度也可以被极端事件和营养补贴所改变。在北美大西洋沿岸的施肥实验中，我们发现添加氮改变了植物的性状，增加了它们对冰冻温度的抵抗力。与未受精的植物相比，这种性状变化在2018年1月的极端冰冻事件中导致的冻结效应可以忽略不计，未受精的植物损失了80%以上的叶子和40%以上的树冠木材。冰冻后未受精植物的凋落物提供了一种营养脉冲，影响了冻结后三年的恢复、生长和红树林覆盖。冻结效应对营养物质的富集和恢复导致红树林林冠的生长和结构复杂性增加，从而进一步增强了温带-热带过渡带红树林的抗冻性、灌木生长形式和红树林取代盐沼的能力。
Low temperature stress is the primary factor determining the latitudinal limits of tropical plants. As the climate warms, tropical species are migrating poleward, displacing native species and modifying ecosystem structure and function. Changes are particularly evident along latitudinal gradients with the highest velocity of change occurring in wetlands. In coastal wetlands, saltmarshes dominate at latitudes above 30°, whereas mangroves occur mostly in the tropics because most species are intolerant of freezing temperatures, but others, likeAvicennia germinans(black mangrove), do tolerate freezing temperatures. In response to a warmer climate and fewer killing freezes, mangroves are currently expanding into saltmarshes. However, the speed of the transition from saltmarsh to mangrove can also be modified by extreme events and nutrient subsidies. In a fertilization experiment along the Atlantic coast of North America, we found that nitrogen addition altered plant traits inAvicennia, which increased their resistance to freezing temperatures. This trait shift resulted in negligible freeze effects during a January 2018 extreme freeze event compared to unfertilized plants, which lost more than 80% of the leaves and more than 40% of the wood in their canopies. The freeze-killed litter from unfertilized plants provided a nutrient pulse that influenced recovery, growth and mangrove cover for three years following the freeze. Nutrient enrichment and recovery from the freeze effects led to increased growth and structural complexity of the mangrove canopy, which further enhanced freeze tolerance, shrub growth form and the ability ofAvicenniato displace the saltmarsh in the temperate–tropical ecotone.