Nitrogen Enrichment Accelerates Mangrove Range Expansion in the Temperate-Tropical Ecotone
Nitrogen Enrichment Accelerates Mangrove Range Expansion in the Temperate-Tropical Ecotone
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DOI：
10.1007/s10021-019-00441-2
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发表时间：
2020-06-01
期刊：
影响因子：
3.7
通讯作者：
Feller, Ilka C.
中科院分区：
文献类型：
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作者：
Dangremond, Emily M.;Simpson, Lorae T.;Feller, Ilka C.
气候变化和养分富集化是影响沿海生态系统的两种现象。在沿海湿地，温带-热带交错带的红树林正在侵蚀邻近的盐沼，这种模式主要归因于冬季气温变暖。气候变化预计还会增加沿海湿地易受富营养化影响的程度，而养分供应的增加可能会进一步影响红树林的扩张速度。在佛罗里达州东北海岸红树林分布的温带边缘附近的红树林-盐沼交错带，我们研究了营养丰富对沿海湿地的影响。我们测试了一种假设，即营养丰富通过增加红树林的生长和覆盖率，使它们能够超越并过度生长邻近的盐沼植物，从而加强了红树林正在进行的、气候驱动的扩张，进入了历史上以盐沼为主的地区。我们对氮磷有效性进行了调控，并测定了氮磷有效性对白骨壤生长、盖度、多样性、叶片性状和营养动态的影响。我们发现，生长在佛罗里达州北部盐沼-红树林交错带的生殖草灌木与对照植物和富磷植物相比，生长在盐沼-红树林交错带的灌木长得更高，冠层更大，繁殖产量更高。营养元素的增加不会改变花生委陵菜的生长和增加树高，但不会改变密度或生物量。氮素的添加增加了海藻盖度，降低了海藻盖度和Simpson多样性指数，说明氮素的富集会通过促进红树林的生长和繁殖而加速入侵盐沼，而不会显著促进盐沼植物的生长。
Climate change and nutrient enrichment are two phenomena impacting coastal ecosystems. In coastal wetlands, mangroves in temperate-tropical ecotones are encroaching on adjacent saltmarshes, a pattern that is primarily attributed to warmer winter temperatures. Climate change is also expected to increase the vulnerability of coastal wetlands to eutrophication, and increases in nutrient availability may further mediate the rate of mangrove expansion. We investigated the consequences of nutrient enrichment on coastal wetlands in the mangrove-saltmarsh ecotone near the temperate edge of mangrove distribution along the northeast coast of Florida. We tested the hypothesis that nutrient enrichment enhances the ongoing, climate-driven expansion of mangroves into areas historically dominated by saltmarshes by increasing mangrove growth and cover, allowing them to outcompete and overgrow adjacent saltmarsh plants. We manipulated nitrogen (N) and phosphorus (P) availability and measured the effects on growth, cover, diversity, leaf traits, and nutrient dynamics of Avicennia germinans. We found that A. germinans shrubs growing in the saltmarsh-mangrove ecotone in northern Florida grew taller, increased their canopies, and had higher reproductive output when enriched with N compared to control plants and P-enriched plants. Nutrient enrichment did not alter Sarcocornia perennis growth and increased Batis maritima height but did not alter density or biomass. Nitrogen addition caused an increase in A. germinans cover and decrease in B. maritima cover and Simpson's index of diversity, suggesting that N enrichment, an ongoing phenomenon, can hasten the invasion of mangroves into saltmarshes by favoring mangrove growth and reproduction without significantly enhancing saltmarsh plant growth.